12 vane water pump

[sujitroy]

A fellow Stag owner replaced his water pump and the gears sheared and destroyed his engine. He bought a 12 vane one from a local USA TR7 place. The head of the shaft looks different to all the 6 vane shafts I have. Is this a common 12 vane type? I removed the impeller off it for him. The shop he bought the pump off, stopped returning calls.
Sujit

[jbuckl]

What is the question ?

the shaft picture is of a press fit reproduction type from rimmers.

originals were splined.

the reproduction isn’t necessarily’wrong’ but also isn’t right either.

sorry to hear of the gear failure. It’s messy.

These reproduction pumps can be rebuilt…. But imho the press fit impellor needs a grub screw adding when rebuilt…. The press fit may not be as tight 2nd time around.

The shaft appears to be scrap though…. In any case.

[sujitroy]

yes. the press fit was something new to me.

[Stagintow]

IMG_2703 (1).jpg
One thing you may like to check is to see if the shaft has been hardened correctly but you need to do this before you put the pump in !!
you should not be able to cut or mark it with a small hack saw as per photo

[sujitroy]

Let's say the water pump shaft is not hardened at all, will the jack shaft gears still strip?

[flying farmer]

Let's say the water pump shaft is not hardened at all, will the jack shaft gears still strip?

Not necessarily, I had the pump gears strip their teeth on my 1st Stag.

The jackshaft teeth were still quite good, however the side load imposed on the jackshaft by the slipping teeth broke down the oil film and caused the front bearing of the jackshaft to weld itself to the block.

This caused the timing chain to snap and bent all the valves on the left cylinder bank. Total engine rebuild was required.

Neil

[Wheelz]

I had a water pump gear fail and it caused no damage other than the gears - the pump just stopped turning. Of course the engine did start to overheat but luckily I had an engine watchdog fitted which set off an alarm.

I replaced both pump and jackshaft with good used parts that had hopefully proven themselves fit for purpose.

[sujitroy]

This is my friends jack shaft. Since has wear on it could it be assumed the water pump was hardened somewhat?

[jbuckl]

Imho the failure can often be down to the torque to turn being too high.

Jackshaft bearing can be too worn too.

if it’s both , it’s worth considering the Ford external kit from stagdad. / Steve hill.

if the jack shaft bearing is still ok …. Just rebuild with new parts….. including the rhp bearing & oem pioneer Weston seal.

most other seals being offered are too high load when assembled.