Do 470s (3.7/LX engines) have heat sensors?

[bryan.kearney]

I have been struggling on and off with a Mercruiser 3.7LX which will run fine, we will stop, and then it will not start up. This weekend.. we cruised for about 30-40 min at a low throttle up to the marina. Stopped the boat, got the kids ice cream (about 10 minutes max) and the boat would not start. No crank.. nothing. No sound. If I moved the ignation I could jump it from the solenoid, and it ran fine all the way home.

I noticed that it was running around 220 or so degrees. However, when we stopped it would shoot up to 240+ until we got more water running through the engine. I do not think that these motors have any "Dont start if too hot" sensor.. but I figured I would ask.

Thanks!

 

[newbieboater1]

Re: Do 470s (3.7/LX engines) have heat sensors?

I have been struggling on and off with a Mercruiser 3.7LX which will run fine, we will stop, and then it will not start up. This weekend.. we cruised for about 30-40 min at a low throttle up to the marina. Stopped the boat, got the kids ice cream (about 10 minutes max) and the boat would not start. No crank.. nothing. No sound. If I moved the ignation I could jump it from the solenoid, and it ran fine all the way home.

I noticed that it was running around 220 or so degrees. However, when we stopped it would shoot up to 240+ until we got more water running through the engine. I do not think that these motors have any "Dont start if too hot" sensor.. but I figured I would ask.

Thanks!

I've never seen anything other than a coolant temp sending unit. If the engine is reaching 240, then that could be part of your issue.. That's overheating. Mine runs (well, ran- she just died on me) at 190 all day, every day. I had similar issues with a no-start condition and it turned out to be corrosion on the inside of the wiring harness. I rewired the entire harness (cut off the connectors and ran new ones), and this solved my problem. Next time it doesn't start, maybe you could try wiggling the wiring harness connectors.

 

[Don S]

Re: Do 470s (3.7/LX engines) have heat sensors?

I do not think that these motors have any "Dont start if too hot" sensor.. but I figured I would ask.

No, it doesn't have anything like that. But at that temp, you could have other problems. Especially on a 470. You NEVER want to see the temp over 200? on a 470. That can cost you a head gasaket.

The first thing you need to do is find the overheat problem. When was the last time the impeller in the drive was replaced?

Next is your starting system. If you don't hear anything, no click, nothing when you hit start, then you need to read this thread and check it out to find the problem.
http://forums.iboats.com/showthread.php?t=167035