1996 135 v6 Possable over heating

I have this 1996 V6 that the over heat alarm sounds sometimes when you slow down to idle. As soon as I increase speed alittle the alarm turns off. I have a hard time beliveing it is overheating becouse AS SOON as I speed the engine up the alarm turns off, I would think any increase in water flow would take some time to cool off the motor.

Is the alarm a temp sender or a pressure sensor? this just started this two trip ago and before the last trip out I replaced the water pump. still the alarm sounds.

One more thing, the charging system over charges but it has been doing that for along time guess I have to replace both regulators as it still overcharges when I disconnect either regulator.

Re: 1996 135 v6 Possable over heating

No body has any idea what this problem could be?
The overheat alarm sounds sometimes (not all the time) when returning to idle after running for a long time. But when I speed up the engine even just a little the alarm turns off, as soon as I speed the engine up. I just can't think the engine would cool down as soon as the engine speeds up even a little bit of speed increase.
Water pump has been replaced and I still have this problem.

Re: 1996 135 v6 Possable over heating

Is the alarm a temp sender or a pressure sensor?

Click to expand...

It is a mechanical sensor.......

I have to replace both regulators as it still overcharges when I disconnect either regulator.

Click to expand...

Have the battery load tested first.....

The overheat alarm sounds sometimes (not all the time) when returning to idle after running for a long time. But when I speed up the engine even just a little the alarm turns off, as soon as I speed the engine up.

Click to expand...

Sounds like you have a t-stat sticking or poppet valve.... Check the poppet valve first to ensure free movement and block seal not cocked restricting poppet shaft.

Re: 1996 135 v6 Possable over heating

Thanks for the responce 'bullet, The over charging problem has been going on for along time...Bought the boat/motor new and it has been doing that for about 6 years, never gave it much thought becouse it will over charge to about 16+ volts for about 3-5 min then would rest back to 13-14 volts for 30 min then do it again. the last time we went out I figured I should see witch half of the system was the problem...sams thing with either side unhooked. Same problem with other older battery, new battery this spring.

I just included this info with the over heat problem just in case.

If it was a t-stat sticking...would it cool down instantly? The alarm turns off AS SOON as I increase the throttle even just a little.
What is the poppet valve? what does it do?

I bought a factory manual when I bought the boat back in '96 but the first time I used it (about 4 years later) I noticed it was printed in '94 and some of the electrical/warning system stuff is not the same. SO I have just ordered two aftermarket manuals...amazon.

When you say the sensor is "mechanical" what do you mean? it is electrical is it not? Does it sense water temp or water pressure?
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Thanks again
Tom

Re: 1996 135 v6 Possable over heating

Tom, The overheat sensor grounds when it detects overheated water in the motor.

On that motor the thermostats cool the motor at low RPM. At higher RPM the poppit valves opens and allows lots of cooling water to bypass the stats. I would check your thermostats.

Re: 1996 135 v6 Possable over heating

Chris, thanks for the info...I will check that this weekend. do you think the poppit valve would open with just a little more throttle than idle? and would that cool the motor enough to turn the alarm off as soon as the throttle is increased? any way I will check them or just replace them this weekend.

thanks again.

Re: 1996 135 v6 Possable over heating

Poppit is spring loaded. When water pressure overpowers the spring the poppit opens. This allows lots of cooling water. Whether that is your issue, I cannot tell. Take a look at the 'stats, and the rubber gaskets. Crap, I would just replace them, rather than bother testing them. That should eliminate the 'stats as an issue.

When I looked at the 'stats in my '93 135HPV6, about three years ago (saltwater motor), they looked like crap. The rubber gaskets were shot, as well. You can do the math....

Re: 1996 135 v6 Possable over heating

This is also a "salt water motor" that has spent most of it's life at Ocean City Md. and the atlantic ocean. I will end up just replacing the t-stats and rubber seals/gaskets.