How long did you let it setup? I used it on my header flanges on my car and we use it on the race car header flanges. I let it setup for 24hrs.
Instructions say to clean rust off, wet the pipes, put a 1/2"-thick bead of sealant on the pipe, put them together and clamp them, wait 30 minutes, then run the engine for 10 minutes.
Forgot to wet one side, and I waited about 40-45 minutes, then ran the engine for about 15 minutes.
That's the only parts where I deviated from the instructions.
The side I forgot to wet ended up leaking, the other side sealed up ok.
Took the car to the local Meineke, had them touchup the weld at the H in the H-pipe (had 2 small leaks there), and they applied some more of their sealant to the joint that was leaking, then clamped it back down.
So far so good, I only got on it all little bit since then.
I'm having a hard time getting the car to be OBD-ready for the state inspection, it doesn't wanna set, even after I drove it a couple hundred miles.
And I have a nagging tinny rattle from the middle/rear-half of the car, floor board area, when I hit sharp impacts with either one of the rear tires. I've checked the shock upper nuts, Watts Link clamp bolts, Watts Link bolts to the body and the propeller, LCA bolts, UCA upper bolt.
Driving me crazy, can't figure out what's causing it.