Boost leak under exhaust manifold

[iguanahotsauce]

So yesterday I was finally able to do a boost leak test after I replaced my bad new PCV valve (Made the stupid mistake of buying one from the auto parts store) I found a few leaks. One in coming from the ISC, so I replaced the o-ring and that one is fine now. Another leak was coming from the throtte body shaft seals so I replaced those and now there is no leak from the throttle body. I have once more leak that I cannot find where it is. It's not huge but it's not small either I pressurize the system to about 8 psi and it's at 0 in about 30 - 45 seconds. It's coming from somewhere under the exhaust manifold. I was going to attempt to take off the manifold but I can't even get the stupid heat shield off so I don't think that's going to happen. Any help would be great

 

[skatershawn]

is the tester on the turbo correct??
There shouldn't be much the boost would be leaking from, from under the Exhaust mani, unless you mean "intake" mani!!

If it IS coming from the exaust area, i would have to guess the compressor housing on the turbo is, weirdly, somehow leaking, or its leaking from the j-pipe!!
Other than those, i wouldn't know where to look!

 

[iguanahotsauce]

Yes the tester is on the turbo. I'm pretty surrender it's from the exhaust manifold but I'm still very new to working on cars so I might be incorrect it's coming from the right of the turbo under the manifold that is over the turbo and to the left of the oil dipstick

 

[mikus]

it's possible that your valves are open on both sides while testing, and you're blowing air through the head, then hearing a leak on the exhaust side.

It'd be nice to hunt and address it, but exhaust side small leaks aren't nearly as big a deal as intake side/metered air leaks.

 

[skatershawn]

Put the engine in top dead center to insure the valves are closed!!
If you do that then there should be very very minimal, if any, air escaping from the valves!

 

[iguanahotsauce]

How do I get the engine to TDC? I know I have to rotate the crank pulley but can I rotate it with a wrench or do I just have to keep turning the key until I get it close?

 

[dsmdeliveryboy]

How do I get the engine to TDC? I know I have to rotate the crank pulley but can I rotate it with a wrench or do I just have to keep turning the key until I get it close?

There is 2 ways to find TDC:

1. Stick a screwdriver in cyl 1 and rotate the crank pulley till the screwdriver doesn't go up anymore(I do not recommend this).

2. They make a whistle you can screw in where your spark plug would go and you crank till it stops whistling(this is the proper way to do it).

 

[iguanahotsauce]

But isn't there a timing mark that the mark on the crank pulley will line up with for TDC? And what I was asking is how do I rotate the crank pulley? Can I do it with a wrench?

 

[9!'clipseDOHC]

You could be leaking from the compressor cover o-ring. It's a pretty common place for a boost leak. The part number for the o-ring is MD613776 and can be purchased from JNZtuning. It's pretty involved to replace, you have to disassemble the turbo itself. Follow these steps up until you remove the center housing. Here is a picture of my center housing when I replaced mine (that large o-ring is the one that needs to be replaced):

 

[Bud92gsx]

There is 2 ways to find TDC:

1. Stick a screwdriver in cyl 1 and rotate the crank pulley till the screwdriver doesn't go up anymore(I do not recommend this).

2. They make a whistle you can screw in where your spark plug would go and you crank till it stops whistling(this is the proper way to do it).

You can do it with a screwdriver yes..But it is not reccomended..The key to doing it this way is not to drop the screwdriver on to the piston..Do it slowely as to not drop it onto the piston..
Also there are two sets of timing marks on the cam gears, so make sure you get the right ones..

Also the heat sheild is only 3 bolts..Are are easiest to get off when the manifold is hot..If the manifold is not warm you could snap the bolts off..It really sucks when you snap bolts off..Also a little wd40 or penatrating oil will help as well..But then you need to burn it off before you take off or your going to think under your hood is smoking from something else..

 

[9!'clipseDOHC]

I don't think TDC is where all the valves are closed. I've heard 30* ATDC and 40* BTDC. Check out this link for more info: http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/169435-boost-leak-test-how-boostpro-net-tester.html

 

[iguanahotsauce]

You could be leaking from the compressor cover o-ring. It's a pretty common place for a boost leak. The part number for the o-ring is MD613776 and can be purchased from JNZtuning. It's pretty involved to replace, you have to disassemble the turbo itself. Follow these steps up until you remove the center housing. Here is a picture of my center housing when I replaced mine (that large o-ring is the one that needs to be replaced):

Yeah that's what I figured when I was searching through different threads. I just wasn't sure since there wasn't a lot of threads on it. When you say pretty involved, how involved do you mean? Would I be able to get it done in a couple hours? Also in the instructions in disassembling the turbo it says to have it rebalanced. Would I need to have it rebalanced after disassembling it to this point or does it only need to be rebalanced if it is completely taken apart?

 

[9!'clipseDOHC]

Yeah that's what I figured when I was searching through different threads. I just wasn't sure since there wasn't a lot of threads on it. When you say pretty involved, how involved do you mean? Would I be able to get it done in a couple hours? Also in the instructions in disassembling the turbo it says to have it rebalanced. Would I need to have it rebalanced after disassembling it to this point or does it only need to be rebalanced if it is completely taken apart?

You have to pull the turbo and partially disassemble it, that's what I meant by involved. There is a c-clip holding the cover on which is a bear to take off and put back on. You will not need to have it balanced if you only disassemble it that far. Based on your earlier post about having trouble just removing the heat shield, I think it will take you a lot more then a couple of hours.

I was going to attempt to take off the manifold but I can't even get the stupid heat shield off so I don't think that's going to happen. Any help would be great

 

[Bud92gsx]

If you have never taken a turbo off before the first time is a real PITA..Hell the first time getting the manifold off is also a PITA..

 

[iguanahotsauce]

You have to pull the turbo and partially disassemble it, that's what I meant by involved. There is a c-clip holding the cover on which is a bear to take off and put back on. You will not need to have it balanced if you only disassemble it that far. Based on your earlier post about having trouble just removing the heat shield, I think it will take you a lot more then a couple of hours.

The problem I was having with the heat shield was that I couldn't get my socket on two of the bolts. One of them was blocked by the radiator and I don't remember what was blocking the other one but I couldn't get my socket in there

 

[elterror]

Did you ever find the leak? I am hearing the same around that area

 

[romeen]

I'm not sure if this applies to your NT motor but on the 4G63 there is a small hole/port in the passenger side wall of the #4 exhaust port. This is for the EGR system. The EGR valve allows some of the exhaust gas back into the IM but is not supposed to allow boost pressure to go from the IM to the EM. A faulty/leaking EGR valve may have been the OP's problem.

 

[elterror]

I'm not sure if this applies to your NT motor but on the 4G63 there is a small hole/port in the passenger side wall of the #4 exhaust port. This is for the EGR system. The EGR valve allows some of the exhaust gas back into the IM but is not supposed to allow boost pressure to go from the IM to the EM. A faulty/leaking EGR valve may have been the OP's problem.

Well as you can see is a non turbo shell with turbo... and egr is blocked off.

 

[9!'clipseDOHC]

Did you ever find the leak? I am hearing the same around that area

As I already mentioned for the OP, look into the compressor cover o-ring. It is a very common place for boost leaks. While doing a boost leak test, feel around hte inner lip of the compressor cover for air, if you feel air or hear the sound change, then its the o-ring.

 

[elterror]

As I already mentioned for the OP, look into the compressor cover o-ring. It is a very common place for boost leaks. While doing a boost leak test, feel around hte inner lip of the compressor cover for air, if you feel air or hear the sound change, then its the o-ring.

OP? Ok ill check it again. Will this cause anykind of high idle or surge?