Overheating problem while trolling

[Ken Brice]

Ok guys, this is the deal. I had my water pump replaced last Dec, it was over heating while I was going slow.. This spring, I noticed while I go over over 2,000 or 3000 RPM's my temp goes from 150-160 up to 180.. I just was doing a test with my planner boards and noticed it.. I talked to my mec. and he it shouldn't be a problem, just give it some gas every once in a while.

Mer 150 Carb

What do you all think? Am I going to run into some big problems this weekend?

[WildeOne]

I ran two '95 Merc 150's last season and they always ran ~ 140 to 145° F at all speeds. 160 or 180° is NOT OK. Something's clearly wrong. When did you last change the Tstats or service the poppet valve?

Maybe you need a new mechanic? The guy is clearly wrong on this one.

Jim

[Dae]

Have you checked you're thermostat? That could be the problem. If you haven't, you can use a thermometer and a pot of boiling water. Just drop your thermstats in the pot of water and watch the thermometer to see when they open.

- Dae

[Fishamajig]

Thermostats are cheap and should be replaced periodically. I t just cost me about $10 to do one on my Yamaha 90.

I replace the wtaer pump every 2 years, thermostat every other time, 4 years. Cheap insurance when fishing big water.

[Ken Brice]

Yes, I had my thermostat was replaced last spring and my water pump replaced just this past fall.

An update, and thanks for your response, I took it to the dealer, I didn't buy it their, but they sell mine.. I bought mine used, its a 2000,.. The service guy said, my thermostat only opens when I go
fast.. He also said it was normal for water to be coming out of the pee hole, not at a full stream when I am going slow.. They are going to check it out.. But when I said, is it normal for the temperature to go from 145-150 to 180, while I am going slow.. He didn't say much..

Thanks again,
Ken

[fixit]

Could be worn water pump plate(s)... Or housing. A few worn spots will cause some cavitation that is very noticeable at slow speeds..

[Reel Life]

Ken, when at idle speed, the thermostats control the engine temperature. As speed is increased (and inlet waterpressure) the control over temeraure is a combination of poppet valve and thermostats. replace them BOTH (there are 2) and for the 30$ in parts, I'd replace the Poppet valve seat, diaphram and spring. Good luck, Mark

[BBCroaker]

Had thermostats replaced a couple of years ago $312 on a 115 Johnson.
thought it was pretty expensive.

[fixit]

BB, That is very high priced on those T-stats.