Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - rattling crankshaft pulley


The belt pulley on the crankshaft of my MGA 1600 has started to rattle. Can one usually fix this by merely tightening the dog/nut or will I have to also replace the pulley itself?
And... what is the best way to loosen/tighten or remove this nut? Is there enough room to remove the nut as it is or must I lift the engine so it can clear the rack as it comes off? Must I also remove the radiator?
Any help will be greatly appreciated.
Thank you in advance!
John Hays
JH Hays

John, it's probably not loose on the crankshaft, but maybe the rivets are loose.
Depending how low your engine has sunk it could be difficult to access. It will likely be very hard to move, in my one experience of having to use a 3 ft extension with the motor on a stand. A good impact wrench should shift it. It is not a big thread, but the resistance comes from the large flat head. To get an impact on it I would think the rad has to come out.
Art Pearse

Yes the rivets do sometimes come loose. My crank pulley was already welded when I bought the car in 1977, and my generator pulley failed the same way after a few more years of driving.

The radiator has to come out for access. The fan and water pump may also aggravate you some. With a long enough wench you can prop the wrench against the left inner fender (right hand looking from front), and bump the electric starter momentarily to crank the engine and break the big bolt loose. Otherwise use a big wrench and hit it with a 2-pound hammer as an impact tool (anti-clockwise to loosen).
Barney Gaylord

You can do this from underneath the car - I just replaced mine two nights ago, so I am talking from very recent experience. Took me 35 minutes from start to finish. The rad does not need to come out unless you have very big hands that don't fit the tight spaces.

Use a socket with a 5" extension and you will clear the rad, and the oil cooler hoses if fitted. You are basically following the line the starter handle takes. The tricky bit is getting the socket into the dognut. If it is too tight to break the dognut loose, brace the end of the wrench against the floor and give the engine a 1 second blip on the starter.

You have to pass the pulley down from above, which makes a second pair of hands useful, but accessing the dognut itself is no problem. To ease off the pulley I just levered gently on alternate sides using a flat bladed screwdriver against the steering rack - it came off in a couple of minutes. I have to also say that I don't use the lock tab here, just loctite, same as everywhere else on the car where tabs were used originally

dominic clancy

Yes I have removed the front pulley the same way as Dominic describes.

The rivets on my front pulley were loose when I first got the car. Many early A Series pulleys were manufactured in the same way and suffered the same problem. I originally tightened my rivets up with a hammer and punch when I restored the car and it was fine for a couple of years. Then whilst one of our tours to France they became loose. I drove home with great care and worry but made it. I then repaired the pully with machine screws and nuts in place of the rivets. Perhaps I could have wired these fixings but I have been happy to simply loctite them.

Here is a couple of images

Robert (Bob) Midget Turbo

the otherside

Robert (Bob) Midget Turbo

It wont be the same but just in case it helps, a couple of weeks ago I replaced the crankshaft pulley on my frogeye (bugeye).
On that car the only way was to remove rad and jack up the engine to get access. The main problem was undoing the bolt. I tried the "turning the engine" trick without success. Bought a powerful impact wrench and it came off in seconds!
Graham M V

I recommend replacing with a MGB cast pulley.
No rivets to work loose!
Barry Gannon

Are there advantages to using an MGB crankshaft damper?
(Aside from the lack of rivets).
Russ Carnes

The biggest advantage would be when used with the MGB timing cover. Then the felt seal is history and a modern lip seal is used.
Not much use however for the concours brigade.
Robert (Bob) Midget Turbo

I thought the MGB crankshaft pulley helped the engine to run just a bit smoother at certain rpm's as a result of the rubber part in the pulley center...?

G Goeppner

I personally would not trust to screws and nuts. While I like Loctite, I just don't feel comfortable with that since the belt tends to spread the halves of the pulley. Did you torque the nuts, or just tighten them?
I have a bad pulley on an engine and am planning on welding it and sending out to be balanced.
Mike Parker

See this page. Moss doesn't have a pulley with damper, and the timing cover is NA.

I have a '57 MGA 1500. If I wanted to replace my cover and pulley with more modern ones (and so I can set the timing from the top), where would I get them?

AJ Mail

I followed AJ post to Moss the early B pully is sold as the A part 460-450 for both.
R J Brown

Yep you need to be careful Mike, not sure welding would be much better. I think fixing with capheads and nuts and then wired is as good as it can get, but I am no expert.

I did not get around to wiring with locking wire as I removed it after a few months when I found and MGB pulley and timing cover. It is now just something to look at in my garage
Robert (Bob) Midget Turbo

G and Russ The MGB Crankshaft pulley acts as a harmonic balancer it helps smooth out the inherent crankshaft vibrations when the cylinders fire. This does help the engine run smoother but also reduces resonance that can lead to crankshaft failure. From the large number of A's running around with riveted pulleys that dosen't seem to be too much of a problem. Elimanitng the chance of loose rivets and the lip seal alone make this a worthwhile improvement. Smoothing the engine a bonus. I had done this to my 1600 using a early 1800 B pulley with the timing marks in the orginal location. After laying on my back to check the timing for the umpteenth time I would go with the later B timing cover and balancer with the marks on top.
Charles O'Brien

sorry - reading more carefully, Moss does have a pulley with damper suitable for both...the instructions are even on line.

This will be a mod this winter, I think.

AJ Mail

This thread was discussed between 16/09/2011 and 24/09/2011

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.