Mercruiser 3.0 high engine temp

[jthor3277]

Hello. I just installed a new 3.0 in my boat. I have an '01 Alpha One, Gen II. The problem I am having is that the temperature rises to 180 fairly quickly and seems to operate at 210. The temp never changes and stays at 210-215 degrees. I have installed all new components such as: impeller kit, thermostat, water pump, tubes, riser gasket and temp sender. The riser was blown out and cleaned up. The manifold had the same done to it. The thermostat was installed correctly with all new gaskets and is a 160 degree stat. I did install some water pump RTV on the sender and I was wondering if that would interfere with the readings. The gauge never moves from that temp once it is stabilized. I do have a hesitation when I advance the throttle...can it be running rich due to timing? Temp gauge? Thanks for reading.

 

[NHGuy]

Re: Mercruiser 3.0 high engine temp

That's too hot. You have to find the issue or you will ruin other stuff.
Did the old engine grenade from overheating? Maybe the externals are clogged or corroded.
Check inside all the cooling passages for impeller bits. Also check down the exhaust. If you get a section of clear hose for the transom to oil cooler "run" you can see how the seawater pump does.
If it gets to 200 just shut it off and paddle. It's not that the engine can't handle 200, but when the temp gauge reads 200 the exhaust is cracking 325, I know because I saw it with my own IR thermometer. High exhaust temps can cook your exhaust flaps and rubber exhaust tubes. And when it's that hot there the combustion chambers must be even hotter.
Fix it before you run it.

 

[IES99]

Re: Mercruiser 3.0 high engine temp

I agree, stop running that at that temperature now, figure out what is wrong. You are headed for a bigger outlay of time and $$$$$, it not.

Best of luck.

 

[Bt Doctur]

Re: Mercruiser 3.0 high engine temp

Supposed to be 140

 

[TiredoleBoy]

Re: Mercruiser 3.0 high engine temp

Hello. I just installed a new 3.0 in my boat. I have an '01 Alpha One, Gen II. The problem I am having is that the temperature rises to 180 fairly quickly and seems to operate at 210. The temp never changes and stays at 210-215 degrees. I have installed all new components such as: impeller kit, thermostat, water pump, tubes, riser gasket and temp sender. The riser was blown out and cleaned up. The manifold had the same done to it. The thermostat was installed correctly with all new gaskets and is a 160 degree stat. I did install some water pump RTV on the sender and I was wondering if that would interfere with the readings. The gauge never moves from that temp once it is stabilized. I do have a hesitation when I advance the throttle...can it be running rich due to timing? Temp gauge? Thanks for reading.

RTV, hmm I have had issues with this stuff breaking away and clogging little passages. I tend to stay away from the stuff.
An engine should not QUICKLY rise to a temp unless a load is placed upon it.
Can you access a infra red temp gauge?
If so take measurements at various areas of the engine to verify the readings are correct.

 

[jthor3277]

Re: Mercruiser 3.0 high engine temp

Thanks for the responses guys. Wow 140!!! I am not running this thing until I figure it out. Well my old engine shelled out due to water in the oil from a hole in timing gear cover created by my water pump. But it did start to run higher temps before I pulled it. Should I replace the manifold and riser? I know I want to keep this engine replacement cheap and maybe spending the money now will do just that. I am removing the RTV from the sender right now.

 

[jthor3277]

Re: Mercruiser 3.0 high engine temp

Okay I just did some troubleshooting. I ran my boat on muffs this afternoon and found the water temp reached the same point on the gauge, 215 degrees, and stayed there in less than two mintues. After that I disconnected the transom water line at the power steering cooler tube. The raw water pump filled a gallon jug in less than ten seconds. I then went to the inlet side of the thermostat and repeated the same with the hose. It filled in about ten seconds as well. The engine, at idle of course, doesn't feel that hot. The exhaust is spilling out water fairly well. The riser gets hot, then it's cool and the same applies for the manifold. I am going to use a temp gun tomorrow to see what the actual temps are. Any other suggestion on what to do? Thanks guys.