bump for a great thread.. most of the people i come across do not appreciate the importance of a proper boost leak test

 

I second the above... I've gone way too long without a test.

 

EGR
If your EGR hose has come off (unknowingly) prior to the boost leak test, you will have a lot of trouble building boost. It will also sound like air is passing right thru the engine out thru the exhaust because it is. When the EGR valve is forced open, it's like having a dime sized bypass hose going from your intake manifold to your exhaust manifold. Reconnect the EGR vacuum hose and you should see boost increase dramatically. This is also the culprit when you throw a P0401 CEL when this hose blows off.

TDC
Also, getting your engine close to TDC (only rotate the crankshaft pulley CLOCKWISE!) will help a great deal because you are insuring at least one valve is closed in each cylinder. On aggressive cams it's more tricky to find the correct timing degree for the crankshaft because of the valve overlap that may occur.

Normal Operating Engine Temp
I also only test my engine after it has reached normal operating temperature so the internal engine parts have expanded like they would be under normal driving conditions. This helps a great deal with blow-by past the piston rings and possibly the valve seals. Buy some MECHANIX work gloves to keep your hands protected when working under the hood when its hot.

No Crankcase Pressure
I also never allow pressure to build in the crankcase seeing as some people plug the valve cover breather hose but I can't see a reason to allow 20+psi to build up in the crankcase when the gaskets and seals are not designed to hold much positive pressure. Evoryder's idea of adding a hose extension to the valve covers air breather port to aid in the ability to hear boost leaks in the engine bay is very wise.


Boost 'Headroom'
Lastly, I always make sure I can hold at least 2 psi MORE than my intended peak boost level. I also make sure it can sustain this level throughout the duration of my test to ensure that no connectors will slowly creep off during a long highway pull or at the track. Reason being, boost spikes in upper gears can force a BOV open if its not adjusted correctly. Some BOV's, once they are cracked open from a leak, it takes almost the entire gear pull before it will close again. This can ruin someones 4th gear pull in the 1/4 mile, impacting the 1/4 mile potential.

 

Great write up...Even though I have no problem building boost I definitely need to do this soon....

 

Good stuff I got a pvc homemade tester from a friend I just need a compressor and Ill be in business.

 

These two links saved me a huge headache. I was having trouble with too pressure leaking and it seemed to be crankcase pressure as it was coming out of the valve cover via PCV and the return to the intake pipe. The fix actually made a difference in throttle response. I am so stoked I figure I would share it with those that may not have seen my other thread.

http://www.dsmtuners.com/forums/arti...cv-system.html

http://www.usplastic.com/catalog/ite...6844&catid=489

The second link here is within the first link and it is also explained there. Hope this helps some of you!

 

GENIUS! Doing mine TODAY! i did a boost leak before i can hear it a lil bit but can not pin point the specific location, but spraying locations and finding bubbles is my next step! thanks for the idea!

 

very good info for newbs.

 

i found out my TB seals were leaking i replaced them with a aftermarket kit that's available huge difference

 

Wow, that is the best write up on the PVC system that I have seen - very informative.

Dan (drb)

 

When performing a boost leak test on an EVO with the stock diverter valve, should the boost leak tester be installed at the turbo inlet, or at the intake side of the intake tube? Did anybody ever put smoke into the intake system to help visually see the leaks?

thanks for the help.

 

Turbo inlet.

 

Bookmarked. Definitely a good guide for any turbo system.

 

That will not work unless one can apply the smoke under sufficient pressure to conduct the test. A smoke test is fine for a NA engine, but will not suffice for a forced induction engine, simply because many pressure leaks do not manifest themselves until considerable pressure is applied.

 

thank you Ted and Redralli. I get a tester together and give it a go. I'll be doing it with a bike pump and a valve instead of a shop air source hopefully it works well.