Cooling system blues....

1995 LT1 Caprice, non tow pack. 73K.

Have owned for 18 months and put 3K on it, with the first 1K in the first week. Anyway,


LT1 Cooling system issue. No visible leaks except around overflow tank. Looks like it is pushing past cap.

Drove it about 180 miles yesterday and 5 miles from destination it overheated but first 170 was straight hwy. Let it cool and it took about 2/3 gallon. Drove short 5-6 mile spurts after and it was ok with only a small drip near the overflow tank (dripping off the bottom but think it's pushing past the cap as the bottom hose is dry.)

Level was good and drove about 14 miles in mix of town and 45 speed limit and it overheated again.

Burped the system and ran it 70 mph for 140 miles, made every light from I95 to my driveway (3). Temp stayed just below half all the way until I pulled in then started to climb. Popped the hood with engine still running and cap running over and aux fan NOT on.

Today, I ordered a T-stat, water pump, and cap. Then I checked the T-stat in a pot of water and it works fine.
The stuff will be here on next Monday (ground from RA). I knew the tstat was fine as both hoses were hot. I'm thinking water pump and this point....with the cap to a lesser degree.

Why? If the pump was good it might leak at the cap, but the temp would stay okay until too much fluid went out. When it overheated yesterday after the in town drive, it only took a cup.

Or I could have a blockage in the radiator. Anyway, it's the excuse to put the green hoses on as I will flush everything out.
Pretty sure it's the OE water pump on there with only 73K. It looks the part

Caps go bad. I changed the one on my 95. Use OEM. Bleed the system while you're at it.

If the radiator is old, it is likely bad. Right now for $106 you can get  new one on Ebay, your other post I gave you the link

Were the fans coming on? If it stays cool going down the road but not when you slow down that would be the first place to look, I think.

"I'm thinking water pump"

This should probably be on the bottom of your list. Other than leaking, there is really nothing that can partially fail.

Had the same symptoms on my first 95 wagon and it was a dirty core. Installed the flush kit on the heater hoses, drained it, ran it with Prestone cleaner and straight water for a few days, and then flushed it repeatedly until all I got was clear water. It was fine afterwards, as was the heater core.

So it was the water pump. Replaced and then the radiator blew out a week later. All fixed now except for the Air Conditioning (leaking badly at the compressor).

I'm curious: what was the problem with the pump?

dmg4 wrote:

I'm curious: what was the problem with the pump?

not 100% sure as it looked like it still turned when I took the front cover off, but it was overheating and replacing it fixed the issue.