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  #1  
Old June 17th, 2020, 09:03
1990JEEPXJ's Avatar
1990JEEPXJ 1990JEEPXJ is offline
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Piston rings

So Iím in the middle of replacing my head gasket and also planned on doing the rings while I was that deep into things. I also had a ton of blowby and was low on power. What brand rings for stock pistons are recommended? The bores look good but Iíll be doing a quick dingle ball hone to freshen it up. I havenít taken any pistons out yet but what are decent rod bearings, if needed?
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  #2  
Old June 17th, 2020, 10:00
RCP Phx RCP Phx is offline
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Re: Piston rings

Hastings rings and Mahle bearings(Clevite).
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  #3  
Old June 17th, 2020, 11:43
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Re: Piston rings

Don't forget to do the ring lands or you may break you rings.
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  #4  
Old June 18th, 2020, 06:27
CJR CJR is offline
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Re: Piston rings

There are a number of things that can cause excessive oil blow-by; cracked pistons, broken lands between the piston ring grooves, broken rings, and rings stuck-closed by hardened oil/carbon. Broken pistons or lands are very noisey. Most times, the excessive oil blow-by is caused by; broken rings and/or rings that are stuck-closed by hardened oil/carbon. Typically, spraying Gumout carb cleaner frees the stuck rings. When replacing rings, I recommend using either a "ductile iron" top compression ring or stainless steel rings if you can get them for your pistons. Likewise, before installing the rings, CAREFULLY clean the sides of the piston ring grooves. The new rings must seal on the sides of the piston ring grooves and against the cylinder bore.

Finally, depending on the aluminium alloy used for the piston, an old piston can "age-harden or fatigue" and may fail with new rings because of the increased ring side-loads on the lands during initial ring- seating. On rebuilds, It's best to use new pistons; either cast or forged. I prefer forged pistons.

Best regards,

CJR
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Old June 22nd, 2020, 07:35
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1990JEEPXJ 1990JEEPXJ is offline
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Re: Piston rings

Quote:
Originally Posted by CJR View Post
There are a number of things that can cause excessive oil blow-by; cracked pistons, broken lands between the piston ring grooves, broken rings, and rings stuck-closed by hardened oil/carbon. Broken pistons or lands are very noisey. Most times, the excessive oil blow-by is caused by; broken rings and/or rings that are stuck-closed by hardened oil/carbon. Typically, spraying Gumout carb cleaner frees the stuck rings. When replacing rings, I recommend using either a "ductile iron" top compression ring or stainless steel rings if you can get them for your pistons. Likewise, before installing the rings, CAREFULLY clean the sides of the piston ring grooves. The new rings must seal on the sides of the piston ring grooves and against the cylinder bore.

Finally, depending on the aluminium alloy used for the piston, an old piston can "age-harden or fatigue" and may fail with new rings because of the increased ring side-loads on the lands during initial ring- seating. On rebuilds, It's best to use new pistons; either cast or forged. I prefer forged pistons.

Best regards,

CJR
Engine wasn’t noisy at all and ran fine. Just tired for lack of a better term. That and a significant oil leak from the passenger side of the head prompted me to swap the head gasket and address the blow by. I already tried the gumout on the rings to no avail and the tops of the pistons and cylinder bores all look fine.
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Old June 23rd, 2020, 06:10
CJR CJR is offline
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Re: Piston rings

1990JEEPXJ,

Could you elaborate on your statement,"I already tried the gumout on the rings to no avail". Sometimes, with a piston with rings stuck-closed and on the bench, you have to flood the rings with Gumout carb cleaner and wait a couple of minutes before the rings snap-out.

Also, a broken ring or broken piston land ,between the piston-ring grooves, will produce massive oil blow-by. It appears, you may have to pull the pistons and look them over carefully. Typically, massive oil blow-by occurs when the piston rings are stuck closed or broken. So when the engine is running, the connecting rods' "oil squirter holes" are spraying oil on the cylinder walls for lubrication. The combustion pressure then blows the oil on the cylinder walls past the stuck-closed rings and/or any broken rings into the crankcase. The crankcase becomes pressurized, which in turn, pressurizes the valve-cover, which in-turn, blows excessive oil into the emission tubing, etc.

Good luck on your tear-down!

