Blow by on a built motor

IdleSurge · Aug 26, 2015

Car: 90 Eagle Talon TSI with wiseco 8.3:1 compression pistons. .020 bore. The head is also built with BC272 cams over sized valves, springs, and retainers and held down with arp head studs and an MLS triple layer head gasket.

All tests were done on a cold motor since my small 16g (oil fed from the head) had a thrust bearing failure. I'm thinking it failed because of oil contamination due to the blow by I'm having which is detailed below:

Compression test (Cold): All cylinders read 168-170psi (I did not do a wet test since I got really good results)

Cylinder leakage test (Cold): 10%-11% leakage across all pistons (all of the air is leaking through the valve cover breather hose if I plug the breather hose then the air will then escape out of the turbo oil return line)
No air is leaking out of the intake or exhaust manifold. No bubbling in the coolant. No leaking through adjacent cylinders. Oil dipstick does not pop out during boost (24psi).

Boost leak test: Air only leaking out of the valve cover breather hose. Tested the PCV valve and it was working great... just to be sure i did pull the hose of the pcv valve and blocked it off that way I could be sure that no air is getting into the crankcase via the PCV valve. It will not hold 15 psi for a minute or so unless the breather hose is plugged and once you unplug the breather hose you can hear and feel a ton of air that just whooshes out and it starts to leak pressure from 15psi to 5psi in about 25-35 seconds.

Anyways I'm on here to see if anyone thinks I should do any other tests or if anyone has had similar results.

This is not a PCV valve issue!!

Thanks all

video

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donniekak · Aug 26, 2015

Those compression and leak down numbers are to be expected from a healthy engine. What exactly makes you think you have a blow by issue?

IdleSurge · Aug 26, 2015

donniekak said:
Those compression and leak down numbers are to be expected from a healthy engine. What exactly makes you think you have a blow by issue?

I think I have a blow by issue because there is too much air escaping out of the breather hose (or it will escape out of turbo oil return line if you plug the breather hose). Also, if you plug up the breather hose with your hand you can feel the pressure building up very quickly (for both the cylinder leak down test and boost leak test).

I should note that when doing a boost leak test it will not hold 15 psi for a minute or so unless the breather hose is plugged. and once you unplug it a ton of air just whooshes out and it leaks from 15psi to 5psi in about 25-35 seconds.

Thanks for the reply

Nate355RS · Aug 26, 2015

It wouldn't leak past the rings in a boost leak test, not with those compression numbers. And the rings held a lot more pressure with a leak down test than you're probably using for a boost leak test. My guess is it's coming back through the valves.

Or leaking past the turbo seals since you have a blown turbo. Boost leak tests really should be done on a warm motor, did it do this before the turbo gave up the ghost?

IdleSurge · Aug 26, 2015

Nate355RS said:
Or leaking past the turbo seals since you have a blown turbo. Boost leak tests really should be done on a warm motor, did it do this before the turbo gave up the ghost?

Sorry I forgot to mention that I did the boost leak test on both a warm and a cold motor. The test results were similar except that it would leak out a little bit slower on a warm motor ( about 10-15 seconds slower so it would take about 35-40 seconds total to drop from 15psi to 5 psi after you unplug the breather hose)

donniekak · Aug 26, 2015

With those compression and leak down numbers, combined with the fact that you aren't smoking, or blowing the dipstick, I'd say your engine is sealing in combustion gasses well enough to leave it alone.

TunedUp · Aug 27, 2015

What do you mean when you are saying blow by? Not being rude but from what you have said so far I'm not sure you know exactly what blow by is. Are you saying air is getting out some where? Blow by is combustion gases seeping past the piston rings into the crank case.

Cruciatus111 · Aug 27, 2015

any contamination from blow by gasses in your oil being the cause of your turbo failure is highly unlikely. The only way that blow by contaminants would do harm is if gasoline gets into your oil from very rich afrs and if there is a high enough amount it will thin your oil and you loose lubrication to the bearings in your engine. And any big particles of carbon and other bigger pieces that could go down into the crankcase should get caught in your oil filter.

