How do you tell how many hours an engine has?
 

I'm looking at another Mariah to buy, and have found one that I'm very interested in. The thing is, I'm a little doubtful about the hours on the engine that the owner claims -- is there an objective way to check engine time, other than experience?
Thanks.

I forget what year they started, but MerCruiser engines have a computer that a technician can hook up to and tell what the actual running hours are. I want to say late 80's or early 90's, but I could be way off. Try calling a MerCruiser tech. and see what they say. Maybe he could give you a full check of the engine/outdrive as well before you make a commitment to buy it.

I have been trying to get the same information... My boat does not have an hour meter and the best guess is what we have been going off. My guess is there is about 375hrs on it now... But I have no way to confirm it.

I'm not entirely sure, so you might want to check with your Mercruiser Technician, but I think you can only hook into fuel injected engines, because they're the only ones with an ECM and a data link.

^ Yep. Carbed engines have no computer, so no record of the # of hours. Unless of course you have an hour meter connected. Even then, it's possible the gauge reading isn't true (mine runs when the key is in the on position, and the engine is not running...)

A compression test might give you an idea of how "tired" the powerplant is, but it would be still be anyones guess as to the actual number of running hours on it.

A quick check that will give you an idea of it's general condition... pop the oil fill cap on the valve cover and have a peek. If there is no sludge and only slight staining of the head and rockers, the engine is probably in pretty good shape. If you can't see bare metal, walk away. The motor hasn't been maintained properly.