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99 Town & Country 3.8L Engine knock...

9K views 10 replies 6 participants last post by  tommcmullen 
#1 ·
Hi All:

I took all the ppistons out today and 3 of the 6 are blasted, extreme damage to the skirt area... never would have thought it... so... if you find yourself with high mileage and a steady noise...

One of the parts guys told me that the wrist pins get a little tight and it's only a matter of time after that...

Take care all...

I"ll be back~:cool:
 
#4 ·
Piston Pictures attached...

Don't know what caused this failure, each piston has a special area on the skirt, maybe a

silicone inlay and on 3 of the pistons there has been a failure in this area... maybe it was ooverheated at one point... my wife bought the van on EBay... it came with the knock... so I never heard it without.

I have a piston part number if anyone needs it. The dealer wants to sell an assembly, rod and piston w rings for $250/ea to rich for me... The pistons I ordered from napa are sealed power for $25.50 each... much better..

We'll see how it all goes together...:cool:
 

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#6 ·
Don't know what caused this failure, each piston has a special area on the skirt, maybe a

silicone inlay and on 3 of the pistons there has been a failure in this area... maybe it was ooverheated at one point... my wife bought the van on EBay... it came with the knock... so I never heard it without.

I have a piston part number if anyone needs it. The dealer wants to sell an assembly, rod and piston w rings for $250/ea to rich for me... The pistons I ordered from napa are sealed power for $25.50 each... much better..

We'll see how it all goes together...:cool:
I've used NAPA/Sealed Power pistons on any number of Chrysler products (including 225s and 318s), and always got great service from them. I'm thinking that at the very reasonable price you're getting them for, you might want to consider a 0.030" overbore and buy six.

Hmmm, if my math is correct, that would bump the displacement of your engine from 3.77 liters to 3.83. He-he, I'll bet you'll feel all that extra power every time you step on it. ;)
 
#5 ·
I bought replacement pistons for my 225 slant six at NAPA. (by the way, this is the ONLY engine that has EVER blown when I was driving it and no, I was not abusing it, #1 piston just exploded like a grenade…:ask_wsign ) They had the Chrysler pentastar on them. I cannot remember what they cost, but they were cheap. I also got pistons for a 318 and a 360 from NAPA.
Were your wrist pins tight? Was there a lot of engine sludge in side? What did the cylinder walls look like in those cylinders? Were the rings broken or stuck in the grooves?
 
#7 ·
The rings were all fine, looked in good shape and not stuck on the piston, the wrist pins were not TIGHT one seemed a little snug but for the most part they were fine... There was a lot of sludge in the lifter area and in the pan, I was surprised to see it.
The cylinders feel fine and look bad... I'm going to hone it and hone it and slip it together hoping for the best... the block is not coming out on this one...
I said that about the pistons too...:cool:
 
#8 ·
Yikes... Wow, it would have been interesting to see a used oil analysis on that bad boy...

You might want to check the roundness and wear on those bores to see if the numbers are anywhere close to being in spec... if the bores are way out of spec, even a new piston might start slapping :( But, hopefully the pistons took most of the wear.

Given the sludge and damage, I'd concur with the overheat diagnosis. Especially if those three pistons were all on one side of the motor.

- G
 
#9 ·
I would be hesitant to put the engine back together without knowing what caused the failure? where the bad pistons #1,3,5 or #2,4,6 or was there no rhyme or reason to the them?
 
#11 ·
3.8 Piston failure...

Three of the pistons failed, each only on one side, 2,3,& 5 failed, the skirt facing the outside of the block on 2 &3 and the skirt facing the inside of the block on 5...

I'm not looking at specs, not measuring, been there done that, this is a "utility" only, it's the "Dogmobile" so... we have 2 Xtra large dogs and another not so large dog... this van is for carting them to the beach for walks and like that...
I'll measure the piston clearance, just so I know but after that, no measuring allowed, not this trip... I'd love to make a 3.83 out of it butno, all this is with the block in the van. I'm putting a timing set in and an oil pump kit and wraping it up... interesting thing was, all of the exaust valves and the combustion chambers on the heads were all the same color... very close in combustion even with 3 blasted pistons (see pics).... it did not smoke either.

If it gets around for a couple of years it will have been worth the effort for sure...

thank you all for your support, i'll send an audio when I get it fired up so you alll can hear it...

I'LL BE BACK~:cool:
 
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