1998 Ford Expedition Overheating, Intake Manifold Leak

Car: 1998 Ford Expedition 5.4L V-8   193,000 miles

Problem: Overheating due to coolant consumption, coolant loss.
Previous owner stated this problem existed for a long time (2 years). He had it worked on by a local work from home mechanic. The mechanic report indicated P304 and P305 codes, misfire for cylinders 4 and 5. Mechanic replaced intake manifold gaskets, and then the car started to leak coolant out the exhaust pipe. Problem became worse. The mechanic report indicates blown head gasket or cracked head. Also indicated were compression results for cylinder 4 and 5, 152psi and 122psi  respectively. Why other cylinder compression results were not posted on the report is beyond me. Maybe he was lazy and didn't actually complete the other cylinder compression tests. His report indicated new coolant was added to the system.

Test Drive: Engine startup revealed a definite misfire condition on multiple cylinders. On the test drive, the engine made a very severe whining noise at the front near the timing chains. Other noises made it sound as if a cylinder main bearing had given out. Steam exiting from the tailpipe, and a quick squeeze to the upper radiator hose indicated lots of air in the system.

Diagnosis: Blown intake manifold gasket, right bank. Upon removal of the intake manifold, I noticed that the intake manifold was tightened down way beyond the 22 ft. lb spec, like monster tightened. With the intake manifold removed, I inspected the mating surfaces of the lower intake manifold, and the head. Nothing unusual found. Inspected the gaskets for damage. Located torn rubber seal at the intake port of cylinder 4. This is right next to the water cooling passage. A chunk of the seal is missing. This appears to be a fel-pro gasket with the blue seal around the ports.

Compression tests yielded:

1. 120 psi
2. 110 psi
3. 120 psi
4. 115 psi
5. 100 psi
6. 90 psi
7. 30 psi Oil test brought pressure up to 110 psi. Leak down test indicates leak at intake valve. hmmm. Scratching my head on this one. 
8. 90 psi

• My compression tester kit comes with a 14mm connector, but it's too shallow to grab any threads down in the cylinder head of this Ford 5.4L engine
• To remedy this I bought 14mm spark plug non-foulers ($5.00), and cut off the head down to the threaded inserts at the top of the spark plug fouler with a hack saw (any special Ford adaptor will run upwards of $13)
• I also placed an o-ring at the bottom of the spark plug fouler to get a good seal during testing

With lower pressure at cylinder 7 and shared low pressure at cylinders 6 and 8, I suspect the head gasket is blown at cylinder 7. While I did this compression test with the intake manifold off of the vehicle, I was not looking or expecting spec numbers for the compression test. My main goal was to see if there were any significant drops in compression between cylinders. I'm not too concerned with compression being at spec by the book right now. The main point is to look for low compression at any given cylinder, which I found at cylinder #7. A few drops of oil added to cyl 7 and compression rose to 110 psi. A leak down test found air leaking at the intake valve.

Fix: 
I decided to remove the engine, which required removing the heads first, and then the block due to clearance issues. I left the radiator in place, but had to remove the front bumper to gain enough clearance for my hoist. What a pain!

The LH head where cylinder 7 resides, had leaks in the intake valve due to deposits on the valve seating area. In fact, all the valves had carbon buildup enough to cause a small amount of leakage. With both heads off  the vehicle, I removed all the valves and cleaned them. I scrapped off carbon buildup,and then lapped the intake valved. The exhaust valves didn't require lapping.

With the block on the engine stand I removed piston #7 to inspect for bad rings due to the compression test results rising when I added oil for the wet test. All 3 rings appeared normal, no significant wear.

Both head surfaces were cleaned, and scraped free of old gasket materials. I have to say, that after working on Hondas, these Ford heads are cast dirty when compared to the Japanese counterparts. The coolant and oil passages on the head still have sharp edges from aluminum slag buildup during the manufacturing process, which poke out above the flat surface. While the excessive slag around the ports are inconvenient for quick and easy cleaning of old gasket material, this is sloppy quality control on Ford's part.

