LB7: Coolant Loss; any ideas?

[thxone]

I've read most of the threads on all the prelimary checks for head gaskets or "cups", but situation seems to be a little different.

1. No "hard" upper radiator hose after sitting over-nite
2. No visible leaks on the ground
3. No excess pressure in the over-flow
4. No boiling over out of the over-flow
5. No over heating
6. Temps remain normal, even when towing, engine runs fine
7. No steam/white exhaust at start-up or while running
8. No water/coolant in the oil
9. Brand new overflow tank cap

I'm using approximately 1 to 2 quarts of coolant every week. Any ideas or additional tests?

Thanks in advance for your help.

Greg

 

[RKTMech]

Well look all over the motor top and bottom and front to back with a goood flash light, for baked on coolant, if it leaks slow enough it might not make it to the ground. Are there any small black specks or a blackish gray haze color to the top water line area in the coolant bottle? Got some vehicle info also, kinda helps.

 

[thxone]

RKTMech,

Thanks for the flash light tip.... I wish I had more info for you, but I just purchased this 03 GMC 10 days ago, so the history is limiited. Some additional info:

03' with 137,500 miles. Appears to be mostly stock with Magnaflow exhaust and Air-raid CAI.

 

[RKTMech]

The thing about dex-cool is it just turns the oil blacker in small quantities if its getting into the engine oil, keep an eye on the oil level..... but sad to say odds are your going to be getting the heads checked and some new gaskets if you dont find an external leak.

 

[Bustedknuckles]

Is your over flow tank turning gray? Check real good in the valley of the engine as it could be leaking down into there and not making it to the ground.

 

[madmax02]

My 02 is now at the dealer for the same. Mine started as a coolant leak with no leaks. Had the oil analyzed and there was coolant in the oil. I didn't have any signs of head gaskets. But I got the call the other day and it indeed needs the heads pulled.

Check the oil filler cap, see of there is any water on it, taste it. That's was my first indication. Oil never was milkie or really seemed to be gaining oil lev.

 

[ImpalaMax]

The heater core lines are aluminum. I had one with a small crack at the mount tab by the exhaust manifold pass side. Never could find it but added 1-2 qts a week. Finally found it and replaced that line fixed my problem. This was a 04 LB7.