Temperature of powerhead?

[scott_maier]

I have a 35hp , 1978. I rebuilt the powerhead myself(had the block bored by a local marine shop), first time delving into an outboard. It started up nicely, water was coming out of the pee hole in a steady stream, but the powerhead seems to be running too hot. Very quickly the head gets too hot to touch. Is this normal?I'm paranoid that i am going to ruin this motor that i spent so much time rebuilding before its even broken in! If I measure the temp on the head what temperature should i expect and what is too hot?

I'm running it in a tank and haven't revved it too much. As soon as it gets too hot to touch I shut it off...

Thanks in advance

 

[crxess]

Re: Temperature of powerhead?

You are doing right in shutting it down once hot.

Did you install New Complete Water pump kit? I say complete as older parts get worn and are less effective at sealing for maximum transfer of water.
Did you install new thermostat?

The new rings must seat them selves within the cylinders. It can take several runs. Especially if cooling is insufficient or if the Bore clearance was set to a tight tolerance.

Did you increase the oil mix for the first tank to give plenty of lubrication? I'd recommend 50% increase since your having quick heat issues. Better to smoke than fry.

 

[wilde1j]

Re: Temperature of powerhead?

Not normal. Should be able to keep fingers on PH for a while (shouldn't be over 145 to 150? F).

Did you rebuild the water pump while you had everything apart?

You need to do some serious temp troubleshooting now, before using the motor.

 

[kenmyfam]

Re: Temperature of powerhead?

Check head temp with an infra red heat gun to begin with. Temp should read 140 to 160 degrees F

 

[freetime99]

Re: Temperature of powerhead?

Where are the 140 - 160 F temp. readings, as being max. normal, coming from? My service manual for 40- 70 hp series EE ( I realize not the same engine as this post ) show that the temp switch closes at either 203F or 240F, depending on whether it's the 2 cyl or 3 cyl engine. Just curious, I know that I'm not the expert.

 

[wilde1j]

Re: Temperature of powerhead?

That's high temp alarm trip, not normal operation. Almost all 2S OB's operate ~ 150?F.

 

[a70eliminator]

Re: Temperature of powerhead?

Funny you mention the overtemp switch, I have an evinrude speedyfour that has a high temp switch also 240, that seems a little too late of a warning for a 140-150 degree running engine. If you hold a meat thermometer in the water discharge you can get a pretty accurate temperature, I verified it with an infared gun and engine and pee stream were within about 10 degrees of each other.

 

[scott_maier]

Re: Temperature of powerhead?

My big problem was not enough water in the tank. I had the level just covering the water inlets, so I filled it until it was above the water pump. That made a big difference.

I previously installed a new water pump assembly,not just the impeller.

I used a meat thermometer to get a rough idea of the temp. I put dabs of grease on a few spots of the engine, ran it for 5 minutes and then stuck the thermometer in the grease. The temp never got above 120, but it felt damn hot too my fingers, so i think I need to use something else to measure the temp. Just for grins i measured the hot tap water here at work with a thermocouple and it is 140F. The water coming out the indicator hole wasn't that hot.

The thermostat is a long story..I bought a new thermostat, but it wouldn't fit so I left it out. I don't know if i ordered the wrong part number or if the previous owner swapped out the head from another motor, but i couldn't get the t-stat to fit. So I left it out...but i bought a used head off ebay and plan on installing that, which i'll do as soon as i get a new head gasket. Which leads to my next question...Since the motor isn't broken in can i reuse the head gasket if it doesn't get mangled when i take off the head? I probably won't, but i'm just curious what you guys think.

thanks.

 

[wilde1j]

Re: Temperature of powerhead?

Don't reuse the head gasket and get the right thermostat. Ok to run for a little while w/o, but not good long term (carbon buildup, etc.)

 

[scott_maier]

Re: Temperature of powerhead?

i think i just need to replace the water cover not the whole head. The head I got from ebay is identical to the one on the motor now, but the cover has a larger "bulge" where the thermostat sits. I wouldn't be surprised if someone in the past 30 years replaced the water cover with the wrong one...

 

[scott_maier]

Re: Temperature of powerhead?

Found out today that the water cover is the wrong one. The motor is a 1978, but someone put a 1977 water cover on it which doesn't have room for the thermostat spring. I'll be putting the right cover and t-stat in it tonight and see what happens. By the way the crowley marine website has a great parts searching setup with good drawings. Thats how i discovered it was a 1977 water cover.