Lumina LTZ - 3800 engne - coolant lose

[77_vette]

Hi !

I drive a 1998 Chev Lumina LTZ with the 3.8 engine and has 90,000 miles on it..

2 weeks ago I noticed it starting to lose coolant from the reservoir tank. Once per week (300 mile) the reservoir tank was empty. There were no signs of leaking under the car. There was also no sign of water in the oil or oil in the water.

I took it to a mechanic friend who thought it was the water pump. He pressure tested everything and there were no problems. He replaced the water pump just in case. This was not the problem as the leak continued at the same rate. I then added ‘Bar Leaks’ to the coolant. Again, the coolant lose was the same.

I then went to my local GM garage. Once again they pressure tested everything. They also did a ‘dye & black light test’ and found no fluid problems. After extensive testing, they decided that perhaps the rad cap was faulty so they replaced it. Guess what – one week later, the coolant lose is still the same, and I’ve pumped almost $400 into this car over the past 2 weeks.

Can anybody help with this one ????

Many thanks in advance........

[sxtasy]

maybe you are not losing coolant at all. Depending on when you check your coolant (after or before driving) the level in your overflow tank will fluctuate due to expansion and contraction from heat. Have you actually had overheating problems? I would carry an extra bottle of antifreeze around with you and see if you actually overheat or not before you spend more money.

[GTS Jeff]

yea the coolant reservoir is just that, a reservoir...what matters is how much coolant is in your rad.

sxtacy is totally right.

[cocoabrova]

Fill up your reservoir to the specified amt., and at the right time (either cold engine or warm engine). THEN look for any drop in the reservoir after a few days. If a leak is apparent, then it could be a leaking heater core, coolant hose leak, or worst-case scenario: headgasket(s)....

[jdmmavericktR]

Originally posted by cocoabrova
Fill up your reservoir to the specified amt., and at the right time (either cold engine or warm engine). THEN look for any drop in the reservoir after a few days. If a leak is apparent, then it could be a leaking heater core, coolant hose leak, or worst-case scenario: headgasket(s)....

wouldn't a pressure test and dye and blacklight test find everything above(except for headgaskets)? I would think it would. I don't know the extent of the pressurization during the test, but I was thinking maybe a headgasket as well...hard to detect burning coolant.