Location of temp sensor on 150HP Merc

[heymon]

I'm troubleshooting a constant temp alarm on my port-side '95 150HP Merc. Engine is squirting and running smoothly through all throttle ranges and loads. There is no temp gage installed. Boat is marina-kept on a rack and I don't get down to it enuf be able to get very familiar with the powerhead(s). <br /><br />I suspect a faulty sending unit and would like to know a little in advance where to spot the sender on the powerhead so I can either swap it with the starboard engine's unit or simply pull it to run a bench test. Also, any idea what the little sender may cost? <br /><br /> Thanx,<br /><br /> Ed

 

[AndyL]

Re: Location of temp sensor on 150HP Merc

It may be some help but without seeing your engine I am just guessing. The temp senders are probably sited at the top two cylinders as they will always run hotest. On my engine, which is a couple of years older than yours, one sender connects to the temp guage on the dash the other I believe is routed through the "module" to the alarm side. The alarm is also indicative of an oil problem so it is vitally important that you get this checked out before you next attempt to run the engine. Your problem may be that the module has failed and the engine is OK but you get a constant alarm. The cost of a module in the UK is around £170 which is about $300. Not a big job to replace. <br />Good luck

 

[heymon]

Re: Location of temp sensor on 150HP Merc

Thanx for the heads-up. By time I grabbed all of the tools and snaked my hands back to the alarm's location, it had stopped making racket! So, I'm gonna let the concern slide a bit... Engine performing perfectly so I feel there is a faulty link, somewhere, but not in the cooling system itself. I'm gonna let the sender stay where it's at, for now.<br /><br />Strangely, you'd think that a temperature gage would be included with a new outboard engine, considering what a unit costs!<br /><br /> Ed