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Low Compression on 2006 Excal 330

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LongLakeWI View Drop Down
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    Posted: April-05-2022 at 8:27am

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!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: April-05-2022 at 5:05pm
Have them do a Leak down test on the bad cylinder.  A leak down will point you towards the exact issue, Rings, Exh Valve or Intake valve.  Then you can make a decision.  A leak down test does not take much more time than changing a spark plug.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LongLakeWI Quote  Post ReplyReply Direct Link To This Post Posted: April-06-2022 at 9:47am
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)  I was told the pressures changed because the boat hasn’t been run in over a year.  My hesitation now is that the delta between cylinders is too far apart.  I read somewhere there should be a 10-15% tolerance between cylinder pressures??…The mechanic said he’s not too worried about it since it doesn’t smoke and runs well otherwise.  Mechanic never mentioned a leak down test either.  Am I thinking too much into all of this?  The boat seems to be in good shape otherwise.  Some of the history of it tells me its been run hard and abused a good part of its life.  Should I stay or should I go?  The problem is it’s 1200 miles away so if I go to look, I’m towing it home.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 63 Skier Quote  Post ReplyReply Direct Link To This Post Posted: April-06-2022 at 11:07am
Curious what Mark says with those numbers.  I would not hesitate myself, have a suspicion the numbers will improve more with some run time, but even if not that's not so unhealthy an engine.  Granted 400 hours shouldn't have any compression loss but like you say who knows how it was maintained and stored.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: April-06-2022 at 12:25pm
Originally posted by LongLakeWI 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!

Originally posted by LongLakeWI 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 Wink

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

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Post Options Post Options   Thanks (0) Thanks(0)   Quote LongLakeWI Quote  Post ReplyReply Direct Link To This Post Posted: April-06-2022 at 12:47pm
This is a private sale and the mechanic appears to be a highly skilled PCM & inboard mechanic in TX.  The seller is small scale wholesaler who buys boats, fixes a few things and resells them.  The mechanic was referred to me by the seller but I’m paying for the inspection and he seems impartial.  The boat is being tested on a trailer in a well so they can put it under some load but I’m guessing  that’s not the exact same as getting it on the lake and running it.  He also found the thermostat was bad and replaced that yesterday.  The boat is a 2006 Air Nautique 216 for $19k so the price seems good enough to make the drive from WI to TX.  Almost a too good to be true deal??  Dunno what to do here..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: April-06-2022 at 1:40pm
With that info, I think you're using good judgement considering that you know none of the people. Tough decision on a long distance purchase without a test drive or at least seeing it in person. I'll just say "I'm no help" from here.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 63 Skier Quote  Post ReplyReply Direct Link To This Post Posted: April-06-2022 at 2:44pm
Originally posted by LongLakeWI 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?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: April-06-2022 at 10:54pm
Compression numbers don’t generally go lower from one test to the next.  I have seen them go up.  If it is the hull you want and that is in good shape along with the interior I would not worry to much about the engine but I fix engines so that is not a big expense for me.   I am more afraid of a bad interior or faded gel coat.
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?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LongLakeWI Quote  Post ReplyReply Direct Link To This Post Posted: April-07-2022 at 8:24am
I was told it wasn’t part of the TX freeze and not any salt water exposure that I know of.  The trailer was brand new last year.  The compression numbers went up slightly on the second test and the hull & interior are in really pretty great shape.  The tranny was replaced a couple years ago along with the all of underwater gear, I was told this happens a lot down there with large swings in water levels.  TX Malibu did the underwater gear & tranny replacement.  I’ve decided to pass on it, but am still thinking about it since it was a deal.  The season of getting boats out of storage hasn’t even started in WI yet, lots of ice yet.  Thanks again everyone!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote malibud Quote  Post ReplyReply Direct Link To This Post Posted: April-12-2022 at 9:08am
sent you a PM ..
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