With new head gaskets in place, I installed new head TTY bolts and torqued to spec. Installed head

bolts snug.
1. 30 ft/lbs Tightened to 30ft/lbs, and then painted each bolt with a vertical line, and a cross bar at the bottom of the bolt, so it looks like an upside down T. (Once it is torqued to yield, it will be an upright T.)
2. Turn 90 deg.
3. Turn 90 deg.
Let me scream about something here. After that second 90 degree turn, several of the bolts went limp, feeling like it stripped inside the block. If you've tightened down a bolt into any aluminum part of an engine, and tightened it too much, you know the feeling of dread of a stripped bolt. It kind of slips past that point of "it can't turn any more." Well, at least 4 or 5 of the bolts did this, and let me tell you how I almost lost sleep over it after cussing under my breath for about an hour.

I Googled this, to see if I had indeed messed up big time. I Youtubed it, watching many videos. And then I found this fel-pro information page, so I didn't have to worry any longer.
http://www.felpro-only.com/blog/proper-installation-use-t-t-y-bolts/
Felpro does a decent job explaining TTY bolts and includes this nifty pic:

What a life saver! I read all of the forum questions until I got to one that sounded like my problem. 

I’m torqueing the TTY bolts per the manufacturer. Bolts 1-8 in sequence to 33 ft/lbs then 90 degrees then 90 degrees again. During the last 90 degree turn a couple of bolts felt like they yielded and turned a little easier than the previous 90 degree turn. I’m concerned that they are not clamping properly and may have over-stretched to the point of breaking. My gut feeling is to remove them in reverse sequence, remove the head, inspect and clean if necessary, install a new head gasket and install new bolts. I’m using Fel-Pro TTY bolts. I’m wondering if I torqued them a little beyond 33 ft/lbs. I used my beam initially on all the bolts but switched to a clicker type set at 396 in/lbs to set the 33 ft/lbs. It seemed that after using the beam and then using the clicker that the clicker turned the bolt about another 1/8 turn to reached the 396 in/lbs. Subsequent 90 degree turning seem tight and the 2nd pass at 90 degrees felt like the bolt had gotten slightly easier to turn as I had previously mentioned. Am I over-reacting? I don’t want to loosen and tighten any of the bolts again. I don’t recall exactly which one yielded under load since at the time it didn’t occur that I may have over-tightened them. I had initially torqued bolts 1-8 in several passes to the 33 ft/lb spec. I didn’t just torque them directly to 33 ft/lbs in sequence.

Felpro's reply:

No need to panic. What you felt during the last 90 degrees is normal. That is the bolt stretching. Once the bolt starts to go into the “plastic” region that means no more torque is being applied to the head gasket. You may or may not feel all the bolts get easier on that second 90 degree pass. Depends on the angle you’re standing at, how far you may have to reach, etc.
Beam type torque wrenches tend to be more accurate than clicker style ones. The gasket will settle a little bit after the initial torque up you did with the beam wrench. Going back over them with the clicker did not hurt anything, it just made sure the bolts were at 33 ft. lbs. Don’t worry if you feel you were a few pounds over the 33 ft. lb. number.
Leave it alone, the installation you did will be just fine. Continue on assembling your project, good luck, and thank you for contacting us! 

The Ford 5.4L V-8 engine. When facing the engine, the left side is considered the RIGHT bank, and the right side of the engine is considered the LEFT bank. Markings on the camshaft gears indicate LH or RH. 

This is the RIGHT bank.                                                               This is the LEFT bank.

With the crank and cams lined up properly and the chains and guides installed, I installed the timing chain tensioners. The left tensioner fit snugly. The right went into place. I manually rotated the engine a dozen times and noticed chain slap on the right side, upper chain guide at every half revolution of the engine. I wedged a metal bar between the chain tensioner and backside of the guide, and rotated the engine a few more times. No chain slap. I'm worried about the RH timing chain tensioner. A new chain set with tensioners, aftermarket, runs above $100. I've read other DIYer's who have replaced the timing chain tensioner only to have the timing chain slap return in less than 10,000 miles. As a career technician, this is unacceptable. I have to find the root cause and analyze an effective solution.

