Rebuilding my 4g63

[sschambers]

I'm a new member on this site, but I am fairly knowledgeable with these cars (this is my second one, the first was a 97 Spyder GST).

Anyway, for a couple weeks I had this weird problem where my O2 housing was smoking. There was some smoke coming from the exhaust but not excessive. I thought maybe the seals in the turbo went bad. Replaced my 14b with a Bastard 20G. Got everything back together, test drove it, parked it in the garage and let it idle for about 30min to see if there were any leaks. When I come back check it 30min later, my O2 housing was SOAKED in oil and smoking horribly.
Took the exhaust manifold off, closely examined the oil feed line. 100% perfect. Closely examined the bottom of the header - and there was a good sized crack. And looked closely at each runner on the head, and they were all covered in oil.

So I figured if it were spitting out that much oil, it was either valve stem seals, or bad oil rings.

Got the motor ripped out, head off the block, block is almost bare as of right now. My crank end play measured a 0.27 DAMN! Oh well, big deal - that wasn't causing my oil problem.
Found a bad rear main seal and oil pump-to-block gasket, also.
The rod bearings looked like they hardly seen any wear at all. The oil rings were worn quite a bit, and the compression rings were damn near immaculate (explains my 180 compression on all 4).
I'm thinking the oil problem I was having is more than likely the valve seals. The oil rings didn't look too terrible. Or maybe a combination of the two?

Anyway, I started cleaning the internals since I have a parts washer. I'm going to re-use the pistons/rods, getting new main bearings, rod bearings, ARP head and main studs, the MBCAD kit, and all new gaskets/seals/rings/etc. I'm not trying to build a 500hp motor, just a reliable stock build for an every day 270hp (or so) grocery-getter.

My question is - I started cleaning piston #1. After lightly scrubbing it with a toothbrush and letting it soak in the parts washer for a couple hours, I noticed the rod is kind of shady. You know how the rod slides side to side on the wrist pin? Well, it does that. But on the one side of the pin, it gets kind of stuck/tight and it makes the rod not want to swing back and forth. When I slide the rod towards the other side, the rod swings perfectly fine towards either side of the piston skirt. I didn't take note of this before washing the piston, but the other 3 pistons are not like this. The other 3 all work flawlessly. I was thinking maybe because after washing it, it removed all of the oil on/in the piston, causing the tightness? But that doesn't explain why it's only *tight* when moved to one side.

Also, one last thing. When I last went to check on the piston, there's still quite a bit of build-up in the oil ring grooves. I tried using the soft-bristled toothbrush to scrub in there, but it's not working so well. Anyone know of a better method to clean the gunk out of the ring grooves? I just don't want to score/damage the piston by using a razor or anything.

Thanks for any help,

Steve

 

[4g64fiero]

The wrist pin is warped. It happens sometimes during an improper install or from excessive heat.

As far as cleaning the ring lands, most people use the old rings to clean out the grooves. You could try soaking it in engine degreaser first or PB blaster.

 

[sschambers]

I went out and dug through the Spyder's motor parts and found the pistons. They all seem to be in excellent shape and the rods all move freely and smoothly. Except, the one piston I came across. It has a very small knick on the top of it, near the two indents on the intake side. It's not a hole, or a deep crater but a very small knick, probably from being stored in a box for quite some time.

I have no idea which piston is which (1, 2, 3, 4) because they all got mixed around in the box. But does anyone think the knick would matter or cause problems? Also, is it even a good idea to use used pistons from another 4g63? The other motor was fairly new, and these pistons are MUCH cleaner than the one I recently took out of my current block.

 

[ilco187]

i had this exact same problem on a set of wiseco pistons you move it to one side is like butter but switch it to other side it like grabby and hard upon removing the wristpin i seen the piston had melted on the one side and wiped out the journal when i ran my finger across the inside it had like sharp shards but i had no choice but to put it back together as for i didn't have my replacement engine and seized and oh well

 

[90rslaser]

i had this exact same problem with the oil soak. the piston rings were bad. as far as a "nick" on the top of the piston. it could be caused from a slightly bent valve. i dont car what anyone says, if a valve is been in the slightest form possible, it effects EVERYTHING! check for bent valves. even if they "look" ok, that doesnt mean they dont have a slight bend in them. sometimes head problems cannot be seen from the naked human eye.

 

[sschambers]

Well the piston with the knick is from my other 4g63, and it was being used with a different head, also. I was just curious if it would be ok to re-use this piston in my current block, wasn't sure if a small knick would affect or harm anything.

As for my current head, it's going to get rebuilt anyway. Just incase it does have bad valve stem seals.

 

[90rslaser]

honestly, i wouldnt trust using a piston out of another block. especially if it has little nicks in it. just spend the extra 200 dollars or whatever and get yourself a set of nice stock ceramic coated pistons. they are fabulous!!!!

 

[sschambers]

Well I've been thinking about it. The other set of pistons that I have - have WAY less miles on them, they're the same pistons, they cleaned up WAY better than the pistons I just took out...And if they all weigh approximately the same (in GRAMS), I should be golden. The piston is there to take up most of the space, the rings seal it. I don't think a small knick should cause any problems...I hope

Tomorrow morning (well, I should say THIS morning) I'm taking my bare block, head, crank, bearing cradle and pistons to the machine shop.
I'm going to get the block hot tanked, decked, cylinders deglazed/honed, head rebuilt/decked.

The guy that does this work is very popular around this area and is well known for doing excellent work.

I'm going to show him the other set of pistons and see what he says about the one having a small knick on the top. I've rebuilt motors before, but when I have to question myself about something that deals with motors, I ask EVERYONE for advice. So if you guys have any more input that'd be awesome.