North American Turbocoupe Organization



Pressurized my intake, blew the breather off, is this right??
Kev Offline
Posting Freak
#1
I pressurized my intake today after building a little pressure fitting that goes over the front of the turbo. I found a HUGE leak on the hose that goes to the breather on top of the intake and fixed that up. Then I pressurized the intake again and didn't hear any leaks. It just sounded like the system was filling with air and then POP goes the intake cap thingy. Is this supposed to happen? I pressurized to 30psi even though I only boost to 18. I'll be looking at a T3 in the near future and wanted to be safe. I took the pcv valve out a couple days ago and sprayed carb cleaner through it. I couldn't blow through it so I assumed it's good. Any ideas or thoughts? I'm not even sure that I have a problem. Thanks

Kev
Kev
1988 TC 5spd
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grey88smokin Offline
Posting Freak
#2
Is the PCV still connected to the turbo? Was there air being fed from the inlet to the breather? That's the only thing I can think of that would cause that other than the PCV.
84 SVO 1C
08 MKZ
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junkedturbo Offline
Senior Member
#3
What do you mean by "intake cap thingy"
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Kev Offline
Posting Freak
#4
The PCV is not connected to the turbo. It is in it's original place right beside the distributor. It is plumbed just as it was from the factory except that I have a clamp holding it on just because. When I say "intake cap thingy", I mean the breather on top of the valve cover. It is what is popping off when I pressurize the system. I can feel a little air leaking around the oil cap as it is pressurizing, but that is not what my question is about. On the side of the turbo inlet, there is a hard line that goes to the breather on top of the valve cover. Since I am pushing air into the turbo, then I am also pushing air into the valve cover via that hard line. So it makes sense that I would feel air there and that the breather would pop off since it seems there is no where for it to go. Where does is go? I guess I don't fully understand this system because I don't have any idea why that hard line feeds boost into the valve cover or if it even does at all.

Kev
Kev
1988 TC 5spd
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grey88smokin Offline
Posting Freak
#5
That line helps to evacuate the crank case. The low pressure before the turbine helps keep pressure out of the VC and oil pan.

Your not just pressurizing the intake, your pressurizing the oil pan and VC.

You need to block or bypass that line, you only want to pressurize the intake and not the entire engine. This is why your breather is leaking.

Everything you posted so far seems normal, just make sure your not sending that compressed air into the PCV or the breather. Then you can look for leaks in the intakes, throttle body or wherever else they might pop up.
84 SVO 1C
08 MKZ
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Kev Offline
Posting Freak
#6
Quote:Originally posted by grey88smokin:
That line helps to evacuate the crank case. The low pressure before the turbine helps keep pressure out of the VC and oil pan.

Your not just pressurizing the intake, your pressurizing the oil pan and VC.

You need to block or bypass that line, you only want to pressurize the intake and not the entire engine. This is why your breather is leaking.

Everything you posted so far seems normal, just make sure your not sending that compressed air into the PCV or the breather. Then you can look for leaks in the intakes, throttle body or wherever else they might pop up.
Sweet, I really appreciate it. I wonder why I have never read to block that breather tube when pressurizing the intake before. Someone should definitely write up an article on this subject and put it in the FAQs.

Kev
Kev
1988 TC 5spd
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jmthunderbirdturbo Offline
Posting Freak
#7
you mean your TB doesnt leak? your PCV doesnt bleed? none of your vac connections leak? at all? i think id store that motor in a glass case...my cars BOTH leak like screen doors on submarines...

-J0N
APRIL 2018 - LOOKING FOR A NEW CAR. PM me if you have an 87-88 roller or cheap TF for sale.
1988 TC 5MT-Blue/Blue check-off car. resto-project.
2006 Honda Odyssey 5AT, baby-mobile.
2013 F-150, 5.0, 6AT, 4x4, snow white paint.
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Kev Offline
Posting Freak
#8
So far, I've found a tiny leak between the upper intake and the throttle body. I'll get a new gasket for it, test the pieces with a straight edge and grind down any high spots. Then I'll pressurize again to see if I can find any more. I'm still getting low vacuum at start up. Well, it's low for about 30 seconds, then it goes to 19. The car instantly dies when I try to start it when it's cold. (I mean the engine is cold; not that it's cold outside). The second start it struggles, but keeps the start and the idle levels out in about 30 seconds to a minute. When it's hot outside, it acts like I'm on the second start up and it doesn't do the dieing thing. Weird, huh?
It seems that something (rubber maybe) isn't sealing unless it's warmed up, but it takes less than a minute to warm it up good enough to seal. I'd listen to any suggestions if anyone has any. For the time being, I'm looking at anything that leaks vacuum when the engine is cold, hence the pressure test.

Kev
Kev
1988 TC 5spd
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Pete D Offline
Administrator
#9
Cold start vacuum will be lower.
Pete Dunham


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Ryan H Offline
Posting Freak
#10
With leaks that minimal, I doubt thats what is causing your rough starting issue. Just my two cents. Fix the leak at the throttle body and get back to us. The gasket there should be thick enough to seal the problem, chances are it is old and brittle.
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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