I had a motor that keep leaking water at the intake manifold. After about 3 or 4 tries I changed to a differnt type intake gasket. Then keep tightening up the intake manifold. I was using a torque wrench & was amazed how many times I had to retorque ( 3 or 4) before they were would not loosen up.

Dyno, you'll need a compressor and a special leak down tool. This is basically a regulator and two gauges. The good ones will actually show the percentage of leakage. The cheap ones will have pressure numbers and make you do the math. You pull out one spark plug hole and turn the engine so it's at TDC with both valves closed. If you don't have the engine at TDC it will try to rotate when the cylinder is pressurized. That's why the other plugs are being left in. When you pressurize the cylinder, try to listen to the carb or exhaust. If you hear air escaping from either you know that a valve isn't sealing. Could be a burned valve, bent valve, damaged seat, or the valve isn't closed. If the air is leaking past the rings, shoot some light oil into the cylinder. Then retest. If the test improved, then you know that the rings are leaking. On a car, you can check the radiator for bubbles which would indicate a head gasket.

Thanks Tim!!!!!

Don't get too hung up with the numbers. This test will reveal things that never knew about your engine (and proably don't want to know). I believe less than 10% leakage would be for a new engine. 20-30% for a well worn healthy engine. Over that you have something happening. Anyways, look for cosistency between the cylinders.

Let me give you an example. On my old 500hour 454 that sank last year, I was loosing some speed. I had drop at least 4mph off my top end. Was baffling me, because the motor still sounded and felt strong. We did a leak down test and found that most of the cylinders tested in the 20% range. Really good for a old engine. I had one cylinder that tested at 40% and a final one at over 60%! On that one cylinder the air could be clearly heard escaping past the intake valve.

When Bruce tore the motor down, he was amazed by the condition of the motor. I guess the intake valve was burned and some rings were broken, but other than that it was in good rebuildable condition. Too be honest, the credit for the engines condition should go to the prior owner. I proably did more to wreck it in 2 years than he did in the prior 10.

Cord if the intake gasket is bad will it show up???and how ???can you hear it? Summit has a kit for $65 but I think I can make one up with some stuff I have laying around...

No, it wouldn't show up. You could try the old trick of starting the engine and passing a unlit propane torch over the gasket. If the rpms pickup, you've found a vacuum leak. Of course, the gasket could still be bad between the cross over and the port. I wonder if, the leak down tester could also be configured to test your water jacket. If you plugged the water outlet and inlet and could hook up a air line to one of the plugs, you then see if you have a leak.

Thats what Tinker told me to do .....I've scammed enough fittings gauges and a schrader valve to make a tester but still need to figure out how to cap off the water inlet and the two outlets at the exhaust.....Tinker told me to make a big loop from one outlet to the other, sounds good.... but the large inlet could be a trick!
Don

Good idea on plugging up all the stuff Cord that should help a lot I would think. As long as the leak is not the head gasket.

Jon

Head gasket should show up real easy with the above tests.

Intake gasket I had leaking I was only able to tell when I tore down & checked gaskets. I did not pressurize the water & check that way.

anything else I can check???