Just tried a boost leak test. Followed the how to threads to the letter or at least I thought so but I feel I failed to properly test the system.

I made an adapter for the compressor to cap it off and inflate the system. As I added air to the system the hose coming from the valve cover that recirc's back into the intake began leaking the compressed air in a big way. So I plugged it. Added air again and the pressure began leaking out of my oil fill cap.

So I am somewhat naive about certain parts of my evo but i do most of my wrenching myself. I cannot figure out how to keep it pressurized to the level I need to check it at. I was able to get it to 21.5psi for a second but thats it.

I did however figure out that I am leaking pressure from around my injectors. My STOCK injectors that have never been removed or messed with! Normal?

Can anyone with some experience with this please give me some much needed advice? I am coming up on my e85 tune and I need to test my system as close to 30psi prior to my tuning session.

Thanks

 

Try searching "boost testing, injector seals", etc. There is a lot of very good info available in this forum. In a nutshell, injector seal leaks are not at all uncommon, and you'll need to replace them. As for the air escaping out of the oil filler cap, try checking the PCV valve. Mine was leaking into the cam cover during a boost test. I bought a new one, and it leaked even worse. I ended up installing a check valve between the PCV valve and the intake manifold. Solved the problem.

 

Thanks for the input. I've searched more than you could imagine. I was just hoping someone who really knew what they were doing mechanically speaking would know right away what my issue was. I did not figure stock injectors that have never been messed with would leak. I will look into the PCV valve and maybe putting in a check valve.

 

Yeah, neither did I. If I remember correctly, several members have used FIC seals and recommend them. Just like you, I was boost testing prior to a tune, and didn't really expect to find any problems! I ended up doing the injector seals, throttle shaft seals, and the check valve thing. (I discovered the throttle shaft seals were leaking after I fixed the other two leaks, so its a good idea to re-test after you're done. Good luck!

 

Your issue is 2 part -

1. Your crank probably isn't at TDC causing your air to leak out very quickly due to it escaping out exhaust and intake valve seals. You need TDC to close these off.
2. You have a bunch of small leaks assuming 1. isn't your issue as evidenced by the leaking injector seals.

Start small, try to hook the tester up to your IM and test that. I've never done this but alot swear by it. It's OK to plug that hose to test, I do it also however IF you do then do not plug the PCV valve. I'm going to assume that you have a stock IC piping system so there are alot of leaks possible in the stock system, hence the upgrade to aftermarket piping only allowing for 8-10 leaks. Leak testing is NEVER fun...there are alot of places the air can go. Find TDC and try again and let us know.

 

Thanks to the both of you. Did some more searching and found:

https://www.evolutionm.net/forums/ev...t-oil-cap.html

By the way, how would I find TDC? Just keep bumping the starter and retrying the test or?

 

Looks like you are on the right track. The attached diagram might help you understand how you are pressurizing your valve cover.

Slowly losing pressure is normal. It all depends on how you catch your valves and your cam overlap. Also a bad turbo seal will leak air into the crankcase.

Try bumping it change the valve position and see if that helps.


Dan (drb)

 

Thanks Dan. Ya looks like trying for TDC is my best bet. I am now figuring out that boost leak hunting is never fun. The other thread has some good ideas as well. I do find it strange that so many people do it differently but claim the same end result.

 

Did TDC allow you to hold more pressure? I'm having the same issue, alot of blow by air coming out of the crankcase breather valve. I can only get up to about 20psi. I tried bumping my starter over but cant get it lined up exactly to TDC.

 

Quiestion ?

when u did the boost leak test u did remove the hose that comes from the intake to the valve cover right ??

 

Yes, I removed that hose. To be more precise I removed the intake pipe so of course the hose from the pipe was removed also I removed the hose that goes from the PCV to the intake manifold. I was still getting large amounts of pressure leaking from the valve cover.

 

I tried "bumping" the starter but got frustrated. I will try this again today but I would like to know if maybe the crank pulley has a mark or something on it to show me when I'm at TDC. Not to mention that I got a check engine light on for the first few starts after attempting this test.

 

you can use the cam gear marks that line up with the marks on the valve cover to find TDC. If its not TDC then turn the crank until the marks line up again and that should be TDC.

hope that helps

 

I have never put my Evo or any other car for that matter at TDC to do a boost leak test. I have never had an issue

 

I always connect the pressure tester directly on the turbo inlet. I zip tie the oil dipstick, crimp off both the pcv and vent on the valve cover, then pressurize it.