Timing Chain Slap
After some lengthy research I discovered a root cause of the timing chain slap. The common fix by many is to replace the timing chain and tensioners. Owners report having to repeat this procedure after 10 to 30 thousand miles, where the problem reoccurs. What I discovered in researching this issue, is that the timing chain tensioners have very small orifices through which oil is pumped. These orifices can get clogged with sludge, preventing the hydraulic action of the tensioner. The oil pump, pumps oil through the engine, and into these tensioners, and through hydraulic action will maintain tension on the chain. Without the oil pumping through the tensioner, it collapses back and you get chain slap. A new set of tensioners run upwards of $80. Ford revised the tensioner design year after year, and they still failed more often than they should have. My solution is to save money by tearing down the tensioners and giving them a good cleaning. I also ordered a Melling oil pump. The Ford pump is all aluminum, and eventually fails at the back plate, allowing oil to seep past the backing plate instead of going where it needs to go in the engine. Watch this video from Jasper Engines & Transmissions, and you'll understand why you should replace your oil pump with this cast iron, steel backing plate from Melling. Jasper by the way, uses Melling pumps in their engine rebuilds.

This convinced me to buy a Melling. You can locate one here:
Melling M176 Oil Pump for 4.6 L (281) V8 Engine

Once the Melling oil pump arrived it was primed by pouring oil into the oil pickup tube inlet, and the pump rotated by hand. Since this is a fuel injected engine, there is no distributor mechanism to turn to prime the oil pump. The only other option is to install a oil pressurization kit at the oil filter pressure pickup on the oil filter housing, and pressurize oil into the pump. If you don't have this fancy kit, you can pour oil into the pickup tube and rotate it by hand like I did. It works just fine.

I'm missing pictures, but I'll do my best to find some. Now some of you might be wondering, why not just buy a new set and be done with it? Well, this is a Ford after all. And during the course of rebuilding this particular vehicle, every little thing needed replacement, and every little thing costs money, and it adds up. If you want to tackle cleaning the timing chain tensioners yourself, then keep reading. For those of you who buy new parts, skip this next section.

To Clean the Timing Chain Tensioner:
Take note that the RH and LH timing chain tensioner are different from one another beneath the plunger.
1. Remove the timing chain tensioner from the engine.
2. Using a pick, push the toothed locking mechanism back and extract the holding plate. In the picture you see here, you would use a pick in the hole above where the locking pin is located. Use the pick to push aside the locking teeth.

3. Remove the plunger.
4. Remove the spring.
5. Spray out all timing chain tensioner cavity.
6. Use a pick to remove the plastic cap inside the cavity. It's in there, hard to see. Use the pick to turn it a bit, and eventually it will come out. You may have to tap the cavity.
7. Repeat the same for the plunger. Use the pick to poke down in from the top hole of the plunger if you have to.
8. The RH and LH tensioner are different in that one of them has 2 plastic caps inside the tensioner, and the other has only one.
9. Spray everything down with carb cleaner. Clean out the small oil orifices with carb cleaner. Spray until clean carb cleaner comes out of the orifices.
10. Reassemble the component caps, and then the spring. Put some oil in the plunger and cavity, and reinstall both components back together.
11. Install the locking mechanism. Use a pick to retract the toothed lock, and push the locking mechanism down. You can also put the tensioner into a clamping tool, and while retracting the locking mechanism with a pick, slowly push the tensioner plunger into the cavity body. When it's seated fully, release the locking mechanism teeth, THEN install a nail into the holding hole. This is the hole with the pull ring pictured above. I had to use a rivet to hold it in place. Small nails didn't really do the trick.  This will hold it in position for reinstallation back onto the engine.

