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MG MGB Technical - Engine making clicking sound

Hi everyone

I have a strange clicking tinkling sound coming from my mgb engine, after having had it tuned on a rolling road, at about 2500 rpm, which disappears under acceleration. I have been told by a classic car restorer that it is not mains, big ends or piston slap, but rather is in the valve train. He then took 995 off of me to change the rocker shaft and camchain and tensioner, but no change in the sound. He now thinks that it may be worn valve guides - and it does burn a bit of oil on the overrun. He isn't getting another penny however! Any ideas from you clever folk as to what it might be?

Regards and thanks
r j symons

Worn fan grommets can make a - possibly - tinkling sound. Run it with the fan belt off and see what happens.

I've never heard of worn valve guides making a noise - smoke after a period on the overrun or idling yes. However if you get smoke *during* the overrun, then something is quite badly worn. Possibly also rings/bores, so do wet and dry compression tests as well.

Use a listening stick (long screwdriver) on the valve gear.

Diagnose, diagnose, diagnose before spending money. Especially with him ...

Hi Rich, if you come down and say hello one day we would have a listen for you. I wasn't aware of any noises when you were on the dyno? You should have come back if you were worried you are always welcome. I can't see how it came to 995 to do r/shaft chain and tensioner.
Paul is spot on with worn grommets on the water pump pulley, they can be very clattery.
Another favourite is the spacers rattling in the K&N filters or even the heat shield vibrating or touching bodywork.
Test filter spacers with engine off and thunp top of filter plate with hand, usually, if loose you will hear a rattling sound.

Peter Burgess Tuning

Hi guys

Many thanks for your replies. Paul - I will have a look at those grommets when I get a minute, and many thanks for your advice! And Peter, nice to hear from you again - I will certainly pop down sometime to take advantage of your ears! It started to tinkle on the way back from the dyno session (nothing to do with you, I know!) and has got worse since. Still pulls well though. I have had to reconnect the engine breather to the carb stubs as the smell of hot oil vapour was a little too strong in the cabin for me! And no, I couldn't see how rocker shaft and camchain and tensioner would cost that much money either - never again!

Regards guys
r j symons

Also have a tinckle at idle that goes as the revs rise, had a quick look last night after been out for a couple of hours and the carb overflow pipes are touching the back of the air filters. Need to have a look again and either shorten the flexi hose that connects the float chamber to the overflow pipe or fit some split hose to the pipe to prevent it touching.

Regards Rob
R Dickinson

The overflow pipes can be close to the backs of the filters. The end of mine are virtually touching the carb ports, which gives a 1/4" or so gap between the bend and the filter base. If yours are closer than that you can probably cut a bit off the end of the pipe as well as shortening the hose to allow the two ends to almost touch.

Cheers Paul all done and sorted this morning another job fixed

R Dickinson

hi rich,
i had a simular noise from my b once. changed all the things you are talking about but still did not solve the problem.mine used to make a rattling noise as you changed up in every gear. did not find out what it was until i rebuilt another engine and put it in the car then stripped old one to have a look. the top piston ring on every piston was broke. don't know how or why but thats what it was ,.wasnt burning any oil.
regards bob.
bob taylor

To be honest Bob the rings usually break when you remove the pistons from the engine because of the wear lips at the top of the bore.
Peter Burgess Tuning

This thread was discussed between 15/09/2016 and 17/09/2016

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