Oil temp mercruiser

[Niels45]

my mercruiser 140 4 cyl 1980 might run hot after 30 min boating. Water temp is ok, but does anyone know what temp the oil should be? Oil temp is the same as the outside of the motor I think?

 

[Bondo]

Ayuh,..... under load, oil temps run 'bout the same as water temps,.....

 

[Scott Danforth]

oil temps may be between 20 and 50 degrees warmer than the water temp.

however unless the 3.0 4-banger has an 871 supercharger, you cant load it enough to worry about oil temps

 

[Niels45]

Thanks for the answer. I thought that if a water canal in the engine is locked, the engine could get overheated but I don’t know if that’s possible and what kind of troubles it will give.

 

[Scott Danforth]

if you have passages blocked, the water temp will be higher

normally if a passage is blocked, its the thermostat passages or the exhaust manifold passages. in either case, it slows or stops the cooling water flow, causes an overheat and with lack of water exiting the system in the exhaust, you also burn up all the rubber pieces in the exhaust system.

 

[Niels45]

[No message]

 

[Niels45]

You can see the spark is to long, and the color says “to hot”?

 

[Bondo]

Ayuh,.... Because they're the wrong plugs,.... ya need MR43T spark plugs,.....

The ones you've got are for the late model Vortec heads,.....

I'm somewhat surprised the pistons didn't hit 'em,.....

 

[Scott Danforth]

or maybe the pistons did hit....and banged a dent in each piston.