I reassembled the engine with the exhaust manifolds and engine mounts. My plan was to use the cherry picker to hoist the engine into place. Radiator and front bumpers had to come off to gain clearance for the cherry picker. I have a 1 ton cherry picker. Was I worried when I planned on using this to lift a 500+ lb engine at full height, at max extension? Yes, yes I was worried. I do not recommend doing this by any means, with a 1 ton cherry picker. At max extension, the cherry picker is load rated to 1/4 ton. This engine with the exhaust manifold and engine mounts installed, is pushing at or beyond 500 lbs. I did this at my own risk. I cannot and do not recommend you do what I am about to tell you regarding lifting this engine with a 1 ton hoist.

I lined up the torque converter as close to the same position as the bolt holes on the flywheel, as I could, making sure to line up the marks I made earlier on the flywheel and the torque converter for balance marks.

I lifted the engine on my cherry picker at full extension, 1/4 ton boom load position. I hoisted the engine as high as it would go, and it cleared the front lip of the engine bay. The boom was flexing-bending at full height from the weight of this engine. You could see the bend. I worked quickly, but safely to lower it into the engine bay, without getting underneath any part of the engine, or the boom arm. This is a very risky move, and again I do not recommend it to anyone. I cannot stress enough how dangerous this is. I would not do this again with this engine hoist. Use a 2 ton hoist to be safe. Once lowered into the engine bay, I move the boom arm to the 1/2 ton position and reattached it to the engine to finalize the engine position. Tweaking the engine into place wasn't easy. It took lots of time, and patience.

Summary:
Once the engine was lined up and bolted to the transmission, and all other lines, cables and pipes clamped into place, I installed the radiator outlet tube that goes behind the water pump. Ford wanted $18 per o-ring for this filler tube.  I used generic rubber o-rings (x2) for less than a dollar. No leaks! The intake manifold with new gaskets were installed and torqued to spec. The radiator was installed, and new generic o-rings used on the lower radiator hose. (The o-rings from Ford were $14 a piece, whereas I used generic rubber o-ring coated with vaseline for the install.). Coolant was added. A new oil filter and fresh oil poured into the filler hole. Battery was recharged and installed. Checked fuel rail for leaks, found none. Checked all radiator connections for leaks...none. Dash gauge oil pressure indicator shows plenty of oil pressure. And guess what? No chain slap noise. None at all! Not at startup, or during the test drive. So how's that for being frugal and not buying new timing chain tensioners like most people would?

The cost between buying a new oil pump or buying a timing chain set with tensioners were relatively equal. At the risk of being wrong by purchasing a chain set rather than a new Melling oil pump, I had to choose the oil pump. Of all the stories I've read in all the forums I've visited for information, I saw time and time again where people had to repeatedly replace their timing chains and tensioners after so many thousands of miles. Only a handful of people replaced their oil pumps to resolve any kind of issue (with Ford OEM oil pumps at that). I decided to do something different. Order a Melling oil pump AND clean my timing chain tensioners. I could have ordered new tensioners, but that's just another expense added to the already climbing cost of this repair.

After a rough start, I remembered I didn't plug in the O2 sensors. Once plugged in, and engine restarted, it purred like a big cat. Test drive, and she's doing well. Seems like I got a leak up high at the coolant recovery/expansion tank form a bad cap.

With that said.... hope you enjoyed the read, and hope this makes a difference to someone out there who has the same issues.

Post work assessment:

2000 Honda Odyssey Transmission Woes

I swear the early Honda Odyssey models were not designed by Honda. Like the Honda Passport is actually an Isuzu Rodeo underneath the skin, so is the early Honda Odyssey. I say this because the Odyssey is missing the design ingenuity and quality that (used to) come with Honda cars. The components are not as smartly designed as Honda of yesterday. The seats and interior quality just isn't there in this minivan. But that isn't what this post is about. This post is about what I've discovered so far in repairing the shifting issue with upshifts from first gear to second. The transmission will sometimes slip, or slam into second.

