The truck in my sig has a very noticeable smell of antifreeze from under the hood when running and I have looked for a leak but no luck. It gets parked on concrete and dosent leak anything on the ground ever. I have to add about 1 inch of coolant into the recovery tank every couple of hundred miles or so. It isnt smoking white and runs fine. The oil isn't milky and I have replaced the reservoir cap already. Before anyone tries accusing me of I have done a search. Any Ideas?

 

do you have access to a pressure tester?

 

I can rent one from the parts store if that's what kind of pressure tester your talking about. I also have a shop air compressor with an adjustable regulator and an extra overflow reservoir cap that Id thought about making into a pressure tester but unsure if that's as accurate as one form the parts store.

 

Can you check the weep hole on the bottom of the water pump?

 

My 04 denali was doing the exact same thing for months until last week I found the leak. Like the guy above mentioned check the water pump that's what was wrong with mine.

 

i've been having the same issue with my s10 for 4 and a half years now (and has over 300,000 miles). it has a cracked head gasket but not enough to hurt anything. the only thing is that i have to add coolant every couple weeks or so but no biggie. as long as it keeps running, i'll keep driving.

anyway, the way i found it was under the truck. the coolant runs down the bellhousing of the tranny (leaving a green trail) while the truck is moving. and then doesnt leak at all when it's parked. good luck and hope this helps.

 

the home made sounds like a good idea haha, but unless you can accurately measure the pressuring leaking down then I'd rent the real one
cause once you pump it to 16psi, close the valve and now the system is sealed. get on the ground, look up the front of your timing cover and try see the bottom of the water pump area, sometimes you can even see the residual dried there. take a look around the head gaskets area, for the back of the heads its easier to see from underneath looking up from the trans bellhousing.
after you spend some time visually looking, when you come back up...see where the pressure tester is, if after 5 minutes its already dropped to like 10PSI and no visual leak found...I'd suspect internal!

 

Ill check the water pump. I also was thinking maybe the crossover tubes might have a leaking o ring on the back side of the heads behind the intake but havent been able to check yet.

 

I know on my 799's the rear cross over ports were rivet sealed from factory, so yours might be the same

 

So no crossover tubes with bolts and an o ring seal like the ls6 cars had? You say they were riveted? I will have to check into that. Thanks.