How do I make / buy / use / troubleshoot a boost leak tester? [merged]

[Turbo Monk3y]

All boost leak tester threads are combined here.

i read somewhere maybe the Vfaq about making or buying a boost leak tester of some sort but never found it.... the reason being my acceleration seems slower than normal and all ive done to my stock car so far is take out the air box put on a K&N filter and cut the dump tube i have my boost guage sitting in a box not hooked up yet. and since those 2 mods it when i go wot on the car i can hear the turbo spool up and it sounds nice but i can also hear a sound as my rpm increases the SHHHHHHHHHHHHHHHHHHHHHH sound does too. the sound comes from the same area as the BOV i think maybe i got a #@%#@%#@%#@% stock bov and it cant handle over 11-13 psi??? Then i shift and it makes the nice BOV sound WHOOOOSHHHH... but my car seems to be a little slower.. any ideas before i go check every tube clamp and tube????

 

[psychlow]

When you guys are checking for boost leaks, how are you making sure that the air isn't escaping through the cylinders into the exhaust manifold? Is it an unwritten/assumed rule that you should be at TDC when boost leak testing?

 

[weith1111]

Boost leak testing is for the intake side. BOV, IC, TB, injector seals even. The leaks found in these areas are the ones that traditionally kill performance with respect to "boost leaks." If you want to check your compression, that's a different story.

 

[Steve Hebert]

I think the question is don't you have to somehow stop the air from leaking thru the cylinders when doing a leak test. If any intake valve is even in a partially open position couldn't air escape thru the cylinders?

 

[Defiant]

He's referring to the situation of having a cylinder's valves on overlap, which would cause a continuous leak out the tailpipe.

 

[psychlow]

He's referring to the situation of having a cylinder's valves on overlap, which would cause a continuous leak out the tailpipe.

Exactly. I tried posting a first-person version of these exact words last night, but for some reason, the site wasn't letting me post.

 

[T is for TURBO]

I too was wondering the same thing

 

[Defiant]

None are on overlap at TDC. The test doesn't much care if either the intakes or the exhaust are open (intake will charge the cylinder, but it doesn't matter, and if the exhausts are open the intakes aren't.... other than during overlap).

 

[staticbrainwash]

i made and performed a boost leak test. only did it at the turbo, but when i went to pressurize the system, all i heard was kissing ari comming from my exhaust manifold.

now, i knew i had a bad manny (and 3 snapped bolts on one side) but i didn't think my turbo would leak into the manny. does this mean i have bad turbo seals? im kinda at a loss here.

 

[steve]

This could be a couple of things other than a problem with the turbo.

Depending on where the crank was when you were pressure testing, it's possible that one of your cylinders was close to TDC intake stroke and he valves were in overlap (both sets open) so that the air was going out the exhaust.

It's also possible that your EGR valve could be bad allowing air from the intake to leak into the EGR passage in the head and out the exhaust.

To help take the turbo out of the picture, try pressure testing at the throttle elbow first.
Make sure that the engine isn't at TDC or 180* from TDC. Depending on which cams you have 30* before or after TDC should a good spot where no more than one set of valves is open in any cylinder.

Steve

 

[staticbrainwash]

wow thanks, im going to try to test at the licp, and the tb elbow.

how would i check to see where my crank has the pistons? after knowing that ill also check again there.

if it is turbo seals (which i doubt because im not throwing oil while on boost) could i replace those myself, or would it just be a better idea to pick up a used 14b? i doubt it's really worth having rebuilt espically if in the near future i plan on going to a 18g.

thanks very much for your help.

 

[4BangerV8Killer]

yes same here

 

[steve]

how would i check to see where my crank has the pistons? after knowing that ill also check again there.

Assuming your crank pulley is good and hasn't slipped, you just turn the crank over until the timing mark on the crank pulley lines up with the 'T" on the plastic timing cover. Check to make sure the cams dowels are at 12 o-clock and the inner two marks line up with the center line of the cam bolts. Now you know that cylinder 1 is at TDC(compression), so advance the crank 30 degrees. Use a protractor if you can't visualize where 30 degrees from TDC is on the crank. You want to do this because when cylinder 1 is at TDC(compression), cylinder 4 is at TDC(exhaust) and has both the intake and exhaust valves open.

It doesn't have to be perfect. I don't remember the stock cam specs off the top of my head but I seem to remember the Exhaust valves closing somewhere around 9 degrees ATDC (turbo) so anywhere past that point but before the other two cylinders come to their TDC's is good.

Steve

 

[Timo1083]

i did a boost leak test and found one big leak i fixed and tested again. Now air is coming out of valve cover and out of the oil cap u can hear it clearly coming from inside what could this be??

Leaky valves?? warped head?? what??? please??

 

[RossY]

maybe you have a bad PCV?

 

[oldman]

http://www.dsmtuners.com/forums/showthread.php?t=174682

 

[ddavisaf]

That's such a mean thread to send him to...
Test is again from the LICP. If you still hear the sound, disconnect and plug the pcv. Still hear the sound run a compression test.

 

[Timo1083]

That's such a mean thread to send him to...
Test is again from the LICP. If you still hear the sound, disconnect and plug the pcv. Still hear the sound run a compression test.

it was a bad pvc and i blocked it off.i retested and i took the valve cover off and there is hissing that sounds like it's inside the head. i did a compression test and got 154 on all.

 

[ddavisaf]

The hissing was after you replaced the pcv and while testing from the LICP and not the turbo inlet correct?

 

[Timo1083]

The hissing was after you replaced the pcv and while testing from the LICP and not the turbo inlet correct?

yes thats right

 

[xucpxeclipsex]

everyone is saying that you need to do a boost leak test.. but how do u go about doing that??.. cuz i think i gotta boost leak.. thanx guys

 

[pnishr]

http://www.vfaq.com/mods/ICtester.html

that'll handle part of your testing/problem. Check all your vacuum lines, and ensure all of them are connected where they belong.

Good luck to you.

J

 

[xucpxeclipsex]

thanx

 

[90gsxmesaaz]

Just an update. I followed the advise of using an air compressor and found some of my leaks. I had leaks on my throttle body gasket (fixed), biss screw, and throttle body shaft seals (just recently put in the new ones bought from oldman). By this weekend I hope to do another boost leak test and see how everything is. Thanks for all your help everyone!

 

[Ski Bum]

I wanted to check and see if I had any vacuum leaks or boost leaks so I created a custom pressure tester using ABS pipe and a compressor plugged into the intake (in place of airbox). I can vary the PSI output from the compressor from 0-20+PSI (as much as needed) Anyways I am getting leaks in a few places that i had some questions about. First leak is right after the first section of the turbo (compressor I think) near an oil feed banjo bolt, which is tight btw, could the turbo have a problem? The second is out of the oil cap. Two questions there, should pressure (5psi) be released at the oil cap? Does that work like a leak down test meaning I have a bad intake valve or is it ok because of the direction? If not it would seem I need a new oil cap.

Any help is appreciated.

 

[Ski Bum]

If anyone has experiencing performing a test similar to this any feedback is appreciated.