Quick Boost Leak Question

[ChvyKc]

I finally figured out that I was losing tons of boost through my stock bov. I borrowed a buddies Greddy and got it on there and did another boost leak test this morning. The bov is definately not leaking but now I have a small amount of air coming out of the valve cover vent on the tranny side of the motor. Just wondering if you guys had any ideas what would cause that? Is it the valve stem seals?

 

[ChvyKc]

Update: I need to try to figure out what is going on with the car. I have done four or five boost leak tests today but I can't find any other problem but this one. I am unable to hold more than 15 pounds on my 16G through redline. Any help will be appreciated, I have a big race tomorrow and would like to try to figure this out tonight.

 

[dub2gsx]

Did you change anything recently other than the bov? Is it stutering or is it just losing it's boost? What psi is your boost set to?

Brian

 

[ddavisaf]

Change your PCV valve.

 

[ChvyKc]

Did you change anything recently other than the bov? Is it stutering or is it just losing it's boost? What psi is your boost set to?

Brian

Boost controller is basically closed. So it should be around 24-25 pounds. I was thinking that it was the PCV valve letting air into the valve cover but I have it blocked off now and it is still leaking air inside the valve cover. I don't understand how the air is getting in there. Nothing else has changed on the car. The only reason that I changed the BOV is because I thought that was the reason for the huge boost leak.

 

[ddavisaf]

Try rotating the engine 30 degrees and running the boost leak test again. It's normal for air to escape past the turbo on a static boost leak test, but could cause the air to escape up into the cylinder head if the valve seals are going bad. Do you hear any air escaping into the exhaust also?

 

[ChvyKc]

Try rotating the engine 30 degrees and running the boost leak test again. It's normal for air to escape past the turbo on a static boost leak test, but could cause the air to escape up into the cylinder head if the valve seals are going bad. Do you hear any air escaping into the exhaust also?

I took the turbo out of the equation. The boost leak tester is hooked to the inlet of the side mount so there is no pressure actually going to the turbo itself when I do the test. Basically I am just testing the intercooler, upper intercooler pipe, bov, and the intake manifold.

It would be hard for me to say for sure if I could hear air going into the exhaust. I can definately hear air leaking but I don't know if it is coming from the exhaust manifold or not. I'm stumped

I think god just doesn't want me to get that 12 second time slip. I'm damned to running 13.4's for the rest of my life.

 

[dub2gsx]

You may just need to block off your egr with a plate! Mine was leaking too! But I'm not sure I lost that much boost! You can make one or buy one sense it looks like you are wanting to run soon just make one, it doesn't take that long! Have you taken your head off recently and if so did you replace the intake mani gasket? Or if you had a back fire that went to the intake mani it could have f'ed something up! If the verdict is the head?

Aside from the leak your cams could be too big for your turbo, I know if the turbo isn't running enough cfm for the size of the cams that it will cause your boost to drop hard because it isn't pushing the cams hard enough! Has this been this way sense you put in the cams? If its not that then your may need to look at the head! Start with the small things then work your way to the valve seals! How many miles are on that head?

Buy looking at your time slip it looks like you are loosing power at the top end, All your times look good, your 60 foot 1.8 and your 1/8 mile is around 81 mph at 8.5. With those cams you should be pushing more at the top end with higher traps than 99 mph. If you look at mine I am running a 2g head with no cams, pegged at 19 psi and a turbo of simular flow, but with a 105 trap and 13.0 time, you should be able to out flow me in almost all aspects! So i personaly wish you the best and have faith your car is close.


Brian

 

[ChvyKc]

You may just need to block off your egr with a plate! Mine was leaking too! But I'm not sure I lost that much boost! You can make one or buy one sense it looks like you are wanting to run soon just make one, it doesn't take that long! Have you taken your head off recently and if so did you replace the intake mani gasket? Or if you had a back fire that went to the intake mani it could have f'ed something up! If the verdict is the head?

Will the EGR leaking cause air to move into the upper part of the head? I have never had the head off and it has about 70,000 miles on it since the guy that had it before me had it rebuilt. I have definately had no backfires through the intake manifold. I actually just put a Magnus intake manifold gasket on it about two months ago which took care of one of the leaks that the original gasket was making.

Aside from the leak your cams could be too big for your turbo, I know if the turbo isn't running enough cfm for the size of the cams that it will cause your boost to drop hard because it isn't pushing the cams hard enough! Has this been this way sense you put in the cams? If its not that then your may need to look at the head! Start with the small things then work your way to the valve seals! How many miles are on that head?

The cams are not an issue. It was holding boost before this past week. I ran a buddy in his LS1 camaro from a roll and finally pulled him. The car has been extremely strong and I know the consequences of running bigger cams with a 16G but you can just fell the car fall off up top and it just recently started doing that. The car was just a beast when I first put the cams in there but something happened to make it loose a hell of a lot of power up top.

Buy looking at your time slip it looks like you are loosing power at the top end, All your times look good, your 60 foot 1.8 and your 1/8 mile is around 81 mph at 8.5. With those cams you should be pushing more at the top end with higher traps than 99 mph. If you look at mine I am running a 2g head with no cams, pegged at 19 psi and a turbo of simular flow, but with a 105 trap and 13.0 time, you should be able to out flow me in almost all aspects! So i personaly wish you the best and have faith your car is close.

