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MG MGA - Engine coolant leak

Looking for suggestions. After a recent drive of approximately 30 minutes and returning home I noticed antifreeze leaking. There was no sign of any leak before when driving the car. After further investigation it appears to be coming from around the bottom bolt on the water pump. Not sure if this would be a water pump replacement or a different issue. Any ideas?
Thanks for any help.
Kevin Brunke


It could be leaking from a number of places. Optimistically, it could be from the end of one of the rubber pipes and just needs the jubilee clip tightening. I have found that one of the problems when chasing this type of leak is that the draught from the fan blades can 'move' the leak.

Most of us have been there. I guess that an extra turn of the screw driver on all the pipe clips and a spanner on the bolt heads is a reasonable first step. Then monitor. It seems only a small leak if it is only happening under pressure.

Steve Gyles

Thanks Steve. I checked all hose clamps for tightness and all are tight. Checked the tightness of the bolts for the water pump and they are tight. I then started the car again and waited a few minutes and watched to see where the leak was coming from again. It appears to be weeping from a small opening or hole on the bottom of the water pump. I turned the car off and it kept weeping out about a drop every couple of seconds. Any thoughts?
Kevin Brunke

Kevin, sounds like water pump bearing seal, in which case you will usually have some up and down movement on the pump shaft (due to water contamination of the bearing), or cracked pump housing, especially if the pump housing is the later aluminium type. Either way, I think you need a new water pump.
Lindsay Sampford

Hi Kevin, I think Lindsay is right - almost certainly the water pump - especially as you have done as Steve suggested and tightened everything else - it's very common for this to happen , the pump tends to only last about 20k miles - at least mine do. Luckily it's a relatively cheap repair and it also gives you a chance to replace the hoses and reverse flush the radiator too whilst it is out of the car.
Cam Cunningham

The water is coming out of the drain hole, see image attached.
This is because of a leaking impeller seal, not the bearing seal. The impeller seal is to the left of the drain hole in the image.


M F Anderson

Thanks everyone for your help. I will order a new pump today. Does anyone know the torque specs. for the bolts of the water pump as the manual does not list any.
Thanks again.
Kevin Brunke

Kevin, the mga w/shop manual gives the torque for the water pump bolts at 25ft/lbs, (see General data 3). The mgb manual gives this torque setting at 17fl/lbs. I personally would not go as far as 25 but would tighten the bolts to 20ft/lbs.

F Camilleri

Thanks for that insight Mick. I must admit I have never looked closely at a pump cross section before. Whenever I have had a leaking pump it usually has had play in the bearings as well, so I had always assumed that the water had caused the bearings to fail. From the diagram it is obvious that water shouldn't ever reach the bearings because of the drain hole, so either worn bearings caused the impeller seal to fail, or all the parts had failed because they were just generally worn out on my pumps.
Lindsay Sampford

Looking at that cross section it appears that the impeller and flange may be threaded onto the shaft. I always thought they were a press fit. Has anyone successfully disassembled one of these? I have a nice cast iron spare I'd like to rebuild. Although, the new cast iron pumps from SF are cheap enough and seem well made.
G T Foster

This thread was discussed between 10/08/2010 and 12/08/2010

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