Water pump and top cover

[MikeParker]

I did not find a spec.
I suppose I’m suggesting 0.015 having done quite a few using that value, sucesfully.
Have designed a few
engine pumps installations .

The bolt head clearance isn’t really a target, just needs to be clear.
Just trying to help dave p.
Its possible that working on a Waterpump can cause pain…
trying to help avoid that.
when the vanes are close, the pump has better efficiency.

I agree completely that getting that clearance down is the secret. With my "problem" cover from MHP 653P, the running clearance was about 3mm initially and the car was very prone to over-heating. I reduced the clearance down to about 1mm and that made a huge difference. Perhaps I should go further, judging from your experience.

Mike

[dasadrew]

I'd be interested in a follow up to this thread too!

https://www.socforum.com/forum/forum/stag-owners-club/soc-forum/779011-some-musings-on-the-subject-of-an-electric-fan

[DaveP]

My pump cover to block was almost flush, 0.003 thou, so now with a 0.020 thou gasket I should have 0.017 clearance, I really hope it's not coming off again, my ears are heightened now to any little noise

[richardthestag]

My pump cover to block was almost flush, 0.003 thou, so now with a 0.020 thou gasket I should have 0.017 clearance, I really hope it's not coming off again, my ears are heightened now to any little noise

balls of steel

There is a lot of effort in getting access to the stag waterpump let alone making sure it is good.

I hope your endeavours are good sir

[DaveP]

my Home question is why are you changing the pump and cover

I have only ever worked with 6 vane pump and cover and not had an issue yet. Is the washer installed under the LH threaded bolt on top of the pump?

I took the manifold off as it was leaking and thought while under there I ought to look at the condition of the water pump. I bought new seals for the old one but wasn't sure the result was good. The top cover was eroded at the edges so as it's all a bit critical I thought I would replace both,

[MikeParker]

I'd be interested in a follow up to this thread too!

https://www.socforum.com/forum/forum...n-electric-fan

I must say I missed that thread at the time, but it does address exactly what I was asking. The standard method is to have a running clearance over the bolt of 0.25 to 0.5mm. But that is clearly less than the running clearance over the vanes. If not (i.e. the clearance over the vanes was the same as the running clearance over the bolt) the why go to all the trouble of having to tolerance two items. For the standard method to work, the bolt head must have a precise thickness, so must the protrusion in the casting on which it rests. Also the position of the impeller on the shaft and the height of the vanes. That is a lot of extra cost, where all you have to do is let the cover sit on the vanes and then add the 0.25-0.5mm gasket.

So, I would argue that the running clearance over the vanes is designed to be greater than that over the bolt. So the clearance should be greater than 0.25 to 0.5mm. The clearance is important as it allows for the tolerances above plus the lack of centering of the cover on the axis of the impeller. A number of tolerances there also. The consequence of getting it wrong is the pump grounding on the cover - not good.

It needs someone with some original pumps and covers to measure what the "extra" clearance is. That is the clearance over the vanes with the bolt resting on the cover. It would be interesting to know how good Leyland were in the day in maintaining that tolerance across their production. My original "good" pump/cover from RVW412M was about 0.6mm and the bad pump/cover from MHP 653P was around 2.5mm.

Mike