Help. '98 Silverado, 5.7L 175,000 miles. After short trip when outside weather is <40F before engine totally warms up I get a leak at upper
radiator hose connection to radiator. Once warm it doesn't leak. Took me a while to 'catch it in the act'. Replaced radiator hose (NAPA) with new one from NAPA, went on kind of easy, didn't have to work on. Ran great for one week and started to leak again. Changed clamp, rant great for week and started to leak again. About ready to give up. Truck has to be over-night cold and cold morning after about a one mile drive it leaks like a sieve. Radiator hose connection looks ok, no cracks. About ready to buy a GM hose. BTW, intake manifold gasket replaced 2nd time about 5K miles ago. I have seen it leak once at the hose fitting and the puddles are always directly below upper hose connection. What am I missing?

 

Are you sure it isn't leaking around the oil cooler fitting in the radiator or the radiator itself might have a crack in it?

 

I don't believe so from the one time I actually saw it running out. I also thought it was the oil cooler fitting as I saw a stain running below it, but when I saw it coming from the hose I dismissed that idea. If it was a crack or leaking fitting I would think it would leak all the time or under pressure (have pressure tested too).

 

I think you have a cracked radiator around the inlet. My dad's chevy did a similar thing. The plastic would expand and contract with the weather. We pressure tested his numerous times looking for that dam leak. And then finally 1 day coming home it really srted to leak and luckily he was not far from home.

 

try putting a small amount of NON granite or lithium,bearing grease(must be petroleum based) inside all around the hose then reinstall.if the leak continues look closely for a hairline crack in the fitting coming out of the radiator.