4 hp maranier over heating

[tichmarshjohn]

Hi all
I have a 4 hp Mariner on my tender which starts on the second or third pull & runs ok for about 15 mins . It seems to build up heat smokes then stops,water pumps out of the tell tail ok.Could it be a blockage in the water jacket, in the engine .Maybe a salt blockage.I got the engine used of ebay just run it up in a tub for ten mins it seemed ok.Bad move .Any way to flush it through any advise would be appreciated

 

[[2068]]

Most likely to be the water pump that is blocked. Flushing rarely works unless you already have some water flow.

If you release the gear shift arm, drop off the lower unit, you should be able to clean out the pump. It's a good idea to change the impellor whilst it's apart.

 

[Dabhand]

Probably also worth checking the thermostat is opening and closing correctly and is not clogged with debris. Easy to check the thermostat using a saucepan of water on the hob.

 

[dpb]

Probably also worth checking the thermostat is opening and closing correctly and is not clogged with debris. Easy to check the thermostat using a saucepan of water on the hob.

+1

Mine had corroded solid.

When I found how much the stat was I left it out, didn't seem to make any difference really!

 

[tichmarshjohn]

Hi can you explaine where the stat is please

 

[VicS]

Hi can you explaine where the stat is please

You dont give any info about your engine.

2 stroke or 4 stroke ?
serial number ?

4 strokes have a thermostat under a cover on top of the head

Younger 2 strokes dont have a thermostat . Older ones do but you have to remove the exhaust cover to access it.

Get the serial number and then look at http://www.boats.net/parts/search/Merc2/Mariner/parts.html

 

[tichmarshjohn]

Hi my engine is a two stroke 4 hp mariner i can not find a thermostat

 

[Hadenough]

Hi all
I have a 4 hp Mariner on my tender which starts on the second or third pull & runs ok for about 15 mins . It seems to build up heat smokes then stops,water pumps out of the tell tail ok.Could it be a blockage in the water jacket, in the engine .Maybe a salt blockage.I got the engine used of ebay just run it up in a tub for ten mins it seemed ok.Bad move .Any way to flush it through any advise would be appreciated

Had the same problem with my 3.2 hp mariner 2 stroke. Was pumping water ok but over heating. Ended up taking the head off and clearing the waterjacket around the cylinder block. The waterways were blocked with a thick waxy gunge which I realised was being picked up from the club flushing tank that had not been cleaned out for years. It has now!