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99 GTP: Replace piston rings?


DrRadar
03-21-2015, 06:52 PM
198k miles on my 99 GTP that I'm fixing up. Love the car, wanna keep it.

Main issue was leaks (oil, coolant, refrigerant). Still ran well and was fairly quick, but not like when new.

Engine is out, heads are off.

I would like to replace the piston rings because I've been told that will make a significant improvement in performance. Doesn't seem difficult, but never done it and don't know what problems I may run into.

I have shop manual and can follow procedure although there's a step or two that I don't understand. Like "pry the connecting rod back and forth and check for binding" - do they at the piston end?

Should I re-use the connecting rod bearings? I don't plan on having the crankshaft or connecting rods machined.

Or am I opening Pandora's box by wanting to do just the rings and not a complete lower end rebuild?

Thanks for any guidance for those who have been there.

Stealthee
03-21-2015, 09:04 PM
Honestly, you would be much further ahead buying a running lower mileage junkyard engine and dropping it in. 3800's are so common its ridiculous and you should easily be able to score one for ~$400.

By the time you add up the cost of head gaskets, exhaust manifold gaskets, rings, bearings, etc, and ESPECIALLY your time, you will far exceed the cost and time in a simple engine swap.

Tech II
03-21-2015, 09:21 PM
I agree.....

Many low mileage 3.8's out there...

DrRadar
03-21-2015, 10:59 PM
That would have been a good option to consider before I started the rebuild. But I'm too far down this road to go back. I've already accumulated the parts (gaskets, motor mounts, hoses, etc.).

As I said previously, my original goal was to fix various leaks. Then upon recommendation, I decided to replace the head gaskets because of mileage and desire to keep the car. I was able to borrow an engine hoist and stand so pulled the engine to make working on it easier.

Now I'm just trying to determine the value vs. the work/risk in taking it a little further with replacing the rings.

maxwedge
03-22-2015, 08:08 AM
Replacing the rings will require measuring the bores for taper and roundness, either way the will need some degree of honing.

Crvett69
03-22-2015, 09:26 AM
amd since you have to take the pistons and rods out you might as well replace the rod bearings while they are out. will also want to have the heads checked to make sure they are flat and might want to do a valve grind and valve stem seals while you are at it. you will want to rent or borrow a bead hone. for a used engine with taper its better for braking the cyl wall glaze than a ridgid stone hone. will also need to check for a lip about 1/4" down from top of the block in the holes, if there is one big enough to catch a fingernail on you will need a ridge reamer to remove it to avoid broken rings once engine it back together and running

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