I am prospecting a 2006 Air Nautique DD quite a distance away from me and am having a marine mechanic very familiar with PCM doing an inspection.  The boat has not been run much in the last year + and on the initial compression test 1 of the cylinders came back with pressure around 100.  The other 7 cylinders were 160-170.  I was told oil pressure is good and there’s no smoke.  He is going to run the boat again today and check pressures again.  Should I continue on with this rig or RUN?  I realize I’m asking ya’ll to diagnose a potential heart attack “over the phone” but let me know what you think.  Engine has about 400 hrs but may have had a rough life so far.  The rest of the boat is in great shape.

Thanks all!

LongLakeWI wrote: on the initial compression test 1 of the cylinders came back with pressure around 100.  The other 7 cylinders were 160-170.  I was told oil pressure is good and there’s no smoke.  He is going to run the boat again today and check pressures again. Thanks all!

LongLakeWI wrote: The mechanic preformed a second compression test after running the engine a longer yesterday.  The pressures came back higher than the first test.  (170, 140, 145, 135, 145, 150, 170, 155)  .

It looks to me like some of  those 160 to 170 readings just got  lower and one unknown cylinder went from 100 to some number 

Is this a mechanic at a dealer selling the boat or is it a private sale and you dug up this mechanic somewhere to check the boat out?

Has it been run on the water under load  or just idled on the trailer for a little while before the last set of readings

If you trust the mechanic and he's telling you things are good, then maybe it's time for the drive.

Like 63 Skier, if I was buying it, I'd be OK with the numbers

LongLakeWI wrote: The mechanic was referred to me by the seller but I’m paying for the inspection and he seems impartial.

I'd find it hard to put much faith in the mechanic under these circumstances.  That doesn't mean I'm saying not to buy the boat, but have to keep it in mind.

Like Ken says, hard to offer advice from this point.  I'm not as up to date on pricing these days, that seems like a very good buy in this market with boats going for higher prices like every other recreational item.

I guess it depends on your risk tolerance.  For me, the visible stuff is easy to get a handle on, if interior is good that's a huge savings, if you have to put new skins on it's a $5,000 job professonally done, less if you can put them on yourself.  Engine ... the fact that it runs would lead you to think it will run when you get the boat and put it in the water.  If it hasn't been maintained with proper oil changes, fogged in the off season or when stored, you could have some light rust in the cylinders that cleans itself up.  If the impeller hasn't been changed you could have some rubber impeller pieces in the cooling loop.  But these are fixable items, when you get the boat you'll change fluids and impeller and belts and start from there.  I'm rambling I guess, you just have to take the plunge or if you really are concerned just look for something in your region that you can test in person.

Last comment - not sure where in TX, definitely hasn't seen salt water, right?

You mention the engine has about 400 hours, how many are on the boat?  The tranny wears also in those boats.,  I would not hook up to an unknown trailer and try to tow 1,500 miles.  I would want to know the bearings are packed fresh with new seals and the brakes are working perfectly.  Boats that sit can have screwy compression numbers after being parked, not just cylinder walls but the Valve faces can rust allowing a little compression to leak.   Run it a few hours and that cleans up normally.   I would not suspect that unless it has been sitting over a year.   Texas Froze hard last year, was the block protected from that freeze?