Mercury 2.5hp 2 stroke impeller change

[MINESAPINT2]

I need to access/inspect the impeller on my Mercury 2 stroke outboard. 2.5hp Serial number OP225089 2003 Made in Belgium.

I understand generally on small outboards the impeller could be located either immediately behind the prop or further up the leg. I have included the serial number in the hope someone will be able to advise where it is located on this engine.

I have undone the 2 M6 bolts holding on the lower leg and it is loose but showing no signs of coming free. I do understand the drive shaft and perhaps water tube will have to part to allow the lower leg to come free. There is no rubber grommet or other access into the leg.

Advice much appreciated

Thanks

Mike

 

[Beneteau381]

I need to access/inspect the impeller on my Mercury 2 stroke outboard. 2.5hp Serial number OP225089 2003 Made in Belgium.

I understand generally on small outboards the impeller could be located either immediately behind the prop or further up the leg. I have included the serial number in the hope someone will be able to advise where it is located on this engine.

I have undone the 2 M6 bolts holding on the lower leg and it is loose but showing no signs of coming free. I do understand the drive shaft and perhaps water tube will have to part to allow the lower leg to come free. There is no rubber grommet or other access into the leg.

Advice much appreciated

Thanks

Mike

Just rebuilding an old one, the drive shaft is square both ends which a drive tube with squared ends which fits over them. Over this is a tube which pushes in to some seals, plus a 5mm tube which takes the water to the power head which also pushes in to a seal. They stick! In a worst case scenario the drive shaft corrodes in the squares and stick! Ask me how I know? I had to remove the drive pinion in the gearbox to get it apart, plus the water pipe and drive cover cracked. Go carefully but firmly twisting and pulling.

 

[VicS]

I need to access/inspect the impeller on my Mercury 2 stroke outboard. 2.5hp Serial number OP225089 2003 Made in Belgium.
I understand generally on small outboards the impeller could be located either immediately behind the prop or further up the leg. I have included the serial number in the hope someone will be able to advise where it is located on this engine.
I have undone the 2 M6 bolts holding on the lower leg and it is loose but showing no signs of coming free. I do understand the drive shaft and perhaps water tube will have to part to allow the lower leg to come free. There is no rubber grommet or other access into the leg.
Advice much appreciated
Thanks
Mike

Simple to find out Just look at the parts diagram

Stop trying to take the lower unit off!

There is no rubber plug because there is no gearshift rod to access

 

[coopec]

I need to access/inspect the impeller on my Mercury 2 stroke outboard. 2.5hp Serial number OP225089 2003 Made in Belgium.

I understand generally on small outboards the impeller could be located either immediately behind the prop or further up the leg. I have included the serial number in the hope someone will be able to advise where it is located on this engine.

I have undone the 2 M6 bolts holding on the lower leg and it is loose but showing no signs of coming free. I do understand the drive shaft and perhaps water tube will have to part to allow the lower leg to come free. There is no rubber grommet or other access into the leg.

Advice much appreciated

Thanks

Mike

Is this video clip any help?

 

[MINESAPINT2]

Simple to find out Just look at the parts diagram

Stop trying to take the lower unit off!

There is no rubber plug because there is no gearshift rod to access

Thanks for replies, much appreciated. So the impeller is behind the prop, Diagram very useful - thanks.

I do not have cooling water ejecting from the engine so guess as well as inspecting/replacing the impeller I will need to clean out the water pathways. Have run into another problem. There are 6 M6 bolts under the engine which should allow the disconnection of the engine from the leg. I have removed the 6 bolts and there is a little movement in the joint but again no sign of it coming apart to access the water pathways. More advice appreciated.

Off to my shed now to inspect the impeller - wish me luck.

Mike

 

[michael_w]

The pee hole often gets clogged, judicious poking with a bit of wire often does the trick.

 

[coopec]

Thanks for replies, much appreciated. So the impeller is behind the prop, Diagram very useful - thanks.

I do not have cooling water ejecting from the engine so guess as well as inspecting/replacing the impeller I will need to clean out the water pathways. Have run into another problem. There are 6 M6 bolts under the engine which should allow the disconnection of the engine from the leg. I have removed the 6 bolts and there is a little movement in the joint but again no sign of it coming apart to access the water pathways. More advice appreciated.

Off to my shed now to inspect the impeller - wish me luck.

Mike

The video explains how to dismantle it.

