06’ Df150 over heat

[Fxnytro17]

Went to go for a nice boat run today with the fam, about 2 minutes in at about 4500 rpm, check engine flashes and then the motor just about dies, loss of power. The over heat light was on so I shut it off. It was pumping water when I left and as well when I was running. Same as it always did. The light went away and then again about 1 minute in same thing. I made it back on without loss of power but this is something unexpected.

steady stream of water. Always Ran good until this happened.

I looked on the past forums, finding a lot of info on the df140s . But these guys usually saying replace the pump, but the steam seems fine to me.

[steve446]

There is more to the cooling system than the water pump, the temperature of the motor is controlled by a thermostat, a temperature cotrolled valve that controls circulation through the block. The thermostat has probably failed in the closed postion. Should be easy to replace.

[Fxnytro17]

I’ll check it, I’m a mechanic by trade, just not outboards lol I’ll check it

[Fxnytro17]

It may be stuck closed, open would keep it cool wouldn’t it

[Fxnytro17]

It’s moving fine, and is closed, I found two temperature sensors both look like new. All wiring looks good. Spark plugs look good.

[Fxnytro17]

So the code I got off the beeping was the cylinder temperature sensor. I pulled two of them off again, I have them both in water, not heated, figuring the water is around 10°, one sensor is reading 4.1ohms the other is at 2.6. Sensors have the same part number on them. This may be my problem? The one reading 2.6 was at the top of the engine, I’m thinking this one was the cylinder temp. I cannot find a diagram saying which is which

[redlowrey]

Are you reading the ohm meter properly, because the check engine light would have come on as soon as you turned the key on with those readings. If they both look new someone before you have been chasing an over hast problem.

[Fxnytro17]

Are you reading the ohm meter properly, because the check engine light would have come on as soon as you turned the key on with those readings. If they both look new someone before you have been chasing an over hast problem.

I placed the two in water unplugged from the engine, after about two hours I checked again and both were reading 2.6-2.7.
You have a good point about past overheating problems. This is my second summer with it, never had an issue before. It’s been on the trailer for 2 weeks sense I last used it. No troubles this year or last year except for now.

the thermostat looked old, but was movable. I’m going to get a new one anyways, as for the sensors I don’t see a point to get new ones for 60 bucks each.
I could get a water pump kit as well but it has a steady stream of water flowing.

[redlowrey]

Are you sure they are 2.6 ohms not 2.6 k ohms.

[Fxnytro17]

Yes you are correct, sorry

[redlowrey]

If you are going to test them in a pot of water, put your thermostat in there as well and you need a temp gauge so you can see the resistance change on the meter as the water temp changes, and see your thermostat open as well and note the temp.

the best way to test them is when the engine is hot with a volt meter

[Fxnytro17]

Maybe I will try tomorrow with the engine hot, as for the thermostat it’s in there pretty good so I’m getting a new one tomorrow because I’m doubtful I will get it out in one peice anyways. As for the sensors I was just comparing the two to see if I was getting the same ohms, at first I wasn’t which I thought I may have found my problem.

[Fxnytro17]

I changed the thermostat, boiled in water. Seemed to open around 60°c which maybe my thermometer is off, I will double check later.
on another note I am changing the water pump and the impeller looks normal to me. But the bottom plate seems scorn pretty bad for just a rubber impeller. Something may have gotten in there at some point.

I am changing it anyways but I do not think this is my problem, but it may be an issue that’s not helping.

[Fxnytro17]

I was thinking I may have a corrosion problem but seems to be better then most other Suzuki’s I’ve seen online. One pic is looking up from the leg, the other is the water pressure valve.
i don’t have a picture looking in from the t stat side but it didn’t look to bad. I tried removing a plug at the very top of the engine but it wouldn’t give so I gave up. It didn’t need to come out anyways.

this motor was always in salt water. It’s at about 550 hours.

[Fxnytro17]

Can somebody chime in.

turned the key ahead just then, without starting, engine is cold. I have the exhaust and cylinder sensor plugged in but not fastened to the engine.

the check engine light reset itself. I turned the key off then back on again and the temp light came on. Bad sensor? Bad gauge?