bigwheel
New member
I am looking at doing leak down test on a truck. Can you perform a leak down test on a 7.3 or would a compression test be better? What should the spec range be? Thanks
Leak Down test?
- Thread starter bigwheel
- Start date
leak down there really isn't a spec.
You do a leak down test after a compression test to find out where it's going..
into the intake, intake valve.
out the exhaust, bad exhaust valve.
into the crankcase, past the rings.
You do a leak down test after a compression test to find out where it's going..
into the intake, intake valve.
out the exhaust, bad exhaust valve.
into the crankcase, past the rings.
Arisley
Moderator
With the ring design on our pistons, I thought that with the engine off there would be a lot of blowby. Thereby making a leakdown test on our trucks pretty much useless.
bigwheel
New member
I was thinking about a leak down test to see how the motor looks. I decided to do a compression test insted.
Arisley
Moderator
I have always run a compression test. Then put a couple tablepoons of oil in the top of the cylinder and repeat the compression test. If it improves, it is the bottom end, if it doesn't, it is the top end. Unless of course, you have a piston with a hole in it. However, you usually know about something that bad before you start the compression test.
Fly By Night
New member
He has been having high EGT issues and a haze that will not go away IIRC. He did do a compression test and averaged ~300 which is a little on the low side for our elevation (6,500'). That being said that is what my truck has and she does just fine.
Leak down testing can be an extremely helpful test when trying to determine what is the cause of low compression. It can also be useful when trying to determine the health of a cylinder when cranking the engine is not an option (in the gasser world this means blown timing belt/ chain type of situation).
