Ok. I've searched an searched, but I can't find the pros and cons of switching the wastegate to pressure actuated. Can anyone help me out?


Sent from my iPhone using Tapatalk

Threre is an EGR valve that joins the intake manifold to the exhaust manifold. It's purpose is to mix a little exhaust gas into the intake to reduce pollution. When it isn't working properly, the ECU can cut turbo boost or restrict airflow by opening the wastegate and closing the ARV, which is another valve on the side of the crossover pipe. So that's what all of this stuff is supposed to do.

The advantage of removing it all is that a simpler control system is less problem prone.

The disadvantage is that you will have a car that pollutes more and is technically illegal for road use. If your state were to mandate an effective inspection program, you can be fined and your car would have to be removed from the road until you put everything back.

There are a lot of moving parts involved in this system...the ARV, EGR valve, two vacuum transducers, the ECU, lots of connectors and vacuum hose. The problem may be as simple as a leaky vacuum hose, or one of the major components may be malfunctioning. Opinions may vary, but I think it's always easier to fix the system as designed. Some believe that there are performance advantages to removing the pollution controls, but that isn't the case. When everything is working correctly, there's very little impact on performance or fuel economy.

Ok...not trying beat a dead horse, BUT: My T25 compressor is TOAST. I'm not exactly rollin' in high cotton, if ya know what I mean and the T3 just needs a simple rebuild kit to close up the oil leaks. I found a T3 to T25 adapter flange on eBay so that takes care of that aspect of the swap. Do you guys think I'll mess something up in the engine by swapping to a slightly larger turbo?


Chris Dragotta
1991 300D OM602 Turbo
Benson, NC

The turbo occupies a very particular place in 3 dimensional space. Even if you install an adapter flange, you will then need to find some way to line up the air outlet, oil inlet, oil outlet and exhaust pipe. Then there's the question of how the big turbo will perform with the smaller motor. None of this is impossible, but it would probably be cheaper to rebuild the T25 than to deal with all the resulting issues.

Let's back up a minute and ask what you mean by "toast". Maybe there's a way to bring it back from the brink.

The bearing went and the compressor wheel bounced around a bit. It's all marred up and the fins are bent. It would have to go to a turbo shop to be rebuilt/balanced.


Chris Dragotta
1991 300D OM602 Turbo
Benson, NC