OT: More MR2 problems

[Mr. Pockets]

Oooooh, this is an evil, hateful little car.

As I've posted about before, I found zero compression on the #4 piston in my MR2. I found that the HG was leaking and the head was pretty badly warped. A new head is on its way, so I figured I'd replace some oil seals and things while I was waiting.

Long story short, I found chunks of piston ring in the oil pan.

I could just cry.

I'm going out to pull the #4 piston, and I'm tempted to o what needs to be done to fix that one cylinder. The other three have excellent compression and don't leak oil, so I'm leaning towards leaving them alone.

But I'd still like to hear some opinions. Understand that, at this point, I'm not necessarily determined to do the best thing for this car. I've put a lot of time and money into it recently and I'm tired. Oh, so tired.

[Beav]

Pull the piston before deciding which path to take.

[Mr. Pockets]

Originally Posted by Beav

Pull the piston before deciding which path to take.

I pulled it, and it decided my path. I ended up pulling all four. #4 is trashed. There's a hole straight through the side of the piston that's so big it covers all of the ring grooves. The rings were literally tangled.

The #4 cylinder wall is scored slightly, which I hadn't seen until the piston was completely out. It will have to be honed, obviously. So I'm going to replace all the rings and hone all four.

I need at least one piston, but no local parts shops can get them any more. A guy in IN has already offered to let me pick through his parts stash, which I appreciate totally. I'm keeping my fingers crossed - if he has pistons, I may have the parts to put the bottom end back together in less than a day.

[Mr. Pockets]

Amazing. An MR2 owner in IN has offered me all seven of his intact spare pistons. All I'll need is a set of rings and bearings, hone the cylinders and I'll be set, it would seem.

[Beav]

Weigh the pistons before you install them. Sometimes different vendors supply parts, sometimes there are running changes made that aren't cataloged. You may think that odd but it happened to my dad once. It wasn't pretty. looking at one side of the block and seeing the other side of the car after only a few minutes running. The piston looked similar but its weight was different enough...

[Mr. Pockets]

Originally Posted by Beav

Weigh the pistons before you install them. Sometimes different vendors supply parts, sometimes there are running changes made that aren't cataloged. You may think that odd but it happened to my dad once. It wasn't pretty. looking at one side of the block and seeing the other side of the car after only a few minutes running. The piston looked similar but its weight was different enough...

I plan on it, and thanks for the words of caution. I'm taking all seven of the pistons from the guy so I can make sure that I put a closely-matched set in there - especially since both sets came from '85s, and mine's an '86.

How close should they be in weight? Is a mail scale accurate enough?

[Mr. Pockets]

I picked up the pistons in IN this morning, and they're visually identical to those I pulled out of my car - just with fewer holes. I'll still weigh them to make sure, but I think I'm good. The three I picked up will replace my three worst-looking pistons. I'm off to order rings, rod bearings and look at tools.

[thundering02]

In a recent mag they parts balanced to .2 grams is used for a high power turbo setup (race?)

[Mr. Pockets]

Just a quick note. I've been busy.

I ordered a new set of pistons from a local engine shop. The owner was a really, really nice guy. My head should arrive today. Maybe in a week or two the car will be running again. Then I guess I'll have to break it in.

I'm very nervous about the whole honing procedure.