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MG Car Repair/MGB Waterpump - unable to remove


Hi, the water pump on my B broke and I've been trying to remove it to replace (found it to be in generally poor condition re corrosion. Got three of the four bolts out without problem (all rusted) but the last one wouldn't budge and bolt head sheared off - it's one of the longer bolts. I've managed to grind the broken end level with the pump 'bolt hole' hoping that the pump would then slide off - i.e. over the broken bolt shaft which I then hoped to remove from the hole on the engine block into which it is fitted. But the pump still won't budge as though the bolt hole is threaded or rusted up. The first three bolt holes didn't appear to be threaded although the removed bolts are threaded along their full length. So are any of the bolt holes through the water pump threaded or just the relevant holes on the block? Any ideas for removing it please? Photo attached. Thanks, Gary.

Hi Gary

The water pump on an MGB is held by 4 bolts.  Depending on the year, there may be two short bolts and two longer ones or 3 short and 1 long.  

All the bolts are threaded for the first inch or so. The remainder of the bolt (the shank) is plain.  The longer bolts have a longer shank.

You have sheared the head off one of the longer bolts.

Here is a diagram from the Moss website.  The bolts are part number 47.

It is quite common for the long bolts to rust solid in the water pump.  

Normally, I would advise you to hit the head of the bolt several times (at least 10 times) in the hope of breaking the rust before attempting to turn it.  Never mind, all is not lost.  

Your water pump is obviously beyond repair, so you will need to buy a new pump, complete with gasket.  I recommend that you also buy a set of new bolts.  

Carefully cut the body of the old water pump with an angle grinder to reveal the remains of the bolt.  Try not to damage what is left of the bolt.  The heat from the angle grinder may be enough to break the hold of the rust allowing you to completely remove the old pump.  

Next, squirt a good penetrating oil such as Plus Gas all over the joint between bolt and block, allowing at least half an hour for it to do its job.  I do NOT recommend WD40 for this operation.

With a stud remover or a Mole wrench you should now be able to undo and remove the remains of the bolt. If it still won't budge, it may help to apply some heat using a small blowtorch, or if you have a welder, then you could weld a nut onto the headless bolt.

Once the remains of the bolt is out, clean the block to remove all traces of the old gasket.

Finally, when fitting the new bolts, lubricate the shanks with a Copper Grease such as Coppaslip so they will not corrode in the future.

Good Luck.

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Barrie Jones


MG Sports Cars from 1949 to 1980 - Including MGB, MGBGT V8, TF1500, TF, TD and modern Midgets. I also specialise in SU carburettors, Lucas wiring, suspension, steering & brakes.


I have owned my 1955 TF1500 since 1966. Technical specialist for the TD and TF with the MG Car Club T Register. Also owned 20 MGBs and currently own an MGBGT V8. Written 3 books on MGs and produced a DVD on how to strip and rebuild the TD/TF gearbox.

MG Car Club.

Barrie's Notes on the 1953-55 MG TF (author). /=====/ Barrie's Notes on the MGB (author). /=====/ Barrie's Notes on the MGB GT V8 (author). /=====/ The Essential Buyer's Guide to the MG TD, TF and TF1500. (author)

M Phil, C Eng, BSc (Eng).

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