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Anyone know what Yamaha 50 engine temp range is? Or outboards in general? Likely all similar? Looking to buy an onboard computer and need a temp range.

Andrew
Mercury Stern drives use 142 deg because salt water corrosion is reduced at that temp. 160 deg on most other seawater cooled engines. Newer EFI's I believe are 185 - 195 deg. Most racing O/B engines run no thermostats but have a restrictor in the passage to allow the pressure to increase, so the boiling point will also increase. I have found that ~12 lb is minimum for no thermostat O/B's and 15+ lb for a thermostated engine. Like to see 20 -35 lb on racing sterndrives.
All outboards should have a purge fitting at the top of the cooling passage.
Confused yet?
Dave E

Sorry Andrew...I missed this...50C (132F) is what your motor's T-stat opens at so you want a gauge that will work in that range.

Totally lost Dave, haha. Race motors are so simple... think this is a mystery.



I don't think the Yamaha has a thermostat in there... but I wouldn't know where to look even. It was built for racing... wouldn't most people remove this? 132 sounds super low? Is that water temp or CHT? And would they differ? I should have said I'm interested in CHT.

I'm sure the T-stat has been removed...but that's the range that the water temp would be...

Are you measuring water temp or spark plug temp? If it's the water temp (in the cylinder head) then it will be in that range when WFO under load and probably stone cold at idle.

I checked the T-stat in my P50 and it is stamped 50C...

Thx. I would be measuring Cylinder Head Temp under the sparkplug itself. With one of these sensors:

I asked around the shop...and...no one has any idea lol.

On another forum 240 F was mentioned for CHT.

Andrew, not sure what the use is for, but if your measurement is for protection just get an EGT guage, it will tell you much earlier if you are going to burn down/overheat.

Issue was resolved. The data logger i was ordering I thought I had to know the temp range. But I miss understood them and it is configurable. It was for the warning lights on the dash board. Thanks though.