Compression.....Need advise!

[DenWbaseball1984]

Ok so I'm looking into buying an older boat with 945 hours on it, its a 1985 Supra and its in great shape and the price in good, the only thing is that a compression test was done and all the cylinders are within 3% but one is at 15%. I'm not sure how bad that is and what could be wrong with it. Any input would be greatly appriciated!

 

[Limited-Time]

Re: Compression.....Need advise!

Engine type? Actual compression readings? This info will help determine your answer.

 

[DenWbaseball1984]

Re: Compression.....Need advise!

Here is what was wrote, and here is what he wrote for the engine....
"As best I can tell they are original hours on the engine. I am the second owner of the boat. I have been through all parts of the engine and have found nearly nothing wrong with it. Regular fluid changes etc. I checked the compression at the end of last summer and all of the cylinders except one were within 3% of each other - both hot and cold. One cylinder was about 15% low. In addition, like I stated above, it has a new 4-barrel Holley carburator and a new drive shaft. This boat fires up on the first crank with little to no extra throttle."


PCM 250 hp V8 (351 Ford)
New drive shaft 2005 (replaced due to age, not damage)
New 11.5 x 13 prop 2005 (awesome low end torque)
New 4 barrel Holley carb
Spare 12 x 12 prop

 

[Bondo]

Re: Compression.....Need advise!

and all of the cylinders except one were within 3% of each other - both hot and cold. One cylinder was about 15% low.

% of What # would be My Question,............

 

[Coors]

Re: Compression.....Need advise!

I was waiting for someone to come in and ask-I thought I was having a senior moment, and couldn't comprehend.

 

[Robj]

Re: Compression.....Need advise!

Need to know actual numbers. Sounds a little fishy to me, especially when it has that many hours on it. I would get the actual numbers and post them here so others can comment.

Have a great day,

Rob.

 

[DenWbaseball1984]

Re: Compression.....Need advise!

Ok so I'm still fishing for actual results but here is what I received in my last email before I could ask about the compression...
"The boat runs great. Starts on the first or second crank every time. Great power throughout the powerband."

He also goes on to mention that we could take it for a test drive anytime, so it must run good otherwise I would figure he wouldn't say all this then say we could take it for a test drive....whats your take on this?

 

[Robj]

Re: Compression.....Need advise!

Easy fix. When you make the deal, say it is subject to you getting it checked out by a marine mechanic. Shops will do inspections for boat purchasers. That way you have an expert opinion on the boats condition. I think that would be $$ well spent and may save you lots of $$$$$ in the long run.

Good luck

Rob.

 

[Haut Medoc]

Re: Compression.....Need advise!

Ask him what the compression was on any one cylinder, he should know that.....
If it is anywhere below 115.....
I would not buy it unless I was willing to re[ower in a year or two....​

 

[DenWbaseball1984]

Re: Compression.....Need advise!

Ok still waiting for an email......But if I did have to do something in a year would it take a whole new motor or just a rebuild.....what are repairs like that costing?