Engine/Transmission (1994 - 1998) Exhaust Leak

[surfbeetle]

If I have my heater/ac set to recirculation, it seems as I don't have a an exhaust smell in the cab. If I set it to fresh air, I get fumes. Obviously not good. I changed the gaskets where the exhaust manifold contacts the head. Cummins Cal Pacific sold me the crush style gaskets. I never seized the bolts and torqued them to 34 foot pounds. I reused the original bolts. I still think I am getting fumes. It's a stock manifold, where do they normally leak or crack? Any other ideas as to what to look for? Boost pressure is still at 30, so I don't really think it's leaking before the turbo, but who knows. Maybe the next step is for me to spray soapy water and look for bubbles.



Thanks.



Craig

 

[surfbeetle]

C'mon, no one has any answers?

 

[Missouri Mule]

additional info

It seems to me it cracks between the 3rd and 4rth cylinder but you can do a search for cracked exhaust manuals in the 12 valve forum. Mine hasn't cracked yet so I can't give you first hand info.

You can also can do search for exhaust smell in cab.

I get exhaust smell in the cab when I back up but going forward no problem.

I would look over the manifold carefully. You can place your hand near the manifold and feel the exhaust comming out. I would check from the manifold to where the down pipe connects to the tail pipe.



Also if manifold is cracked or anything is loose toward the front end the noise from the exhaust will be a lot louder up front.

 

[surfbeetle]

Okay, today after work, I checked the manifold, no leaks that I can tell. In fact, the only thing I could see was a bit of black discoloration where the two halves of the turbo meet. I cleaned that off to see if that comes back, but I could not feel any thing coming out there.

 

[MBieger]

Did you ever discover the cause? I have same problem for the past two years. Replaced exhaust manifold, no help. Cleaned and resealed turbo connections, no help. Replaced turbo housing, no help. Took to multiple exhaust shops, no one finds a leak in the exhaust system.

 

[surfbeetle]

Wow, I had almost forgotten about this one. What I think was happening is that when I was warming up the engine, the exhaust fumes were blown by the wind towards the front of my truck by the wind while sitting in my driveway and then getting sucked into the cab by the AC/Heat system. After checking the entire system, never found a leak. I did notice a faster spool up on the turbo after changing the manifold gaskets at the head.

 

[fest3er]

Wow, I had almost forgotten about this one. What I think was happening is that when I was warming up the engine, the exhaust fumes were blown by the wind towards the front of my truck by the wind while sitting in my driveway and then getting sucked into the cab by the AC/Heat system. After checking the entire system, never found a leak. I did notice a faster spool up on the turbo after changing the manifold gaskets at the head.

That's a natural safety advantage of the diesel: you can smell the exhaust when it is drawn into the cab. No accidental CO poisoning.