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Excessive oil consumption


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Hey folks, my 02 legacy is eating up a ton of oil. It's going through about a liter every 300 - 350kms. I only ever notice smoke out the tailpipe after engine braking, which points toward valve seals, but it rarely smokes on startup ( I've noticed a small amount of smoke on start up maybe a handful of times. Car sat for 4 days last week and no smoke on startup) I can usually smell burnt oil after driving for a bit. Anybody have any ideas or input? From what I know worn valve seals always smoke on startup, and worn rings smoke constantly ( correct me if I'm wrong) .. Car is an ej25 N/A, manual transmission with 235k kms.
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It could be a mix a of a few things. The head gasket could be leaking oil in or out the engine. Piston oil control ring could be gummed up or worn allowing oil to be left over on the down stroke. The valve stem seals could be dry and always letting oil pass between the valves. You have a oil leak from the oil pan.

 

 

Check your PCV, if it's clogged with oil, you've been burning it. I would just vent everything to atmosphere. Delete the pcv and vent it with a hose, take the valve cover vent hoses off the air box and then plug the box.

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It could be a mix a of a few things. The head gasket could be leaking oil in or out the engine. Piston oil control ring could be gummed up or worn allowing oil to be left over on the down stroke. The valve stem seals could be dry and always letting oil pass between the valves. You have a oil leak from the oil pan.

 

 

Check your PCV, if it's clogged with oil, you've been burning it. I would just vent everything to atmosphere. Delete the pcv and vent it with a hose, take the valve cover vent hoses off the air box and then plug the box.

 

I just had the head gaskets replaced, so that shouldn't be it.. Unless they botched it 😑. I replaced the pcv a while ago and it was pretty gummed up, when you say vent to atmosphere do you mean just run the hose off the pcv to under the car somewhere? Or completely remove the pcv valve and run a hose from the hole. Would some sea foam in the crank case potentially free up the oil control rings? Never any oil puddles after parking, and i can't see any fresh oil anywhere. Thanks for the tips.

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I would called that blown at that point.Yours is worn out. Take the valve out, match it up with a brass hose fitting from the hardware store(I forgot the thread size) run a hose from that. The engine will last slightly longer. you will stop all that oil burning be put back into the engine. PCV is only for emissions.

 

You can try frequent oil changes or running a some sea foam 5 mins before changing your oil to try and clean it out. I wouldn't drive with it in the crankcase.

Edited by RumbleRumble
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I would called that blown at that point.Yours is worn out. Take the valve out, match it up with a brass hose fitting from the hardware store(I forgot the thread size) run a hose from that. The engine will last slightly longer. you will stop all that oil burning be put back into the engine. PCV is only for emissions.

 

You can try frequent oil changes or running a some sea foam 5 mins before changing your oil to try and clean it out. I wouldn't drive with it in the crankcase.

 

Ah, like you figure the engine is probably blown hey..that's a bummer for sure. I'll try venting the pcv into atmosphere, it runs good and smooth and has got good power, so hopefully I can just keep dumping oil into it and it'll last me a while yet. Will try some sea foam in there right before my next oil change as well. Too bad I just got the head gaskets done.. $$$ :/ is it really possible for the cats to mask this much burned oil smoke? I would imagine there to be constant and heavy smoke if all this oil really is being burned.

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It could be a mix a of a few things. The head gasket could be leaking oil in or out the engine. Piston oil control ring could be gummed up or worn allowing oil to be left over on the down stroke. The valve stem seals could be dry and always letting oil pass between the valves. You have a oil leak from the oil pan.

 

 

Check your PCV, if it's clogged with oil, you've been burning it. I would just vent everything to atmosphere. Delete the pcv and vent it with a hose, take the valve cover vent hoses off the air box and then plug the box.

 

Regarding venting the pcv, I would vent straight from where the pcv currently is using a fitting, and then plug the inlet that routes from the pcv back into the intake? As well as the vent on the airbox?

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I'm saying constantly smoking out the tailpipe while driving is serious, That would be blown. Consuming some oil is just a common thing in a worn engine.

My brothers forester burns a quart every 350 miles! His engine had a head gasket job done but didn't change any valve seals or anything like that(previous owner..) We're doing the same pcv delete and changing oil regularly till I have time to swap the engine.

You need to remove the PCV and add a new fitting or hollow out your valve. Remove the breath hoses off the air box. the ones that run from the valve covers.

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I'm saying constantly smoking out the tailpipe while driving is serious, That would be blown. Consuming some oil is just a common thing in a worn engine.

My brothers forester burns a quart every 350 miles! His engine had a head gasket job done but didn't change any valve seals or anything like that(previous owner..) We're doing the same pcv delete and changing oil regularly till I have time to swap the engine.

You need to remove the PCV and add a new fitting or hollow out your valve. Remove the breath hoses off the air box. the ones that run from the valve covers.

 

It barely ever smokes out the tailpipe, which is why I'm a bit confused, unless the cats are filtering out that much smoke. I'll try venting the pcv this week though, thanks.

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I'm saying constantly smoking out the tailpipe while driving is serious, That would be blown. Consuming some oil is just a common thing in a worn engine.

My brothers forester burns a quart every 350 miles! His engine had a head gasket job done but didn't change any valve seals or anything like that(previous owner..) We're doing the same pcv delete and changing oil regularly till I have time to swap the engine.

You need to remove the PCV and add a new fitting or hollow out your valve. Remove the breath hoses off the air box. the ones that run from the valve covers.

 

Why not just buy a new PCV?

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  • 2 weeks later...
Unless the new head gasket is a different thickness it won't change the compression. A thicker gasket would actually reduce compression.

 

Headgasket jobs on worn motors can cause blown rings. If you have failing head gaskets and you replace them with new (even oem spec) there can definitely be a change in compression if the old ones were bad.

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