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Discussion Starter · #1 ·
Hey guys, I need a little input to see if my thinking is correct.


I just picked up an '87 Shelby Z. The last owner put many mods on it, and sold it when he thought he blew the turbo and didn't want the project anymore. Lucky me the turbo is fine, but it is still blowing oil out all over.

I found the oil is coming from dip stick and the PCV. Well, the last owner put an open air filter and tube to the turbo, and instead of tying the PCV back into it, put a breather on it and put it over the transmission.

My reasoning: The PCV has a vacuum on it from the intake manifold. BUT when the turbo is boosting the intake manifold is blowing air back into the PCV, instead of sucking. The sucking should then come from the intake right? And since they are no longer tied together the boost in the intake manifold is blowing oil out the breather. AND since it looses it's vacuum the crankcase builds pressure and blows the dip stick.
SO, if I make a nipple for the intake tube it will replace the vacuum that was once on the PCV.

I need to make sure this is correct before I make the nipple and have the thing blow oil into the turbo.


Thanks guys!!
 

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You've got blow-by. Do a compression test.
Test 1st and if its OK, then read below


Hey guys, I need a little input to see if my thinking is correct.


I just picked up an '87 Shelby Z. The last owner put many mods on it, and sold it when he thought he blew the turbo and didn't want the project anymore. Lucky me the turbo is fine, but it is still blowing oil out all over.

I found the oil is coming from dip stick and the PCV. Well, the last owner put an open air filter and tube to the turbo, and instead of tying the PCV back into it, put a breather on it and put it over the transmission.

My reasoning: The PCV has a vacuum on it from the intake manifold. BUT when the turbo is boosting the intake manifold is blowing air back into the PCV, instead of sucking. The sucking should then come from the intake right? And since they are no longer tied together the boost in the intake manifold is blowing oil out the breather. AND since it looses it's vacuum the crankcase builds pressure and blows the dip stick.
SO, if I make a nipple for the intake tube it will replace the vacuum that was once on the PCV.

I need to make sure this is correct before I make the nipple and have the thing blow oil into the turbo.


Thanks guys!!

PVC ideas are debatable, but you have it correct IMO. Here are a couple options I've found that work for others when the intake is in boost and pcv is not getting vac from the intake.

-Some people just run the hose down low on the car(kind like you describe over the trans), the air moving under the car is supposed to pull a little vac. The positive would be that you keep some oil out of the turbo.

-You can hook it to the air filter pipe like you mention. But I wouldn't use a nipple on the pipe. Most cut the hose at an angle(like 45deg, slashcut) then just insert into the air filter pipe with the slash facing the turbo so air is not pushed in the hose, its pulled out towards the turbo.

-You can use an exhaust vac setup, some people say it works others say they get positive pressure instead of vac, so YRMV. Hook a hose from the pvc to a slash cut pipe in the exhaust to draw vac in all conditions(boost and vac), this would take all the oil out of the intake tract.

-most expensive option is using a vac pump to pull vas but i haven't seen any on TD's yet.

Some things to remember, many believe that pulling vac from below the rings(or crankcase) is best, this also helps oil drain from the head and block to the bottom end where its needed. People have done this using unused ports on the block to pullvas from instead of the VC. Personally I'm working on pulling vac from the dipstick tube(instead of the VC) because it easier for my situation. At least one other says that they do this method using a nipple welded to the dipstick tube and it works great.
 

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Discussion Starter · #4 ·
I was gonna run the tube into the intake with an oil catch can.

I havn't done a compression test yet, but the engines runs really well and all the spark plugs looked nice.
I was expecting more power from a stage 5 computer and a pegged boost guage. I was thinking it was running rich, but low compression is a possibility. I hope the rings aren't bad, because I just want to drive the damn thing so I can park my truck.
 

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Discussion Starter · #6 ·
Well I drove the car to and from work today. It drove really nice...spooled well.
The oil dip stick stayed down nice and tight, but it's still blowing oil out the PCV breather...ONLY the PCV breather.

I havn't done a compression check yet, but I have to assume that the PCV has to be tied into the intake.
 

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Discussion Starter · #8 ·
Compression test shows pistons 1 and 3 at 50psi.

I can only assume the rings are bad. The last owner decked it out with performance stuff, and she runs about 18-20psi boost. I know the block should handle that, but I don't know how the last guy drove, or cared for the car.
 
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