Boost leak test question?

[Flybiyou]

I have searched and didnt find what I was looking for. Befor you do the test how do you know if the valves are all shut. Does anyone have a picture of where the crank is supposed to be set at. Also I have the 264/272 combo so will the valves all seal or not.
I tested the turbo to the pipe before the elbow and its fine. So I hooked it up to the elbow and pluged the hose from the head to the pcv valve,boost controller, and I dont have any vacume lines (removed EGR) is there something else I am not pluging that I should. I can build pressure but it goes out after a few seconds and I can hear it coming from the exhaust side of the head (manifold is off the car).
All in all where is the crank supposed to point so the air will not leak by the open valves.
Thanks in advance and for reading all this.
AJ

 

[oldman]

30* after TDC. Your valve seals/guides can also be worn, open the oil cap and listen for leaks.

 

[Flybiyou]

30* after TDC. Your valve seals/guides can also be worn, open the oil cap and listen for leaks.

So how do I know if I have the crank a 30* is there somthing that I line up with something I have never turned the crank or even looked at that area befor.

 

[oldman]

Follow this timing belt vfaq to put it in TDC (Top Dead Center), then turn the crank CW for about 30* from TDC. This does not have to be exact, you can even turn the crank CW during the pressure test until the hissing at the exhaust manifold stops, just make sure to never turn the crank CCW.

 

[Flybiyou]

Thanks for all your help I got it to work only thing is there is a hole in the 4th exhaust cly port that the air comes out of if I plug it with my finger it hodl pressure but its hard to keep it pluged. Why is the air comeing out of there and how do I plug it. Thanks picture of what I am talking about below.

 

[steve]

Hey Bruce, here a picture of the EGR passage I've been talking about and somebody with a leaking EGR.

Steve

 

[Flybiyou]

How is it leaking should I remove it and use a block off plate. Its on right now pluged off with caps.

 

[steve]

The EGR valve is ment to seal between this exhaust passage and the one in the intake.
Try removing the EGR valve and cleaning it first. Plugging the nipples on the valve doesn't do anything.

Steve

 

[Flybiyou]

So are you saying it's stuck open. Can I just block it off and does that mean that when I boost it is always leaking from that point. The air comes out fast if I move my plug.

 

[Flybiyou]

I put the marks at top dead center then turned it to 30* ptdc and this is where the mark it now.

 

[oldman]

If you're sure pressure is coming out of the EGR passage in the #4 outlet, it's definitely coming from the manifold through EGR like steve said. Explain exactly how you have it blocked off.

Hey Bruce, here a picture of the EGR passage I've been talking about and somebody with a leaking EGR.

I suspect the EGR was not properly removed and blocked off.

 

[Flybiyou]

If you're sure pressure is coming out of the EGR passage in the #4 outlet, it's definitely coming from the manifold through EGR like steve said. Explain exactly how you have it blocked off.


I suspect the EGR was not properly removed and blocked off.

First off I really apprecitae you two guy's helping me out . I am sure it is coming from there because if I hold my finger on the hole it will hold pessure till I cant hold the boost with my finger then it all flys out. The Egr is still there but I capped the vac ports on it with caps when I removed all the emmsions lines and canister. Does the car need power for the egr to hold pressure? Also what is the proper way to remove it and block it off?
Thanks again guys

 

[oldman]

First off I really apprecitae you two guy's helping me out . I am sure it is coming from there because if I hold my finger on the hole it will hold pessure till I cant hold the boost with my finger then it all flys out. The Egr is still there but I capped the vac ports on it with caps when I removed all the emmsions lines and canister. Does the car need power for the egr to hold pressure? Also what is the proper way to remove it and block it off?
Thanks again guys

The EGR is like a BOV, proper opening and closing are activated by the vacuum lines connected to it, without the vacuum lines it's just open and a huge boost leak. You need to either properly re-connect all the vacuum lines in and out of the EGR or completely remove it and install a block off plate/gasket.

 

[Flybiyou]

Thanks man I am going to buy a block off plate right now. Know where I can get one cheap. As for the gasket could I use RTV to make the gasket would it hold. Again thanks for all the help.

 

[oldman]

The one I picked up on ebay, $12, came with a plate, metal gasket and two ss bolts.

 

[steve]

without the vacuum lines it's just open and a huge boost leak.