 

[MINESAPINT2]

Success. Had a look at the impeller and it is obviously in good order.

I had the cylinder head off yesterday and the water jacket was full of brown dust, completely dry which indicated no water has passed that way for some time. Would really like to clean the water pathways out if anyone could offer advice.

Thanks

Mike

 

[VicS]

Thanks for replies, much appreciated. So the impeller is behind the prop, Diagram very useful - thanks.

I do not have cooling water ejecting from the engine so guess as well as inspecting/replacing the impeller I will need to clean out the water pathways. Have run into another problem. There are 6 M6 bolts under the engine which should allow the disconnection of the engine from the leg. I have removed the 6 bolts and there is a little movement in the joint but again no sign of it coming apart to access the water pathways. More advice appreciated.

Off to my shed now to inspect the impeller - wish me luck.

Mike

RTM (Read the manual)

Boatinfo - Mercury Service Manual for 2,2-2,5-3,0-3,3 hp

 

[MINESAPINT2]

RTM (Read the manual)

Boatinfo - Mercury Service Manual for 2,2-2,5-3,0-3,3 hp

Thanks for the link. Before I posted this morning I had a good google for the manual but failed to find anything. We do struggle with internet speed here officially measured at 0.0 to 0.2 mb/s. Often results fail to load. Thanks again for your help.

Mike

 

[Malish]

The pee hole often gets clogged, judicious poking with a bit of wire often does the trick.

I'll add that in operation position the flexible pipe of the pee hole has a right angled bend in it, take the cowl off to straighten it out and use nothing thicker tha Monel locking wire to unblock the pipe at the inboard end.

 

[coveman]

Success. Had a look at the impeller and it is obviously in good order.

I had the cylinder head off yesterday and the water jacket was full of brown dust, completely dry which indicated no water has passed that way for some time. Would really like to clean the water pathways out if anyone could offer advice.

Thanks

Mike

Mike, Now you have the head off you should be able to clean the channels out with a small screwdriver. I had this problem on the same engine and even after cleaning the channels I couldn't get any water to run out of the pee hole ( I had already tried poking wire up it). The problem actually was the pipe from the impeller up to the cylinder head which was blocked. The lower leg should come off after extracting the two bolts - one short one and one longer. After blowing up the pipe with compressed air it cleared - very satisfying!

 

[[159032]]

The water passages are either side of the powerhead flange. Easy to clean out once the powerhead is off. two small holes from these galleries through to the cylinder head need cleaning out.

Use a smidgeon of silicone gasket to seal the joint again.

 

[coopec]

Thanks for the link. Before I posted this morning I had a good google for the manual but failed to find anything. We do struggle with internet speed here officially measured at 0.0 to 0.2 mb/s. Often results fail to load. Thanks again for your help.

Mike

Keep in mind there is a lot of "badge engineering" with the outboards. The Mercury, Mariner and Tohatsu 2.5hp outboards are exactly nthe same motor.

 

[Beneteau381]

The water passages are either side of the powerhead flange. Easy to clean out once the powerhead is off. two small holes from these galleries through to the cylinder head need cleaning out.

Use a smidgeon of silicone gasket to seal the joint again.

On mine that two bolt flange had disappeared, the seal had turned in to a burned mess and the mains were shagged because of it.. I made a new flange out of a piece of aluminium, all hand tools by the way, then git new seals and bearings from Simply Bearings, the bit where the shaft cover goes in to, I got some 22mm silcon hose and fixed it to the new seals

 

[[159032]]

Yes. You can see a snapped power head bolt on mine (top right). Easy enough to get out at this stage, but these motors run until they bust, so there is normally some collateral damage to repair.

 

[Beneteau381]

Yes. You can see a snapped power head bolt on mine (top right). Easy enough to get out at this stage, but these motors run until they bust, so there is normally some collateral damage to repair.

Just finishd the refurb, new mains, seals, drive shaft tube and gearbox bearings and seals, Total cost about £30. Jobs a good un!

 

[MINESAPINT2]

Thanks for all your advice. To gain access to the water channels at the top of the leg/underside of the power block I realised I just needed to undo the 6 bolts and pull the leg off, the drive and water tubes are just a push fit. Pulling manually was not working so I rigged up a Spanish Windless and it came off very easily. In fact with it being a 2 stroke the whole of the inside of the leg was very oily, no chance of anything seizing in there!. Cleaned everything out and water running freely now.

Mike