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Discussion Starter · #1 ·
My slip lies about 3 miles from open water. This weekend I had a chance to use my brand new outboard for the first time. Checked the oil, good to go. I was using the internal tank, and I had three gallons on board to refresh as we went along. No problems going out. I kept the throttle at less than 3/4 WOT.

On the way back in, running at 3/4 for about 30 minutes, the engine quit and the high oil temperature light came on. Trying to re-start had the high temp oil light continue to come on as I pulled the cord. Raised the jib for some forward motion, and to let the engine cool for a bit. After about ten minutes, the engine started. I kept it at about 50% all the way back to the slip with no further problems.

Considering the this is a brand new engine, and that I babied it for the most part, what would cause it to stall like this? Oil level was WNL, I saw no evidence of seaweed tangling, and the prop was clean in the end. Water circulation through the engine was constant as well.
 

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My slip lies about 3 miles from open water. This weekend I had a chance to use my brand new outboard for the first time. Checked the oil, good to go. I was using the internal tank, and I had three gallons on board to refresh as we went along. No problems going out. I kept the throttle at less than 3/4 WOT.

On the way back in, running at 3/4 for about 30 minutes, the engine quit and the high oil temperature light came on. Trying to re-start had the high temp oil light continue to come on as I pulled the cord. Raised the jib for some forward motion, and to let the engine cool for a bit. After about ten minutes, the engine started. I kept it at about 50% all the way back to the slip with no further problems.

Considering the this is a brand new engine, and that I babied it for the most part, what would cause it to stall like this? Oil level was WNL, I saw no evidence of seaweed tangling, and the prop was clean in the end. Water circulation through the engine was constant as well.
I think the little red light indicates low oil pressure? I will look at the manual later. Tank vent? crimp in fuel lines? Filter? Have to go now, later.

Paul T
 

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I had same issue with my Mercury 4, got stranded in my RIB a mile out and had to row the barge.
It's 6 years old, but first time I used it.

When I got back to the boat I laid it down tiller side down (as indicated). The next day the majority of the oil came running out when I lifted it vertically to mount on rail.

I've not looked at it yet, I think my next move is to put a for sale sign on it.
 

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Your brand new motor failed the first time you used it? It's a little 4 hp thing that can be lifted and moved? Simple - take it back to the dealer and make them replace it.

First, be sure it wasn't operator error. Some 4 strokes ship with little or no oil present to avoid leakage. Check the level to be sure that it's correct. Also, as someone else mentioned, if you lay the motor on its wrong side, oil can leak out into the carburetor, air filter (if it has one), or inside the cowling. Make sure that didn't happen, because that could cause your oil level to be low.

Second piece of advice: Don't buy chuckles motor. lol
 
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My oil leak was / is the gear oil by the way.
Lower unit gear oil? How does lying the motor down on its side cause that to leak? You have unique talents! ;) :p
 

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Read thru the manual. The light is for low oil pressure. The manual calls for less than half throttle for the first two hours. Having it quit could have been fuel starvation? There is a rubber cap that goes over the external tank connection on the motor. Not sure, but if it becomes loose the motor may suck air at that point?

The other possibility, hopefully not, could be that a plastic bag got sucked up over the one & only , unlike my older Evinrudes, water intake, causing it to heat up enough to thin the oil, setting off the light, & maybe temporarily seize the engine?

If the "pee stream" is solid, it is probably pumping adequate water. With the cowl off you should be able to touch much of the motor without burning your hand. Or, as mentioned, an infra red heat gun should give you temps on the various engine surfaces.

What is "WNL"? You should come back to PRWG, been very quiet without you. :D

Paul T
 

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Discussion Starter · #10 · (Edited)
Read thru the manual. The light is for low oil pressure. The manual calls for less than half throttle for the first two hours. Having it quit could have been fuel starvation? There is a rubber cap that goes over the external tank connection on the motor. Not sure, but if it becomes loose the motor may suck air at that point?

The other possibility, hopefully not, could be that a plastic bag got sucked up over the one & only , unlike my older Evinrudes, water intake, causing it to heat up enough to thin the oil, setting off the light, & maybe temporarily seize the engine?

If the "pee stream" is solid, it is probably pumping adequate water. With the cowl off you should be able to touch much of the motor without burning your hand. Or, as mentioned, an infra red heat gun should give you temps on the various engine surfaces.

What is "WNL"? You should come back to PRWG, been very quiet without you. :D

Paul T
In hindsight I'd say I was closer to 50% WOT than I was to 75%. WNL = Within Normal Limits. That said, when I checked the oil today, it was just below the midpoint on the dipstick, well WNL.

One thing that I can't figure out is how to flush the engine after use. My other Evinrude had the water intake on the side of the shaft. This Mercury has it on the bottom, and the earmuffs I used on the Evinrude won't work on this one...

PRWG is a lot less interesting than it once was.
 

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In hindsight I'd say I was closer to 50% WOT than I was to 75%. WNL = Within Normal Limits. That said, when I checked the oil today, it was just below the midpoint on the dipstick, well WNL.