Best regards,

CJR
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Old June 29th, 2020, 16:45
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1990JEEPXJ 1990JEEPXJ is offline
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Piston rings

Quote:
Originally Posted by CJR View Post
1990JEEPXJ,

Could you elaborate on your statement,"I already tried the gumout on the rings to no avail". Sometimes, with a piston with rings stuck-closed and on the bench, you have to flood the rings with Gumout carb cleaner and wait a couple of minutes before the rings snap-out.

Also, a broken ring or broken piston land ,between the piston-ring grooves, will produce massive oil blow-by. It appears, you may have to pull the pistons and look them over carefully. Typically, massive oil blow-by occurs when the piston rings are stuck closed or broken. So when the engine is running, the connecting rods' "oil squirter holes" are spraying oil on the cylinder walls for lubrication. The combustion pressure then blows the oil on the cylinder walls past the stuck-closed rings and/or any broken rings into the crankcase. The crankcase becomes pressurized, which in turn, pressurizes the valve-cover, which in-turn, blows excessive oil into the emission tubing, etc.

Good luck on your tear-down!

Best regards,

CJR

I did the method you described in another thread. A whole can divided among the six cylinders and let it sit.

So Iím trying to pull the pistons and I expected there to be a carbon ridge at the top of the bore. However, the ridge I have seems metallic. Itís not black and it almost looks like an insert or something as you can see a ring on the deck as well.



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  #8  
Old June 29th, 2020, 18:41
RCP Phx RCP Phx is offline
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Re: Piston rings

No, that's just the ridge wear left by the rings.
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Old June 29th, 2020, 20:50
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1990JEEPXJ 1990JEEPXJ is offline
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Re: Piston rings

Are they usually pretty pronounced?
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  #10  
Old June 30th, 2020, 06:09
RCP Phx RCP Phx is offline
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Re: Piston rings

Sometimes they can be very ridged depending on the years of service.
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  #11  
Old June 30th, 2020, 06:13
CJR CJR is offline
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Re: Piston rings

I agree, that is "ridge wear". IIRC, there are reamers available to remove that ridge to allow removing the pistons without breaking them. Then the bores would need to be honed. The amount of ridge formation depends a lot on how well the rotating assembly was balanced.

Best regards,

CJR
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Old June 30th, 2020, 08:29
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1990JEEPXJ 1990JEEPXJ is offline
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Re: Piston rings

All the ridges seems to be equal in all cylinders and uniform around each bore. I’ll attribute it to normal wear. Engine ran smoothly. Guess I’ll get a ridge reamer. Also, I’m assuming seeing some copper on the rod bearings is normal, but just a sign of wear. The crank is still smooth so I’ll probably get new bearings since I’m there
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Old June 30th, 2020, 08:37
RCP Phx RCP Phx is offline
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Re: Piston rings

You can borrow a reamer from O'reilys and no seeing copper is not a good thing!
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  #14  
Old June 30th, 2020, 09:44
CJR CJR is offline
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Re: Piston rings

You might want to get a micrometer and "mike" each crank journal at two(2) places, 90 degrees apart. That would tell you if the crank journals need to be re-ground. It's not good to put oval crank journals into round bearing IDs. Reason? Crank journals must float on a uniform pressurized oil layer. An oval crank journal inside a round bearing cap can increase bearing wear quickly. Likewise, an improperly balanced rotating assembly in an engine can also increase bearing wear.

Best regards,

CJR
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  #15  
Old June 30th, 2020, 11:36
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Re: Piston rings

I hate it when others try to spend my money but I have to say that at this point you should seriously consider doing it right and pulling that block for some machining. You are already signed up to replace the bearings and rings. It is really going to suck if you put it all back together and find that you have to redo everything.



Based on what it sound like you have done, you are already on the hook for new:


- rings
- main bearings
- rod bearings
- gaskets
- rear main seal
- head bolts
- possibly main bolts (like head bolts, these are "torque to yield" and should probably be replaced if removed)


You are probably getting close to (or over) $300 in parts with this list alone. Adding pistons, ($100 at SummitRacing), cam bearings ($35), timing chain ($54), lifters ($66), and harmonic balancer ($52 - yours "might" have another 100K in it depending on a number of factors). This adds another $300 in parts and, oh yeah, if the engine doesn't hold up you are going to pay another $300 for the "re-do" on all the stuff you bought the first time.


Machining is going to cost you about $125 for a bore and hone, $80 to install the new pistons, $50 for a good clean and possibly another $120 for any crankshaft work.
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