going to do a leak down on my 500 hps next week, my question is, that it is cold here and i cant start the motors yet to warm them, so is it acurate to do when motors are cold. i will put heat in the garage the boat is in and warm up to like 60 or so.

thks

depends on what you think you are looking for... the results are going to be bad. not going to be much in the way of ring seal...but if you suspect abent valve or something like that it will tell you that... frankly without a real reason to do it , ide say you are wasting your time

I was thinking of doing the same thing. My valve train is kind of noisy and read a couple of posts where people stated the 500 was known for valve train problems. Would this test let me know everything is ok? If I do have a problem I would like to know now and get it fixed before summer. All suggestions are greatly appreciated.

The leak down will provide insight into general health by showing an imbalance from cylinder to cylinder. Problems like bad head gaskets, bent or non-sealing valves, broken rings and/or pistons will be evident when one cylinder shows 35%, and the rest show 4% (an example). Lightly oil the cylinders and exhaust valve, then turn motor over before performing the test since you are not going to start it. This will move the rings off from their current "home" position, and help the open exhaust valves clean the seats.

Mikey, the valvetrain problems on 500's are valve spring issues-esp. the carbed 500 blue motors. Pulling the valve covers and looking real carefully is the best way to check for valvespring issues. Most shops will recommend valve springs at about 200 hours on all the 500 motors.

Forget about it cold, unless you're looking for a hole in a piston.
When I've done it cold, the readings on the same cylinder change a lot after only a few cranks of the motor.
My $0.02
Gary

good info to know

Depends on your mechanics rate. How many engines? Does it take 1 mechanic and a contortionist to reach your rear center spark plugs on your side-by-side twin engine boat?
Gary

For me it's a $65 leakdown gauge and a 12 pack. For a staggered engine setup with no room, it would be a *****.

I plan on breaking in my new engine and then getting a baseline leakdown test. Then maybe once per season before storage to compare results.