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MG MG Y Type - Water pump problem

Since replacing an original type water pump with a currently available remanufactured version, I have a re-occuring problem with the self-locking nut(nyloc nut) that holds the fan belt pulley and fan to the water pump shaft.
The fact is that the nut keeps undoing itself and the danger is that if this goes unnoticed, the pulley and fan could dislodge and grind itself through the radiator(expensive)together with other collateral damage.
The OEM pumps had a slot nut and split pin(cotter pin) so that it could not unscrew itself.
Is this problem peculiar to me and my pump or is this a universal problem?

I propose to drill the shaft and use a slot nut and split pin to cure the problem. I just hope that as it has been running loose it has not damaged the keyway in the pulley.
Any thoughts or advice appreciated.
Keith
Keith D Herkes

Hi Keith

I know you shouldnt have to with a nyloc nut, but have you put a shakeproof washer below the nyloc nut at both ends? Also, have you followed the advise in the Hint and Tip of Engine Tie Bar and Water Pump Damage?

Check the fabricated bracket for damage/splitting and also replace the cup washers and rubber washers at both ends, and ensure that there is no movement in the engine by properly tightening the opposing central lock nut. This bracket arrangement, and that of the fabricated bracket on the inner wing, are effectively an engine support bracket and get a severe hammering from engine vibration.

The Worksop manual covers the fitting of this steady arm and the tip can be found on the Hints and Tips section of www.mgytypes.org.

Paul
Paul Barrow

Keith check that the nylon insert is still there. If you cannot get a new nut [they should be changed every time it is removed] try squeezing the chamber slightly either in a large vice or hitting it with a 1lb hammer with the nut on its back. [not to hard mind you] this will compress the insert a little. The pulley could also be a bit sloppy on the shaft.
B Mellem

Bryan has got me thinking there too and maybe to threads are stretched on the bolt too over the years so there is not a good bind which can lead to slackening too - just a maybe.

If so, new ones are available from Moss/NTG/Abingdon Spares LLC etc.

Paul
Paul Barrow

Keith,
If you can get a new nyloc nut to suit the thread on the shaft I'd start with that - make sure you get a nyloc to suit the install (thread & temperature), not just any grade. The engine block/pump can get rather warm at times.

XPAG water pump pulleys/fan blades are often way out of balance, so this is probably the source of your vibration, but a quality nyloc should not unwind. Check the nut is bearing down on the pulley and not the key or shoulder on the shaft - you may need a thicker washer under the nut.

There are other types of locknut that you could try other than nyloc if the problem persists after inspection all is seated properly.

Check your fan blades - they can be fitted the wrong way which can contribute to vibration issues too.

The alignment of the three pulleys - crank/generator/pump is also important for smooth running. Adjust your belt with a bit more slack than you would like - it is a heavy section belt, so it not designed to be run tight - your pulley bearings will thank you !.
A L SLATTERY

Thank you all for the advice and comments. I haven't stripped it out yet, but I clearly remember that there was no washer either under the Nyloc or inside the pulley where the felt oil seal and retainer used to go on OEM pumps. I am pretty confident that if I refit it with these items, then hopefully it will be OK. I shall report back in due course. I agree with Peter Cornelius that pattern parts are not to the same spec as the originals! Once again the worldwide Y Type "team" shows its muscles- great!
Keith
Keith D Herkes

This thread was discussed between 23/05/2011 and 24/05/2011

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