How to tell if my rings are worn?

[stocky]

Im trying to diagnose the problem with my engine. My last compression test pulled some bad results. 1 cylinder was fine at 150psi, 4 were average at 120psi, and 1 was bad at 90psi. My two reasons for this are either blown headgaskets from running too lean under boost, or worn rings. I also think the inlet manifold gasket is in need of replacing too.
Basically, I want to know how I can diagnose between the headgaskets and rings without having to take the engine apart just yet? The engine runs fine, just a bit sluggish at times, uses a little too much fuel, doesnt idle well on warm starts. Apart from that, it seems fine.

[azkwazere]

Im trying to diagnose the problem with my engine. My last compression test pulled some bad results. 1 cylinder was fine at 150psi, 4 were average at 120psi, and 1 was bad at 90psi. My two reasons for this are either blown headgaskets from running too lean under boost, or worn rings. I also think the inlet manifold gasket is in need of replacing too.
Basically, I want to know how I can diagnose between the headgaskets and rings without having to take the engine apart just yet? The engine runs fine, just a bit sluggish at times, uses a little too much fuel, doesnt idle well on warm starts. Apart from that, it seems fine.

Head gaskets will usually yeild differnet results.

H/Gaskets have lower compression in 2 adjcent cyclinders... ie. 2 and 4 or 1 and 3. Best bet is to redo the compression test and add a table spoon of oil to the lower comression cycilders. If they increase, you have worn rings. If they dont, you have sticky valves. If they increase dramatically, again, valves.

Do you have any other symptoms to indicate head gasket? oil in water? Water in exhaust? overheating? There all potentional head problems but also indicate worn intake manifold gasket issues.

Step One: redo compression test.. add oil to check.
Step Two: Strip manifold and replace gasket on the intake. Cost about $50 and about 6hours of non stop work if youve never done it before.

Sounds like you have ring issues... 90psi is really really low.. you may completly loose compression in it soon.

aZk.

[stocky]

looks like i might not bother at all. may have another good condition v6 ready to go in hopefully soon.

[Emackulation]

Cars breaking down hey stock block? And you were picking on my car

[stocky]

Cars breaking down hey stock block? And you were picking on my car

hey at least mine starts

[Emackulation]

hey at least mine starts

Give me a few days

[pow3rslave]

just out of interest, what's it cost to get rings replaced?
when i got the cam in they said it'd probably make me need new rings sometime soon.

[immortality]

just out of interest, what's it cost to get rings replaced?
when i got the cam in they said it'd probably make me need new rings sometime soon.

that really depends on what else needs doing. if there is very little wear (not likely on a 300,000km engine) in the bore then just the cost of new rings and gaskets and a quick hone to deglaze the bores. if there is some wear in the bores you might get away with oversize rings but this is not the best option. lots of wear means gettingthe block bored out and new oversize pistons are needed.

however if oyu pull the heads to fit new rings you have a situation where you have good ring seal with average heads. at the very least strip the heads and give em a good clean (couple hrs work) and maybe lap the valves in to make sure they have a good seal (assuming the guides aren't worn to badly)

thats just me however, i fix things that aren't broken so says my missus anyways

edit: just read your "ride" thread, ignore the bit about the heads, they look sweet.

[azkwazere]

you can do rings from the top down? didnt think theyd come out and you'd have to pull the piston out from the bottom... hmmm...

time for a full rebuild!

aZk.

[ScoHar]

Thats how you do rings from the top, otherwise you can't (or almost impossible) to use a ring compressor to squash the rings to get the piston back into the bore.

[PaRaDoX]

you can do rings from the top down? didnt think theyd come out and you'd have to pull the piston out from the bottom... hmmm...

time for a full rebuild!

aZk.

quite right you can only remove 2 pistons if your lucky without the heads off..


its a engine out block apart job

it will be headgasket, rings dont wear from detonation, headgaskets do, i had similar results in my v6... imo hes better off with a new block his bearings are probbly rooted waiting to go for a trip round the world :P and possibly give a rod the chance to see the world outside the block jail break style!

soo, imo new motor and get a AFR test done again...

[vnv8driver]

as well as rings and headgaskets theres also possibility of worn valves, cam lobes, etc.

if it was a headgasket theres a good chance that it will show, either water vapor/liquid out the exhaust, oil&water mixed in radiator, overheating, etc......

[Nev25]

If they increase, you have worn rings. If they dont, you have sticky valves. If they increase dramatically, again, valves.
aZk.

What do you classify as dramatic?
Seems as there is a fine line between the two

[nicko]

if you can do a crap as big as your fist, then your ring is worn!

[vnv8driver]

if you can do a crap as big as your fist, then your ring is worn!

hahahahaha!

[PaRaDoX]

if you can do a crap as big as your fist, then your ring is worn!

talking from experiance??

[ScoHar]

if you can do a crap as big as your fist, then your ring is worn!

thats prob the best comment i've heard on here!!!!