Vicki's Engine Tear Down

[MSHardeman]

Well, I FINALLY took a little time to get the passenger side head off of Vicki's old motor to see what happened in cylinder three to make it completely lose compression. After breaking one bolt off in the block and using some choice words while getting the rest of the bolts out I finally got the head off and got a peak inside.


Here is a shot looking straight down at the cylinders on the passenger side of the motor. Cylinder three is the one in the middle (Cylinder One is to the right and Cylinder Five is the one to the left). You can easily see the massive amount of carbon build up in all of the cylinders.


Here's a close up shot of cylinder three. There is a LOT of carbon built up on the top of the piston.


Here's an angled close up of cylinder three. Again, you can see the carbon build up, but the cylinder itself looks like it's in good shape. You can still see the cross hatching in the cylinder wall, but that makes me think that maybe the rings weren't seated against the cylinder wall completely. I would think that after 130K miles the cross hatching would be worn away if the rings were sealed tight to the cylinder wall.


Here's a close up of cylinder one and..


cylinder five for comparison.


Here's a shot of the underside of the passenger side head, and as you can see the exhaust valve in cylinder three is a bit wonky. Looks like a burnt valve is the culprit. It isn't sealing against the head completely so the cylinder couldn't hold pressure.


Close up of the cylinder three head. Again, the burnt valve is clearly visible.


Here's a shot of the cylinder one head and...


the cylinder five head for comparison.

It's all very interesting (to me), but I hope that this can help out some of the other owners that are having engine issues.

[jhigareda]

Question. What should a good shop charge for overhaul? Approx. thanks

[Scott Larson]

Well there it is Mark, kinda looks like what we discussed in your original thread on the subject. Excessive carbon buildup due to a possible misfire condition causing stuck rings and/or valves. That burnt exhaust valve was most likely caused by the increase of compression in that cylinder due to the carbon buildup...increase in compression causes an increase in exhaust gas temps that in turn burns the exhaust valve. That engine looks to be an excellent candidate for a ring and valve job for another 150,000 miles. Good investigative work there Watson!! You might want to consider having it done and sell it as a fresh rebuild or sell it as a rebuildable core and recoup some of your expenses...

[MSHardeman]

jhigareda, I don't know how much a rebuild would be yet. I do plan on calling a few places to see what it would cost to get the engine back to perfect.

Scott, I was really surprised that just one burnt valve would cause the cylinder to completely lose compression. I mean there was ZERO pressure in that cylinder during all the tests that I had done on it. I haven't had a chance to really get into it yet, but that burnt valve must really be wonky if it's not seating to the head at all.

So, with Scott's comment about the excessive carbon build up possibly causing increased compression/ exhaust gas temperatures, my question is; how do we get rid of the carbon build up in the cylinders without completely tearing the engine down to scrape it off of the pistons? I ran some sea foam through the motor, a few months before replacing it, but obviously that didn't do anything. Did I do the Sea Foam too late? In other words was the carbon already "bonded" to the pistons and wasn't coming off no matter what I did?

As I get deeper into the engine I'll report back on the condition of the rings and whether they were gunked up with carbon too causing them to stick.

If it's not too expensive I do plan on having the engine rebuilt, but I haven't decided what I would want to do with it yet. I would hate to sell Vicki's original heart, but recouping some of the replacement engine expenses would sure be nice.

[Leon R]

Look up MOPAR Compbustion Chamber Cleaner. Many people SWEARby it... I used it a few times and can't tell if it makes any difference...

That piston has some carbon deposits but not enough to cause a significant compression reading increase or cause a problem... Also, that valve looks bent! I would clean off the piston and inspect it for contact marks with the valve.

[MSHardeman]

Leon, I'll have to take a closer look at the valve when I have some time. I took a quick look at the piston and didn't immediately notice any kind of contact mark on the top, but who knows. I'll get into it later. I don't think that it would be a bent valve, as our engines are supposed to be non-interference, but if the valve broke off, somehow, and extended farther down than normal I guess it's a possibility. I would think that if the valve broke off, it would have stayed in the cylinder and caused more damage. Also, it didn't fall out of the head as I was flipping it around.

[SilverBullet75]

Hi Mark,
If you are interested in selling the bottom end (as long as there are no problems with it) let me know.
I bought a Trooper with rod knock that needs a short block!

Thanks!
JIM

[Leon R]

It might be a shadow trick, but it appears to have a bend at 9 o'clock position.

[Scott Larson]

That doesn't look like it's bent to me, it looks burnt at the eight o'clock. It sits straight in the seat and no way is it broken, that would be soooo obvious. It doesn't take much buildup to increase compression a few points, a millimeter or two can wreak havoc! Marks pictures aren't telling lies, it's all right there if you look closely and know what you're looking for. As for decarbonization, there are several cleaners available to do the dirty deed, Sea Foam directly in the cylinders and left to soak for a few days is one of the oldest tricks. There are newer products on the market claimed to do the job faster and more thoroughly but color me a skeptic to alot of them...

By the way Mark, I was looking at those pictures again and those cylinder walls look awsome!!

[jhigareda]

Thanks

[MSHardeman]

By the way Mark, I was looking at those pictures again and those cylinder walls look awsome!!

Scott, to tell you the truth I was a little surprised at how good the cylinder walls look. That engine burned 3/4 of a quart of oil every 350 miles from the day I bought it with 35,000 miles on it right up until I had it taken out of the VX at 130,000 miles. That's about 215 quarts of oil over the engines lifetime (and about $1500 if you estimate $7 per quart - OUCH!). With it going through that much oil I figured that the cylinders would be toast, but as the pictures show, that isn't the case.

I still wonder about my theory that the rings don't seat well against the cylinder walls so they don't scrape the walls like they should so the walls stay relatively clean and smooth.

[Buffy]

i was wondering if you could add a vaccum pump to the motor. Racers use this to pull the rings out against the cylinder walls and improve performance. Just have to have a catch can and figure out a place to mount the pump.