5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

[SS140]

I didnt get much response from my other post, so I guess I'll keep it one issue at a time per thread.

This other guy seams to be having the same issue on his Evinrude V6 as shown in this video on YouTube: http://www.youtube.com/watch?v=1JLJVjba0Ho
One explains "Speed Limiting Overheat Warning (SLOW)" Once the alarm comes on only way to reset it is turn off for a minute and turn it back on.

It doesnt appear to smoke when this happens, but Im mixing correctly. I added oil to tank one time it did this and it ran REALLLY RICH the next day. Wouldnt hardly start or idle.

Still havent been able to get a model # with this G3300993 number from the plug on the top of the head. It's definitly a VRO that has been removed. 1989-1990 Evinrude 70.


Im hoping someone can help me address this issue. When the motor is worked hard it doesnt wanna do it's job. Either WOT or lots of weight in the boat.

Thanks

 

[kenmyfam]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Tell us how you know the water pump and thermostat are good.

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

The pee is always steady and it comes directly out of the block, so water runs through the thermostat to get to the block, I think?

 

[kenmyfam]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Because you get a pee stream it does not mean all is well.
When did you last change out the impeller or test the thermostat ??

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Honestly, I havent done it. It was done before I purchased the boat, a new t-stat and waterpump in 2005 but not much use since then, which there are other bugs present from the sitting up and work that was done previously.

Perhaps I shouldnt rule out t-stat/impeller, I just figured since it wasnt alarming or "rev limiting/misfiring" when taking it slow and pees good...

But why no oil smoke? It usually smokes a little or a lot, sometimes it's rich sometimes its not, and I mix it the same everytime.

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Is it possible that when the engine is really hot it burns the excess oil insted of smoke it, which is why Im not seeing smoke when I get the alarm?

Under normal conditions, the engine smokes rich. Which is better then not seeing smoke or oil on the top of the water...

The colder the engine the richer it runs?

 

[wvmedic]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Ss140, I had a similar problem with a new to me 90 HP Yamaha. Got what appeared to be good water flow, peeing good but when I would try to run at high RPM it would alarm and not run over 2000 RPM. I changed the impeller because I had no idea when it was last changed, I also changed the T-stat and inspected the popit valve all looked good.

Well after I found a damaged top piston, probably due to an over heat issue. I tore the engine apart for a rebuild, and after taking the powerhead and lower unit off I found the problem. The previous owner apparently let the impeller go long enough that it came apart and clogged the water pickup tube. There was enough water passing thru it to cool the engine at any thing under half throttle, but would heat up fast at anything above that.

If you can get you?re hand on a Non-Contact Laser Thermometer, check the temperature of you?re engine when you are running it and when it alarms.

Jeff.

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Ok. Im going to get an N/C Thermometer so I know if it's actually getting hot or not. Would a tempature gauge do the same? I want to put one on my dash anyways, is that a wire that would be in the controlbox up front or do I need to wire one from scratch?

Thanks experts

 

[wvmedic]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

ss140 I have not installed a temp gauge, but if it goes to the same place as the temp sensor it would work. Others can confirm but you might be able to get a gauge that plugs in where the current temp sensor plugs in, I'm not sure if it would have a built in alarm though.

Jeff.

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Is it possible that my alarm is somthing other then HOT? Cause the water from the pee hole is always the same tempature, about the same tempature as the lake.

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

Screw it im fixing to make a video of this thing right now

 

[wvmedic]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

ss140 it is possible that you have a faulty temp sensor. That is why I recommended a Non-Contact Laser Thermometer, so you can rule that out.

Also is there a VRO, I thought I had seen where you were pre mixing you're gas.

I am no way a pro, I still have a lot to learn but also have learned allot here and another forum. Also from my personal experience.

Hopefully someone with some more experience can chime in if it could be something other than a over heat alarm or a low oil alarm.

Jeff.

 

[ezeke]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

The temperature sender that sounds your alarm is a switch; it is either on with an overheat or off. When the overheat alarm sounds the constant horn, the engine has already overheated and the motor should be stopped immediately and the problem corrected. The sender for a temperature gauge is totally separate from the temperature switch and alarm system and is a variable resistor, not a switch.


The tell-tale tells you that the water pump is functioning, but not how well; it tells you nothing about whether the water is flowing through the engine or not.

Water flows through the engine's cooling passages to the thermostat, not the other way ariound. If the thermostats stay closed the engine will overheat, period. The tell-tale will keep right on working as always.

When the engine overheats, good shop practice is to replace the cylinder head gasket(s).

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

So it may have overheated and the water from the pee hole still warm?

Bummer.. Is it possibly a low oil alarm? But it's a VRO with VRO removed, so I premix 50:1.

I just got back from a ride, it ran ok. Low rpm roughness and a little hard to start today, acting like dirty carbs again.
I was going to make a video of the whole situation but I ran WOT for about 10 minutes, it was too rough on the lake right now to go any longer, never got an alarm or the misfire, go figure.

She kept spitting on me this afternoon, hard to start. Had to push in the choke a few times with full idle bar to start it back up.

 

[ezeke]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

"So it may have overheated and the water from the pee hole still warm?"

Yes.

If the oil alarms are sounding, the VRO harnesses were not disconnected when converting to pre-mix. The alarms would be beeps, not a constant horn.

 

[SS140]

Re: 5Mins WOT, Overheat Alarm. Good waterpump, good thermostat.

yeah the horn fades sometimes, like louder and softer. I dont run it with the alarm, I shut it down and start it back up a few mins later and it is fine.