Hello all I have a 1990 350DA with...

[jimboc]

Hello all I have a 1990 350DA with 7.4L Mercs and Hurst V drive trans' in tunnels.  I am the 3rd owner. The 2nd owner was very meticulous on maintenance and he claims the 1st owner was as well.  At this point, (knocking wood) everything, including original radar and auto pilot is still functional.  Engines have about 1600 hours on them and she will still get up on plane and run at as original spec levels for rpm, cruising speed with tabs and top speed @ proper WOT.  I live in the northeast with a short boating season which explains relatively low hours for the year (but will retire to Florida where I can boat year round in 10 years )

I keep her slipped at our boat club near Albany NY on the Mohawk River which is part of the NY State Canal system, and usually only go no more than 7 to 14 miles on a given weekend between 2 locks.   And a lot of time is spent rafting off at  anchor hanging out with friends listening to music eating drinking  swimming etc

Question is, I plan on taking a long trip this year through the canal which combines natural rivers and man made cuts to the Oswego river to Lake Ontario to my parents cottage.   It is about the 2 and a 1/2 day trip each way  And about 420 miles round trip.   

Although she's running good now, I was thinking of having compression tests or leak down tests done on both engines to make sure they are up to the challenge, and if so, besides plugs and fluid changes, replacing all the belts, hoses and risers as preventative maintenance before the trip to minimize the likelihood of things failing.

I know something else could still go wrong but I thought I would feel safer if I do all this.  Asking my friends a lot of them say if it's running good now why bother spending the money and I'm not satisfied with that answer because it would be worth it to me if it would make her more likely to handle such a trip. I thought I'd put this out there and ask the experts?

[Peteatthebeach]

Check the raw water oil coolers. I had one go unexpectedly and changed it on both engines. The boat was used in seawater but only had 400 hours

[RaceCarRich]

I sort of agree with your friends. No need for a compression or leak down test but yes do all maintenance that is close to being due. And use the boat a few times between getting the work done and the trip just in case the work wasn’t done right or you got a defective part.

[jimboc]

The thing I don't understand is If I am willing to spend the money on the compression test which is easy to do one cylinder at a time while the plugs are being changed, why not? Especially since if the compression is bad on one or more cylinders I won't take the long trip

[RaceCarRich]

Why not? Hmmm... I guess it’s related to spending money efficiently. My thoughts are a compression test is going to have one of 3 results:
All Good - you take the trip
Showing Significant Wear - good to know but would not expect significant change in performance over the next 420 miles. Take the trip.
You Got Big Problems - if you had a hole out ( cracked piston, hung valve, etc.), you’d probably know already because it wouldn’t be running good.

At least that’s my opinion based on not learning anything that would be a decision criterion. If it makes you feel better then do it as feeling better could be a good return on investment.

[jimboc]

@Rich Galli there you go! The logical answer I was looking for thanks!