1997 chev picup 5.7L is there a way to tell if i have a intake manifold leak or a head gasket or cracked block?it doesn loose enough fluid to overheat. it emits white smoke after sitting a day or more, skips for a while and smoothes out after a mile or so. and is this a big job.
The cooling system can be pressurized to locate leaks. This should be done with the engine cold and at full operating temperature.
The most common cause for coolant loss on this engine is because of a defective intake manifold gaskets. You also want to keep an eye on the oil condition as coolant can end up in the oil, causing damage to the engine.
I went through this with my 2000 Blazer. Right after I changed the coolant at 40k, the coolant level in the overflow tank started to drop slowly (~ 1 pint a month). When I had the oil changed, the mechanic noticed a few drops of coolant when the last bit of the oil drained out of the pan. He was pretty sure it was the intake gasket and told me to get it to the dealer ASAP. Any coolant that gets into the oil will displace the oil on the crankshaft bearings and destroy the engine.
The dealer confirmed the leak and replaced the gasket, I haven’t had any problem since (3.5 years). It’s in your best interest to get this taken care of, better a $400 or $500 repair versus replacing an engine.