4SFED Z

So I read all the threads and had CF members guide me on boost leak testing on a A and A vette. I've been told to cap off supercharger inlet and hit the brake booster hose. Another one is to cap off the throttle body and supercharger inlet and hit the supercharger inlet side. So questions are:

What's the best method to boost leak test?

How do you prevent it from exiting the exhaust?

Do you have to wait a while for it to fill the engine and associated tubing and couplers to find leak? If so how long?

What will it sound like? High pitched?

Thanks guys. Please offer me a step by step, materials used and an explanation. Not looking for noob or smart remarks, just help.

- 4SFEDZ

Corvette-Chris

Hey man, I'll explain how i rigged a boost leak tester up for my TT setup.

I bought a couple of properly sized rubber caps from lowe's to go over the turbo inlets. I drilled a hole into one of them and threaded a male air chuck into it and put some silicone around it to help seal it up.

Then, I used my leak down tester as a regulator to regulate how much air from my compressor was going into the inlet. I just kept turning it up to until it heard seeping air. If I knew I was surpassing the pressure where I knew it wouldn't boost over while driving, I would start putting my hands on the charge pipes where couplers where and shake it a little bit.

Using this method, I've found every boost leak I've ever had. One was the air pump hard line that I capped off and one was a loose coupler.

Hope this helps man.

4SFED Z

Thanks Chris.

p1bz

What kept the air from going right out the exhaust valves? Did you pull the rocker arms off?

4SFED Z

^heard you have too. Then again some people never mention it. Sucks to not have a definative answer

Corvette-Chris

I didn't pull anything off. I'm sure air was going through the valves, but this method has located every boost leak I've ever had.

4SFED Z

^what u set compressor to for stock ls6. 15 psi?

4SFED Z

So supercharger capped, 15 psi through brake booster. Hear air filling up in engine only. No hissing sound indicating a leak. Not enough air to make the boost gauge in car rise either. I assume no leaks then?

Corvette-Chris

I had noticed that the car wouldn't go past 8psi even if it was set on 15. So I opened the regulator up to 8-9 psi and the leak showed itself.

I noticed my boost gauge rising when I did mine. If it's electric, make sure the key is on (I'm sure you did).

p1bz

The air is going out the exhaust. Think about it.

4SFED Z

^ We need to hit it higher than 15 set on regulator of compressor. Until 15 reached on boost gauge

RMS-MAN

I've been pressure testing for boost leaks this way for years. You DO NOT have to remove rockers arms for this test. All exhaust valves will be closed on a LS motor at rest. Don't ask me why they will be shut, just know that they WILL be shut. No air will leak past them when you pressurize the intake.

I've capped T/B's for years to find vacuum leaks on n/a setups too and never even pull a valve cover off. You do need to remember to cap off PCV lines if trying this on a n/a setup since it won't have a check-valve installed inline.

I prefer to tee in my manual boost gauge off the BOV hose and be able to see exacted how high I can get the system "boosted" to while searching for leaks and poor clamping areas. I like to hit a test pressure about 5psi over what that particular build should be running at before the car ever hits the road for tuning.

p1bz

All exhaust valves will be shut at the same time???? No Sir, they most certainly are not. Go look at a camshaft and tell us if all the lobes are in a nice straight line. Then explain how when you have valves open air don't escape.

p1bz

My previous post wasn't meant to sound rude. Just stating that simply looking at a camshaft should clear up any confusion.

Chrisrokc

Plug the intake of the sc compressor. Use something like a leak down kit to compress the system through the break booster. I created something that would work with brass fittings and a 25 psi gauge. I then charged the system to 15 psi. Use a spray bottle with soapy water to find leaks. Use your ears. Air should naturally leak down, but not quickly.

RMS-MAN

Gotta love "internet" mechanics.

The only confusion is in your theory. It's clear to me you've never used the procedure we are describing. It's works period. Have a nice day.

Corvette-Chris

p1bz-I see your point and in theory, I understand what you are saying. However, I've never removed a valve cover and the test I described works perfectly.

p1bz

Ok, I guess it works, even though the OP has already stated that it didnt. I will now bow out of this tread and let you Guys lead people in the wrong direction.

p1bz

I just went outside and hit mine with up to 40 psi. It didn't work for me, I don't know. Maybe cam LSA plays into it. You guys say i worked for you, so i guess it does. It hasn't worked for the OP or me now either. FWIW I teed into the BOV line with a pushlock. I will do my Turbo car next just to see. Capping that inlet is a little more involved.

4SFED Z

I will try again shortly I have the supercharger inlet capped. Have water/soap in spray bottle ready. Also put a mechanical gauge in line to see boost when pressuring up. Keep fingers crossed.