Normal Engine Temp Range for 4s 60hp Merc OB -vessel View ??

[Canufixit2]

Hi all, 2 + season old 60 hp Merc 60hp 4 stroke Bigfoot on an 18' pontoon Fresh water Pond with minor weeds in New England. .Runs great but have had an over temp alarm twice - at high speed.

I Hooked up my vessel View and I'm getting a wide range of readings for temp. Idle 120F. Full throttle runs 138 to 150 - but "sometimes" climbs to 160 then drops down to 140 - 150F range. I do do a lot of low speed cruising. Hours on engine about 400. Checked for weeds on Lower unit - ok. And, I just hose flushed the engine.

For Reference - what is the "normal" range of temp 120F (therm opening) to what?? What is the Temp the engine triggers over temp alarm ??

I will today change the thermostat and I have a merc water pressure tester on order for delivery next week.

My experience thinks it's one of the following - blockage, thermostat or impeller. Iin my experience, over many years, tells me that the Impeller "should" be at least 3 years to 5 plus of service. And, I cannot see how a bad impeller can "sometimes" work fine at high speeds. IT is usually good, going bad, or crap - but not inconsistent. My clean flush indicates no blockage and I have not gone though mud or sand waters. That leave me thinking a possible sticking thermostat ?? .

So ... For Reference - what is the "normal" range of temp 120F (therm opening) to what?? What is the Temp the engine triggers over temp alarm ??

Any comments on the cause ???

Thanks All !!
SteveC

 

[Canufixit2]

Oh yes, could be the temp sender too, but I consider that remote ...

 

[QBhoy]

120 is about the constant normal temp these are I think. You can check what the water pressure is too on the vessel view. But I was surprised to hear that the vessel view works on a 60hp. I thought it was 75hp and up only. Does everything work on it and show all info ?

 

[Canufixit2]

Some items on vessel view will not work as the sending unit in the motor is not there (i.e. sea water temp).

Also I found thin on the net ...

But the only location I can find this is in a Russian site?? But this looks like a great document .... ??

Outboard FourStroke IITechnician’s Guide

90-898313

Page 103 ...


Overheating Control
When the engine speed is less than 2,000 rpm, this control mode is delayed 60 seconds after the engine is started. When the engine speed is 2,000 rpm or more, this control mode is delayed 20 seconds after the engine is started.The engine is considered to be over-heating if its temperature increases from 167° F (75° C) to 185° F (85° C). If its temperature exceeds 194° F (90° C),this control mode begins. The overheat warning buzzer sounds, and the ignition and injection are cut according to the misfiring rate.If the engine overheats, the ignition of both cylinders #1 and #4 is cut,however the ignition of cylinders #2 and #3 is not cut. After the engine temperature decreases to less than 167°F (75°C) the overheat warning can be cancelled by decreasing the throttle opening angle to less than 2° and turning the ignition key to the off position.

So it look like after motor warm up 120f and allowable up to 167f Alarm and guardian kiks in at 194F. ??

Comments ???

 

[Canufixit2]

Also ...
From the Merc 4s service manual 2K+ ;

- Thermostat cracks opens at 118-123F.
At 145F the thermostat should open min .120" /3MM

Water Pressure
@1K RPM ~ 5.75 PSI .... MAx out at @6K RPM 20.25 approx.

So I'm thinking that "normal" design temps should be at least 120F to 145F Min.

 

[Canufixit2]

OK, I apparently have a solution .... I changed my Thermostat and it appears to be running fine. As for my original question ... What's normal Operating Temp for 4Stroke 2018 60 hp Bigfoot... Remembering that Local Temps, Water Temps, water flow from pump , and possible intake port interference (i.e. weed pick up) all vary - I found the below temps with my new Thermostat (My Impeller I consider Ok at 2.5 years old but I have not yet done a pressure test yet ...);

Warms to 120F. Under 3K RPM stays around 120 - 124F. 3k to 4k temp does rise into 130F range. 5600 RPM it ranges from 135F to 145f and tends to bounce a little - possibly due to weed pickup on lower unit ... Never went into 150F range.

IF possible next week I'll do an impeller pressure test and advise if my Impeller flow is acceptable.

Thanks All !!

 

[QBhoy]

You can get sw temp. I have it on my merc 115 on smart craft. You’d think the vessel view would have it too. Think I’ll connect my vessel view and have a look.