bad blowby even with good compression

[4BangerV8Killer]

So my car has really bad blowby and i cant figure out why....if crimped the dip stick so it wouldnt pop up then i did a compression test and my compression was 170 across....what else causes blowby? and when i push my car a little bit of smoke comes up from under my turbo...where could that be coming from? I have the pte50 trim

 

[RayPeters]

So my car has really bad blowby and i cant figure out why....if crimped the dip stick so it wouldnt pop up then i did a compression test and my compression was 170 across....what else causes blowby? and when i push my car a little bit of smoke comes up from under my turbo...where could that be coming from? I have the pte50 trim

It is possible to have smoke from several places. Any of the bolt together locations in the exhaust manifold including the manifold to the head. It is also possible to have a turbo drain tube that is damaged (cracked or rusted) After that, define bad blowby. The rubbers on the dipstick shrink if you run the car without the manifold heat shields, or just old age, then it pops up and there has been no change in blowby. Also check your crankcase breather system, somtimes the hoses get plugged or the check valve freezes up. I'd start there, you can also do a leakdown test to see if an unusual amount of air leaks past one piston more than others.

 

[romeen]

It could be a leaking PCV valve pressurizing your crankcase causing your dipstick to pop out. Does it pop out when you do a boost leak test? If yes, repeat it with PCV disconnected or just replace your PCV. If that is the case there is a thread that discusses this and using check valves to correct it. Let me know if you need the link.
I doubt it's your turbo seals as you are not smoking out through the exhaust, correct?

The smoke could be from a poor seal between O2 housing and downpipe or an oil leak.

 

[4BangerV8Killer]

im not sure where its coming from exactly i may or may not be coming out of my exhaust....people that have followed me have told me its out of my exhaust but im not sure if they are right or not....and whens its really bad it will fill the inside of the car up with smoke.

When you say leaking pcv valve what do you mean exactly? that link could help....iv replaced the valve and valve cover because of a broken valve already so i know its good.

And my idle is very wierd...just the other day i was sitting at a light and my idle started to go up and it went all the way up to 2500 rpms and today it was surging and jumping from -15 to -10 psi when i would start the car or sit for a period of time idling.

before i bought the car i believe it did sit for a while.....(8 months or more) so i thought it could be the seals drying out.

but with the smoke. It will either smoke while im pushing it and get smokey in the car or it will smoke alittle and then after i let off it will dump a bunch of smoke out the back of the car.

Like i said before i fixed the dipstick when i had a bad "blowby experience", i was tuning my car and oil shot all over the engine bay and up my windshield which i assumed came from my dipstick....(i have a rre hoodvent) id say i spit out at least a half of a quart there.

besides bad rings leaking pressure into the crankcase, is there anything else that causes blowby?

 

[romeen]

My experience has been that most oem PCV valves leak past approx. 10psi. You can check by removing your PCV from VC but leave it connected to the intake manifold. Pressurize your intake (boost leak test) and check for leakage past PCV valve. If it leaks here is a discussion of a possible fix:

http://www.dsmtuners.com/forums/showthread.php?t=229338&highlight=pcv

If you're getting smoke inside the car then I would check for exhaust leaks. Does your car smoke more between shifts? Your turbo seals could be bad. This could account for the smoke and pressure in the crankcase.

 

[talon91tsiawd1]

Check your actuator for the wastegate. Mine went and I had some serious blowby. Make sure that the door moves freely and then make sure that the actuator moves. Also check your intercooler piping for oil.

 

[romeen]

Check your actuator for the wastegate. Mine went and I had some serious blowby. Make sure that the door moves freely and then make sure that the actuator moves. Also check your intercooler piping for oil.

A faulty WGA would cause problems controlling boost pressure but I don't see how it could affect blowby in any way.

 

[oldman]

Like i said before i fixed the dipstick when i had a bad "blowby experience", i was tuning my car and oil shot all over the engine bay and up my windshield which i assumed came from my dipstick....(i have a rre hoodvent) id say i spit out at least a half of a quart there.

You didn't fix anything, you made it worse. It's like instead of putting out the fire, let's shut off the alarm and pretend there is no fire. The fire here is "excessive crankcase pressure" and "dipstick popping" is the alarm, by pinching tube shut, you're simply forcing the pressure to go else where. In your case, up the turbo oil return tube and probably valve seals.

besides bad rings leaking pressure into the crankcase, is there anything else that causes blowby?

Pressure in the crankcase doesn't always mean excessive blowby, here is what can cause excessive crankcase pressure.

1. Excessive blowby, piston rings.

2. Inake pressure leaks, PCV valve or intake valve seals.

3. Poor crankcase ventilation, many due to improper re-routing of the PCV system.

 

[4BangerV8Killer]

well its hard to tell....im pretty sure its smoking between shifts (if i push it hard)

and the pcv valve is routed fine and ill check if it leaks today. is there a way to check if its my seals on the turbo? and what would account for my idle problem? iv already done a boost leak test, cleaned the throttle body.

 

[PieEyedPiper]

Also, in regards to your other threads about slow spool, well I think we just uncovered your problem. You said you have smoke coming from underneath your turbo? Possibley from just anywhere under your heatshield?

