Oil In Intake Manifold

87GTSnake

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A little over a month ago i did switched to a cobra intake on my 87 and i also put an accufab tb on there at the same time. About two weeks after that the car started smoking when I started it up and i could not figure out why. So the other day the tb started sticking so i went in to clean it and found that i am getting oil sucked up into the tb and into the intake.

Now i know that this is obviously causing my smoking problem but i cannot figure out why im getting oil in there. When i put the intake on i replaced the pcv valve, screen and grommit as well as all the vaccum lines.

I dont know if this could effect it but i also disconnected the egr and got rid of all the smog pump lines and capped off all the vac lines that were used for them.

I'm really not looking forward to taking the intake back off since its not exactly warm out, but i know im gonna have to. I just need some idea as to what im looking for when i get in there cause im drawing a blank.

Any help would be greatly appreciated.
Thanks.
 
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srothfuss

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ON your cobra manifold: Did the PCV hole have the baffle in place? some of the aftermarket (FRPP made in china) parts don't and a lot of oil gets sucked up through this hole. IF this is the case, you can install a Air/Oil seperator for a few dollars and that will clear up your issue.

IF your lower intake has the baffle, install the seperator anyways to eliminate the possibility and then look at the line running from the filler neck to the TB.
 

87GTSnake

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From what i remember the lower did have the baffle in it, but i think ill put an oil seperator on there just incase. From what i can tell it seems like the oil is comming in through the line that comes from the valve cover.

I thought about plugging the tb and leaving the line off the valve cover open to see what happens but i really dont want oil spewing out all over my polished engine compartment:notnice: .
 

HISSIN50

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87GTSnake said:
I thought about plugging the tb and leaving the line off the valve cover open to see what happens but i really dont want oil spewing out all over my polished engine compartment:notnice: .
If you are still SD, that should work fine. I would put a breather on the end of the oil-filler nipple since that line's primary purpose is to allow air into the motor.

FWIW, if you were spewing oil into the intake via that oil filler to TB line, that suggests that the PCV valve and line are overwhelmed or malfunctioning. If worst at WOT, that suggests the blowby is too much for the [lower] PCV valve and line, and the TB to oil filler line is being recruited to vent blowby. And in your case that blowby is a little oily.

Good luck
 

87GTSnake

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HISSIN50 said:
If you are still SD, that should work fine. I would put a breather on the end of the oil-filler nipple since that line's primary purpose is to allow air into the motor.

FWIW, if you were spewing oil into the intake via that oil filler to TB line, that suggests that the PCV valve and line are overwhelmed or malfunctioning. If worst at WOT, that suggests the blowby is too much for the [lower] PCV valve and line, and the TB to oil filler line is being recruited to vent blowby. And in your case that blowby is a little oily.

Good luck
The car is converted to mass air so i probably shouldnt put a breather on there, correct?

Also, could this problem have anything to do with the lower intake not being seated correctly, becasue when the car is running if you stick your head as close to the back of the intake as possible i beleive i can hear a small vaccume leak, but then again it might not be one.

Thanks.
 

vristang

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I went through this recently with the motor in my sig. I have not yet found a great solution.
Yes the lower intake manifold can cause some problems, but only if it has slipped quite a bit. When I dropped the lower intake manifold in place the lower intake gasket slipped down. It slid just far enough to create a vac leak common to the front left runner and the lifter valley.


This is what my TB looked like.

The motor was still hot when I took this so you can see some smoke deep in the bowels of the intake. All of this oil had come through the vac leak described above. The TB to VC line was bone dry.
If the problem is the lower gasket you should be able to see either the forward or aft end of the top of the gasket sitting lower than the other. A visual inspection should be adequate for this.

many aftermarket TBs have whistle to them. Mine is pretty loud at idle. Some think it sounds like a supercharger.:rlaugh:
Stay away from the breathers on the VC, unless you pitch the pcv (which I don't recommend). A breather cap will basically create a vac leak through the crankcase via the pcv.
I have installed an oil seperator, and it worked fairly well. I also installed a 1/8" restrictor in the TB/VC hose, to help limit the volume of air passing through the pcv. Both of these did help, but I am still having some oil trouble.
jason
 

HISSIN50

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I agree with Jason not to do a breather since you are MAF (with a SD set-up, there is no unmetered air issue).

Good luck.
 

87GTSnake

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vristang said:
I went through this recently with the motor in my sig. I have not yet found a great solution.
Yes the lower intake manifold can cause some problems, but only if it has slipped quite a bit. When I dropped the lower intake manifold in place the lower intake gasket slipped down. It slid just far enough to create a vac leak common to the front left runner and the lifter valley.


This is what my TB looked like.

The motor was still hot when I took this so you can see some smoke deep in the bowels of the intake. All of this oil had come through the vac leak described above. The TB to VC line was bone dry.
If the problem is the lower gasket you should be able to see either the forward or aft end of the top of the gasket sitting lower than the other. A visual inspection should be adequate for this.

many aftermarket TBs have whistle to them. Mine is pretty loud at idle. Some think it sounds like a supercharger.:rlaugh:
Stay away from the breathers on the VC, unless you pitch the pcv (which I don't recommend). A breather cap will basically create a vac leak through the crankcase via the pcv.
I have installed an oil seperator, and it worked fairly well. I also installed a 1/8" restrictor in the TB/VC hose, to help limit the volume of air passing through the pcv. Both of these did help, but I am still having some oil trouble.
jason
My tb looked exaclty like yours. I actually had to replace the tb gasket already because oil was seeping out of the bottom of it.

I didnt think it was possible for the oil to get that far up the intake which was why i was assuming it was comming in through the tb/vc hose.

I guess i'll be changing that lower gasket.

Thanks For the Help.
 

50canuck

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oil in intake

i have same issue with my new cobra i/T,on my 86gt, oil is being sucked up from pcv valve, when I remove pcv and just use breather cap on oil fill, no oil comes up. I may pull it off this winter, and modify baffle, but i'm not sure if it will help.The only thing that has stopped oil so far is bypassing pcv. I have seen a few posts from other sites with same issue with new cobra I/T's.
 

18mustangs

New Member
Cobra intakes are known for increased oil in the PCV (two vacuum connections as opposed to one???) which is why it's important to check for the baffle on the underside. And Vristang is right about the breathers...so summary baffles yeah, breather caps boo! hehehe
Tim