High-Pitched, Grinding Engine Noise

[cliffpeters]

Hi, I'm back in the UK for a week, and, of course when it's great weather, I'm having a problem. I've got a grinding, high-pitched noise coming from the engine. It occurred for the first time yesterday when the engine was warm. I parked the car and let it cool off and then drove it again and it didn't reoccur until after an hour's driving, but then it got worse before I could get it home. I can't really tell where it's coming from, but perhaps it is the back of the engine. It occurs even at idle with the gearbox in neutral but it isn't constant. It occasionally goes away for some moments without any obvious cause, such as engaging the clutch, shifting gears or changing throttle conditions. It sounds too high-pitched to be the bottom end. I thought it might be something like the oil pump, but there is no loss of oil pressure, no more than the usual oil burning and no change to the engine temperature, and the car's performance isn't at all diminished. I thought it could perhaps be a con rod bearing, but wouldn't that cause more of a knock? One thing that might or might not be related is that the car recently had a Bosch fuel pump fitted after the Lucas one bit the dust (stranding me on my last visit to the UK!). Any ideas from you experts?

 

Thanks!

Cliff Peters

Witley, Surrey

1971 TR6 PI

[Tony Millward]

Hi Cliff,

 

I'm certainly no expert but would hazard a guess that it sounds like your clutch thrust bearing. The fact that the noise goes away when you depress the clutch could be an indication. As it also comes and goes depending on throttle could also indicate slight movement of the crank (worn thrust bearings), it may be that it is touching and then not touching the clutch plate. I'm sure someone will be along and point you in the correct direction soon.

 

cheers

 

Tony

[foster461]

Hi Cliff,

 

I'm certainly no expert but would hazard a guess that it sounds like your clutch thrust bearing. The fact that the noise goes away when you depress the clutch could be an indication. As it also comes and goes depending on throttle could also indicate slight movement of the crank (worn thrust bearings), it may be that it is touching and then not touching the clutch plate. I'm sure someone will be along and point you in the correct direction soon.

 

cheers

 

Tony

 

I'm with Tony, sounds symptomatic of a failing clutch release bearing. You can often change the pitch or make it worse or go away by gently pressing the clutch pedal, not enough to move the clutch plate or push the crank forward but just enough to make contact with the fingers in the clutch cover. If you disconnect the slave rod from the lever on the gearbox you can mess with the bearing position by moving the lever by hand (push the end of the lever towards the rad) and get the bearing away from the clutch so that the bearing is not spinning and if that alters the sound (ie stops it) I would say you have your smoking gun.

 

Stan

[cliffpeters]

Thanks both of you. I may not have described it well. Depressing the clutch does not change the noise. It seems to come and go on its own but if it stops it's only a brief respite.

 

Cliff

 

I'm with Tony, sounds symptomatic of a failing clutch release bearing. You can often change the pitch or make it worse or go away by gently pressing the clutch pedal, not enough to move the clutch plate or push the crank forward but just enough to make contact with the fingers in the clutch cover. If you disconnect the slave rod from the lever on the gearbox you can mess with the bearing position by moving the lever by hand (push the end of the lever towards the rad) and get the bearing away from the clutch so that the bearing is not spinning and if that alters the sound (ie stops it) I would say you have your smoking gun.

 

Stan

[RogerH]

Hi Cliff,

I'm with Tony and Stan on this one. grinding sounds often come from rotating bits - big ends and small, although they do roatate, have the most common sympton

of knocking. If the grindng is from the rear of the engine then thrust washers, clutch bearing, clutch pressure plate fingers etc.

If it come from the front of the engine then we have water pumps, alternator, oil pump (but they are usually well lubricated!!!) dizzy drive shaft etc.

Remove the fan belt momentarily to eliminate/prove the water pump and Alternator.

 

Have you used the screw driver/stethoscope trick to try and localise it.

 

I still fancy the clutch end.

 

Best of luck

Roger

[foster461]

Thanks both of you. I may not have described it well. Depressing the clutch does not change the noise. It seems to come and go on its own but if it stops it's only a brief respite.

