Agreed, a leakdown test is better to see where an issue is. Probably the lower number cylinders are leaking by the exhaust. Head refesh is easier and cheaper than a bottom end.

Def re-do with some oil in the cylinders to see if it is rings/pistons or valve work which is far easier cheaper. The block/lower end very well might be fine.

For comparison sake, what would you expect to see for compression numbers on a brand new/rebuilt stock motor?

Also, per the Mercury manual, compression should be minimum 100 psi and the minimum recorded compression in any one cylinder should not be less than 70 percent of the highest recorded cylinder. These motors seem to fit that bill.

I have no dog in this fight and don't know the buyer or seller. It sounds like the OP is moving on unless he can work a better deal. As an owner of a boat with a motor having similar compression numbers, I just wanted to see if more information could be added to this discussion.

I don't really find much wrong with those numbers. They're within 10% and 15% of the spread of readings, respectively. Test results can vary depending on the person testing (and tools, procedures, etc). I don't know that I'd pass on it.

Man, I've never known anyone to have such a hard time finding a boat! I wish you luck, but in the price range you're looking, I think your standards may be just a bit too high.

Let me add... that was not meant to be discouraging or disrespectful. I just think you might be missing some nice opportunities over some issues that may not be much at all.

-Tom

Tom, no disrespect taken. I have missed out on literally two I should have jumped on. One was a 2000 Marlago with two stroke Yamaha's (just wasn't sure the big CC life was for me, but if I spun the clock back, I'd own that one) and the 1995 Formula 303 that a dealer was selling on the east coast of Florida in March, when my search was really ramping up but it had unidentifiable blow-by issues (for new engines) that were a no-go by a reputable surveyor and many folks on this site. But, for the price it ended up selling for, I still would have bought that one (over $8,000 cheaper and with 25 hours on the motors than the boat I opened with). The rest of the boats I am seeing are priced too high for what condition they are. Maybe if I don't buy one of them someone else will. But, I'm not gonna over pay for a potential future project boat. I know something will come around. It's also tough being all the way down here in South Florida and not being able to fly. So, I have to make judgements and decisions remotely, which doesn't help.

Nothing wrong with those numbers at all. The motors have 700 hrs now? I'd run them to 1000 and check again. You'd be surprised how many hours they can last.

Yep, I'd talk the seller down based on needing engines refreshed, stash that savings and run them until they're on their last legs.