Hello,

I have been going through the list of things to check, I have both a hard upper radiator hose and white smoke along with a rough idle. It just started and I have not driven it anywhere. I was wondering if it can be driven, or will the hose explode? It is a 1998 vin code F with 160,000 miles. The engine was replaced in 2000, but I think it was a short block. Injection pump was replaced in 2005 at 113,000. I put new injectors in around 120k, they were high performance ones from kennedy diesel. PMD is on cooler (ss diesel) on intake with stock harness and ground. PMD is a Dipaco? I know it is not the AC delco, it was replaced about 9 months ago. Any help? I can do some of the tests myself, but I am not sure how to do some. The GM 4 part service books are confusing in some ways.

Head gaskets or cracked heads or block

like he said, blown head gasket or cracked block. Check out the head gasket/heads first as thats easier than buying a new block. Also, not to go off topic to far but should the truck live to see anothert day, remove the PMd and heat sink from the intake. Its been proven to shorten the life of the PMD as instead of cold fuel cooling it its getting torched by the engine heat flowing over the heatsink. Recommend you relocate to outside the engine bay on a heat sink. Good luck.

One of the easiest way to check which side of the block blew the head gasket is to check the crossover caps at the rear of the engine.
The heads are interchangeable so there are caps where the water crossover pipe connects to.
Run the truck to operating temp. relieve pressure at the cooling pressure cap so you will not get burned. Take a wrench and remove the bolts both caps. You should be able to see bubbles. Compression from side of the engine should be noted.

While the engine can be driven like this without blowing the upper radiator hose, I would highly suggest that you don't run the engine like this. If it is in fact a blown head gasket, and you run it too much, it could wash the oil off the cylinder walls with coolant, and score your cylinders, creating more problems.

It is VERY good that you caught this problem so quickly, and had the sense to stop driving the truck :) Do the check that GenBiltstein recommended, to see where/if there are bubbles coming out.

I would probably back the truck onto ramps, or jack up the back end some, so that you ensure that if there are any bubbles, they will rise to where you can see them. Remember, the engine sits at a tilt.