The true cost of a 'free' boat

[audiophool]

Back in '83, dad bought a boat. A 16' Springbok aluminum sport type with a 90HP Evinrude, CN (82) date code. This boat saw little use over the years as we're inland in Calgary AB. Maybe 20 hours per year at most.

I'd worked at a marina for a couple of summers and got experience working on outboards so I maintained it over the years doing tuneups, waterpump R&R and general stuff. Nothing ever went wrong with it.

Fast forward to 2015 and I now 'own' this boat (for the princely sum of $1) and have been getting it ready to run this summer.

With 1 person at the helm when newer, this rig would hit 5400rpm and about 44mph, coming out of the hole like a rocket. Last time I ran it I was lucky if it would do 4200 tops and felt generally sluggish.

Problem: just ran a compression test and I got 110/105/100/95 repeatedly. Not good.

Powerhead has never been off and the boat had been used in the salt for a couple of weeks every year. Probably break a bunch of bolts trying to take it apart...

Big question: is this worth rebuilding if I did the labour myself? I'm not sure the hull is worth re-powering. Maybe just run it until it dies?

[Solarman]

If used so little, may be stuck rings. Could try running some ring free additive in tank of fuel for a couple hours, or entire tank, before rebuilding. Then recheck compression. If improves, run more, couldn't hurt, only help. Just run from idle to 3k to 4k through the tank, just like breaking rings in again. Hold off on wot unless compression changes (evens out) for the better. If compression improves after a full tank (12 gal), check compression, if you have to run a second tank same way, go for it. Just don't over rev in neutral, or in gear ( 3k max in neutral, 5.5k max in gear).

But rebuilding is good if you know how. still pricey on parts.

Good luck. Post back if find out anything.

[try123]

Change head gaskets. If compression comes back-rebuild carbs. Those compression differences shouldn't cause that kind of rpm loss though. IMO.

[audiophool]

I was thinking it may be stuck rings as well due to so little use. I have a tin of OMC engine cleaner that I picked up in the '80s and never used - may do that treatment first since I still have the cover off the carbs.

I've already done a full carb rebuild. It hasn't been on the water yet this year.

If the cleaner doesn't make a difference, off come the heads - maybe it'll reveal clean bores with no scoring, maybe not.

[Solarman]

Let us know if the cleaner helps.

Good luck.

[audiophool]

No joy on the cleaner. Blasted, soaked and ran to no avail. Checked compression warm and it was the same.

Also noticed the starboard bank was running way hot. Yanked the thermostats and put them in a pot on the stove with a pair (originals) that I'd kept from the last change. The old ones opened first and evenly. One of the ones I just took out opened with a 'snap', then, the other did. Repeated cool/warm cycles kept showing the ones that were just in the motor didn't open evenly. I'll just put the originals back in since they work.

All set for a test dip this weekend. We'll see how it runs.