Coolant problem

Hi out there! My 2002 Jimmy has a mysterious missing coolant problem. I've looked everwhere for a leak but cannot find anything. I have added maybe 3 litres in the past month! Any suggestions would be great.

Check for signs of water exiting the tailpipe. If you still have the original radiator cap you need to replace it with a Stant from Advance Auto. (Stant is the best but anyone other than AC Delco will work.) The AC Delco ones that orginally came on the vehicles are defective and allow air to get in the system. You need to check your radiator for signs of sludging too.

Check the engine oil and tranny fluid for signs of coolant. (it will look milky)

Also check the passenger side floor for water. Has the windshield been fogging up a lot lately?

Hey thanks alot guys, I just got the truck 3 months ago, I will have to check that out. I checked my oil and tranny and it is not leaking inside. rad looks fine(no sludge)why does air affect the system? An explaination would be appreciated. Thanks again.

Hey thanks alot guys, I just got the truck 3 months ago, I will have to check that out. I checked my oil and tranny and it is not leaking inside. rad looks fine(no sludge)why does air affect the system? An explaination would be appreciated. Thanks again.

I would replace the rad cap with something that is not AC Delco, get a Stant from your local parts store.

Air entering the system will become entrapped in some areas.

When you go out to the truck tomorrow, take the rad cap off when the truck is completely cold and see if the rad is right up to the top. It should be literally almost pouring out.