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Old 09-15-2009, 12:18 AM   #1
gopsu
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Default Blown cam shaft seals while performing DIY leak check... question for guru

I had pressurized intake manifold by connecting DIY leak check tool directly into throttle body to detect source of leak (tuned for 19psi, but only hitting 14-15psi). Everything went fine until when I heard something pop at around >15psi. We also found leak on one of intake manifold gasket which was later replaced.

It turned out that pressure had caused cam shaft seals to blow....

I would like to repeat the test, but am afraid of blowing cam shaft seals again. Any idea what I did wrong? I've heard that PCV should have been disconnected, but wanted to verify.

Thanks in advance.
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Old 09-15-2009, 12:24 AM   #2
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I'll be the first to ask...

How do you know you were only putting in 15psi.

As in, did you have a regulator hooked up to the system only allowing 15psi?

I'm wondering, could it have something to do with the position of the valves, etc when the car is off.

I've thrown 30psi+ into the motor and that never happened.
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Old 09-15-2009, 08:35 AM   #3
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I know for sure it was less than 19psi as my buddy was watching the boost gauge. When you were throwing 30psi+ into the motor, did you plug two hoses off of breather cover?
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Old 09-15-2009, 12:59 PM   #4
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You shouldn't have to plug any breather hoses because the PCV will shut when the manifold pressure goes positive. The heads should not have been pressurized when you did your test unless you did something very wrong, but for the life of me I can't figure out what...unless you have a defective PCV valve.

Have you messed with any of your PCV/breather hoses, catch can, etc?
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Old 09-15-2009, 01:01 PM   #5
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That's very interesting... I plugged two hoses off of breather cover anyway when performing this test.

What may have caused cam shaft seals to blow then? Any idea?
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Old 09-15-2009, 01:06 PM   #6
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Take the oil cap off if you don't want to blow out the cam seals.
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Old 09-15-2009, 01:17 PM   #7
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Quote:
Originally Posted by gopsu View Post
That's very interesting... I plugged two hoses off of breather cover anyway when performing this test.

What may have caused cam shaft seals to blow then? Any idea?
Maybe it's because you plugged the breather hoses.
When you pressurize the motor, especially cold, some air will leak by the piston rings into the crankcase. If you don't have any breathers hooked up to vent this air, the crankcase and head pressure will build, and might be why you blew out your cam seals.

removing the oil cap would accomplish the same thing as having the breather hoses hooked up.
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Old 09-15-2009, 02:21 PM   #8
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Thanks for the suggestion. It was one painful lesson I learned (had to get new TB b/c oil sprayed all over the place).
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Old 09-15-2009, 08:14 PM   #9
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Is it normal for air to leak by piston rings on a healthy engine regardless of engine temperature?

I am not sure if tuners unplug two breather hoses when performing pressure test?
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Old 09-15-2009, 09:20 PM   #10
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Quote:
Originally Posted by gopsu View Post
Is it normal for air to leak by piston rings on a healthy engine regardless of engine temperature?

I am not sure if tuners unplug two breather hoses when performing pressure test?
Yes it's normal
Maybe what you were reading is people unhooking the breather hoses from the turbo inlet when pressurizing the intake system? They should be removed in that case, they should not be removed when pressurizing the manifold though.
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Old 09-15-2009, 11:36 PM   #11
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Kind of confused - how can you pressurize intake system with breather hoses unhooked?

Bottom line is: remove oil cap when performing pressure test, right?
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Old 09-15-2009, 11:52 PM   #12
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Quote:
Originally Posted by gopsu View Post
Kind of confused - how can you pressurize intake system with breather hoses unhooked?

Bottom line is: remove oil cap when performing pressure test, right?
Personally if I go over 10 psi I take the cap off to save the cam seals. If you want to be totally safe take it off no matter what.
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Old 09-16-2009, 12:11 AM   #13
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Quote:
Originally Posted by gopsu View Post
Kind of confused - how can you pressurize intake system with breather hoses unhooked?

Bottom line is: remove oil cap when performing pressure test, right?
You would plug the holes. You have to plug the breathers when you pressure test the intake otherwise it will blow the air into the intake manifold as well as pressurize the crankcase. When you pressure test the intake manifold the PCV closes so you don't have to worry about plugging the breathers, but if you plug them you could have problems with pressurizing the crankcase, which you seem to have.
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Old 09-16-2009, 12:37 AM   #14
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Thanks guys - when repeating pressure test, I will make sure to unplug breather hoses & remove oil cap this Thursday.
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Old 04-24-2013, 08:30 PM   #15
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Bumping this. I think this same thing just happened to me. Car never leaks oil, but we did a boost leak test today and sure enough heard a pop and then it didn't seem to build pressure (referencing boost gauge)...

Went for a drive and it started smoking from the header so I jacked it up and there's oil all over underneath. Seems to be coming from behind the timing area near the passenger side header flange. Car still builds boost.

The only thing we blocked off was the lines going to the check valve next to the alternator since we tested from the inlet.

I'm guessing its the cam seal. Does it just push oil when this happens or does it need to be replaced now?
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Old 04-24-2013, 08:52 PM   #16
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Never mind. Let the car sit and it still leaks at idle. ****.
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Old 04-27-2013, 10:10 PM   #17
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You pressurized the crankcase and blew out the cam seals. You can't drive the car until you replace them, so dive in.

Hopefully you didn't destroy the engine by driving it around with no cam seals, but listen for rod knock after you replace them just in case.
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Old 04-28-2013, 09:13 AM   #18
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Link to a good diy manifold leak test setup???
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Old 04-28-2013, 09:39 AM   #19
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Quote:
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Link to a good diy manifold leak test setup???
http://forums.nasioc.com/forums/show....php?t=2205161
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Old 04-29-2013, 09:13 PM   #20
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Quote:
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Read through the leak test link,. Do you need all the valves closed to perform the manifold leak test and how do you go about making sure they're all closed? If you don't have to close them why?
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Old 04-29-2013, 09:27 PM   #21
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Quote:
Originally Posted by k mier View Post
Read through the leak test link,. Do you need all the valves closed to perform the manifold leak test and how do you go about making sure they're all closed? If you don't have to close them why?
I assumed that you were looking to boost leak test your intake tract and not a compression and leak down test.
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Old 04-29-2013, 09:53 PM   #22
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Yes, having an idle issue that is proving hard to resolve have leak tested the fmic and piping, now have to check throttle body intake to heads for vacuum leak.
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