crankcase pressure

[bowens1414]

well in doing a boost leak test with my neighbor tonight i discovered a potentially s***** problem. doing the test i have air coming out of the oil cap along with my dipstick popping out. my pcv valve checks out i cleaned it so it works fine but that didnt fix the dipstick. now i bought the car used and one of the previous owners did a emissions delete (i believe) meaning almost all the un needed vac lines were deleted. now this test showed that air is pressurizing the crankcase. is there any other entries for air to get there other than bad pistons/rings? i will be doing a compression test soon to confirm that. or is there a fix to this problem? any help will be greatly appreciated

cars a 97 gst

 

[T is for TURBO]

Could be a bad PCV. was the car warm or cold when you did the boost leak test?

 

[bowens1414]

ughh id say cold i drove it across the street i was on for about 2 minutes then we started testing. would you recommend a warm test?

 

[primo513]

I had a 6 bolt that had a LOT of blow-by, and still passed on the compression test with 150 across the board. How much pressure are you putting through the system when you are doing your BLT?

 

[habitatguy187]

one of the previous owners did a emissions delete (i believe) meaning almost all the un needed vac lines were deleted. now this test showed that air is pressurizing the crankcase. is there any other entries for air to get there other than bad pistons/rings?

Egr valve, turbo seals, pcv valve.

 

[bowens1414]

I had a 6 bolt that had a LOT of blow-by, and still passed on the compression test with 150 across the board. How much pressure are you putting through the system when you are doing your BLT?

i did a compression test about a month ago with 180s across id say i was upwards of 10-20 lbs i wasnt paying exact attention when the dipstick popped out.

Egr valve, turbo seals, pcv valve.

im positive the egr was deleted pcv valve is good. turbo seals im not sure

 

[benstian]

Do a leak-down test. As long as your pcv is ok, I am afraid your piston rings may be gone...

 

[XiKeiyaZI]

Well,

1 : Remove the PCV and see if you can blow through it both ways. If even a small amount of air is allowed past from the nipple end of the PCV - change it. This is allowing any boost you generate to flow from the intake manifold, into the valve cover, and then directly into your crank case.

2 : From there, perform a Leakdown test if the PCV checks out. This will show you the overall condition of the cylinders' ability to retain air pressure and help you diagnose if you have something such as bad rings/extreme blow by. http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

3 : Check the turbo seals if the above seem fine.

4 : Next would be EGR, however, since you stated that you have deleted that then-...

Get back with results after you have checked the above. Going to bank on it either being PCV or rings, personally.

 

[T is for TURBO]

1 : Remove the PCV and see if you can blow through it both ways. If even a small amount of air is allowed past from the nipple end of the PCV - change it. This is allowing any boost you generate to flow from the intake manifold, into the valve cover, and then directly into your crank case.

I would just block the PCV off completely while doing the boost leak test. That would rule it out right away. This is what I do every time I do a boost leak test, as even my brand new, OEM, PCV leaks a little.

Get back with results after you have checked the above. Going to bank on it either being PCV or rings, personally.

I second this.

 

[XiKeiyaZI]

I would just block the PCV off completely while doing the boost leak test. That would rule it out right away. This is what I do every time I do a boost leak test, as even my brand new, OEM, PCV leaks a little.

Well it's not something I recommend doing during a boost leak test. This is just something you can check at any time by removing the hose, unscrewing the check valve, and then blowing through it. It's surprising when you remove it and can blow through it both ways with no resistance. Then you're left scratching your head, wondering why you didn't try it sooner.

 

[bradselph]

Do a boost leak test at the throttlebody and see if you still have the same symptoms, if not then it was the turbo.

 

[rydereclipse]

Can he just get a new PCV valve and then get a check valve too?

My brand new PCV valve still allowed very tiny amounts of air through the wrong way, so I bought a check valve to be sure no boost is getting in there that way.

 

[XiKeiyaZI]

Can he just get a new PCV valve and then get a check valve too?

My brand new PCV valve still allowed very tiny amounts of air through the wrong way, so I bought a check valve to be sure no boost is getting in there that way.

Well I would suppose so, but I've never had bad lucky finding a PCV that would close properly. I don't see how a check valve in addition would be a bad thing, if not a little overkill. Just be sure to install it facing the right direction.

Do a boost leak test at the throttlebody and see if you still have the same symptoms, if not then it was the turbo.

As for doing a BLT at the Throttle Body to determine if it is the turbo or not.. you are aware that the PCV gets it's source from the intake manifold, correct? Beyond that, you're also ruling out that it could also be bad blowby? Care to explain?

 

[bradselph]

As for doing a BLT at the Throttle Body to determine if it is the turbo or not.. you are aware that the PCV gets it's source from the intake manifold, correct? Beyond that, you're also ruling out that it could also be bad blowby? Care to explain?

n0 7m n0t awar3 of th3 pcv g3tting 7t5 sourc3 from the intak3 manif0ld



I never mentioned anything with the pcv, i just mention if you still have the symptoms after you do it at the throttle body then its not the turbo. Why would i mention how to see if it is the pcv when there is at least 5 other posts saying its just the pcv.

 

[XiKeiyaZI]

Hey, gotta be proactive when it comes to making sure people know what they're readong. I'm more shocked that you used l33t speak to reply.

 

[bradselph]

Hey, gotta be proactive when it comes to making sure people know what they're readong. I'm more shocked that you used l33t speak to reply.

Haha, 1337 is a lost art these days.

 

[95dsmevo3]

Even new after market pcv valves leak they are not made to hold boost buy oem.

 

[bowens1414]

ok so i wont be testing until the weekend. now today out of curiosity i made sure the dipstick was in snug (which is a pos without a o ring) and drove the car hard. about 7 psi though due to me not having a boost controller. got home checked the dipstick. good. no oil still in the same way i left it. what could this mean. a running engine is getting rid of that crankcase pressure where i do not see this during a boost leak test.

 

[T is for TURBO]

ok so i wont be testing until the weekend. now today out of curiosity i made sure the dipstick was in snug (which is a pos without a o ring) and drove the car hard. about 7 psi though due to me not having a boost controller. got home checked the dipstick. good. no oil still in the same way i left it. what could this mean. a running engine is getting rid of that crankcase pressure where i do not see this during a boost leak test.

7psi is pretty low, so I wouldn't expect the dip stick to pop out. What where you BLTing at?

When the car is running, and you are in boost, the turbo is creating a vacuum in the intake snorkel, which SHOULD be connected to the valve cover vent. This is there to help eliminate crankcase pressure. When the valve cover vent is no longer sufficient (too small in size), that's when the dipstick usually pops. That's why you see some higher powered cars running two big ass -10 AN lines off the valve cover.

If you are certain that the car does not have an EGR valve, and that the PCV is 100% then you need to do a compression test, and a leak down test.