Intermittent Metallic Screaming Noise clutch/gearbox?

[288NNM]

Hi all,
After going out for a 20 minute drive in my 1964 2 door minor. Then helping to prepare to remove a gearbox from my sons modern car I pass the spanners then said my goodbyes. Was literally 40 yards down the road there came a horrible metal on metal noise similar to a band saw cutting through metal. Lasted about 4-5 seconds then went. On my 6 mile journey this noise reappeared around half a dozen times lasting from 5 to 15 seconds then disappearing. Dipping the clutch seemed to be related to the noise sort of? Also the revs of the engine in any one gear might have some influence. ( maybe load on the gearbox?) Not saying it is gearbox related but it sounded awful like something was being damaged somewhere on my treasured guilty pleasure. Come on you Morris Minor technical whizzes any ideas as I do not wish to bugger up a gearbox or be culpable to much more complex and expensive failures.
I have had a quick look and there are a wide range of possible issues, its never done it before and thankfully I did get back home. It drove ok apart from this horrible intermittent metallic scream!

Cheers,

Paul

[martin418]

clutch release bearing carbon worn down to metal sounds likely

[King Kenny]

Have you got disk brakes? Twice I have had a similar horrible metallic (expensive) sound and it turned out to be a small piece of gravel stick between the disk and the brake pad.

[don58van]

Slipping fan belt?

Don

[288NNM]

Carbon release bearing sounds possible, I’ll check the fan belt for tension first and adjust if necessary. That’s the quickest cheapest solution if it’s works. The old boy who had the car before me had the dynamo swopped out for an alternator. No disk breaks fitted just the life affirming push as hard as you can with that powerful right leg and drive like your a vicar who’s in no rush braking system.
It did sound very much metal on metal worryingly! Cheers for the feedback I’ll let you know how it goes.
Paul

[philthehill]

Whilst you have the fan belt slack/off check the condition of the crankshaft pulley - If it is a multi-piece pully they have a habit of coming apart.

[oliver90owner]

Slipping fan belt?

Don

I thought that might be a possibility but thought better of possibly offending the poster as he insists it is a ‘metallic’ screaming sound. Rubber on metal is definitely a different sound!

[RobThomas]

Are the rubber boots on the gearbox good? Could a stone have entered the gearbox bellhousing?

[simmitc]

Fan belt very likely, but when the sound appeared, did you notice any difference in road speed vs engine speed? If yes, then it could be a slipping clutch.

[Trickydicky]

Could be a bearing in the alternator?

[RobThomas]

remove the fan belt and go for a very short drive to see if the noise has gone?

[288NNM]

Once again thanks chaps for all the theories and advice I will get onto it as soon as is possible. I do love just tickling about in it and this noise definitely needs further investigation before I go anywhere in it.
* Definately no rise in engine revs when the noise kicked in.
** Did seem to occur when revs hit a certain level in the lower gears. ( I kept it down to 45mph in 4th as was worried what might happen if I hit noise bleeding 50+mph) Again further investigation may help.
*** Sounded very much like metal on metal but did disappear ( for now! ) after 5-10 seconds. Didn’t sound healthy at all.
**** Depressing the clutch did have some effect again more investigation required.
Finally I will check the pulley with the fan belt not in tension. The engine is tired original 148,000 miles with only a decoke and Mini tappets replaced. Timing chain noisey but got my son’s bride to the wedding with time to spare in December 2018.

[RobThomas]

Nice photo!

The idea of removing the fan belt is just to ensure the waterpump and dynamo aren't the cause, assuming the noise continues afterwards.

Could also be the cowl part at the front of the propshaft, couldn't it? They have been known to come loose and could touch the steel seal on the back of the gearbox. Wild guess. Previous suggestions sound more plausible.

[TDV102]

7/2 on for the clutch release bearing

[288NNM]

Well folks,
I have truly got egg on my face. It turns out the fan belt tension theory was correct. Started it up on Saturday and immediately an awful screeching noise came from what I considered to be the front of the engine the belt had about an inch and a quarter of play between alternator and crank pulley. Was a bit of a fiddle getting the old fan belt off. Checked the pulleys and not an excessive amount of play but some. New belt installed as old one was a bit tired and smoother. Still good as a get me home spare. Alternator was installed by the old boy who I bought the car off. He’d done a great Heath Robinson job on connecting one of the tension bolts and the retensioning of the alternator
Once again can I say massive

[oliver90owner]

Glad it is sorted. One must remember that an alternator will charge at a high rate at relatively low speed, compared to a dynamo. If the belt is worn or wrongly tensioned it will lose grip under heavy load. Another problem may be a battery that is losing its charge (ie close to the end of its life) - sufficient to start at the present time but getting low on voltage under load.