Compression Test HELP
07-28-2010, 04:32 PM
#16
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What color is the smoke? white? Smell? A compression test and leakdown would be helpful. Three cylinders should read identical, the fourth would be off if you have a problem.
07-28-2010, 09:43 PM
#17
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A forged piston engine will consume more oil than non forged also. The ring gaps are greater to allow for additional expanision of the denser piston. I went with an even bigger gap on my rings, I went with the maximum suggested by the manufacturer. I put your right in the middle of the spec. My engine does consume some oil. But i knew it was going to consume more oil. I was planning on beating the **** out of it from day one. better loose and burn some oil, than tight and having a piston lock up.
are you running a cooler thermostat?
while the pistons are still cool and skirt slapping loudly, higher rpms will also cause excessive oil consumption
are you running a cooler thermostat?
while the pistons are still cool and skirt slapping loudly, higher rpms will also cause excessive oil consumption
07-28-2010, 10:47 PM
#19
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How many miles on the block?
On the heads?
On the Turbo?
Engines with forged pistons...when properly built ..consume no more oil than with OEM pistons.
I've had engines with all four pistons suffering from cracked ring lands, consuming >1liter of oil in 500 miles without throwing a misfire code.
On the heads?
On the Turbo?
Engines with forged pistons...when properly built ..consume no more oil than with OEM pistons.
I've had engines with all four pistons suffering from cracked ring lands, consuming >1liter of oil in 500 miles without throwing a misfire code.
07-29-2010, 12:02 PM
#21
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what up buddy-
im with the others on here: though a compression test would be good test just for peace of mind, (letcha know if you have a piston ring that's lost compression) in your case its most likely a valve seal, considering the age and mileage of your heads.
you're planning on head work anyways, so if you do a compression test and everything checks out (it should) then you know those heads are coming out for sure, perhaps sooner rather than later.
my guess is most of the guys on Nabisco just went straight to the "do a compression test " reply because they dont know the full details of your build. - in most massive oil consumption cases on the 2.5 EJ257, its due to cracked piston ringands, and probably the most common oil consumption issue on STi blocks.
so, like i said: a compression test is a good thing to do (hell we may all be proven wrong and perhaps you did have a cyl loose compression, but in most cases you have a valve seal (or a couple ) that may have gone.
as it was mentioned earlier- pull your spark plugs- its the easiest way to see which cyl has the leak. the cyls with the oily plugs are your culprits.
cheers bro, hope that helps
- Milo
im with the others on here: though a compression test would be good test just for peace of mind, (letcha know if you have a piston ring that's lost compression) in your case its most likely a valve seal, considering the age and mileage of your heads.
you're planning on head work anyways, so if you do a compression test and everything checks out (it should) then you know those heads are coming out for sure, perhaps sooner rather than later.
my guess is most of the guys on Nabisco just went straight to the "do a compression test " reply because they dont know the full details of your build. - in most massive oil consumption cases on the 2.5 EJ257, its due to cracked piston ringands, and probably the most common oil consumption issue on STi blocks.
so, like i said: a compression test is a good thing to do (hell we may all be proven wrong and perhaps you did have a cyl loose compression, but in most cases you have a valve seal (or a couple ) that may have gone.
as it was mentioned earlier- pull your spark plugs- its the easiest way to see which cyl has the leak. the cyls with the oily plugs are your culprits.
cheers bro, hope that helps
- Milo
07-29-2010, 01:46 PM
#23
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If it were your rings, you will have loss of power, oil blown out of your vents (i.e., valve cover, and crankcase), and smoke out your exhaust almost all the time, especially under load. Oil then is reintroduced into your combustion chambers through your PCV hoses and into your intake. If you had a catch tank, it'll be full. An AOS might not help returning oil because there's so much pressure in the crankcase from blowby that you'll just have to do a rebuild.
A blown valve seal will let oil in from the cylinder heads' rotating assembly via vacuum and be burnt in the chambers. The characteristics of a blown valve stem seal is plumes or puffs of smoke on cold startup, accompanied by oil consumption. And loss of power because compression is escaping past your seal and will also blow oil out of the same side valve cover. Other than checking plugs for oil, you can also pull any side valve cover hose and see which one has more oil sludge in it.
A blown valve seal will let oil in from the cylinder heads' rotating assembly via vacuum and be burnt in the chambers. The characteristics of a blown valve stem seal is plumes or puffs of smoke on cold startup, accompanied by oil consumption. And loss of power because compression is escaping past your seal and will also blow oil out of the same side valve cover. Other than checking plugs for oil, you can also pull any side valve cover hose and see which one has more oil sludge in it.
