Head and cylinder temps on 58 Johnson Super Seahoese 35

[Marcus]

Just got my rescued Super Seahorse running and wondering about temps. Using a thermo gun I’m getting around 150-160 degrees at head and thermostat housing and around 200-210 at cylinder walls just forward of head is this typical.  Replaced impeller. When first started I blew about fifty wasps out of water/exhaust port on rear of engine. just don’t want to burn it up. Was wondering if there is some blockage? these temps are at a high idle as I’ve only run in a barrel so far. Want to get it on the lake next week. Any wisdom out there?

Westbrook

[bob-d]

Marcus, here is how they checked motor temperatures in the days before thermo guns.
They were looking for no more than 163°.
Bob D

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vintin

[Michael Anfossi]

Those temps are high, thermostats are 143 and I think temps should no more than 150

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vintin

[fleetwin]

Yeah, those temps are high, are you sure your temp gage is working properly?

How are you running, testing the engine?  On the boat in the water?  In a bucket?  On a flushette?   These engines can be fussy when not running in the water on an actual boat.  Make sure the water level is high enough in the barrel to bury the gearcase completely in water, up over the gearcase/exhaust hsg joint.   Flushettes rarely work properly on these engines as well.

Did you run the engine before doing the water pump job?  If so, did it cool OK then?  You replaced the impeller, did you use an OEM impeller or aftermarket?  Are you sure you got that gearcase installed correctly, this is real tricky having to line up two water tubes and the driveshaft.

Is any water/fine spray coming out of the exhaust relief while running?  Have you had the thermostat cover off?  Keep in mind that the thermostat, cup, spring, and relief valve must be in place and working properly or else cooling water can short circuit out of the block without circulating properly.  Try running the engine with the thermostat cover removed, you should see water bubbling up out of the thermostat pocket/housing.   This is a complicated cooling system, alot of things have to be right or it won’t cool properly.

[Marcus]

Running engine in a barrel with water about 6″ above water intake, it was around 100 degrees out that day and water in barrel was quite warm to start with. the water spitting out of water /exhaust port is pretty hot. Ran engine before doing impeller for a few minutes and was pumping water, did not monitor temp at that time, I was so excited that it was running, but it had been sitting on a rotten boat for years so just figured it was time to change impeller. Bought parts from Sea Way Marine in Lynnwood Wa. Impeller is either OMC or Sierra. as that is what everyone. seems to stock. the thermostat seems to be working, after about a minute or 2 of running it starts a nice spray from exhaust/water port. Will try to get on lake and pump some nice cool water through and check temps. Was very careful to make sure that both water tubes were seated properly in new. pump grommets. Thanks to everyone out there for the help. I’m pretty new to this outboard stuff but I’m learning.

Westbrook

[fleetwin]

Marcus wrote:

Running engine in a barrel with water about 6″ above water intake, it was around 100 degrees out that day and water in barrel was quite warm to start with. the water spitting out of water /exhaust port is pretty hot. Ran engine before doing impeller for a few minutes and was pumping water, did not monitor temp at that time, I was so excited that it was running, but it had been sitting on a rotten boat for years so just figured it was time to change impeller. Bought parts from Sea Way Marine in Lynnwood Wa. Impeller is either OMC or Sierra. as that is what everyone. seems to stock. the thermostat seems to be working, after about a minute or 2 of running it starts a nice spray from exhaust/water port. Will try to get on lake and pump some nice cool water through and check temps. Was very careful to make sure that both water tubes were seated properly in new. pump grommets. Thanks to everyone out there for the help. I’m pretty new to this outboard stuff but I’m learning.

OK, well there is a fine spray out the back when the thermostat opens, so it seems more likely than not, you got everything back together properly.  It could be just like you say, a hot day, pumping hot water through the engine.

I would give it a try on the boat.  But be careful when running at high RPM, it only takes a few seconds to overheat it to the point of seizing….

[Marcus]

Won’t be able to hit the lake until after the 11th, will try to record some video to post showing spray and results with thermo gun . thanks for the moral support

Westbrook

[Author]

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