Thermostat- yes or no?

[mark1961]

I have recently aquired a 1982 Evinrude 60 E60TLCNM which now starts and runs great on muffs after a carb rebuild/plug replacement. I decided that before i headed to the boat ramp for the water trial i would replace the thermostat. When i pulled the cover i discovered that the old one had been removed or it has never had one? I have no idea how long this has been the case. As far as i can tell the motor has never had any overheating issues which would warrant its removal, the original paint on all parts of the powerhead looks to be unaffected by heat, infact, bearing in mind the age of this thing, it looks fantastic. Would i be wise to go ahead and install my new themostat or will going without cause premature failure? Would appreciate it if you guys could give me your thoughts.

Thanks.

 

[Vic.S]

Re: Thermostat- yes or no?

Yes it should have a thermostat , and a pressure relief valve parts, #12 thru 16 in THIS DIAGRAM

All must be fitted in order for the engine to run at the correct temperature and pressure within the cooling system.

It is a popular misconception that the thermostat is only required in colder climates but this is not so and it should always be fitted.

PARTS LIST

 

[emdsapmgr]

Re: Thermostat- yes or no?

Engines that run without thermostats can run cool in some cylinders. Engines which run cool don't have the same combustion cyl temps and cool temps can cause coking around the rings. Coking is carbon accumulation which can lead to other long term detrimental issues. Also, the thermostat acts as a restriction point in the block. The thermostats insure that the powerhead fills completely with cooling water before it is allowed to exit the block. Without thermostats, the powerhead may not properly fill the top cylinder(s) with adequate cooling water. Follow Vic's advice and run the factory stats.

 

[coolguy147]

Re: Thermostat- yes or no?

they started putting t stats in the motors in the 50's. i believe by the 80's if they thought it was bad or useful to have it in there then they would have taken it out by then. cars have them and modern outboards have them.

its also needed for the cooling system. ever use a running hose? you sometimes may cover the hole where the water to shoot the water further. same for a t stat. it keeps good pressure for the motors at high speed and warms them up in 2-3 minutes ( about 140degrees for my motors) yours may take a little longer but same concept.

 

[muskrat]

Re: Thermostat- yes or no?

I would go through the cooling system w/p kit & all thermostat parts.Test run,if there is a higher speed overheat,There was a service bullitin for moving the tell tall elbow.

 

[Texasmark]

Re: Thermostat- yes or no?

Other thing is, depending upon the location of the stat and if equipped the high speed pop-off valve, you could starve your engine's top cylinder(s).. I know my Merc 90 hp and son'd 150V both would suffer fatal damage if run without both installed.

Mark

 

[kenmyfam]

Re: Thermostat- yes or no?

Yes. Keeps motor at optimum running temperature. Less wear and coke build up.

 

[mark1961]

Re: Thermostat- yes or no?

Thank you all very much for your informative replies in the affirmative gentlemen. The new stat will now be fitted as soon as the pressure relief valve parts arrive which also happened to be missing , an extra thanks for the heads up on that one Vic.

Cheers.

 

[northernmerc]

Re: Thermostat- yes or no?

You may find that whoever removed the thermostat did so for a reason. Based on experience, I can say that Evinrude and Johnson outboards can be quirky when it comes to cooling. My 35, for example, will only run at full throttle without a thermostat. The dealer worked on it and won't touch it again. It's also had the help of the experts on this forum. After disassembly and the replacement of numerous parts, it still only runs well without the thermostat.

 

[Texasmark]

Re: Thermostat- yes or no?

Well all due respect to everyone and their particular engines and unique personal situations....If the stat is located at the top of the block then you could probably get away without it. If it is lower than that, cooling water will exit the stat hole before it can completely fill the block and the top cylinder will fry.

But I don't care. Suit yourself. I told you what you could do to your engine and if you choose to ignore it, no skin off my cat.

Mark

 

[Big Bubba]

Re: Thermostat- yes or no?

I wholeheartedly agree with TEXASMARK about installing and keeping a serviceable thermostat inside your outboard motor. The manufacturer/designer of the outboard has that thermostat in there for a reason. So if it where my outboard I would have it in there. Take care, Bob

 

[northernmerc]

Re: Thermostat- yes or no?

No one is arguing that it's better to run without a thermostat than with a thermostat. But what would you if you owned a motor that won't run without overheating with the thermostat in place?

The previous owner, the Johnson dealer who took it as a trade in, and I all tried to get this Johnson outboard to run cool. Disassembly and replacement (twice) of the waterpump, checking and clearing all water tubes and flow channels, removing the head and replacing the head gasket, thermostat, overheat sensor, and flow diverters around the head made no difference. For good measure, the carburetor, fuel pump, and fuel lines were redone. The pistons and cylinders are in good condition and the compression is even at about 130 psi. Even though they can't fix it, the dealer refused to honor his written promise to take the motor back if it did not work.

If the only way it will run is without a thermostat, so be it. If it does self destruct, I hope it will be over deep water . . .

 

[mark1961]

Re: Thermostat- yes or no?

As most here are probably aware the thermostat on this motor is located at the bottom of the block. A new water pump kit housing included was fitted by me a few weeks ago, compression checked and found to be 125 per pot with very short cranking times, 145 if cranked slightly longer. Bearing all of this in mind and all of your responses the consensis appears to be that i am better off with than without at this stage. I will be sure to closely monitor the situation and look into that service bulletin if i have issues(thanks muskrat) during the water trial in the near future.

Thank you all very much gentlemen.