Is there any difference in symptons between a blown head gasket and a cracked head? With the radiator cap on the upper rad hose will get rock hard in about 20 seconds. with the rad cap off it appears there is a small amout of smoke coming out of the radiator. It's not steam because the coolant is still cold. It looses a small about of coolant, but it doesn't look like there is any coolant in the oil. The truck idles and runs fine, no loss of power. It does miss and blow white smoke for about 10 seconds after a cold startup, however, but after that it runs great. Any help is greatly appreciated.

I would think symptoms would fit both situations.
Hope for head gasket, expect a cracked head.

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Symptoms the same. Quick test,Drain coolant down a bit, pull the T-stat housing and Serpentine belt. Start engine and watch for bubbles in coolant. Bubbles are not your friend, pretty much guarantee blown gasket or crack. don't run too long or you will see boiling. This test has worked for me about half the time. When it does work, just finish draining and start wrenching. Rusty

although I'm sure I'll cath heck for saying it. If your in a pinch I had a 6.2 that had those symptoms. Get GM coolant tablets availible from the stealer. Throw a package in the rad. I got three more years out of my 6.2 and was still holding when I sold it. It was burning antifreeze so bad you couldn't drive it from the steam coming out of the exhaust. Downside..kiss the heater core goodbye and probably water pump. But it held.

6.2s and 6.5s have the water crossover plugs on the back of the heads because the heads are meant to fir on either side of the engine. Run the engine for a bit, relieve the pressure from te radiator cap and watch for the bubbles from each cap as you crack the caps off with a wrench. Least ways you will be able to tell which head to take off. a Compression test might be in order. Cracking a head isn't the first thing I would look for, my bet would be for the blown gasket. 6.2s and 6.5 are prone to em especially from heat.

Thanks for the advise, it will be a few days before I get a chance to really look at it. With 360,000 miles on it I guess this gives me an excuse to rebuild the engine, just hope the heads and block are in good enough shape to reuse. Also gives me a chance to throw some more mods on it. Thanks again.

Thanks for the advise. It will be a few days before I get a chance to really look at it. With 360,000 miles on it I guess it give me a good excuse to pull the motor and rebuild it. Just hope the heads and block are in good enough shape to reuse them. May also get a chance to throw some more mods on it. Thanks again for the advise.

Symptoms the same. Quick test,Drain coolant down a bit, pull the T-stat housing and Serpentine belt. Start engine and watch for bubbles in coolant. Bubbles are not your friend, pretty much guarantee blown gasket or crack. don't run too long or you will see boiling. This test has worked for me about half the time. When it does work, just finish draining and start wrenching. Rusty

I used this method when I had a cracked head "tested" and it still was leaking. This will tell you which side has the leak.

To narrow down a leak to a cylinder:
If you pull the glow plug from a cylinder and check for bubbles, the bad cylinder will reduce or stop bubbling. Don't pull more than two at once, the engine starts to buck pretty hard. Don't run it very long, a couple seconds, because your pumping raw fuel down the cylinder.

although I'm sure I'll cath heck for saying it. If your in a pinch I had a 6.2 that had those symptoms. Get GM coolant tablets availible from the stealer. Throw a package in the rad. I got three more years out of my 6.2 and was still holding when I sold it. It was burning antifreeze so bad you couldn't drive it from the steam coming out of the exhaust. Downside..kiss the heater core goodbye and probably water pump. But it held.

The tablets don't always work on compression leaks, very well!!! I tried that, no go.

With 360,000 miles on it I guess this gives me an excuse to rebuild the engine, just hope the heads and block are in good enough shape to reuse.

Looks like we are in the same boat, but I only have 330,000 on mine!
Ah... if only a tablet would solve the problem... some Ibuprofen for my head...
:D

Iv'e tried the tabs he's reffering to on a 350 gasser, they worked great for me.....
My 2 cents.

Louis