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Please help.
I have a Mariner 8hp 1998 saildrive, model 8MLSM.
Recently serviced with new impellor.
When running, the flow of water from the engine is intermittant. From full flow, the stream tails off to nothing, then after a few seconds comes back boiling hot and steaming, runs fine for a few seconds then tails off again. This is a constant thing, the cycle lasts about 15 seconds and happens the whole time the engine is running. Does this engine have a thermostat, and could it be this? Or is this perfectly normal. Any other suggestions greatfully received, otherwise back to the repair shop for another few weeks!!!
Many thanks
 

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Please help.
I have a Mariner 8hp 1998 saildrive, model 8MLSM.
Recently serviced with new impellor.
When running, the flow of water from the engine is intermittant. From full flow, the stream tails off to nothing, then after a few seconds comes back boiling hot and steaming, runs fine for a few seconds then tails off again. This is a constant thing, the cycle lasts about 15 seconds and happens the whole time the engine is running. Does this engine have a thermostat, and could it be this? Or is this perfectly normal. Any other suggestions greatfully received, otherwise back to the repair shop for another few weeks!!!
Many thanks
This is perfectly normal behaviour. If the engine was pumping cold water through constantly the cylinder would never reach operating temperature and warm up. The thermostat in an outboard is slightly different from a cars enclosed system but works along similar lines to keep the engine at the correct operating temperature.:)
 

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Thanks for your help everyone.
Going to try a few things now, see what works. Many Thanks.
Happy sailing.
Laura
:boat:
Hi I forgot to ask is this happening on when running stationaryon muffs. Or when you are out in the boat?
You will get an entirely different thermostat cycle of opening and closing when motoring along.:)
 

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Quote:
Originally Posted by Brambles
Please help.
I have a Mariner 8hp 1998 saildrive, model 8MLSM.
Recently serviced with new impellor.
When running, the flow of water from the engine is intermittant. From full flow, the stream tails off to nothing, then after a few seconds comes back boiling hot and steaming, runs fine for a few seconds then tails off again. This is a constant thing, the cycle lasts about 15 seconds and happens the whole time the engine is running. Does this engine have a thermostat, and could it be this? Or is this perfectly normal. Any other suggestions greatfully received, otherwise back to the repair shop for another few weeks!!!
Many thanks

This is perfectly normal behaviour. If the engine was pumping cold water through constantly the cylinder would never reach operating temperature and warm up. The thermostat in an outboard is slightly different from a cars enclosed system but works along similar lines to keep the engine at the correct operating temperature.
All the outboards that I have owned or operated , "the tell tale" runs constantly from the moment it is started to the moment its switched off , with no fluctuation in between, the tell tale is what it is a constant signal to show that the motor is receiving a constant supply of "fresh water".

When running, the flow of water from the engine is intermittant. From full flow, the stream tails off to nothing, then after a few seconds comes back boiling hot
This would indicate a potentially serious problem with motor cooling,possibly a blockage which clears as the pressure in the head builds up .

Cheers Ian
 

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All the outboards that I have owned or operated , "the tell tale" runs constantly from the moment it is started to the moment its switched off , with no fluctuation in between, the tell tale is what it is a constant signal to show that the motor is receiving a constant supply of "fresh water".



This would indicate a potentially serious problem with motor cooling,possibly a blockage which clears as the pressure in the head builds up .

Cheers Ian
Hi don't know if you have a Merc? My Mercury does the intemittant flow thing. Has done since new. The time cycle varies on load.
Tickover is intermittant and higher revs less so and almost constant.:)
 

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i had twin merc's and both of the tell tales ran full bore all the time, once i cleared a small blockage in one,
If you read the original post it says the flow is at intermittant intervals. Just as my 8hp one is. The thermostat is just opening and closing. A blockage would not be so regular. It would be blocked.
 

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"This would indicate a potentially serious problem with motor cooling,possibly a blockage which clears as the pressure in the head builds up ".

Ok who put the thermostat in upside down?



 

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If you read the original post it says the flow is at intermittant intervals. Just as my 8hp one is. The thermostat is just opening and closing. A blockage would not be so regular. It would be blocked.
Hi SurenuffandyesIdo, i was just saying that all the outboards (including merc's) i've had always ran full bore on the tell tales, whether they were cold or hot,

in Brambles original post he said, the stream tails off to nothing, then after a few seconds comes back boiling hot and steaming, that doesnt sound good to me,

Andy
 

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Had a similar problem with my Mariner engine, same as Merc, suggest you flush out the engine in a large tub of fresh water and mix some SALTX solution in the water at the given mixture.

See link here http://www.salt-xuk.com/

Run it then stop and wait, run it again and stop it, repeat this over 2 -3 hours and you may well find it makes a huge improvment to the tell tail. Sounds like if the engine has some corrosion build up if not regulary flushed in fresh water after each trip.

Hope it helps

Dave
:boat:
 

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Hi SurenuffandyesIdo, i was just saying that all the outboards (including merc's) i've had always ran full bore on the tell tales, whether they were cold or hot,

in Brambles original post he said, the stream tails off to nothing, then after a few seconds comes back boiling hot and steaming, that doesnt sound good to me,

Andy
I checked my Mariner and a Yam 4hp backup motor I use for my boat in a big plastic bin yesterday. The Yam has a constant flow sometimes very strong sometimes less so depending on revs. It goes warm to hot and so on.
The Mariner stops to a dribble then goes full on flow but cooler then slows heats up and back to a dribble, again depending on revs.
I has always been that way since I bought it new or should I say ex demo new.
I always assumed that was okay as I have never had any problem with it, when using it.
It does not get used in salt water (maybe once?) and is kept on a boat In the summer on a Trout Loch I fish.:g:
 
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