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Old 23 August 2012, 07:30   #1
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Mariner 6 HP, 4 stroke, cooling problem

Brand new Engine 2011

My son have burned off the impeller by lifting the engine out of the water. I have now changed the impeller and cleaned the housing and the pipes with air.

It still wont cool. I am 100% sure that the impeller is correct mounted. I have tryed to put the lower leg in water and turned the drive shaft aksel with a smalle drilling machine. Water comes out of the top but when i mount the leg and start the engine, no water !!!!

Advice please

Cheers from Denmark
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Old 23 August 2012, 08:20   #2
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Sounds like your water pipe isn't connecting properly.
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Old 24 August 2012, 03:46   #3
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So the impeller is in the lower leg, driven by a drive shaft which comes from the power head?
If the drive shaft is free to turn in the lower leg, and the new impeller pumps water OK, then I'm guessing the drive gear in the power head is stripped.
If the impeller "melted off" as you say, it probably siezed/stalled the drive shaft and stripped the drive gears.
I would imagine the drive gear will be nylon and designed to fail if the impeller stalls, to avoid further damage. Or maybe there's a split pin like on the propeller.
So you'll have to dismantle the power head and have a look, fortunately it's not too big a job on that little 6hp engine.
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Old 24 August 2012, 06:49   #4
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As far as i know on the old motors, the driveshaft-crankshaft connector is make out of metal.
The impeller needs to be in water, in this case the water acts as lubricant too. if you lift it out of the water the impeller gets dragged along the metal sides of the pump at a few RPM, and it gets shredded.

Try removing the spark plug, putting the motor in gear, and turning the Prop manually, to see if the pistons move.

If that doesn't happen, maybe Lightning would be right.
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Old 26 August 2012, 14:41   #5
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So the impeller is in the lower leg, driven by a drive shaft which comes from the power head?
If the drive shaft is free to turn in the lower leg, and the new impeller pumps water OK, then I'm guessing the drive gear in the power head is stripped.
If the impeller "melted off" as you say, it probably siezed/stalled the drive shaft and stripped the drive gears.
I would imagine the drive gear will be nylon and designed to fail if the impeller stalls, to avoid further damage. Or maybe there's a split pin like on the propeller.
So you'll have to dismantle the power head and have a look, fortunately it's not too big a job on that little 6hp engine.
The impeller is driven off the main drive shaft and there are no nylon drive gears. The driveshaft splines go directly into the crankshaft.

I have had plenty of these engines apart, it can be quite difficult to get the water pipe, driveshaft and gearshift all lined up and in properly. Very frustrating some times. As Downhilldai says this is the most likely cause.

You say the impeller melted, are all the inlets and outlets of the water pump clear and not blocked with the remains of the old impeller? Remains of the old impeller could have been sucked up into the powerhead and may be restricting the passages.

There is a small metal keyway with the impeller, which is easily lost. did you make sure this went back in?
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Old 26 August 2012, 15:01   #6
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The impeller is driven off the main drive shaft and there are no nylon drive gears. The driveshaft splines go directly into the crankshaft.

I have had plenty of these engines apart, it can be quite difficult to get the water pipe, driveshaft and gearshift all lined up and in properly. Very frustrating some times. As Downhilldai says this is the most likely cause.

You say the impeller melted, are all the inlets and outlets of the water pump clear and not blocked with the remains of the old impeller? Remains of the old impeller could have been sucked up into the powerhead and may be restricting the passages.

There is a small metal keyway with the impeller, which is easily lost. did you make sure this went back in?
Thanks to all of you.

I still have the problem.

Today i tryed again. I disassembled the lower leg, check impeller, "keyway" was in. I testet again for parts blocking in the power head, i lignedet it all up and put it together, still same problem...

Cheers Thomas
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Old 26 August 2012, 15:10   #7
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Thanks to all of you.

I still have the problem.

Today i tryed again. I disassembled the lower leg, check impeller, "keyway" was in. I testet again for parts blocking in the power head, i lignedet it all up and put it together, still same problem...

Cheers Thomas
How long are you running the engine for?
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Old 26 August 2012, 15:18   #8
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How long are you running the engine for?
today longer than the other times. I think about 2 min. I saw gas and litle bit of water (very little) comming out of the drain

Cheers Thomas
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Old 26 August 2012, 17:12   #9
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today longer than the other times. I think about 2 min. I saw gas and litle bit of water (very little) comming out of the drain

Cheers Thomas
Are you shutting the engine down because it is hot or because the is no jet of water coming out the tell tale?

If its because there is no jet coming from the tell tale I would make sure this is clear with wire or a small drill.
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Old 26 August 2012, 18:01   #10
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Might be best to book it in for service and give someone else the headache : )
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