1983 150hp Merc XR-2 peeling paint/overheat question

about a year ago I bought a boat with a 1983 150hp Merc on it, it has great, even compression of 125 across all cylinders, runs, and idles great. I have had no problems at all with it.when I bought it I made the rookie mistake of not noticing some peeling paint on the one side of the block and a couple of the head bolts were missing small flakes of paint. so, i now have to assume it overheated at some point and was worked on. considering everything is perfect with it(from what i can tell), pumps water great never overheats or anything and have been using it fairly for about a year now with no problems, how concerned, if at all, should i be about the peeling paint? heads themselves look like they have newer/shinier paint on them as well

Re: 1983 150hp Merc XR-2 peeling paint/overheat question

Pealing and discolored paint is a indication of a overheat of the motor. As long as it is pumping water fine and not getting hot it should be fine. A simple test by placinf your hand on the motor should tell if it is running hot. You should be able to be able to touch it and hold it there for a short time. The other option is to install a water temp gage or a water pressure gage (Best). Not that $$$and will always be there for you to check when running the motor.
Oldman570

Re: 1983 150hp Merc XR-2 peeling paint/overheat question

oldman570 said:

Pealing and discolored paint is a indication of a overheat of the motor. As long as it is pumping water fine and not getting hot it should be fine. A simple test by placinf your hand on the motor should tell if it is running hot. You should be able to be able to touch it and hold it there for a short time. The other option is to install a water temp gage or a water pressure gage (Best). Not that $$$and will always be there for you to check when running the motor.
Oldman570

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The original heads would have had hand written markings on them. Those markings are done with heat crayon. Sometimes you find traces of it on the block also. If they're still white then no problem but if they've turned yellowish brown then it's overheated. Unfortunately, if your heads have been replaced or repainted they're not going to be visible anymore. You could guess that an overheat occured because of the peeling paint but it could also mean that there was just not a good bond when the paint was applied. That wouldn't be the case if it was factory paint but it might be if it was a touch up job.

If you're in doubt and think it may be overheating now then the heat crayon method is an excellent way to record it. You can get heat crayons at most welding supply stores. Get one that changes colors in the 185-210 degree range. A temp gauge and your temp alarm if equipped will warn you when your in that range and the crayon will verify it.