Exhaust leak search - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

EA1191 · 05-19-2003, 05:07

Has anyone used the pressure from a vacuum cleaner to test for leaks in the exhaust system?
The car is not used often and there is a problem which means that it is best not to idle for any length of time from cold.
With the exhaust cold and with air pressure applied it should be easy to feel for a leak.
Would air leak past the pistons on the exhaust stroke? And would that remove the oil around the piston? For a six cylinder how many cylinders would have the exhaust open.
I thought if the plugs were removed the air would escape from the plug hole with the open exhaust valve, and some oil could be injected and the plug replaced.
Or is there an easier way.

Aussiblue · 05-19-2003, 05:40

OK I doubt a vaccum cleaner would generate the required pressure and if it did it would initially start the pistons moving. In any event, some inlet valves would also be open or partailly open allowing the air to leak out the inlet system. Instaed

a) Have someone hold there had over the end of the exhaust pipe when the engine ahs been started from cold (so nobody get a burnt hand) and see if you can see smoke coming from other parts of the exhaust.

b) If this doesn't work do the same thing while the car is on ramps and run your hand along the exhaust feeling for leaks.

In doing these test be very careful to avoid breathing in any exhaust fumes; do the tests as quickly as you can and keep your head away from any fumes.

Most leaks can found by looking for holes in the pipes when the engine isn't running and listening for where the odd sounds are coming from.

Aussiblue · 05-19-2003, 05:43

PS park on some long grass with engine running and look for where the leakk is blowing the grass around when you rev the engine.. Watch out for grass fires though or keep the hose handy.

EA1191 · 05-20-2003, 18:50

Did a quick check but only for a few minutes without finding a leak but will add oil to the cylinders with the open exhaust valves for a longer check.
There seemed to be a fair pressure in the system which should make a leak easy to find if it was not too small. Will try soapy water on suspect places.