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Joined: Jul 12 2016
Posts: 772

Anyone know how the pumps are assembled/disassembled?

Wondering what mine looks like inside and if it can be rebuilt cheaply as a spare. The bearings and impeller look and feel absolutely fine so hopefully it's just a seal that needs replacing.

At a guess the wheel the pulley bolts to is pressed or threaded on to the shaft which holds everything else in?

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Joined: Dec 30 2015
Posts: 3208

I think they are pressed in although I've never tried to take one apart, or not a P38 one anyway. I have on a different car where it was found that the bearing, seal and shaft was identical to those from a different car where a rebuild kit was available for one but not the other.

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Joined: Sep 14 2016
Posts: 325

Yup, normally pressed up together, maybe on splines.

New seal probably in the £10 to £20 retail range if it can be got at all. Motorcycle ones are commonly found as spare parts but car ones will take bit more finding. I imagine suppliers are geared to the hundreds and thousands a month trade sale market not individuals.

Hafta change the outer seal too to keep crap out of the bearing. You'd need to be very sure of bearing condition too if you were going to re-use it. The serpentine belt puts hefty side load on it.

Doesn't seem economic when £40 - £60 gets a half decent new unit good for 50,000 + miles. After all changing a pump you put on yourself is only a couple of hours work if you have the tools and took the time to do the extra stuff to make it easy next time round. DIY reconditioning water pumps is another job life has got too short for.

Clive

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Joined: Jul 12 2016
Posts: 772

It might not go anywhere but I was just curious about it. Figured I'd take a stab at it simply as I have the old pump and I don't need to return it for a surcharge anywhere.

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Joined: Dec 30 2015
Posts: 3208

I threw 3 or 4 away when I moved house but all of those had slop in the bearing which had caused them to start leaking. Then there was the one where the bearing exploded on me so the seals are of lesser importance. If it starts to leak chances are it is because of slack in the bearing.

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Joined: Feb 02 2018
Posts: 196

My metal bladed pump cost around £30. Is the problem that the wrong type of bearings are fitted in them? I can't remember what type but I read that side load thrust should be one type of bearing (roller or taper - I'm not an expert on this) and these water pumps have ball bearings which are not good for side loading from the serpentine belts. I'm not a mechanical engineer so it's all hearsay for me.
However I have had a plastic bladed water pump and all it's ball bearings explode on me hahaha

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Joined: Dec 30 2015
Posts: 1340

I'd have thought that side loading isn't unusual for a bearing (although roller bearings should last longer). Taper bearings would be for end loading, no?

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Joined: Feb 02 2018
Posts: 196

I don't know mate, to be honest I didn't realise that different bearings were for different things, I just thought it was the usual manufacturers playing lets use 30 types of nuts and bolts, 7 types of screw and hex heads, allen bolts etc. To be honest I'd never really thought about it
I live and learn :-)

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Joined: Sep 14 2016
Posts: 325

Almost certainly deep groove ball bearings.

OT techie stuff.

Deep groove bearings are the most common type because they can carry considerable axial, side to side load, as well as the main radial load. See https://www.astbearings.com/single-row-deep-groove.html . Symmetrical so they don't care which way they are mounted.

If you need to carry more axial, end, load you use angular contact bearings which have asymmetrical races with much more contact area on one side than on the other. See https://www.astbearings.com/angular-contact-ball-bearings.html and http://www.skf.com/uk/products/bearings-units-housings/ball-bearings/angular-contact-ball-bearings/index.html which has a useful picture. If you push them the wrong way they can pop apart. Some types easier than others. Generally used in preloaded pairs. Often opposed to take loads in both directions but sometimes both same way round if the main load is in one direction and other arrangements can be made to stop them pulling apart. Usually expensive, especially machine tool spindle types which usually come in matched pairs ground for specific spacings.

Taper rollers take pretty much equal loads in both directions but have to be used in precisely spaced pairs, which can in practice be much harder to arrange reliably than you'd think at first sight.

Thrust bearings just hold stuff apart with negligible control of wobble.

Clive