Boost leaks

[jroze37]

how do you no if you have a boost leak and how can you fix it. i used to be able to hold the brake and gas it before i would race and it would spool up to like 12 psi now it goes to like 5 psi so how can i fix it?

 

[crimsondragon]

1. Disable your mbc.

2. Turn your motor to 30* ATDC to avoid valve overlap.

3. Start your test at the TB elbow and focus on area behind the TB first.

4. Spray soapy water at TB gasket, BISS, TB shaft on both sides, IM gasket, injector insulators, brake booster, afpr and all vacuum lines/connections.

5. Open your oil cap and listen for leaks. (PCV, valve seals/guide, rings)

5. Listen to your tailpipe for leaks. (EGR, valve overlap, jumped timing, bent/unseated valves)

6. Once all leaks are fixed, move the tester back to the turbo inlet.

7. Spray down the compressor cover (known leak), BOV return/flange (DO NOT TAP YOUR BOV LINE FOR YOUR MBC!!!), IC end tank/fins and all connections. Re- test.

8. Note that you will leak air into the crankcase through the turbo seal but do not panic, this is normal during a static pressure test as long as there are no shaft play.

The desired test result from the begining of the LICP (bypassing turbo) is around 20psi (on boost gauge) with the compressor set at 30psi, while taking no less than 30 seconds to bleed down to 0.

As a reference, my last test on my 500 mile new engine, I was able to pressurize the system to 25psi, bled down to about 16psi (my 1G bov) in about 30seconds, then took about 3 mins to 6psi and just kinda lingered there for a while. It's not easy to do but the point is it's possible. My next goal is 30psi After motor break in and Dodge modding my BOV. A boost leak test is one of most pita but important regular maintenace task, the key is patience and endurance, have fun.

Follow these guidelines.

 

[jroze37]

thanks

 

[woodnbronze24]

Make sure u use the wonderful search option on this site.

 

[ttsrq]

Use a boost leak tester, link is on VFAQ Site - Visual Frequently Answered Questions and its usually a line that is broken or some worn out o rings.

 

[Mr PopUps]

Now that im getting back into the 'scene' ill start making these again. I used to sell a LOT of stuff for DSM's, a lot of it i made, and even have some materials for these. It allows you to pressurize from the turbo inlet.

 

[Colt4G63 also]

I followed that guideline for boost leak testing for a while, but I've discovered that step 2 isn't really needed. At least not for my car. I run BC272 cams, and stock cam sprockets, and I just test it in whatever position the engine happened to stop in last time I shut it off. So far, I've never had a problem with valve overlap while performing a boost leak test. Maybe that's why people always say BC cams don't produce great numbers. Not enough valve overlap. Or maybe something with longer duration would require step two, I'm not sure. I have heard other people say "you don't need to position it at 30 ATDC" too, so who knows. Maybe it's just an old wives tale?