overheating???

[lost_boys]

I have a 1991 johnson 60HP outboard....last night while fishing, motor stopped on the way home...restarted and it started right up but had a continuous alarm beep...read that that alarm is for overheat

this morning, everything seems to be running fine...alarm is gone

MY question is, if the pisser is shooting out a nice stream of warm water, does that mean the impeller is working fine...also, does that mean the water is being circulated properly in the engine block....

the pisser hose seems to be attached to the engine block....

thanks for any advice

 

[racerone]

A healthy pisser does not mean water is cooling rhe engine properly.----Is oil injection in service ?----Does tell tale hose come off the side of the block or the top ?----Start with a compression test on this motor.

 

[lost_boys]

The oil pump has been disable for some time now, gas is pre-mix

The tale hose comes off side of the block (on the lower side)

OK, will do compression test next

 

[lost_boys]

any ideas how to check if its really overheating

 

[Ike-110722]

Buy one of those hand held infrared heat sensors and measure the temp while the engine is running. I have one I use on my 43 year old mercruiser 165 and it gives a much more accurate reading than the gauge. Of course you have to measure the temp of the block which means taking the cover off.

 

[lost_boys]

haha, I just came back from doing that...

I let the engine idle for 30min, temp at block was ~140F....is running at idle a valid test to determine if I have any blockage that would cause overheating or I do I have to run at high speed....

I guess my question is "how to determine if I have any kinda of blockage that would cause the motor not to cool correctly"

 

[emdsapmgr]

When the engine overheated, you may have sucked up a plastic bag around the lower unit water pickups. Did you raise the lower unit out of the water to see if there was a bag there? The telltale does indicate if the water pump impeller is working. It does not assure that the block is not overheating, however. 140 is the correct (normal) temp. Looks like you are good to go. Your overheat horn (or a laser temp gun) will determine if it's overheating, both at idle and when on plane.

 

[boobie]

You have to run it at WOT for at least 5 to 10 mins to see if it will overheat.

 

[lost_boys]

ran at 4000rpm for 30min....took temp reading every 10min with motor off....temp was between 140-150

ran an extra 5min just at idle, motor was significantly cooler, about 110 (not sure why it was 140 last nite)....it was cooler to the touch also

I think you might be correct...maybe it was some debris blocking the intake....unfortunately, I didnt look that nite

 

[boobie]

Sounds like everything is normal now.

 

[lost_boys]

thanks all for your advice

 

[lost_boys]

just a followup question to same concern

I installed a temp gauge after the initial "overheating alarm" incident....I've been driving around at 4000 rmp and temp gauge normally max out at 158degrees....i verified it with the IR gun and temp is accurate....op temp is between 140 and 158 during my testing

However, I noticed when I slow down at a "no wake" zone under the bridge for maybe 30 sec...after passing the bridge, I speed up again up to 4000 rmp...I noticed the temp gauge will go up to 175degrees within minutes....this has happened three time already...usually, when this happens I slow down so that I dont go over 175....

Any idea, why this can happen

 

[joetheis]

If it were me.................
1). I do a impeller kit
2) Replace the thermo
3) Whilist I had it apart, I back flush the block with a hose
4) Check the intake screens
I know it's anal, but those parts are fairly cheap, one afternoon and then you KNOW all is well.
Run a compression test, make sure you didn't tale out a head gasket.
You would think at 4000 rpm, impeller is pumping water like, well, pumping well.
The you idle, the block is warm, water flow is reduced, cuz impeller is spinning slow, so temps SHOULD go up, then off you go and it should go down to running temp.
Don't forget water temp will affect you running temp, by a few degrees!
Joe
Remember take any advice I give with a can of beer er 2!

 

[lost_boys]

"The you idle, the block is warm, water flow is reduced, cuz impeller is spinning slow, so temps SHOULD go up, then off you go and it should go down to running temp."

Actually, I experience the opposite...at idle, temp does down drastically....

BTW, did run compression test and its all about 110 across all three cyclinders