?

I always though that a good EGR valve seated/sealed by default and needed a vacuum applied to open. I'll have to double check it to make sure.

Steve

 

[Flybiyou]

Did you double check?

 

[Black94DSM]

Hmm. This is interesting to hear. I've ran my EGR with plugged vac lines thinking it will seat and not open. Have had it like that for like 2 years. I would like to hear about this.

 

[oldman]

I always though that a good EGR valve seated/sealed by default and needed a vacuum applied to open. I'll have to double check it to make sure.

Honestly, I'm not sure either, I just ASSumed so or else why would there be a need for a block off plate in the first place?

 

[Ultimatedsm]

LMFAO!! Oldman sometimes you crack me up. Just wondering, why would you want to block it off anyway? You gain nothing out of it except maybe neater looking engine due to less vacuum lines. You will never pass another emission test again and will always have to go "under the table" to pass. In Canada, that method is like $200 CDN Versus $38 CDN if you pass.

 

[oldman]

LMFAO!! Oldman sometimes you crack me up. Just wondering, why would you want to block it off anyway? You gain nothing out of it except maybe neater looking engine due to less vacuum lines. You will never pass another emission test again and will always have to go "under the table" to pass. In Canada, that method is like $200 CDN Versus $38 CDN if you pass.

You're right it's pretty much pointless besides a cleaner looking engine bay. Mine was blocked off after my intake manifold was ported and cleaned, I have been wanting to reinstall it to see if it will improve my fuel economy but I broke one of the fitting on my thermal valve off the thermostate housing during the removal.

 

[oldman]

Steve, do you konw which type of EGR valve we have, my head hurts from reading too early on a Sat morning.

http://www.asashop.org/autoinc/dec97/egr.htm

 

[steve]

According to the 1G Technical Manual the spring in the EGR valve holds it closed and the vacuum source is used to open and modulate the EGR flow.
The 2G Technical Manual discusses the addition on the MDP sensor for EGR monitoring.
I assume that blocking off the EGR on a 2G leads to a P0400 error.

With the hoses disconnected from the valve it shouldn't open. The valve opens to the intake side so that boost pressure should be working to hold the valve closed so the spring only needs to hold against exhaust backpressure.

Like I said before, the first thing I'd do is clean it and see if it seals better.

Steve

 

[Flybiyou]

This is getting confusing. I have read other threads about people leaving the EGR in place of a block off plate and it worked fine for them. I am going to get a block off plate and see what happens. This is really strange though I have never heard anyone mention anything about this before when they do a boost leak test. Am I the first? I wonder if the EGR has been leaking like this for awhile now? I removed it cause I was supposed to get a Magnus intake manifold but funds went short. I threw everything away already so I cant put it back in. I will try investaging about this and see what I can find since the anwser is yet to be found. Does my Cam Timing mark look where it should be for a boost leak test. I spun the crank till they meet in the center and then turned it to the location in the picture above. Thanks for all the help again keep the idea's coming.
AJ

STORY TO ADD
Last summer I was having trouble hitting full boost on my s16g. It would shot up to 10-13 psi around 2800 and then slowly build it's way up to 20-22 psi around 5600-5800. The turbo spooled fine till one day it started doing this. I boost leak tested the turbo to elbow interooler pipe and it was fine and I tryed from the 2g elbow to motor and I could build pressure but it would exit right after. I heard it coming from the exhaust side and thought it was the valves open. ( I didnt know you had to put the motor at 30*PTDC) I tested the wastegate it worked fine ran out of ideas and ran the car like that for about 3-4 months and it has been in the garage ever since.

This could explain what was going on last summer. Hey Steve I see you live in Illinois as well you dont live to far from me. Want to come over and help he figure this out. I have to get this fixed before I can put my new setup on and get the car ready by march 6th.

 

[steve]

This is really strange though I have never heard anyone mention anything about this before when they do a boost leak test. Am I the first?

I doubt your the first but your the first to post a picture of the port on the exhaust side that I've been talking to Bruce about for a while when we discuss places that could leak.

Want to come over and help he figure this out.

Sorry, I'm still not cleared by my doctors to work on my cars yet after the heart attack.
I was right in the middle of a rear brake job on one of the Stealths the day it happened and that car is still up on jack stands and I expect will be for a couple more weeks.

Steve