Last night I got a call from my wife as she was driving home saying that her car was overheating. The needle was into the red which has never happened before even with some of the excessive warmth this car has developed on hot days. This was after dark and cool out, so that usually isn't a problem that time of day. Anyway, she pulled over and the temp started to drop to about the 3rd line and a bit below. She got it limped home and I took a look. There was coolant on the plastic splash guard under the radiator and the radiator and overflow tank were pretty much empty. The level of coolant hasn't changed noticeably since I did the LIM/UIM manifold repair and now suddenly its all gone. I refilled everything and started it up and it immediately cooled down and ran properly. I saw nothing leaking and after driving it this morning, it hasn't lost any either. I'm confused as to what could have temporarily failed and allowed all the coolant to blow out, and then fix itself. Could a failing radiator cap do that?

Gotta let it get warmed up to normal operating temp. Then check all your hoses, caps, lines etc. Check your oil to be on the safe side too. Sometimes it'* hard to see a pin hole leak on the bottom of a hose.

Are you sure it isn't burning it? I persoanlly would think that if it was the cap, you would know it, right? I mean wouldn't it be all wet?

Chris...he..uh.. SAW it on the splash guard.

I assume this is the splash guard under the entire front of the car? If so.. check both radiator endcaps for signs of wetness. The plastic endcaps over time and heat cycles will crack and develop small seep/leaks that eventually will drain the system down.

I have gotten it up to operating temp since refilling it and have seen no leaks inside the engine bay or under the car. It really looks like it all just came out at one time from somewhere because there were puddles in the engine bay. If it was burning that much, the exhaust would be white and it isn't. I tried to look for leaks on or around the radiator but since it was dark last night and this morning when I looked, it was difficult to see for sure. If it is leaking, it just started and lost coolant quickly because the level has been unchanged every time I've looked over the last month. I will look again tonight when I have some light. I will take a close look at those endcaps as well.

this sounds like a pinhole leak in one of the hoses to me. It probably only leaks when the radiator pressurizes.

I'd check the oil for chocolate milk sydrome, though.

I second this suggestion. It'* leaking somewhere.

I agree with Bill and Bob that it is likely a failure in the rad or a rad hose. Once your system heats up and the system pressurizes, you can lose a lot of coolant in a short period of time. Many times there'* very little indication it is happening, since it pisses out onto the road and then stops leaking as the car cools.

If it is a small hole, I sure hope its a hose and not the radiator. Although this would give me an excuse to upgrade to the 1" radiator...

Well let us know what you find.

BTW, jr's3800 loves his new, larger radiator! It'* apparently a good upgrade.