Guys, how do I check to make sure...
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that my intercooler has no leaks? I have this really annoying problem. It happens when the car sits in traffic or is driven hard (I have come to believe it has to do with it being hot in the engine compartment or maybe with pulling too much vacuum). A WHOOSH sound appears and the damn car loses some pep. The turbo still boosts, but with less oomph. How can I test the IC for leaks? Is there a pressure test or something I could do? I doubt its my cbv because the problem is intermittent(sp?)

What else do you think could be the cause of my problem? I've had the car over the year now and this problem just won't fix itself :-)! My mechanic can't find what it is, and I feel like fixing it myself. The WHOOSH really starts to come on a lot more in the summer months, which is why I think it has to do with heat. Oh, and one more thing; if I push the car hard, the whoosh will dissappear in third gear.

I need to get rid of this problem because its stopped me from turning up the boost. This, as you all know, is a tragedy. I've just been too busy to really examine in there and I need the car to sustain its longevity, hence me being a @#%$ about turning the wastegate. However, pretty soon I WILL have time to tinker, and any hints on where to start will be greatly appreciated. Hell, I only have the car running at 7psi.

In the next two months, I'm going to add an elec pri fan, new 3-row rad, coolant flush and 180 thermostat. Should keep it plenty cool. Just one more question though; whats a good ratio of coolant to water? I'm in NY, so I have to make sure its not going to freeze up. Can I do 60/40 water-coolant?

Whew. I'm going to get to the bottom of this eventually. SORRY for the long winded post.

Roguls
New York, USA

Rarely do the intercoolers on our cars have problems. When they do have problems it is under sustained high boost. That high boost being around 18 psi and from months of this kind of boost the plastic end tanks will give.

If you wanted to test the intercooler, I would use some kind of rubber hose, big enough to fit over the big outlets, and plug those with something non flexible. Like a plastic PVC end. So in essence u would use the rubber unions like they are in the car, but with PVC ends where the hose would be.
Then I would find some kind of fitting that would thread into the drain plug and allow you to fill it with compressed air. This would allow you to find the smallest of leaks and under pressure as well.

The simplest approach would be to clean it and see if it leaks from anywhere but the outlets.

I would personally check all the hoses. Especially the rubber flex ones that join the intercooler pipes and the metal hoses. These have been known to look ok, but under close inspection reveal cracks that would only show up under boost.

I am like you also, very precautious. my car is only currently running 6 psi.
Friend and I intercooled it, so it was actually running 6 psi before intercooled. I could theoretically turn the boost up now since the engine ingests cooler air after the intercooler addition, but I not going to chance it.

But that is because I want it tuned well before I up the boost and make sure I dont grenade the rebuilt motor soon. (bought it with rebuilt motor)
I will make sure all my fluids are synthetic, the cooling system is working well, I have good mixture and a CBV welded in, then I will incrementally raise the boost.
What model car is it? 200s used rubber hoses a lot, the 90 degree rubber/flourosilicone/whatever they used is also prone to this kind of cracking.


take care
hope this helps

Luke
82 242Ti 167k miles

Its a 91 744. Its a manual, which is how I can really decipher when the "leak" comes in and out. I replaced all the hoses when I got the car, and that did nothing to the problem. Maybe there's a vacuum tank somewhere that expands with too much heat? I will really get to inspect everything when I change the rad and add the elec fan, hopefully I will find the culprit then.

Roguls
New York, USA

Maybe the intercooler has a crack in it that opens when you reach a certain pressure? Or perhaps one of the lines. I know that sounds obvious, but it might not be apparent when car is not in boost. Maybe the waste gate is having a problem.