Mercury XR4 150HP Operating Temp??

[Marks500]

Hey, I recently just got a used boat with a Merc 150HP XR4 on it, Was told the water pump was replaced with in the last year and boat has only been out a few times since changed...Got water coming out of the pee hole and seems to have water flowing good.... Well I have an indash stock Temp gauge, Ranges from 100 deg to 240 deg. with lines in the middle of the numbers so I cant get an exact reading... When Idling It is running right in the middle or a litte above it and when I am at full throttle it is a little below the half point... Is that normal?? Cause from my calculations it is operating at 170-180 Degrees. I dont know hoe accurate those things are.And the water coming of the pee hole is luke warm. I am also from GA, and the Lake water temps are around 90 degrees.

 

[Chris1956]

Re: Mercury XR4 150HP Operating Temp??

Mark, The thermostats are usually set to open at 140 degrees. Run it with the cover off and see if the heads get too hot to touch. You should be able to touch them w/o burning yourself, but you won't be able to leave your hands on them.

Normally we use water pressure gauges instead of temp gauges.

 

[j_martin]

Re: Mercury XR4 150HP Operating Temp??

Sounds fine to me. Don't worry about it.

the stats open in the low 40's, but when you consider you're burning a couple million BTU's/hour in that thing, a little variation would make sense, especially running a little warmer than the stats.

Anectdotal evidence:
1. They warm up to operating in about 30 seconds at idle.
2. If you hit something that plugs up the cooling, the alarm (at 240 degrees) will go off in about 6 seconds. (been there, done that)
3. There's no guarantee that uncalibrated gauge is linear. It probably isn't

hope it helps
John

 

[Marks500]

Re: Mercury XR4 150HP Operating Temp??

Thanks guys, I did Take the cover off an did touch the head after running it for about 5 min. It was hot, I could touch it but couldnt leave my hand on it to long.