 

Cliff

 

Cliff, this may be a case of eliminating one potential cause after another but since there is a bit of pre-load on the release bearing I still think it would be worthwhile disengaging the slave rod, make sure that the release bearing is not touching the clutch fingers and rotating and see if you still hear the noise. The most common cause of grinding, chirping and squeaking would be this bearing and eliminating it as the cause will allow you to focus on other likely causes. A quick check of the crank end float would not be a bad idea. You can do that by levering the fan pully back towards the engine and then have someone press the clucth pedal while you observe. If you have any signiicant movement here (more that a few thou) you have wear and if you have gross movement like 1/4 inch you are in deep doodoo.

 

Stan

[cliffpeters]

Cliff, this may be a case of eliminating one potential cause after another but since there is a bit of pre-load on the release bearing I still think it would be worthwhile disengaging the slave rod, make sure that the release bearing is not touching the clutch fingers and rotating and see if you still hear the noise. The most common cause of grinding, chirping and squeaking would be this bearing and eliminating it as the cause will allow you to focus on other likely causes. A quick check of the crank end float would not be a bad idea. You can do that by levering the fan pully back towards the engine and then have someone press the clucth pedal while you observe. If you have any signiicant movement here (more that a few thou) you have wear and if you have gross movement like 1/4 inch you are in deep doodoo.

 

Stan

 

 

Thanks. I thought of the big end, having read about it here before, but didn't have anybody handy to do the 'assistant' job. I've tried the screwdriver bit but not as extensively as I should. Will follow the tips and report back. As I'm only here for a few days before going back to Bangkok, I might have to pop it in to the garage to sort out.

 

Cliff

[cliffpeters]

Thanks. I thought of the big end, having read about it here before, but didn't have anybody handy to do the 'assistant' job. I've tried the screwdriver bit but not as extensively as I should. Will follow the tips and report back. As I'm only here for a few days before going back to Bangkok, I might have to pop it in to the garage to sort out.

 

Cliff

 

I took it to the local garage which did the Bosch fuel pump conversion for me and the guy used an electronic thing to scope out where the noise was coming from. It wasn't the clutch. It is the metering unit. Maybe a bit of metal got into the fuel line when the Lucas fuel pump let go on me. The mechanic speculated that it wouldn't hurt to try driving it and see if it works itself out...or the unit fails. I'm thinking that because the noise doesn't happen until the engine is warm, it's probably a bearing in the metering unit.

[foster461]

I took it to the local garage which did the Bosch fuel pump conversion for me and the guy used an electronic thing to scope out where the noise was coming from. It wasn't the clutch. It is the metering unit. Maybe a bit of metal got into the fuel line when the Lucas fuel pump let go on me. The mechanic speculated that it wouldn't hurt to try driving it and see if it works itself out...or the unit fails. I'm thinking that because the noise doesn't happen until the engine is warm, it's probably a bearing in the metering unit.

 

Cliff, good news !. I'll take a clapped out metering unit over a whining release bearing any time. Any day that you dont have to pull the tranny is a good day.

 

Stan

[Tony Millward]

Cliff, good news !. I'll take a clapped out metering unit over a whining release bearing any time. Any day that you dont have to pull the tranny is a good day.

 

Stan

 

Certainly saves a gearbox out job..definately good news Cliff..

 

Tony

[cliffpeters]

Thanks. It's a pretty irritating noise that should scare off stray cats and small children. But I'll drive it a bit today and see what happens.

 

Appreciate the helpful advice, all.

 

Cliff

[TR 2100]

My experience of what seems to be a similar noise to yours may not

be relevant - if it was, there would have been previous experiences and

posts on the subject.

Then again, as no-one has come up with a possible cause based on their

previous experience, it seems your problem must be an unusual one.

 

Back in 1986, I had the pleasure (privilege, really) to drive my TR6 into

China (Gweilin to be precise). This was about 800 miles each way.

An unforgettable journey and experience that I think my namesake Wayne

wrote up in TRAction at the time.

 

On the way back, my 6 started making a screeching noise. It started as an

intermittent noise but ended up just about permanent.

