ANY HELPWOULD BE APPRECIATED.... I have a '99 Tahoe Sport, 350, 4X4. at about 100K miles it began overheating occasionally, It resulted in my replacing the engine about 5000 miles ago (threw a rod), but I STILL HAVE THE PROBLEM>>>> I've replaced the thermostat (twice), the temp sending unit, and the radiator has been flushed... When I start the engine cold, the thermostat opens up at about 235-245 degrees, and the fluctuates between 155-235 degress from then on.... THANX for reading... CG

 

Cliff, I had a smilar problem. You said you had the radiator flushed. Was this done with a back flush machine ?? If it was, take out your radiator , take it to a radiator shop and have it rodded and cleaned by them. It's the right way to clean a radiator !! Call around for prices, there seems to be a lot of different prices for the same job ! Good Luck, Dondobe

 

Cliff, I agree with dondobe, if you didn’t pull the rad and have a shop do it I’d pull it.

One other thought would be your hoses. I assume you put new hoses on it when the new motor went in. I know what do hoses have to do with over heating… I’ve seen, not very often, that bottom hose partially collapse, causing the engine to cook. This is pretty rare, but if that’s the problem it would normally occur when you are driving not at idle. There’s not enough suction from the water pump at idle to create the problem.