I pressure tested my coolant system today on my 1999 Yukon 5.7L after suspecting an internal coolant leak somewhere with a sometimes rough running engine, a little white tailpipe smoke and the loss of about 4 oz of coolant every 250 miltes.
I pumped the pressure up to 16 lbs. Waited 15 minutes and it leaked down to about 11 pounds. Waited an hour and it leaked down to around 7 lbs.
I could not find any external leaks. I put drip papers underneath the whole engine area and it was clean. NO DRIPS.
First, can anyone tell me if the loss of pressure from 16 to 11 PSI's in 15 minutes is a problem. I suspect it is. And then it leaked down to 7 lbs around an hour.
Second, I have no oil in water and no water in oil. Both are absolutely clean and normal. Is it possible for an intake gasket to leak cooant into an intake port and for it to get burned up like that? I'm reluctant to believe it is a headgasket problem because I put remanufactured heads on it 1-1/2 years ago and I torqued everything to specs.
I'm working on the third set of intake manifold gaskets with the last being the most current Fel-Pro Updates. I took my time and felt like I did everything right so I'm wondering if maybe my intake manifold is warped. If so is there a good way to determine if it is.
I would appreciate any opinions and suggestions.
Thanks,
RonC
I pumped the pressure up to 16 lbs. Waited 15 minutes and it leaked down to about 11 pounds. Waited an hour and it leaked down to around 7 lbs.
I could not find any external leaks. I put drip papers underneath the whole engine area and it was clean. NO DRIPS.
First, can anyone tell me if the loss of pressure from 16 to 11 PSI's in 15 minutes is a problem. I suspect it is. And then it leaked down to 7 lbs around an hour.
Second, I have no oil in water and no water in oil. Both are absolutely clean and normal. Is it possible for an intake gasket to leak cooant into an intake port and for it to get burned up like that? I'm reluctant to believe it is a headgasket problem because I put remanufactured heads on it 1-1/2 years ago and I torqued everything to specs.
I'm working on the third set of intake manifold gaskets with the last being the most current Fel-Pro Updates. I took my time and felt like I did everything right so I'm wondering if maybe my intake manifold is warped. If so is there a good way to determine if it is.
I would appreciate any opinions and suggestions.
Thanks,
RonC
Last edited:
