Hey HOHN how can I check the wastegate with shop air???

 

Disconnect the wastegate hose at the compressor housing (where the air goes in).

Regulate your shop air down to 20-25psi or so and using a nipple or something, pressurize that hose with the shop air.

You should see the wastegate arm travel-- the more pressure, the more it will travel.

Justin

 

The easiest way to see if the wastegate is the culprit is to wire up the wastegate arm to prevent travel and see if boost comes up. This is easy to do on 99' and newer HX 35's because there is a flange on the compressor housing molded to hold the WG Actuator, that you can use to hold one end of the wire loop. Other end of the wire should be cradled around the bottom of the wastegate actuator rod/ WG lever connection to prevent it from moving backwards and away from the front of the truck.

If the diaphram in the wastegate actuator is bad, it can bleed off a ton of boost, best way to check that out is to buy a 1/4" brass male pipe plug and tread it into the compressor housing of the turbo where the brass elbow/ hose connects. With those two things done, you totally eliminate the wastegate's potential for problems.

Another common place for a boost leak if that does not fix the problem is the actual compressor housing. The housing can leak where it mates up to the center section of the turbo. The best way to check for boost leaks if the wastegate does not turn out to be the problem, is to buy a 4" Rubber Pipe Cap with included large hose clamp at Home Depot. Then drill a hole in the cap and insert a tire valve stem. Connect contraption to air inlet on the turbo, rubber cap is a little too big but you can get it to seal. Using the air compressor, fill the system up to about 30 psi and find the leaks. Ten bucks says you will find at least one small leak but not enough to terribly hurt performance. Big leaks will kill you. Another ten bucks says leaks will either be at compressor housing mating surface, on the boots/pipe connection, intake manifold by grid heaters, or rock dings in the intercooler itself, best fixed with propane torch and brass fluxed rod or easily fixed with JB weld or some sort of metal epoxy.

 

The pipe plug needed is 1/8", not 1/4" NPT.

At least on my truck..