Honda Impeller Replacement

[1066]

I know that this has probably come up before, but me old-timers is kicking in and I can't find it.

 

I have an old - guesstimate 1975 ish - Honda BF75 7.5 hp outboard ... (it's blue and white) ..., and since the boat is out of the water at the moment, I would like to replace the impeller. I know that there are two types, and to be on the safe side I bought both of them. The question now is, how do I replace it?

 

To get at the water pump, can I just drop the gearbox, or do I have to drop the whole of the lower leg ..... or is there a simpler way?

[bottle]

Have a look here, there is PDF downloadable manual

 

http://www.honda-marine.com/owners/OwnerMa...delGroup=BF75hp

[1066]

Thanks, Keith ..... I do have that, but unfortunately it is only a general "how to change the oil" type guide.

 

I suppose the real answer is to buy the proper workshop manual.

 

Confuscious, he say ...... "Man who have boat never die rich!"

Edited August 15, 2008 by 1066

[bottle]

Hi Les

 

Must admit I did just google, didn't read it.

[gazza]

here is how yamaha do it : -

 

unscrew gear link rod - located at front of leg.

 

remove gearbox bolts. gentle tap to seperate from leg. withdraw 'box from the leg, being careful not to clout the splines of the drive shaft as you withdraw it from the power head

 

clean drive shaft - mine had a good build up of crud and needed a gentle emery to make sure the impeller came of without a hitch

 

remove 4 impeller housing bolts.

 

carefully remove impeller - it needs drawing off of drive shaft

 

replace impeller, gaskets etc as needed.

 

re-assemble is reverse of dismantle.........

 

its dead easy with a little mechanical knowledge - i am a maintenance engineer so find most task not too difficult. i am sure the honda will be slightly different, but the way it works will be identical - the impeller has to be on the drive shaft which comes from the power head to turn the prop. think logicaly and you will no doubt get it sorted

Edited August 15, 2008 by gazza

[1066]

....... its dead easy with a little mechanical knowledge ....

 

Cheers, Gazza ...... if only I shared your confidence!

[Alan Jones]

From a Honda Mechanic:

 

Under the hood at the crankcase end (front) you will see hopefully a square box with wires (voltage regulator for charge coil if equipped) and to the right of this there should be a rod and arm attached to your gear change lever, put it in forward gear and it should raise the arm - you need to remove the pin through this to disengage the gear change rod. (pin is secured by a split pin in the end)

 

Once done undo the five bolts under the anti cavitation plate that hold the gear unit to the leg. Drop the gear unit off, and on top you will see the impeller housing with the driveshaft sticking out (or more likely the drive shaft will be stuck to the engine and still in the leg). Undo 4x 10mm head bolts, pull the impeller cover off and remove the impeller from the pinion shaft - don't pull the shaft out or you'll be needing to dismantle the gearbox to put it back in! There is a metal plate under the impeller with gaskets either side. it;s worth replacing these and seeing how blokced up it is beneath the plate at this stage.

 

Putting back together is the reverse, but as your putting the impeller cover back on turn the shaft (with the impeller on) clockwise and lower the hosuing onto it, cover it in grease to help as well.

 

Hope that helps - it's a damned fiddly process so it may be worth getting an expert to help, should only take an hour max. (much less if all is well)

 

Alan

[1066]

Thanks, Alan.

 

I did the job this morning, and it went pretty much exactly as you describe, except I had to pull the pinion shaft out of the gearbox complete with impeller, because the latter didn't want to come off - the shaft went back in OK, though .... I think!?

 

The acid test will come next Sunday when it goes back into the water. I'll either go back to the moorings under power, or get the oars out!

[Greg_F]

If you want more power out of your outboard I believe there is a screw in the carb that limits throttle travel, once removed you should have the power of a 10hp model.