One thing that I can't figure out is how to flush the engine after use. My other Evinrude had the water intake on the side of the shaft. This Mercury has it on the bottom, and the earmuffs I used on the Evinrude won't work on this one...

PRWG is a lot less interesting than it once was.
It wouldn't hurt to have the oil level right at the full mark. Why the light came on & why it stopped is puzzling. If it got hot & seized, it is possible that it might rattle a bit after you got it running again? Hopefully, it was fuel related?

Oil viscosity may be a possibility? The manual has the specs.

There is a hose fitting under the power head for flushing, see page 49 & item #4 on page 11.

http://www.tohatsu.com/tech_info/own_man_pdfs/Toh_MFS4B_5B_6B_003-11059-6.pdf

In any event, maybe a few short trial runs close to home?

PRWG is picking up, Bent is bent out of shape because he is accused of trolling, great fun, good entertainment. :D

Paul T
 

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Eric,

As we have the 6HP version of your motor, this is of interest to me. These engines have rev-limiters in them. Perhaps they also have an overheating limiter/shut off feature also?

When I get a little time I will do a search on it.

Do you see any discoloring or peeling of the paint on the power head anywhere?

Paul T
 

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The break in procedure is less than half throttle / less than 3000 rpm for the first 2 hours, then rising progressively up to 10 hours. It would also be advisable to avoid long periods at the same rpm.

Tohatsu Outboard Engines - Break In Procedures

You didn't follow the break-in procedure, so it's possible that the engine siezed. Unlike car engines, where it's possible to skip the break-in procedure these days due to very tight tolerancing, it appears to be essential still on outboards.
 

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Well, I did a search & it appears Tohatsu does have water temperature sensors, but on the larger models?

http://www.tohatsu.com/tech_info/brochure_pdfs/2004_brochure/Toh2004_FullBro.pdf

However, this site shows one for the MD4, if I am reading the chart correctly. No mention of it for the MD6, however?

3T4-72514-0 WATER TEMPERATURE SENSOR

In any event it doesn't say how it works? My guess is that it may shut down the ignition when the engine over heats, just guessing? A call to a friendly Tohatsu dealer might be the answer?

If your motor is equipped with one, it may be faulty, or the engine did get hot & triggered it?

Paul T
 

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Discussion Starter · #16 ·
Well, I did a search & it appears Tohatsu does have water temperature sensors, but on the larger models?

http://www.tohatsu.com/tech_info/brochure_pdfs/2004_brochure/Toh2004_FullBro.pdf

However, this site shows one for the MD4, if I am reading the chart correctly. No mention of it for the MD6, however?

3T4-72514-0 WATER TEMPERATURE SENSOR

In any event it doesn't say how it works? My guess is that it may shut down the ignition when the engine over heats, just guessing? A call to a friendly Tohatsu dealer might be the answer?

If your motor is equipped with one, it may be faulty, or the engine did get hot & triggered it?

Paul T
As it was new, I was monitoring the engine the entire time. It never got overly hot, as I touched it several times right before it stalled. The pee hole shot a constant stream the whole time as well. It was low on fuel when it stalled and I did not immediately try to restart it when it did because I did not want to damage it. I'm beginning to believe that it was a fuel starvation issue, but I will fill the oil to the top of the dipstick and baby it for the next few hours. Thanks for your help.
 

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Interestingly, the Mercury manual didn't say much about the light. The Tohatsu manual has much more to say. It is a normal oil pressure warning light. It is NOT an oil temperature light, or anything else for that matter. The manual mentions that it lights for a couple of seconds during cranking, as a self-test.

So it appears that the OP's symptoms do agree with a simple fuel-starvation issue.

You still should be breaking it in more carefully, though.
 

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Discussion Starter · #18 ·
You still should be breaking it in more carefully, though.
This, I will do religiously...

The manual states 10W-30 for "general purpose" oil, but that 25W-40 can be used if it is "preferred". I live in SoCal so I don't need to worry about cold weather. Do you have an opinion on which to use?
 

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This, I will do religiously...

The manual states 10W-30 for "general purpose" oil, but that 25W-40 can be used if it is "preferred". I live in SoCal so I don't need to worry about cold weather. Do you have an opinion on which to use?
It was low on fuel when it stalled and I did not immediately try to restart it when it did because I did not want to damage it.
Ah, that sounds much better. For the last 2 years I have been using 10-40.
Water temps gets up to 70 degrees in the summer, down to about 40 in the winter. Seems to be working OK?

From your previous post it sounds like it is cooling OK? That is a good thing. Seizing a 4 stroke would be unfortunate. :D

I followed the break in schedule to a "T". The motor ran perfectly right out of the box & continues to do so, 2 years later at 6,000 feet elevation with no jetting changes.

Keeping the oil at the full mark is probably a good idea, holds about 15 ounces, IIRC. Doesn't seem like very much, but that is what is called for.

Paul T
 

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Discussion Starter · #20 ·
Keeping the oil at the full mark is probably a good idea, holds about 15 ounces, IIRC. Doesn't seem like very much, but that is what is called for.

Paul T
I just ran out and bought a quart, and I'll top it off.

Now, to flushing the motor. Seems I need a "flushing attachment" that, to my dismay, did not come with the motor.
 
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