3.0L GM 140Hp running temp

I just read a post about a different engines running temp, so now I have to ask. I ran my motor hard and it got up to about 180 pretty quick, but it stayed there. The next day, early morning when I started her up, it was still around 160, and went up to 180 within a few minutes. Is this running to hot?

Re: 3.0L GM 140Hp running temp

My 3.0L has ran just a tick past 175, since the day that I got her.

There is nothing wrong with what you are seeing.

For what it's worth, the overheat alarm switch is set for 190....

Happy boating!

Re: 3.0L GM 140Hp running temp

Overheat alarm?Thats good to know that it SHOULD have one, I hope that I never have to hear it!! Thank you Rocky_Road

Re: 3.0L GM 140Hp running temp

U.S.S. Too Tall said:

Overheat alarm?Thats good to know that it SHOULD have one, I hope that I never have to hear it!! Thank you Rocky_Road

Click to expand...

Don't be too quick! Many of the 3.0Ls were delivered with the wiring for the alarm system in place...but the sensors only installed if ordered by the original buyer. My 3.0L had to be upgraded, and it was the best thing that I ever did. I picked up a plastic shopping bag on my outdrive, and my alarm warned me before I overheated.

If you have a constant buzzing when you turn your key on, that goes away within seconds of your engine starting, then you have the alarm system.

Happy boating!

Re: 3.0L GM 140Hp running temp

Thats funny. Like I said, SHOULD have one. I havent heard this buzzer when starting. I guess that I dont have it. Is the sensor hard to install yourself? Or cheap and easy to find and buy one?

Re: 3.0L GM 140Hp running temp

U.S.S. Too Tall said:

Thats funny. Like I said, SHOULD have one. I havent heard this buzzer when starting. I guess that I dont have it. Is the sensor hard to install yourself? Or cheap and easy to find and buy one?

Click to expand...

Your options are numerous: buy the temp switch from Mercruiser and simply screw it into the existing hole on your thermostat housing. The wire is already there taped off. I can show you where this goes and where you should find the wire. You need to go under your helm and look for the buzzer somewhere near your fuse panel. It will look like this:



The correct temp switch (Merc part #48952) for your engine will have the red band (190 degree):



You can probably get the switch right here on iboats.

With the temp switch installed, you will not get a verification horn with the key at "ON"...that takes the low oil pressure switch also installed. But you would still have the temperature monitored. To get the full system, you have to install the oil pressure switch and the gear lube reservoir w/float.

I'll answer any questions instead of just rattling on!

Re: 3.0L GM 140Hp running temp

1987 3.0L 130 HP Mercruiser Ohio summer water temps running WOT a couple miles with new lower impeller and housing old 145 degree thermostat about 150 on gauge . Pulled to look a stat after it got to 160 deg. when first got to run and it was rusting looking and later thought it came loose and in hose so I ordered new stat andhose and what i found was new hose has spring in it I guess to keep hose from colapsing.

Re: 3.0L GM 140Hp running temp

Awesome! thank you for the details. I am hoping to get time before work tomorrow to look at a few things in her. This will be one of them. I will let you know what I discover!!

Re: 3.0L GM 140Hp running temp

Well, I guess that I am not so lucky. Under the dash, I have nothing. Just the gauges. No fuse panel. I guess that a 1979 boat is not good enough for a fuse panel. Most things have an inline fuse when needed. So, I dont think that I will be just adding on a sensor. For now, I need to work on the starter. Anyway, thanks for the info Rocky, its been informative!