Garrett Turbo

[GregZ]

Hi All,

Two issues, one relating to the waste gate and the other to the blow off (bypass) in a Garrett T3 turbo on a 300SD.

1. Any specific reason why the waste gate valve has a hollow stem that discharges behind the membrane? I tried to check when the valve opens with my compressor but I guess it does not deliver enough air as the valve opens at 40PSI shown on the compressor. How much (how many) thread must show on the valve stem more or less for the waste gate to be set approximately right?

2. As the membrane on my blow off valve was shot and broken and I could not easily locate a new one, I went junkyard hunting. I checked about 15 300SD-s all with the Garrett T3, and only three of them had blow off valves and among the three that had them, there were two different style of blow off valves. Anyone care to elaborate why that is?

Thanks,

Greg

Any 1978-1985 300SD that has a Garrett turbo will have the same turbo and wastegate as yours.

The only way it could be different is if one has a KKK turbo.

[GregZ]

Sorry, that is not an answer to any of my questions. They were all T3 Turbos and the difference was on the intake side, i.e., blow off valve.

It is not a blowoff valve, it is a recirculation valve. It lowers the boost pressure to force more exhaust gasses into the intake through the EGR valve.
Find a turbo without one, swap the compressor housing onto your turbo and plug the vacuum line that used to goto it.

[GregZ]

Thanks Lance. Well, it shorts the two ends of the compressor just like a blow off valve. I do not need it if I get rid of the EGR then, right?

[ARINUTS]

Originally Posted by GregZ

Thanks Lance. Well, it shorts the two ends of the compressor just like a blow off valve. I do not need it if I get rid of the EGR then, right?

Do you have a pic of this thing so we know exactly what you are speaking of? I'm a little confused. I'd like to know and help.

Originally Posted by ARINUTS

Do you have a pic of this thing so we know exactly what you are speaking of? I'm a little confused. I'd like to know and help.

On the face of the turbo.

[GregZ]

Yes, that looks like mine. It is the one held in place by three bolts (vs. four in another setup I saw). I'll consider to get a cover without the valve just to have a clean look or I'll disconnect this one.

Okay, now back to my first question about the hollow valve stem, and about how many thread should I see hanging out on the waste gate vale (assuming that the spring is all right).

[GregZ]

Lance, are W115 300D intakes rare? I saw one in a local junkyard would it be worth getting it?

Originally Posted by GregZ

Lance, are W115 300D intakes rare? I saw one in a local junkyard would it be worth getting it?

Depends on if anybody wants them.

[ARINUTS]

I have one of those, I just though it was the (adjustable) wastegate actuator. I never heard of a blow off valve.

The wastegate is down below the turbo coming off the exhaust side.