Common Problems with an MGB – 5 Key points to Consider when Buying your MGB
This is by no means a comprehensive MGB buying guide. We simply aim to point out some of the common known faults on MGB classic cars.
1 Listen to the engine
When the engine is idling, you should be able to hear rocker noise from the top of the engine. If you don’t, it is possible that the tappets have been over adjusted to compensate for excessive wear. If you hear a rumbling emanating from the bottom end of the engine, there is wear in the crankshaft/main bearings.
2 Look at the engine
Check to see if the oil is emulsified. If it is whitish, it means that there is water present and indicates at least a blown head gasket and at worst, a damaged cylinder head. The usual oil leak sites are the timing chain cover, tappet side covers, gearbox bell housing cover and the drain hole. Check the oil in the valve covers just after the engine has been running. If it is frothing, it indicates worn cylinder bores or valve guides. When the engine is started from cold, smoke on start up could indicate a failed oil seal on the valve gear. Not a massive problem but to repair it will need the head to be removed to repair it.
3 Waggle the steering and clutch
If there is more than about an inch of play in the clutch, it could mean that the master or slave cylinder is worn and will need replacing. similarly, more than about an inch of free play on the seteering wheel indicates wear somewhere in the system.
4 Drive the MGB
Don’t just enjoy the test drive! Make it work for you and focus on potential issues. Check that all the gears work smoothly, including the overdrive. You may hear a clunking sound as you engage the drive, that is OK. Come on and off the power at 30 mph – if there is a lot of clunking, then is means that there is excessive wear in the differential or halfshafts. Look at the oil pressure, it should be around 50psi when running in 4th on a warm engine. A much lower reading could indicate the presence of several faults, the worst of which is probably worn bearings.
5 Check the bodywork
The trailing edge of the boot lid are prone to rust as are the lower edges of the doors, rear wheel arch lips, sills and behind/below the bumpers. Check the cross member under the engine, it is usually well protected by oil drips but if it is unsound the front suspension could be compromised. The battery holder is also prone to corrosion so check that too. When checking for corrosion, check also to see if any repairs have already been made. Remember, this vehicle is a monocoque and relies on the body panels to give strength and rigidity.
Well, there you go. That is a starting point for you. Please don’t use this as a definitive guide to common faults of an MGB, it isn’t. This is for information and entertainment only and is not intended as technical advise so please don’t take it as such. When buying a used MGB, we strongly recommend that, unless you are an experienced and confident mechanic, at least purchase and study a buying guide or pay for an expert to come with you when you go to buy. OK, that will cost a bit but could save you from buying a pig in a poke.