Compression for 2000 502 EFI's ???
 

Buying a used boat, and had a Formula Dealer perform a compression check for twin 502's. Ranges were 106-120.

Can someone with more experience tell me what good and bad numbers are?

Thanks.

Hours are 135. Boat was not used that much for a 2000. I am not sure if test was done correctly, but they are a formula dealer and boat is a 400 SS.

I talked to another service person, diff't area of country, and he indicated usually 140-150. But it all depends on the gage and testing conditions.

I have $25,000 in escrow to cover final boat testing before it is ship'd to me.

I think another test should be done, don't you? If they are too low, what would be the next step?

The numbers are low, but it could be the persons gage. The real concern is the total variance. Best to worst should ideally be 5% or less, merc says 10% and you are beyond that.

Rod

Comp on my 2000 502's MPI's with 175 hrs was
1-155/155/155/145/155/155/150/150
2-145/150/155/150/155/150/150/155

RPM hits it on the nail I think.

Once the ECM is plugged I think the hours can be verified also you might want to do that

96Vyper, They sound too low to me too, 140-150 is what mine tested out at. A simple compression check. A leak down would be better. But I think you will be disapointed based on the compression test if the compression test is really that low. Positivly have it checked again. I have a comp tester if you need to borrow it. - No problem

The test has to be done while the engine is warm too. The ECM will tell you hours but it wont tell you if it was neglected or beat hard.

Thanks for all the responses guys. I am going to have it inspected again and discuss with my surveyor.

Anyone live near Laconia, NH?

96vyper, Those compression numbers sound low. I have my heads in the shop now for low compression. My #3 and #4 were at 120 and #8 at 90, those cylinders had poor valve seating, the other 5 were around 150. If all eight cylinders are that low, I'd put money on someone doing a poor test or bad equipment. I was told to use a good guage, test with a hot engine, remove all plugs, keep throttle open and make sure batteries are full. Keeping a battery charger on it helps, need constant cranking power balance. Hope this helps and good luck. Also try squirting some oil in the cylinders to see if that helps to seal the rings for blowby and a cylinder leak down test would be next step. Hope all goes well. Derrick

Just got off the phone with the dealer. They will be doing another compression test tomorrow along with a leak down test.

I'm glad I have an escrow to cover these expenses. I will say, the dealer has been a great pleasure to work with. They don't want this boat leaving for Michigan until everthing is working as it should.

I will know more on Monday.

It just sucks that we probably will have to wait longer to get the boat if there are problems. Even if the tests do well, the ship date will have to be moved to a later date.

Have them do it again with the engine warm and throttle wide open.

get the same readings, and your in for at minimum some heads work.

DO A LEAK DOWN TEST
 

I'd do a leak down test aswell they are very helpful a comp test will tell you what it is and a leak down where its going .
on a comp test the man thing as you know is they need to be with in 10% of each other >>If you have alot of lek down it doesn't matter where its all going its just that its going and how to fix it (RINGS OR VALVE JOB ) :D :D Good Luck !!!!!