Okay, guys, I have about 400 miles now on my new stroker motor, and it seems to be running just fine .... except it keeps weeping coolant out somewhere, but I can't find the leak. It's a 109 block, and ported stock heads, and I had an engine builder I trust do the machine work, and put it together. The block was decked and squared up, and the heads were surfaced during the build. I'm using a FelPro 9441PT (I think that the right number) HG, and used ARP 12-point 7/16 head studs. I got my builder the good high-temp Permatex teflon sealant for the threads, and he used ARP lube on the top side to get correct torque. We retorqued the gaskets three time over a day and half prior to engine install. The coolant appears to be coming off the passenger side area, wetting the starter area and dripping on the cross-over pipe. It's not much coolant, maybe a couple of teaspoons, but since it's dripping on the cross-over pipe, it smokes and smells. To complicate matters, I'm running Evans NPG+c waterless coolant, so I can't throw just any seal tabs in the cooling system. I have put 4 BarrsLeak tabs (which are supposed to be compatible with Evans), and one of my engine builders professional seal tabs from Pioneer engine rebuilder products. Neither has seemed to staunch the weepage. Just this last couple of days, I removed the pass side headers (GN1 flange to turbo mount brace broke again so it needed repair.... just like ATRs), crossover, starter etc, and used my Stant hand-pumped rad checker tool to pressurize the coolant system. I pumped it up to ~18 psi, and got no leakage anywhere. It does look like there may have been signs of coolant loss at the passenger side block/head mating surface (very slight amount of moisture clinging to the HG) at some point. Left the system pressurized for about three hours total, no drips or obvious weepage that I could find. I felt the top nut area of the head studs, and they seemed dry. I did not see any appreciable loss of coolant level, and the pressure dropped very slowly like I would have expected. I also re-torqued the four bottom head studs to 80 ft-lbs, and didn't really seem to get any additional movement from the nuts. I did not loosen the nuts since it's very tight clearance on that side. I pulled the pass side spark plugs, and they all looked beautiful, no signs of being coolant washed. I have not done a leak-down or pressure test, but really don't believe I've lost cylinder seal, but am willing to listen to the experts. Like I said, the car runs great save for this annoying leakage. I put the car back together today, and it still weeps after a short drive... I've watched for leaks numerous times while the motor is idling, put it on jackstands again today, and lay under it for a half an hour, running, and it never leaked sitting still. Ugh... I'm out of ideas.
Any thoughts on where the coolant is coming from?? Any other type or manner to testing I should do to verify where the coolant is coming from?? I hate to pull the motor out if I don't really have an idea of what the exact problem is, kind of fumbling in the dark. Is it possible to push coolant out under low to moderate boost conditions, but not under normal non-boost loads?? I'm willing to switch to water-based coolant, but I'm suspicious that won't fix the problem. I can't figure out why I'm not able to catch the damned car leaking when it's sitting still and idling, but drive it around some and it leaks. And why hasn't the stop leak done it's job?? Any thoughts on things I've overlooked would be greatly appreciated.
Thanks,
John A, Turbohh
Any thoughts on where the coolant is coming from?? Any other type or manner to testing I should do to verify where the coolant is coming from?? I hate to pull the motor out if I don't really have an idea of what the exact problem is, kind of fumbling in the dark. Is it possible to push coolant out under low to moderate boost conditions, but not under normal non-boost loads?? I'm willing to switch to water-based coolant, but I'm suspicious that won't fix the problem. I can't figure out why I'm not able to catch the damned car leaking when it's sitting still and idling, but drive it around some and it leaks. And why hasn't the stop leak done it's job?? Any thoughts on things I've overlooked would be greatly appreciated.
Thanks,
John A, Turbohh