Subframe woes. I bought this car for what I thought was dirt cheap, and now I know why. I looked at this car after the sun went down, literally, in the dark. I test drove it and understood the tranny was acting kinda, well, horrible. It was only in the daylight the next morning that I discovered a long 1/2 diameter bolt that had been sheared off from who knows where, laying in the passenger door side pocket. Hmmm, wonder what that goes to. Upon further inspection I that this bolt goes to the rear subframe on the passenger side of the car that hold the engine cradle in place. This is the cause for the slamming noise when the transmission is going from first to second gear. With the transmission slipping, and having done my homework on this year model Odyssey, it looks like the transmission would have to be removed and rebuilt.

Removing the engine and transmission was my option, since I intend to replace the timing belt in the process of this work. Drilling out what was left of the subframe bolt that is still inside the frame of the vehicle body is nearly impossible with the subframe in place.

I removed the subframe, transmission and engine. Inspecting the subframe I found three places where cracks had formed either on the topside or bottom of the subframe. Not good, and probably catastrophic if the subframe were to fail on the highway. I've never seen severe cracking like this before on a subframe. I obtained one from a wrecking yard for $40. The engine and tranny and steering assembly were already detached from the subframe.

Pulling apart the transmission is no easy task. There are many parts, and any lack of organization will no bode well when it comes time to put it back together. With that in mind, I studied diagrams, and read the service manuals. I removed the casing and disassembled the gear assemblies and valve bodies. The gearing looked healthy, and bearings were intact without any slop or freeplay. I had a few pistons in the valve body that didn't want to come out due to the stop caps gouging the orifice. After cleaning the valve body with brake cleaner and cleaning the bores and pistons I checked bore movement in the valve body. Each piston moved freely, so that's a good sign. I reassembled the valve bodies and lay them aside for reassembly into the transmission when the time comes.

Inspecting the 1/2 drum baskets and dis-assembly were the next items. Discovered second gear friction plates and steels were worn badly. Several friction plates were either missing friction material on one side or on both sides of the friction plate. The outer steel plate had gouge markings on the flat surface that contacts the friction plate. Some of the inner steel plates had gouge marks as well. Further inspection revealed that first gear friction and steels were in good shape. These friction plates are 1.8mm new, and my measurements indicated 1.2mm on the first gear frictions. Steel plates for first looked good, some dark and appear burned, but still in good shape. What gets me on this is that this transmission had already been rebuilt. Telltale sign is that the friction plates for second gear are of a different manufacturer than the first gear friction plates. The friction pads are of different design from one another, indicating that someone had been in here before. Furthermore, they had only replaced the second gear friction plates, and not the first and second friction plates together. I do not know if Honda did this as a recall item for their transmission class action suit, as the local Honda dealership douche bags at the front service desk claims he is unable to tell me the vehicle history unless it was done at his dealership. Douche bag, that guy. Vehicle history is in Honda' s database somewhere, else how can they know who and what has been recalled and fixed if not to have to replace a transmission several times on Honda's bill? Douche bag service guy!

Waiting on parts for the tranny.....

In the meantime, I've fixed the interior lighting issue where none of the overhead lights are coming on. After troubleshooting and trying everything that the internet suggest I check, including replacing the interior fuse box-mini controller assemblies on both sides of the car... I discovered some wires that had burned beneath the carpet in the front passenger door sill. Cause of burned wires? Unknown...other than the damp carpeting, which when followed lead to the air conditioner condensation drain hole being plugged up...allowing water to spill into the interior and cause rust, rot, and damage to the wires that run alongside the floor of the passenger door. This also burned out the wires to the passenger rear window motor, which wouldn't open or close. See... this isn't Honda built quality engineering, and my suspicion that the Odyssey line was manufactured by some other company.

I've never been so unhappy with a car purchase as I've been with this model of Honda. I've worked on many Honda passenger cars... and I have to say the Odyssey sucks as far as its engineering is concerned. I do like the interior comfort. My daughter likes to look out the windows as I drive, and that is a good thing instead of being on her tablet all the time when we're in the car.

Updates to come on the transmission as I complete work.....

2001 Honda RVT 1000, Honda RC51 Fuel Problems

Vehicle: 
2001 Honda RC51

Problem: 
Poor mileage and poor performance. This motorcycle was spectacular in it's debut. I picked it up from a friend who hadn't ridden it in years. It sat in his garage, had been dropped and even rebuilt after a crash once. The issue with this motorcycle was poor performance, skipping throttle response, and running rich. At throttle, the bike would hesitate, as if it were running on a single cylinder instead of two.

Test Drive: 
At highway speed the bike would move along, and then die, then kick on, die and then fire, die and then fire. It was a constant hiccup when driving down the road, that happened occasionally, but became worse over time. It was as if the engine governor would kick in even though you were nowhere near the redline. The engine would die, and then resume power repeatedly. Frustrating when you're on a trip between states, let me tell you!

Diagnosis: 
At first I thought the problem was electrical, and so replaced one of the coil packs. This didn't resolve the issue. After some online research I saw some poor souls being ripped $2000 for a new fuel rail assembly, which did indeed cure their problems. The same problem I was having. However.... as a do it your selfer.... I find it hard to part with $2000 when the only components on the fuel rail consists of a few injectors, piping, and a fuel pressure regulator. It took me some time to bite the bullet to even think of parting with $2k just because some shop or even Honda recommends it. There had to be something else!

Fix:
Further troubleshooting..... gasoline is comprised of an ethanol mix these days, made of corn oil derivatives. Corn oil gets sticky when it's overheated, much like when you overheat corn oil in a frying pan. The design of the RC51 fuel system is that the fuel rail sits on top of the engine in a confined area, with poor air circulation. heat rises and slowly cooks that fuel pressure regulator after you've turn the key off and parked your bike.  The residue buildup acts like plaque in your arteries as the residue clings to the interior of the fuel rail pipes and the fuel pressure regulator. Ever seen your lawn mower float bowl in the carburetor after it's been sitting over a winter? It's like that. Buildup of residue. Enough with the justification already,, lets move on....

The problem with the fuel rail assembly isn't with all of the components. Honda might suggest a new fuel rail assembly to save their technicians time in diagnosing the root cause. The problem as in my case, was with the fuel pressure regulator. The gasoline in the system had been sitting in the bike in this guys garage for two years or more. Internal residue is nearly impossible to get rid of or clean out of your fuel pressure regulator. Cost for a new regulator runs about $50.

Find and order one here..
HONDA REGULATOR, PRESSURE - order part here

1. Work on your bike when the engine has cooled off. Lift your fuel tank up.
2. You might be able to access it without removing your air box. I recommend removing the air box to get full view of the fuel rail assembly. So... remove the air box.
3. Place a shop rag beneath the fuel pressure regulator. Hang some of the shop rag over the top of the fuel pressure regulator to catch any fuel spray as you remove the fuel pressure regulator. Use an open end box wrench to remove the fuel pressure regulator. Rotate the wrench counter-lock wise (righty-tighty, lefty-loosey) to loosen it. Unscrew the old one out with your hand.
4. Screw a new one into place. Do you need teflon tape? Not likely. Just reassemble with all components (washers etc...). Use new washers if you prefer, and, IF there is one. I can't remember, it's been awhile.
5. Tighten the new fuel pressure regulator into place with the wrench. Don't monster tighten it, but you do want it tight.
6. Key on, to test the fuel pressure in the system and check for leaks. With the tank up, and fuel lines connected, turn the key on, and pressure should build up. Look for any leaks at the fuel pressure regulator fitting. If there are none, cycle the key on/engine off several times to build up proper fuel pressure within the fuel rail. If no leaks occur, then you are good to go. It's tempting to start it up right now, and if you do, for goodness sake, remove all your tools, screws, bolts, loose components and shop rags from the intake path and throttle bodies so they don't get sucked in there and cause all sorts of horror.
7. Reassemble the air box, remove any other tools and rags. Lower your tank, button it up, and take your baby down the road for an obnoxious roar or two!
8. Check for leaks over the next few days or rides. You can never be too careful. The last thing you'd want is to ride down the road with your crotch on fire.