There are many reasons as to why a turbo can fail one being lack of oil and many other questions that you have to ask such as how old is the turbo? How many miles are on it? How were you driving the car as well as how many lbs of boost were you running when the turbo blew.

this is the real world things like a turbo blowing for no reason happen all the time. Seeing as how well your engine did in all of the tests and what the others have said I would say to just leave it alone and just throw on another Turbo and just drive it

also as to you having actual blow by issues is unlikely as you say your dipstick is not popping out on full boost. if the dipstick is popping out at Full boost then you know for sure something is wrong with your crank case ventilation and something needs to be done to fix it.

TunedUp · Aug 27, 2015

Very bluntly put Cruciatus111, but so accurate. I completely agree with Cruciatus111 he has good knowledge there I would take it and roll with it.

Nate355RS · Aug 27, 2015

I've seen a number of threads like this when I'm just searching through and reading the forums. I think it's important to remember you're not pressurizing the combustion chamber when you do a boost leak test, you're testing the intake track for leaks. Boost leak tests have nothing to do with the combustion chamber or blow by.

If you have the PCV disconnected and plugged and you have air coming through the valve cover, your intake valves are open. Rotate the engine so the intake valves are closed and try the boost leak test again. Where that is will depend on what cams you have and how they were installed. Sounds like you have a very healthy motor, I wouldn't worry about blow by at this point.

IdleSurge · Aug 27, 2015

Cruciatus111 said:
any contamination from blow by gasses in your oil being the cause of your turbo failure is highly unlikely. The only way that blow by contaminants would do harm is if gasoline gets into your oil from very rich afrs and if there is a high enough amount it will thin your oil and you loose lubrication to the bearings in your engine. And any big particles of carbon and other bigger pieces that could go down into the crankcase should get caught in your oil filter.

There are many reasons as to why a turbo can fail one being lack of oil and many other questions that you have to ask such as how old is the turbo? How many miles are on it? How were you driving the car as well as how many lbs of boost were you running when the turbo blew.

this is the real world things like a turbo blowing for no reason happen all the time. Seeing as how well your engine did in all of the tests and what the others have said I would say to just leave it alone and just throw on another Turbo and just drive it

also as to you having actual blow by issues is unlikely as you say your dipstick is not popping out on full boost. if the dipstick is popping out at Full boost then you know for sure something is wrong with your crank case ventilation and something needs to be done to fix it.

I have sent a sample of the engine oil to blackstone laboratories to conduct some testing which will tell me exactly whats present in the oil and this should clear up alot of questions about contamination.

I have read and appreciates everyone's comments and suggestion thus far.

Thanks

IdleSurge · Aug 27, 2015

TunedUp said:
What do you mean when you are saying blow by? Not being rude but from what you have said so far I'm not sure you know exactly what blow by is. Are you saying air is getting out some where? Blow by is combustion gases seeping past the piston rings into the crank case.

Yes exactly the crank case is being pressurized when I'm performing a cylinder leak down test or boost leak test. Its not a PCV valve or blown turbo seals issue.. I'm almost sure that the combustion gases are either seeping past the rings or valve stem seals. But as pointed by many members its highly doubtful that its the rings and the blow by isn't excessive So I'm hopping to hear from some members who have had similar test results and all of their leakage through the crankcase.

No worries I'm not offended and just happy that people are responding and posting to this thread

IdleSurge · Aug 27, 2015

I took a video today.
You're looking at the turbo oil return line towards the end of the video.. All of the crank case pressure is pushing oil out into the clear bag which is zip tied to the turbo oil return line. I inspected the oil and it looked black even though the car just had a fresh oil change. When I smelled the oil it had a strong stench of gasoline.

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TunedUp · Aug 27, 2015

I'm actually kinda stumped on this and will be following this to see the outcome. I mean obviously I could probably help a lot more in person, but it's a lot harder over a computer haha. Hope you get a solution soon!

BogusSVO · Aug 28, 2015

All engines have a bit of blow by....a small amount of combustion gasses will work past the rings.

When you do a BLT, you pressurize the intake and by default one cylinder, so yes you will get air into the crank case.

There is no position you can rotate the engine and have all 8 intake valves closed.

You ran a leak down and came up with 11%, tho that's not bad, it is not great either, Most say the rings are shot in the 20-30% range.

How many miles on the build?

Has the engine ever been over heated in excess of 250*?

