Problem with water pump Volvo MD11C

[CAPTAIN FANTASTIC]

I opened the pump cover to inspect the impeller, the impeller looked good so I lubricated and pushed it back to the shaft properly, and before I put the cover on I just turned the engine a bit to make sure that the pump rotated; I then put the cover back with a new gasket and screwed into position. However, now it does not pump any water anymore. Prior to opening the cover for inspection, the pump was working well.

The water cock is on , water goes through the pump when the cover is off but when I put the cover back and turn the engine on, no water is pumped through. I took the pipe off at the thermostat to see if water reaches the thermostat, but no water. I took the impeller out again, checked everything and put it back, still no water. Any ideas please?

 

[bedouin]

Isn't the impeller held onto the shaft with a Grub Screw - it is on my MD11B.

 

[earlybird]

Is it possible that the impeller is slipping on the shaft?
The cover plate will be a close fit on the impeller, and if the new gasket is thinner than the old one, the friction on the impeller will be increased, causing unseen slippage. Try rotating the impeller with a pair of long-nosed pliers, or a thicker, cardboard gasket.
A bit of a long shot perhaps!

 

[VicS]

Isn't the impeller held onto the shaft with a Grub Screw - it is on my MD11B.

MD11B ? Do you mean MD2B ?

I opened the pump cover to inspect the impeller, the impeller looked good so I lubricated and pushed it back to the shaft properly, and before I put the cover on I just turned the engine a bit to make sure that the pump rotated; I then put the cover back with a new gasket and screwed into position. However, now it does not pump any water anymore. Prior to opening the cover for inspection, the pump was working well.

The water cock is on , water goes through the pump when the cover is off but when I put the cover back and turn the engine on, no water is pumped through. I took the pipe off at the thermostat to see if water reaches the thermostat, but no water. I took the impeller out again, checked everything and put it back, still no water. Any ideas please?

My recollection of the MD11C water pump is that there is a pin/ screw right through the impeller that engages with a slot in the end of the shaft but there may be different pumps that could be fitted fitted. The parts diagrams show three ( although two look pretty much the same) for the MD11 and MD17 series.

The workshop manual on http://www.bluemoment.com/downloads.html show the drive pin/screw passing through a hole in the shaft on some and through a slot in others.

If your pump has an impeller driven by a key check that the key is in place and that the rubber part of the impeller has not become detached from its "hub" allowing the hub to turn without turning the rest of the impeller.

Good idea to install with the vanes bent backwards but they do sort them selves out quickly if not.

used the right gasket ?


Blocked pipe/hose ? Checked at the Tee piece under the manifold ?

 

[CAPTAIN FANTASTIC]

Thanks for the information and tips. I found the fault; although the impeller looked in good condition, the actual rubber was rotating slowly on its own bush. it looks like the impeller was failing and the inspection and relocation finished the impeller off. Luckily, I had two spare impellers. Thanks again.