Don't look at my time slips. That time was before the water injection/sidemount/cams. After I installed those three parts the car has really picked up a lot up top. Just like I said before, when I ran my buddy the car was just screaming up top. If I would have run him from a dig he would have had no chance. I was able to pull him by a car and a half from a second gear roll, but there is no way that I could do that now with the boost falling off like this.

 

[dub2gsx]

Will the EGR leaking cause air to move into the upper part of the head?

At top dead center almost no air should be moving through the head. I'm not sure if the leaking egr would go into the head but my guess would be that it does sense it's atached to the intake mani. The only other thing that could be wrong other then valve seals would be the tb. A common part of the tb that goes out is the o ring and the shaft that goes through the plate some times will let air pass into the intake mani when closed, and when you hit throttle it will leak really bad out next to the throttle cable. When I had to replace the tb I found my leak by when I had 20 psi built up during boost leak test I would open the throttle to see if it leaked out the shaft when open and it was a horrilble leak. So I bought one from this guy:

http://cgi.ebay.com/ebaymotors/1990-63mm-Throttle-Body-1G-DSM-Eclipse-Talon_W0QQcmdZViewItemQQcategoryZ33558QQitemZ8072018799QQrdZ1QQsspagenameZWDVW

It never leaks now and it's not too bad of a price for the quality of work it is. If that isn't it then I hope it's not the valve seals, but if it is then you get a really good excuse to get a rebuilt race head

Brian

 

[ChvyKc]

At top dead center almost no air should be moving through the head. I'm not sure if the leaking egr would go into the head but my guess would be that it does sense it's atached to the intake mani. The only other thing that could be wrong other then valve seals would be the tb. A common part of the tb that goes out is the o ring and the shaft that goes through the plate some times will let air pass into the intake mani when closed, and when you hit throttle it will leak really bad out next to the throttle cable. When I had to replace the tb I found my leak by when I had 20 psi built up during boost leak test I would open the throttle to see if it leaked out the shaft when open and it was a horrilble leak. So I bought one from this guy:

http://cgi.ebay.com/ebaymotors/1990-63mm-Throttle-Body-1G-DSM-Eclipse-Talon_W0QQcmdZViewItemQQcategoryZ33558QQitemZ8072018799QQrdZ1QQsspagenameZWDVW

It never leaks now and it's not too bad of a price for the quality of work it is. If that isn't it then I hope it's not the valve seals, but if it is then you get a really good excuse to get a rebuilt race head

Brian

I rebuilt the TB about three months ago and I know that it's not leaking. The noise that the leaking air is making is not coming from that part of the motor. I just need to figure out how the air is getting into the top part of the head. I understand that if the TB is leaking that it could possibly leak into the manifold and into the lower part of the head, but I actually have air building up in the upper part of the head for some reason (where the cams sit) If the TB was leaking then that wouldn't cause that to happen. It would just cause air to go past the TB and into the motor which would be fine with me if that was the only problem.

I ended up taking it to the track yesterday and just trying to run it for what it would do. It actually ran better than I thought that it would. The car ran a 13.035 @ 104.92 with a 1.700 sixty foot. A buddy of mine actually ran that time. I was having problems getting the car into second because I was shifting out of first to late and the synchro wasn't able to handle the rpms. He was able to get the car into second and run that time. Once he figured that out, the tranny was starting to get really bad and actually started popping out of first gear so I put it back on the trailor and we went home. I ran three 13.3's missing second gear so the car has the power to make it into the 12's if the tranny was there. Looks like it's at least time for a tranny build. I guess I might as well go ahead and pull the head off and at least rebuild it while I am at it (maybe with a little port work and some oversized valves )

 

[dub2gsx]

Good run for it not having all of its power, that's about what I ran at full power
I did some research on the egr leaking and if you have ever seen the holes they are big and if it's leaking then it would be a huge leak! Take a look at it and block it off anyways because you don't have to have it! Just another emisions thing that can hurt your car. It would also leak into your head and out of your exhaust side, even at top dead center! If your valve seals are going out then I'm not so sure you could have pulled that good of a time, hell with that big of a boost leak I didn't think you would run that good anyways so the only way to tell is try blocking off the egr and then if your gonna take the head off anyways then blocking it can't hurt. If the valve seals were going out then wouldn't your car be burning oil when at idle. Just like a lot of the Crown Victorias do? Well anyways best of luck to you.

Brian

 

[ChvyKc]

I ended up asking FFWD what they thought about the boost leak that I have and he said that either the piston rings are leaking boost into the crank case and causing pressure to build up in the upper part of the head or that the valve seals are leaking, but that would probably mean that a lot of them are leaking to build pressure that fast. In other words, my motor is just crapped out on me. Guess it's time for a rebuild.

I ended up breaking the lower end tank on my side mount. The lower intercooler pipe ended up popping off while I was going down the interstate at WOT. I guess that once it popped off it hit the radiator support and slapped back at the intercooler causing it to break (so much for plastic end tanks). Looks like I might be going fmic before I do the rebuild. I just wanted to add this info in case someone else has to same problem with a boost leak.