Post work assessment:
Problem solved with the new fuel pressure regulator installed. previously my problem was sooooo bad I was getting 3mpg. No joke, it sucked! With the new regulator installed, everything was fine, fuel economy if you can call it that with this bike, had returned. No more skipping throttle response, no more dead throttle spots. Everything was great! And I saved $2000!

Hope this helps someone out there!

2002 PT Cruiser Over heated and related electrical problems relating to cooling systen

Car: 
2002 PT Cruiser

Problem: 
1. Overheats, blown head gasket.

2. Electrical issues relating to proper cooling, voltage regulation, and transmission problem.

3. Engine vibration

Test Drive: 
No test drive, Dead on arrival.

Diagnosis: 
      This car came to me with a blown head gasket. And later overheated again after the head gasket was replaced, with  a new thermostat and new water pump. This was an incredibly difficult diagnosis, because it isn't typical for a car to overheat after replacing major cooling components where it would lead to a major electrical problem within the car itself within the same malfunction. The root cause was electrical, where the initial diagnosis was a problem with the cooling system.

Fix:
Car came to me dead on arrival. Removed the engine due to limited work space in the engine bay. New head gasket installed. New water pump, new thermostat. Radiator didn't appear to be clogged as the coolant wasn't dirty or yucky coming out of the drain tube. If there had been residue buildup, I would suspect clogged plumbing. But there was none. With the head gasket replaced and passenger sidewall engine mount replaced, the engine was re-installed. Test drive indicated the cooling problem was resolved. Drive to the dealership to return the car and the car is overheating, boiling over. After much research and troubleshooting a few days later, I find a single post out of 100 that indicate the problem might be with the electrical system failing to turn on the cooling fans. But why?

Further diagnosis with the car....

Headlight dimming. Car idling funny when shifting into gear from P. Interior lights flickering. All of this indicates it may have a weak battery. New battery installed, and same symptoms still persist. Install a used alternator. Same problems still persist.

Further troubleshooting electrically.... Voltage meter on the battery reads proper output voltage from the alternator. and battery voltage. What gets me is that the headlights dim when you turn them on, and the engine idle dies down when you go to high beam. Turn on the AC and it idles even more roughly. Put it into gear and it almost dies.

Root cause analysis:
After all of this work, the problem is related to the electrical system. While the original head gasket did need to be replaced, the root cause of the problem is voltage regulation. After thorough troubleshooting, as this was a doozy to fix.... the root issue was with the car's main computer. Chrysler decided to put the voltage regulator in the main computer box. What was happening was that as the car idled, the voltage regulator was able to keep up with demand, however if you loaded the electrical system down by turning on the high beams, the AC unit full blast, and shift the transmission into gear, the computer has to decide which system to keep alive, and will shut down all unnecessary functions. The computer was resetting itself  when the voltage/current demand was not enough to keep the main computer functioning, which caused the rough idle. When it resets, the idle air control system had to hunt for it's proper setting because, at the moment of reset, it did not keep in memory where the idle air control valve position. With lights flickering, and when the car's electrical load increased due to being in gear, the AC unit on, the system would reset. It could not regulate voltage properly, dropping voltage below the 5VDC threshold required to run the system computer.  Research and discernment to the root cause was that the internal voltage regulator in the main computer was failing.


THE FIX: 
After the head gasket was replaced and new thermostat and water pump installed, and the engine installed into place, and after further diagnosis with the electrical system......

The main computer in the car needed to be replaced. This Chrysler car main computer box is filled with a gelatinous substance, and the metal box is the heat sink, which is bolted to the rear firewall.