Do you have any idea of what grit stone was used to finish the cylinder bores?

The big question is why the oil has gas in it?

You need to check your tune and your FPR or AFPR, along with your fuel pressure setting.

Check for a dripping/leaking injector.

What are your AFR?

What fuel pump and FPR do you have installed?

Stiff/look for gas in the FPR vac hose. You may have a leaky FPR diaphragm that sucks raw fuel into the intake.

Raw gas in the oil will break the oil down and would easily cause a thrust bearing failure, along with other bearing damage in the engine and turbo.

donniekak · Aug 28, 2015

You have an overfilled crankcase if you can push oil up the turbo return.

How are you tuning, and what are your afr's under boost, at cruise, and idle.

IdleSurge · Aug 28, 2015

BogusSVO said:
All engines have a bit of blow by....a small amount of combustion gasses will work past the rings.

When you do a BLT, you pressurize the intake and by default one cylinder, so yes you will get air into the crank case.

There is no position you can rotate the engine and have all 8 intake valves closed.

You ran a leak down and came up with 11%, tho that's not bad, it is not great either, Most say the rings are shot in the 20-30% range.

How many miles on the build?

Has the engine ever been over heated in excess of 250*?

Do you have any idea of what grit stone was used to finish the cylinder bores?

The big question is why the oil has gas in it?

You need to check your tune and your FPR or AFPR, along with your fuel pressure setting.

Check for a dripping/leaking injector.

What are your AFR?

What fuel pump and FPR do you have installed?

Stiff/look for gas in the FPR vac hose. You may have a leaky FPR diaphragm that sucks raw fuel into the intake.

Raw gas in the oil will break the oil down and would easily cause a thrust bearing failure, along with other bearing damage in the engine and turbo.

800 Miles on the build
When I got the car it was overheating due to a failed fan thermosensor in the lower radiator.
Not sure what grit stone was used
The injectors are evo 550cc and they were flow tested and checked for leaks at a local dsm/evo shop (results were great)
The AFR during cruise are 14.5-15.2....At WOT 11.0-11.3.....cold start up 13.3 -14.0.... idle 14.7-15.7
Walbro 190 fuel pump with a 2g fpr and 2g maf

And yes I agree with you its impossible to get all the intake valves to close and hence why the crankcase will pressurize if its not properly sealing the combustion chamber.

donniekak said:
You have an overfilled crankcase if you can push oil up the turbo return.

How are you tuning, and what are your afr's under boost, at cruise, and idle.

The AFR during cruise are 14.5-15.2....At WOT 11.0-11.3.....cold start up 13.3 -14.0.... idle 14.7-15.7

I'm using an AFC neo with very little correction +6% my 2g mas 2g fpr with a 2g fuel rail and evo 550cc injectors and a small 16g which at most is spiking to 24psi

BogusSVO · Aug 29, 2015

With the 190 and stock FPR, you still may be over running the FPR, rare but could.

I would expect to see some messed up AFR tho.

Unless you have adjusted for a leak through the FPR into the intake???
Not sure you could.

The gas smell in the oil is still what has me.

When was the last time the wideband was calibrated?

IdleSurge · Aug 30, 2015

BogusSVO said:
With the 190 and stock FPR, you still may be over running the FPR, rare but could.

I would expect to see some messed up AFR tho.

Unless you have adjusted for a leak through the FPR into the intake???
Not sure you could.

The gas smell in the oil is still what has me.

When was the last time the wideband was calibrated?

I have not made any adjustments for a leak through the fpr into the intake. ( There is not a hint of smell of gasoline in the intake manifold)
The wide band is 6 years old without any calibration. (There are no indication that its going bad)

BoredDSM · Aug 30, 2015

With a thrust bearing failure was it a lack of oil? Was the shaft over heated? If you had excessive blow by your main concern would be oil failing to return to the pan and causing poor oil flow to the turbo. If it was a question of fuel contamination in the motor you would have wear on all bearing surfaces and possible failure not just isolated to the turbo.

You will not smell gasoline in the intake manifold if your FPR is leaking. Not much of an accurate way to test it besides applying a vacuum via a vacuum pump and priming the fuel system and see if fuel leaks out or the vacuum does not hold.

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Blow by on a built motor

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