Mercury 650 1970 Vintage Outboard Engine Repair/Tune-up

[scottwoodward]

I recently acquired a 1985 SportCraft trihull with a 1970 vintage Mercury 650 Kiekhaefer engine. I'm not new to boat handling, but I'm new to engine maintenance and repair. I took the cover off and discovered that some of the wires look like they're disintegrating from age and there's one line (I'm not sure what it is) that's come apart. The original wire casings disintegrated in my hand. I'd like to get the engine running, but I also don't know what I'm getting myself into if I go down the road of replacing wires and such. Easy, not so easy? Doable for a mechanically inclined newbie?

See attached photos of the various wires and rubber line that's come apart, as well as the propeller. I wouldn't know if the one ding on the propeller means it should be replaced.

 

[jimmbo]

It would be easier to get replacement Wiring Harnesses. The deterioration of the wires is pretty much the Norm for older Mercs. Kiekhaefer must have gotten a real deal on that wire, and bought enough to go to the moon and back a couple of times.
The prop can be repaired

However, before spending any money, Inspect the engine fully. Compression, Good Spark(can jump a 7/16" gap) to all 4 cylinders. Oil, Water, or combination of those in the gearcase, probably needs a Reseal? Water Pump Impeller should be replaced. Parts for that engine can get Pricey, an example, the Rotor-Distributor Shaft is over $200,

 

[scottwoodward]

Thanks for the tips! Since I won't be able to get the engine warm, would the compression test still be valid/worthwhile? I watched a handy video on doing compression gauge readings and it said the compression test should be done on a warm engine. Spark plugs are easy. I've also read that it's pretty much a given that the water pump impeller will need to be replaced, so that's consistent with what I've read before. Not sure how to check the gear case, but I should be able to figure it out. Thanks again for your advice.

 

[jimmbo]

Warm or Cold, a compression test will provide Information.

 

[scottwoodward]

Jim, FYI, ran the compression test this morning on a cold engine and all four cylinders registered at 120 PSI. Thanks again for your advice. Appreciate it.