Compression and leak down question

[Hugh H]

Just received a freebie 250 sundancer '86 with a 260 / alpha. Previous owner ran it last year till it lost power, brought it to marina for diagnose and they removed starboard side head and told him he needs a new engine. I inspected the head and found an exhaust valve ( the smaller of the two?) with pieces missing around it's edges some rust and a rusted mating surface on the exhaust manifold. (I suspect water intrusion via gasket or rusted through exhaust) I still have to look at the pistons and cylinder walls. Before i pull the engine could i and would it be worth doing a compression test on the port side that is intact and based on those numbers do a leak down test if needed. I suspect the compression readings will be higher than on a intact engine but major differences between the cylinders would still spell trouble. No signs of rot or water anywhere in the boat but i will probe deeper with some test holes. Engine oil showed no signs of water, will check by volume when oil is drained.
boat on tires.jpgcracked exhaust valve.jpgexhaust manifold.jpg

[Oshkosh1]

You can't warm it up...a compression test cold is pretty useless.

Based soley on the looks of those valves...there's bigger issues ahead.

[Hugh H]

The service bulletin calls for room temperature. I agree with bigger issues ahead. boo hoo

[tpenfield]

If you can get a used cylinder head (or 2) off of CL or eBay, and the lower end looks OK, then you might have something. Looks like the Exhaust manifold needs work as well, perhaps a replacement.

You could do a leak test, just to see if there are major differences, but without being able to bring the engine up to operating temperature, it will not be 100% valid.