Leakdown Test vs Compression Test? Help with a used boat.
 

I have a friend buying a Maxum 19ft bowrider with a Mercruiser 4.3. The boat only has 50hrs on it and has never been stored in the water. It looks new. I took a test ride on it and it drives fine. Do you think a Leakdown or Compression test is needed? and if so, which one? The marina wants to charge $125 for the compression test and $150 for the Leakdown. Im not sure why the Leakdown would cost more since I didnt think it takes any more time.
Thanks

Compression test is static and does the combustion area only... where a leak down test is dynamic and tests the entire intake thru exhaust plus the combustion area. Opt for the leak down test and they do take more time compared to a static compression only test.

Leakdown test. You can have good compression numbers and still have a crap engine. Leakdown test will tell the real story.

I paid for the compression test and it tested good. I noticed a lot of blow by and ran a leak down and discovered 2 bad cylinders. Engine had to be rebuilt. By the way mine had 50 hours and garage stored. Problem was it sat for long periods without being properly prepped

Thanks All. Does anyone know what numbers Im looking to hit with a Mercruiser 4.3?

Compression can be fudged a little by how many compression cycles you run it through .I good tight seal will shoot the pressure up pretty high on first stroke .Typically four compression strokes in each hole is what should be done. You can hear it compress and watch the needle rise on each compression stroke. If you just keep spinning it to the highest number it is not the best way and may show decent compression even when it is somewhat low ..Leak down is the way to go and does take longer. Not only will it tell percent of leakage, but also where it leaks ..intake ,exhaust or rings/cylinder

Is 4.3 a vortec motor

I think its this motor.

http://www.mercurymercruiser.com/mer...odel=4.3%20TKS

what year

Sorry,
Its an 08, the original owner took delivery in 2010 as a left over. Its an inexpensive 19ft Maxum bowrider with 50 hrs. Looks new. Ran fine during the test this past weekend.