87 Merc 135, to service or not to service?

[fender22]

This is probably a question without an answer but just bought a boat with an 87 Mariner (Merc) on the back. The mechanic checked it out before I bought it and all was well but he said he'd recommend doing a full service replacing all the main head, engine gaskets. He quoted between $600-800. I know the guy well and trust his judgment and I'm sure he's not just drumming up business but hard to get away from the "leave well enough alone" thing as it's running perfectly. He reckons if one of those gaskets fail and water gets in it's goodbye motor.
What do you guys reckon?

[finga]

An engine of that age needs the water jackets done as well as the top and bottom seals done as well as probably the head gaskets done as well as at least water pump impeller put in and a good serice/tuneup.
And he's right about the water going in.

[BM]

I'd be inclined to look at the compression numbers and the salt seepage from the head gaskets and make an assessment from there.

If its running well then theres no reason that should change in the immediate future.

However, head gaskets should be replaced every 5 yrs or so (again not a big issue really) as a matter of prudence.

Its your call mate. If its running well and the comps are good then I would probably leave it (that would be my advice to one of my customers).

Cheers

[PADDLES]

tough call fender, as you know i had one of those motors and asked myself the same question. i did the stuff these guys have said and made the decision to not disturb the head gaskets. my mechanic who inspected the motor before i bought the boat had a little doover that let him look inside the cylinders through the spark plug holes so he inspected each bore for any problems. get the water pump impeller and plates replaced though, this should only cast about $45 for parts and the labour is usually included in the flat rate of the service.