Another stupid question:

Is there an after market supplier for solenoids as used for the trim & planes pumps? It seems an automotive solenoid would do the same thing, but Merc units are HI $$$ stuff.... any ideas????

Look into Sierra Marine Parts. A lot of the on-line sites sell this brand.
They manufacture/sell Mercury equivalant parts at a much lower price.
My trim pump solenoids are p/n 18-5817 from Sierra.
I did a quick search on the p/n and found them for 13.67 each.
Is that low enough?

I ran lawnmower solenoids on an old outboard tunnelvee I had. $6 each. All brass and plastic (with zinc plated mount). I covered the connections with liquid tape and never had any troubles at all.

Even sunk it once (freshwater) and the solenoids still worked fine.

Why the Mercs are big $$$ - who knows, greedy I reckon.

A friend of mine has used Ford starter solenoids for years. Fresh water environment they work fine. I don't know if I'd use them around saltwater though. He did change the nuts to stainless from the original "plated" nuts.

Yea, Ive used the Ford started solenoids too. They were less than $10 at Napa and completely sealed.

You can buy marine solenoids from NAPA they have a marine catolog. same as serria

That's sort of what I thought. There is a rubber gasket on the Merc units, but they are by no means water tight. I thought the Ford solenoid's were a kind of "multi-purpose" solenoid for everybody!.

Mc Collistin- what lawn mower relays??? Manuf/brand/part #???

Thanks guys, guess I'm just cheap!!

I rebuilt mine by opening the case and filing the contacts
then sealed with liquid electrical tape, I did this on the water
had no choice and I have not had to replace it.

Ok, I went to my O'reilly's auto parts store this evening...... I asked what do you have in a SMALL solenoid/relay, he goes to the rack in the middle of the store & shows me a packaged solenoid/general purpose for $7.00 !!! It looks exactly like the Mercruiser unit except better! The case is riveted not crimped. A heavy rubber & cork gasket in place of a tiny thin membrane like Merc's unit.... and a single operating/actuating contact. I bought 8 for less than what two Merc's cost.....going to try them this weekend!!