Engine/Transmission (1994 - 1998) Pressure-testing charge air system

[WBusa]

My 'new' 94 CD has wimpy boost... barely 10 PSI at WOT climbing a hill. I've inspected all the usual suspects (hoses, clamps, etc. ) but found nothing, so now I want to pressure-test the whole air system. I know this was the topic of a recent TDR article, but I'm a newbie and don't have access to that issue.



So: I'm clear on using a PVC plug tapped with an air fitting, clamped onto the end of the line just after the turbo. But what I'm not clear on is this: should I also block the other end of the charge air system (just before the intake manifold), or not? I guess I'm not clear on whether the pressure would leak through the cylinders if I don't block the other end. Any tips?



In return, here's a trick I learned a long time ago for locating the exact position of a hissing noise: take a length of tubing and place one end near your ear, then move the other end around the suspected location of the hiss. When you're right over it, you'll know it. It should go without saying that you shouldn't stick the tube firmly in your ear; otherwise, you'll end up leak-testing your eardrum. :{

 

[SEmerson]

The cylinders will leak some but not a big deal. You will hear other leaks as you held the pressure. Also use a regulator to limit the pressure. Be carefull of the pvc plug blowing off the turbo.

 

[CMorrow]

If your Turbo has a threaded boost fitting like on the hybred turbos, you can add air thru that and use a black rubber drain cap. The caps are sold in the plumbing section of most home stores. This saves having to construct the one mentioned in the TDR article. The cap will look like it won't seal but with the hose clamp on it should seal nicely. I've had no problems and it works like a champ.