Evinrude '94 150hp E150EXERV overheating

[woodycooper]

Hello, hopefully I can get a few questions answered re: the cooling system on my Evinrude. I've been getting overheat alarms. I replaced the thermostats (both bad) and the port and starboard overheat sensors (both bad). My SELOC manual says to take temperature readings with a heat crayon or an infrared gun. It also says to take the reading inside the sensor pocket if possible. What I ended up doing is placing the temp probe of my multi-tester into the bottom of the pocket and then held it in place with a rubber plug. Those temps can go as high as 170 by that instrument. The book says normal is ~145. I've also noticed that the temp on the cylinder heads outside surface is much cooler than in the pocket, although I've commonly heard that just using the gun on the cylinder head is sufficient. What's the proper way and is this thing running too hot?
I'm in the process of rebuilding the water pump though my pressure guage reads 30 at 4000RPM, just FYI. Done some other stuff but I don't want to muddy the waters at this point.

Thanks woodycooper

 

[Chris1956]

30PSI at 4000RPM is good, however, you have already fixed the other obvious parts of the cooling system. I would replace the impeller, gaskets, and housing and see if it gets better.

If overheat still persists, you will need to look for other causes like clogged water passages, compression leak and lean running.

 

[woodycooper]

30PSI at 4000RPM is good, however, you have already fixed the other obvious parts of the cooling system. I would replace the impeller, gaskets, and housing and see if it gets better.

If overheat still persists, you will need to look for other causes like clogged water passages, compression leak and lean running.

Thanks, I'm in the process of doing just that (re-building water pump) and I'm also going to do an acid flush while the lower unit is off. But does anybody know how I can tell the proper place to read temperature? While the horn prevents damage in the short term, I'd imagine running just below that limit mustn't be good either.