I ordered a used vehicle ecm from a company out of Florida via website. They needed the VIN code, and the mileage. Given that, and free shipping, the first computer they sent me was a refurbished unit that failed to even start the car. So I won't recommend them, or give their name here. The replacement computer arrived after another week of waiting for free ground shipping. I tell ya, customer service used to mean something, but not to these folks in Florida at this company. With the second car computer in hand, programmed with the right VIN code and mileage.... the car started up. The cooling fans came on properly, and the lights no longer flickered. The vehicle, even under full load with the AC running, car in gear, high beams on, and cooling fans running, the car held up and didn't die.

Post work assessment:
Everything on the car was working as it should have been. The cooling fans kicked on at the proper temperatures. The electrical system was no longer getting bogged down, and the idle was running smoothly. I had to make a minor adjustment to the engine tilt due to the new engine mount to eliminate engine vibration.

Like I said, this was a doozy of a problem car. While everything pointed initially to a cooling problem with this car, the end result turned out to be a problem with the main computer. Who would've thought? If I didn't have my 15 years of experience as an electronics technician, I would never have guessed the problem was electrical if my only experience was mechanical expertise. These newer cars require more in depth knowledge at times, to understand the input and output of system electronics. Some sensors are no longer just a high/low, on/off configuration. They're starting to pulse width modulate signals, meaning that where you thought a single wire was just carrying 12 volts to a sensor, might be multiplexed to carry other signals as well. That complicates things for some mechanics. I never would have guessed this overheating problem with a blown head gasket would lead to a root cause of the main computer voltage regulator.

2002 Pontiac Grand Prix - vibration at 50mph

Car: 
2002 Pontiac Grand Prix 3.8L V-6, automatic transmission
202,000 miles

Problem: 
Owner states the vehicle vibrates at around 50 mph when accelerating. Check engine light on, and tire pressure warning light on.

Test Drive: 
Vehicle begins vibration at about 50mph and continues above this speed. Vibration is a slight side way shimmy, instead of up or down, or front to rear of car when driving. Hard braking from 50mph produces massive shudders throughout car body. When driving at high speed and shifting into neutral to disengage drivetrain, the vibration is not as present as with drivetrain engaged.

Check engine lights produces mass air flow sensor code and egr system malfunction. However, engine is running smoothly, and not stumbling at any speed, or while parked, or in neutral. Fast to low engine idle speed is smooth and no indications of stumbling or hesitation.

Tires were at 25psi. Filled to 35psi and pressed the Tire Pressure Monitor button to calibrate the warning system at 35psi. Test drive again, and vibration is still present.

Visual inspection beneath car and found driver side CV axle inner boot broken, clamp loose. Passenger side CV axle boots in good shape. Check bearing free play and steering knuckle free play, none found in either system.

Checked all motor mounts, and they are in good shape, no tears or worn rubber.

Brake calipers have some free play in them from worn down brake pads, however this doesn't seem out of the ordinary from normal wear and caliper free play, as brake calipers sort of float when brakes are not being applied. Brake pads have 20% life left in them.

Diagnosis: 
Suspect the driver side CV axle, the low brake pad levels to be main culprits which are causing massive vibration above 50mph, and when braking. Also tires are worn, and have 30% life left.

Fix:
1. Replaced driver side CV axle. The original axle inboard boot was torn, and did have some lube left over, but not much. While it was not dried out, rust was present on the roller bearings within the inboard CV joint.

2. Both front rotors turned. The shop technician who turned the rotors indicated the rotors were warped, but were they were able to turn them ant still remain in spec. While most of the rotor was turned true to flat, there was a semi-circular arc that was not touched during the turning process, about 1/4 inch wide at it's widest point. Tech stated that the rotor was indeed flat all the way around despite the half arc present towards the outer edge.

3. New brake pads installed.

4. Front wheels balanced at shop. Each tire required 2lbs of weight to the inside of the wheel rim after removing the original wheel weights from the outside of the wheel rims.

Post work assessment:
Vehicle vibration problem is resolved. No vibration at any speed up to 80 mph. No vibration at any speed with hard braking.