I would guess that you have a pre-turbo leak. Being that your mani is cracked, or your head to mani gasket has failed or your mani to turbo gasket has failed.
Time to rip it apart and find out for sure.

Just something to think about.

 

[oldman]

I would guess that you have a pre-turbo leak. Being that your mani is cracked, or your head to mani gasket has failed or your mani to turbo gasket has failed. Time to rip it apart and find out for sure.

I tend to think his turbo smoking problem is a direct result of excessive crankcase pressure while the dipstick tube is pinched shut causing even higher crankcase pressure, his turbo oil return capability is probably next to none causing oil being forced out of the turbo seals on both cold and hot side.

 

[4BangerV8Killer]

the smoke comes from under the turbo housing PTE saids its cool. its just the seals leak alittle when the cars cold idk.....anyway it smoked before my blowby problem. and i will definately check my gaskets

 

[kenamond]

well its hard to tell....im pretty sure its smoking between shifts (if i push it hard)

and the pcv valve is routed fine and ill check if it leaks today. is there a way to check if its my seals on the turbo? and what would account for my idle problem? iv already done a boost leak test, cleaned the throttle body.

What were the results of the boost leak test? How much did you pressurize, and how slowly did it leak down?

Did you clean your TB before or after the boost leak test. If after, did you repeat the boost leak test?

Is the smoke black or blue-white?

 

[4BangerV8Killer]

no i just did a quick little boost leak test and the smoke is white i believe, smells like oil burning not coolant. and i cleaned my tb before my leak test

 

[kenamond]

no i just did a quick little boost leak test and the smoke is white i believe, smells like oil burning not coolant. and i cleaned my tb before my leak test

I suggest doing a real boost leak test, checking your PCV valve during that test as well as the flow out of your VC breather.

Warm up the car (seals things up A LOT versus a cold motor) and pull the PCV from the valve cover for the leak test. Pressurize your intake and see how it holds and if any air is leaking out of the disconnected PCV (still connected to the vac line to the IM, but unthreaded from the VC). If the PCV is leaking badly at 15-20psi boost, that can overrun your VC breather line which is the only way out of your crankcase under boost (the PCV closes when you start boosting, so there's no place for air to go except the VC breather). That means you're pressurizing your crankcase with boost pressure. That might be one of the reasons your dipstick tube was popping out.

If the PCV is leaking, get an OEM valve from a Mitsu dealership or online (DON'T get one from Autozone, etc. - they look the same but aren't designed for turbocharged applications and will leak terribly out of the box).

If the PCV is holding, reinstall it (don't strip the VC threads by overtightening). Pull the oil cap off the VC and disconnect the VC breather hose from your intake pipe. Blow through the end of the VC breather hose and make sure it's not blocked (with the oil cap off, you should be able to blow through it). If it's blocked, the blowby you get naturally during the compression and power strokes or from leaking intake valve seals has nowhere to go, and you pressurize your crankcase. That could be another reason your dipstick tube was popping out. If that's the case, figure out if the VC nipple is clogged or if it's the vaccuum line and fix it - it's the only way to relieve crankcase pressure when you're under load.

If the VC breather is flowing fine, repeat a boost leak test with the VC breather line still disconnected from the intake pipe. Notice how much air is leaking out of the VC breather.

If a lot of air is leaking out of the breather, my guess would be intake valve seals. Oldman might have other suggestions in this situation.

If the VC breather isn't leaking much but you can't hold boost, then track down the normal boost leak locations: couplers, leaking IC, BOV flange, vac lines, TB gaskets, BISS o-ring, TB shaft seals, IM/head gasket, injector insulators. That may be causing your idle problems. You should be able to hold 20psi without leaking down more than a psi every couple of seconds.

That's my suggested path for eliminating certain things as possible suspects. But it all requires boost leak testing.

 

[PieEyedPiper]

I tend to think his turbo smoking problem is a direct result of excessive crankcase pressure while the dipstick tube is pinched shut causing even higher crankcase pressure, his turbo oil return capability is probably next to none causing oil being forced out of the turbo seals on both cold and hot side.

I like the way you think

 

[4BangerV8Killer]

thanks ill get back to you guys when thats all done

 

[Turbo Talon DL]

If you have no shaft play on the turbo then the seals are most likely going to be fine with no leaks. Inspect it anyhow but make sure you look at your exhaust valves when you pull off the turbo drain line and manifold. I have some blow-by issues also that I dont have much time to fix right now that I traced to possible bad valve guides. My compression is also within spec at 190-195 accross.

Does it smoke when you start it up, boost really hard for the first time in the mornings, and leaks from under the exhaust manifold?

 

[Turbo Talon DL]

If you have no shaft play on the turbo then the seals are most likely going to be fine with no leaks. Inspect it anyhow but make sure you look at your exhaust valves when you pull off the turbo drain line and manifold. I have some blow-by issues also that I dont have much time to fix right now that I traced to possible bad valve guides. My compression is also within spec at 190-195 accross.

Does it smoke when you start it up, boost really hard for the first time in the mornings, and leaks from under the exhaust manifold?

I fixed this leak. Car starts in 3 compression strokes in cold winter weather. Compression is still the same.

 

[Hcaruso4]

i had this same problem and a leakdown test revealed the blow by was being caused by bad piston rings