150 Verado overheats above 2800rpm

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breausaw

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https://youtu.be/TydI3L9jqi0

See above video, motor would overheat above 3800 rpm. Temp would rise above 210 and tiger alarm and digital overheat screen on Mercury smart gage, would actually reduce RPM automatically. After about 2 hours went back to normal. ..steady 148 to 152.
Thinking sticky thermostat, so replaced. 20 hours later same thing 80 miles from port, think I know the fix but just thought I'd through this out there. BTW, water pump recently replaced and water pressure on gauge within factory specs.
Could make about 15mph, just hope engine not damaged.
Called Mercury outboard customer service from remote Village of Chiniga in sawmill bay on Cell, actually got ahold of someone that seemed to know what they were talking about, told me what would most likely be the problem.
Called local dealer but was not able to talk with mechanic, even offered to pay shop time for time spent discussing issue.
Not something you necessarily want to happen that far from Port, did not seem to worsenson so did a bit of fishing before heading back.
 
I cant view the video due to security block

Are the thermostats defective when testing in hot water or full of debris and clogged?
 
Does it have a poppet valve or pressure relief valve? It is spring loaded valve in the water cooling systen and designed to maintain water pressure at low rpms to help out the water pump then opens at higher rpms and the water pump can provide adequate water flow. Should it fail and not open or is clogged, it can restrict flow at higher rpms. On Yamaha, they un screw and easily accessed from the outside on the midsection leg

Also a sensor might be bad

Good puzzle
 
Well, the rest of us are guessing. What did the factory rep say was the problem? Relieve our curiosity.

BTW, given the info you've told us, the factory is the most likely to know the answer, in my opinion.

Boris
 
BrentB":15335mat said:
Does it have a poppet valve or pressure relief valve? It is spring loaded valve in the water cooling systen and designed to maintain water pressure at low rpms to help out the water pump then opens at higher rpms and the water pump can provide adequate water flow. Should it fail and not open or is clogged, it can restrict flow at higher rpms. On Yamaha, they un screw and easily accessed from the outside on the midsection leg

Also a sensor might be bad

Good puzzle
Click to expand...

Hit it on the nose most likely it's the poppet valve.
Never heard of one until last Friday when I called Mercury customer service, have the part on order and hopefully it will fix the problem.
 
BrentB":32i8tdni said:
Even a blind squirrel finds a nut once in a while
Click to expand...

Indeed, I often feel like a blind squirrel when looking for answers. First time this happened I called Murcery customer care and was told it was most likely a senser or thermostat issue, no mention of a poppet valve.
When the problem reoccured after installing a new $150 thermostat I asked the Murcery Tech of chance if there was an additional coolant regulater other then the thermostat. It was at that point the Tech mentioned he thought there was a poppet valve.

Sometimes it's the blind leading the blind.
 
When I picked up the poppet valve from the dealer had a chance to talk with the mechanics and got the impression it wasn't going to fix my problem, and it didn't.
So three-day fishing trip planned for this weekend cancelled. Took the boat to the dealer and left it, hopefully they will have a look at it in 3 or 4 days.
Truly a bummer, weather is awesome and the fishing is hot.
Oh well guess I'll catch up on some of my honey dues.
Will post updates when I know more.
:thdown :sad
 
Weather turned snotty so don't feel so bad, hopefully have it out of the shop by next weekend and after I stuff a plug of money in the proverbial hole.
 
It's possible that salt deposits are constricting flow or even blocking water passages. Do you flush regularly with Salt Away or a similar product?
 
AK Angler":2g1m5sn5 said:
It's possible that salt deposits are constricting flow or even blocking water passages. Do you flush regularly with Salt Away or a similar product?
Click to expand...
Gets a flushing after every trip. But even if there were restrictions in the water jacket it would not explain the sudden onset. First time it happened the problem cleared up after about 2 hours, engine temperature stabilized at about 149 150 regardless of RPM as it should be.
As I stated the problem presented itself as if the thermostat was sticking or just not working properly so replaced it and the problem reoccurs about 15 hours later; truly a head-scratcher.
 
Update,
Left the boat with the 5 days with my dealer of choice, the mechanic just replaced the entire water pump assembly. He showed me the parts where it looked like there was some abnormal wear, saw some shiny and dull places didn't look that bad to me.
He ran the motor in the tank to about 3000 RPM four 15 minutes and it stabilized around a hundred and fifty degrees. But then he said when he cut it back to idle the temperature shot up to about 200, at this point I was skeptical that anything was achieved.

I took the boat down to the launch ramp and ran the motor up to 3000 RPM in gear, the temperature shot up above 200. I backed it off to around 2000 RPM and the temperature slowly creeped down to 150 and stabilized there for about 5 minutes. I backed down on the throttle and shut the motor down then restarted in about a minute. The temperature shot up to around 180 then stabilized again at 150, I throttled between 2000 and 4500 RPM. I shut the motor down again for about a minute then restarted. Took it up to around 3000 RPM again but this time the temperature shut up above 200 and I got the overheating alarm.
So at this point it's obvious that nothing was done to fix the problem. I called the only other Mercury dealer in town which is Bass Pro Shop and as it turns out they have a verado certified tech. I have an appointment Saturday morning at 9 o'clock, I'm hoping to get some answers. If not I guess I'll pay the $50 on the verado users group to see if their are Mercury certified verado techs can shed some light.
At this point I'm thinking it's a sensor problem.
 
Static testing of the engine in the water is going to create a much different temperature response than if you are moving through the water. You are basically lugging the engine at much lower RPM than you would experience out on the water. That is the reason that shops use test props that don't push water.

You may have fixed the problem and don't know it because of the way you are testing.

Put it on the lake and take it for a spin if you want to compare apples and apples with the times you were on the water and noticed the problem. Static testing is very hard on the engine without a dummy prop and will cause overheating.

Your shop guys should know about that potential problem and potential damage to the engine doing the testing that you are doing. Flushing the engine is one thing, but operating statically at high RPM's is not good.

Think of it as a car that has the wheels locked and you are popping the clutch. Something will give--xmission or engine overheat etc. Same thing with the testing you are doing.
 
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