Detroit Diesel 8 V 92 coolant in oil pan.

I would suspect the intercooler under the blower.

 

You suspect that might be the path the coolant took from its tank down to the oil? A leak in, ( or around ), the intercooler? Would something like that have to happen while the engine is running? Thanks for all your help.

 

I agree with Robert, to properly diagnose where coolant is coming from.

 

The plugs in the block beneath the blower are threaded plugs not cup plugs. With an aftercooler installed the rear plug is a bushing that supplies coolant to the aftercooler. Any leaks in this area would show up in the airbox & leak out the airbox drain tubes. Early engines routed the tubes back to the pan which would provide a coolant path directly to the oil. That was a bad idea. Most of those tubes were removed from the pan & routed to the ground as they should be.
The water pump is gear driven & is a possible cause if the weap hole is plugged. The head gasket is mostly o'rings & a common leak path.
Dropping the pan is the least invasive & the best way to identify the leak.

 

Thanks for clearing that up, knew it was some kind of plug.
The memory is fuzzy 35 years after the fact.

Agree, drop the pan first, check the liners and bearings, maybe fill and pressurize the cooing system if the leak isn't obvious.

 

I have had a liner crack and put water in the pan. Unfortunately, it took the crank with it too. I pulled the pan and couldn't see the crack until I rolled the engine over and the piston went up high enough to see the crack.

The air box drain routed to the pan was to help stop the oil/fuel puddles under the trucks after idling all night. Real dumb idea to route oily unburnt fuel into the engine oil.

 

Just a point of clarification, the blower on a 2 cycle Jimmy is not a supercharger, it's a scavenger blower, ie it blows the exhaust out the valve because there is no exhaust nor intake stroke on a 2 cycle. Small 2 stroke gasoline engines accomplish this by the piston pressurizing the crankcase with the piston on the power stroke.

 

No, it's a supercharger, a gear driven air compressor.

Big 2 stroke diesels, 8V92TA's, have intake and exhaust valves, blower has nothing to do with exhaust, turbocharger handles the exhaust.

 

You sir are very very wrong. The 2 stroke Detroit’s need the blower to even run. They do not provide any positive pressure to the engine. Thats why Detroit labeled them as a naturally aspirated engine. If you look all the 2 strokes from the small 1-53’s all the way up to the 20-149’s all have the same style root blower on them. I do believe that you are confusing 2 of the exh valves on the 92 series as intake valves.

 

And just to add here is a screen shot and link to Wikipedia, it is for a 71 series but the 53 and 92 series are designed the same way. Detroit Diesel Series 71 - Wikipedia