Another senior moment. Somebody remind me what to spray around an intake manifold to detect an air leak.
Starting fluid is very risky if the exhaust manifold is close by and hot, but I've got by using it when the engine was cold and just been started. I'm sure less flammable options works, I just haven't tried them myself.
I have always used wd40 to detect intake leaks in motorcycles.
What about a mist of water?
I've always used an unlit propane torch. The gas will be drawn into the intake side where there is a leak. The upside is keeping your engine clean and it is highly unlikely you will start any fires.
I too use the propane torch.
For others reading this:
The idea is to increase the combustible's to provide a richer mixture. If the engine RPM increases you know there is a leak. WD40 does the same thing as it contains a petroleum product but it drips and runs down the side of the engine.
I never thought of propane. Excellent idea.
I think the WD40 also temporarily "plugs" the leak, removing the lean condition so the engine picks up speed. Either way, it works.
In fact, my 1919 Dyke's recommends dribbling light oil around the intake manifold gaskets to detect an air leak.
I have always used oil. You find out real quick if it is leaking. As George states it improves running immediately if that is the problem. Mgh
Ditto the propane Steve. I just tried that trick last week 'cause I thought I had an intake leak...it's tight as can be.
I have used smoke bombs but propane would be easier
I remember the first time I tried the propane trick. Didn't find my intake leak, but jumped good when I found the exhaust manifold crack and lit the torch! (A little too much propane?) I just use oil now...
I like to use motor oil in a trigger squirt can. It does not explode and it shows being drawn in or bubbles when there is a compression or exhaust leak.
Steve, which car is needing the intake leak diagnosis?
Really enjoyed seeing your family re-union pics, glad you had a good time.