Merc 500 thermos

[tmcalavy]

Hey all,<br />I need to check/replace the thermostat(s) on my 74 4 cyl. Merc 500 50 hp. Also want to pull and clean/rebuild the carbs. Where are the thermos? With the cover off I can see flywheel, starter, coil, fuel pumps, distributor, linkages, plug wires and plugs in the cylinders. What do the thermos look like and where do I start looking? Does this engine have thermos? Can I drench the carbs with spray cleaner while its running and do any good? Doesn't run bad, but don't know its history so....

 

[petryshyn]

Re: Merc 500 thermos

Don't believe you have thermostats....<br /><br />Spraying the outside of carbs will only improve their appearance....<br /><br />If you don't know its history...<br />>get a manual<br />>replace gear oil<br />>go through carbs<br />>check water pump impellar <br /><br />a little maintenance goes a long way

 

[oldboat1]

Re: Merc 500 thermos

If it's running OK, I don't think I would be too quick to do carburetor work. It sounds like you need a manual (thermostat will normally be housed at the top of the head). If the motor is running OK and pumping water, check to see if it is running sufficiently cool (Put your hand on top of the head after running a bit -- should be able to hold it there for a few seconds without getting burned.)<br /><br />It may be that the best treatment for you motor will be to run it. Use fresh gas and oil, and run a tank or two through it at all speed ranges, then decide if you need some work.