Yanmar 3GM Water Pump Dismantling

ctva

ctva

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Wee quick question to the knowledgable out there.

I am in the middle of dismantling a Johnson raw water pump off a Yanmar 3gm. Despite searching the net, I can not decide which way the spinal comes out. I think it comes out on the pulley side as that is where the circlip against the pulley bearing has been removed but I need to know if I am correct before applying too much BF&I. Also I assume it just comes straight out?

Even Viv's site is not 100% clear on this.

I'm sure that I've seen instructions on the dismantling but can not find them, if anyone has a link...

Many thanks

Chris
 
The basic pump is designed to be dismantled from the front (impeller) side but you will have to take the pulley off first. I'm not sure if it has both seals and bearings but either way, the shaft should pull free with a bit of umph.
 
There are full instructions and diagrams in the Yanmar GM/HM workshop manual, which you can download free from various places.
 
Thanks, got the shaft out now and need to remove the two bearings? How?

I love this seat of the pants engineering!!
 
Ideally use a three leg puller or cobble something together with large nuts, washers, sockets but make sure you keep them square on the shaft or they will stick. Same applies when putting new ones on.
 
Presumably you are replacing the bearings. The new ones will be an interference fit on the shaft. To fit them make sure you apply any force directly onto the inner race. Loading or tapping the outer race will cause damage which shortens the life of the bearing. This caution also applies to removal if the bearings are to be re-used.
 
Hi I have rebuilt my Yanmar Raw Water Pump last month.I replaced the Shaft, Bearings , and Seal.I used Stainless Steel Bearings and Stainless Circlips and a Double Lip Seal. I got the Bearings from R S Components much cheaper than Yanmar.
nash1
 
ghostlymoron said:
Ideally use a three leg puller or cobble something together with large nuts, washers, sockets but make sure you keep them square on the shaft or they will stick. Same applies when putting new ones on.
Click to expand...
All sorted and dismantled. In the end I used a 15mm deep socket over the end and used a bench vice to push it off. Really simple.

Good point, earlybird re the inner ring, I'll make sure I use a spacer to put the force on the inner ring.

Now to get the new bearings and seal which was knackered.

Thanks again one and all.
 
ctva said:
Thanks, got the shaft out now and need to remove the two bearings? How?

I love this seat of the pants engineering!!
Click to expand...
How did you do that? I put a screwdriver on the impellor end of the shaft and given it a few knocks with a lump hammer but doesn't move. Do i just keep thumping it?
 
I wouldn't use a screwdriver, it's too sharp and may damage the shaft. A hardwood dowel would be better. It shouldn't need excessive force. Alternatively press it out in a vice .
 
ghostlymoron said:
I wouldn't use a screwdriver, it's too sharp and may damage the shaft. A hardwood dowel would be better. It shouldn't need excessive force. Alternatively press it out in a vice .
Click to expand...
Thanks for response. I don't get how you use a piece if dowel. You have to press on the forked, impellor end, of the shaft. If you use something broad you stress the forks. And the forks will split any wood unless it is a big bit of hardwood, in which case very diffixult to line up square. If you use something thin, to go between the forks, it needs to be hard to take the strain. Catch 22 or more.
 
vyv_cox said:
Pressing it out is by far the better way to get the old one off and essential to install the new. Only press on the inner race to avoid damage
Click to expand...
I get that, but i don't have a press. But see my last response above. What do you press against the forked end of the shaft? Thanks for input.
 
Given the cost of a new water pump ( I think there’s a useable spare ‘offered’ on eBay right now for £250 odd) , I gently suggest to the NP that he ask a friend or a friendly mechanic to assist at this stage . Or take it, part dismantled, to a machine shop.
That will save considerably in the labour component thus far.??
Knocking out and replacing seals and bearings is straightforward enough given patience and assembling a vice ( press) and the right drifts , and some sort of mechanical aptitude /know how/show how, but shortcuts made in haste just create opportunity for further stress and damage .
IMO.
I think the new poster senses this?
 
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IanCC said:
How did you do that? I put a screwdriver on the impellor end of the shaft and given it a few knocks with a lump hammer but doesn't move. Do i just keep thumping it?
Click to expand...
If I recall, that is what I used the 15mm deep socket for. And yes, it is a push fit!
 
So drifted out the shaft ok. But getting out the metal external rim of the seal proved so difficult i knackered the little 4 legged plastic spacer thing.
 
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