Hey All

[LyleD]

Hi, my name is Lyle and I discovered this forum as I have an 83 GMC that I have recently purchased and been working on. Currently, while replacing a fuel injector, I happened to look in the pipe that runs from the turbo to the intake and saw a small pool of oil. Now I am wondering if I need to rebuild the turbo!
This looks like a friendly and highly informational forum. I am looking forward to learning and participating/contributing here!

 

[ak diesel driver]

Nice looking truck. Snap a picture of your engine bay so we can see what turbo and CDR your using.

 

[LyleD]

Thanks! Here are those pics. I just found where it says its a GM5.

 

[jrsavoie]

Nice looking engine compartment

 

[SnowDrift]

Welcome.

Someone much more space under the hood with the older body style

 

[Will L.]

Welcome, Looks great.
Please fill out your signature line with the rig and details regarding it. This helps a lot in chasing problems over time.

We can’t see how you get rid of crankcase pressure. In a gasoline engine this would be the pcv valve & hose. Originally on the 6.2/6.5 this is done through the cdr and hose that would have fed back to the incoming air supply.

On a natural aspirated engine it would have been to the port you have plugged on the side of the intake manifold & fed from a can that looks like a tunafish can plugged into a valve cover.
On a 6.5 turbo the tuna can would look the same but feed to the intake hose that is between the air filter and the turbo.

 

[LyleD]

Welcome, Looks great.
Please fill out your signature line with the rig and details regarding it. This helps a lot in chasing problems over time.

We can’t see how you get rid of crankcase pressure. In a gasoline engine this would be the pcv valve & hose. Originally on the 6.2/6.5 this is done through the cdr and hose that would have fed back to the incoming air supply.

On a natural aspirated engine it would have been to the port you have plugged on the side of the intake manifold & fed from a can that looks like a tunafish can plugged into a valve cover.
On a 6.5 turbo the tuna can would look the same but feed to the intake hose that is between the air filter and the turbo.

Thanks for the insight and advice Will. I will get that done.

 

[ak diesel driver]

So you have a 6.2 style CDR system where it evacuates from the oil filler neck and then it looks to go to a catch can and then from there to the intake piping. Depending on the catch can (can't tell from the pictures) it may be doing little to no good or possibly even be full unless it's setup to drain back to the crankcase. Also the hose going to the intake piping should be closer to the turbo.

 

[LyleD]

So you have a 6.2 style CDR system where it evacuates from the oil filler neck and then it looks to go to a catch can and then from there to the intake piping. Depending on the catch can (can't tell from the pictures) it may be doing little to no good or possibly even be full unless it's setup to drain back to the crankcase. Also the hose going to the intake piping should be closer to the turbo.

Thanks, I checked the oil catch can and it has a very small amount of oil collected in the bottom. It is mounted higher than where the hose comes out of the filler neck. So should drain back if full?

When you say the hose should be closer to the turbo, are you talking about the hose coming from the catch can? Or the rubber boot connecting the turbo to the intake piping? I don’t remember how tight the clamp was when I took it off the turbo, but lookinh at the picture it does look like it was only on about an inch of it and the clamp was over the raises lip and not behind. Could oil be getting sucked in through there?
I did notice the elbow on the underside was loose and had been leaking so took it apart, put a new gasket in and permatexed the threads. It’s tight now.

 

[ak diesel driver]

is it set up to drain back? can be either way. the hose from the catch can that ties into the intake piping pre turbo is what I was referring to. The stock setup is very close to the turbo, the vacuum drops off pretty fast the further from the turbo you get. the other thing to check is how much blowby you have

 

[Will L.]

A picture or three of how the hoses route from the catch can would be good.
We can see the hose from the filler neck to the catch can. Can see a hose from the passenger side valve cover goes under turbo, but can’t see to where.
There has to be something sucking the other side of the catch can.

What we are expecting to see is a hose from catch can to the intake piping pre-turbo. Wherever that is- open it up and check for oil leaks getting into it there.

Maybe look at the turbine compressor wheel to see if oil is getting into that way. That is where most the oil is expected to get in. Not that it is most desirable, but how these are designed to create the vacuum to extract the crank case pressure.

If there is no oil coming in from the crank case- then yes the oil seal in the turbo is probably the issue. That would require rebuilding the turbo.
In rebuilding the gm5, is when it becomes the questioning happens of moving to a bigger turbo to lower psi but increasing volume to have same power levels but less heat build up. (Or if a nut job like me, push it for more power too. Haha)