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2G Piston rings and oil seepage on 4g63

dsmjaime

Probationary Member
5
2
Apr 18, 2021
Kennewick, Washington
I have a question and it might sound dumb but I couldn’t find any info about it. I have a 7 bolt 4g63 for my 2g eclipse that I’m currently rebuilding.

A couple days ago I rotated the crank until all 4 pistons were even across. I filled each cylinder with oil. When I went back to look, the oil had seeped through, there was no more oil.

Can someone tell if this is normal or not, my guess is my piston rings are toast. I don’t want to put the whole thing together just to have compression issues.
 

Kryndon

Proven Member
669
353
Jan 10, 2014
Bulgaria, Europe
Hey. Don't mean to be rude but that really isn't a good test for anything, really. On a cold, unsealed motor, all piston rings will have gaps which will let air/water/oil through no matter what. Also, when the pistons are cold, they are slightly smaller than their intended operating dimension, same goes for the rings. As the metals expand, they produce a much better seal against each other. But even in that case, the piston rings never fully hermetically seal between top and bottom. There is always some leakage (blowby).

With all that said, it's still hard to determine whether your rings or pistons are sealing right. You really need to do a compression and leakdown test in order to conclude. What you can do is take into account the mileage of the motor, visually inspect the cylinder walls and honing, remember if the motor ran well before the teardown (did the oil smell of fuel? Did the PCV system operate normally?)...

If you have the oilpan off, for peace of mind you can just install a new OEM set of rings. Hope this helps!
 

97egl

Proven Member
194
55
Feb 6, 2014
Brownsburg, Indiana
I'd pull the pistons out and check your ring gaps just because the engine is that far apart already. If the gaps are good then the other thing I would suggest is cleaning the oil ring groove and the holes in it. Then just reinstall them. Gaps will vary a lot depending on what your doing. Anyone running an engine with high boost usually runs in the neighborhood of .020 gap on the top ring and around .025 on the second. Having all your gaps the same between cylinders is important too.
 

dsmjaime

Probationary Member
5
2
Apr 18, 2021
Kennewick, Washington
Hey. Don't mean to be rude but that really isn't a good test for anything, really. On a cold, unsealed motor, all piston rings will have gaps which will let air/water/oil through no matter what. Also, when the pistons are cold, they are slightly smaller than their intended operating dimension, same goes for the rings. As the metals expand, they produce a much better seal against each other. But even in that case, the piston rings never fully hermetically seal between top and bottom. There is always some leakage (blowby).

With all that said, it's still hard to determine whether your rings or pistons are sealing right. You really need to do a compression and leakdown test in order to conclude. What you can do is take into account the mileage of the motor, visually inspect the cylinder walls and honing, remember if the motor ran well before the teardown (did the oil smell of fuel? Did the PCV system operate normally?)...

If you have the oilpan off, for peace of mind you can just install a new OEM set of rings. Hope this helps!
Thanks dude. I really appreciate your reply! I did not know that. I pulled the oil pan and it turns out this motor that I bought for $150 had eagle rods and arp rod bolts. 😅
 
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