Not much I could do about it - not many repair shops in China! So, I just

drove it until something fell off and in the end, made it back to Hong Kong.

 

Not many repair shops in Hong Kong either, so I drove the car for a few days

and the noise got less and less, quite quickly and then disappeared, never to

return.

 

With hindsight, I'm sure it was lack of lubrication for the (Lucas) metering unit.

The petrol in China didn't have the same lubrication additives and metering

units need that.

Looking back, I'm amazed I got so far on petrol that was about 89 octane.

 

So, have a thought for lubrication.

Experts may put me straight on this, but I don't think it would do any harm to

add some normal engine oil to the fuel, just to 'over-lubricate' the metering unit

as a way of eliminating that as a possibility. Don't ask me how much!

 

What do the experts think?

 

AlanR

[stuart]

My experience of what seems to be a similar noise to yours may not

be relevant - if it was, there would have been previous experiences and

posts on the subject.

Then again, as no-one has come up with a possible cause based on their

previous experience, it seems your problem must be an unusual one.

 

Back in 1986, I had the pleasure (privilege, really) to drive my TR6 into

China (Gweilin to be precise). This was about 800 miles each way.

An unforgettable journey and experience that I think my namesake Wayne

wrote up in TRAction at the time.

 

On the way back, my 6 started making a screeching noise. It started as an

intermittent noise but ended up just about permanent.

Not much I could do about it - not many repair shops in China! So, I just

drove it until something fell off and in the end, made it back to Hong Kong.

 

Not many repair shops in Hong Kong either, so I drove the car for a few days

and the noise got less and less, quite quickly and then disappeared, never to

return.

 

With hindsight, I'm sure it was lack of lubrication for the (Lucas) metering unit.

The petrol in China didn't have the same lubrication additives and metering

units need that.

Looking back, I'm amazed I got so far on petrol that was about 89 octane.

 

So, have a thought for lubrication.

Experts may put me straight on this, but I don't think it would do any harm to

add some normal engine oil to the fuel, just to 'over-lubricate' the metering unit

as a way of eliminating that as a possibility. Don't ask me how much!

 

What do the experts think?

 

AlanR

If you want to try that then use some of the good old Redex, probably double dose it just to try.

Stuart.

[Eyetee]

Or posible a drop of 2 stroke engne oil, a bit less than the regular 20:1 mix.

[cliffpeters]

My experience of what seems to be a similar noise to yours may not

be relevant - if it was, there would have been previous experiences and

posts on the subject.

Then again, as no-one has come up with a possible cause based on their

previous experience, it seems your problem must be an unusual one.

 

Back in 1986, I had the pleasure (privilege, really) to drive my TR6 into

China (Gweilin to be precise). This was about 800 miles each way.

An unforgettable journey and experience that I think my namesake Wayne

wrote up in TRAction at the time.

 

On the way back, my 6 started making a screeching noise. It started as an

intermittent noise but ended up just about permanent.

Not much I could do about it - not many repair shops in China! So, I just

drove it until something fell off and in the end, made it back to Hong Kong.

 

Not many repair shops in Hong Kong either, so I drove the car for a few days

and the noise got less and less, quite quickly and then disappeared, never to

return.

 

With hindsight, I'm sure it was lack of lubrication for the (Lucas) metering unit.

The petrol in China didn't have the same lubrication additives and metering

units need that.

Looking back, I'm amazed I got so far on petrol that was about 89 octane.

 

So, have a thought for lubrication.

Experts may put me straight on this, but I don't think it would do any harm to

add some normal engine oil to the fuel, just to 'over-lubricate' the metering unit

as a way of eliminating that as a possibility. Don't ask me how much!

 

What do the experts think?

 

AlanR

 

Yours sure sounds like my screechy sound, and mine started almost immediately after fuelling the car with Shell V-Power, which is what I try to use all the time. But I didn't get as far as you. Today I took the car out and after 30 minutes the engine started to bog down, like it was only running on 3 or 4 cylinders, so I decided to turn back and get it to the shop for repair. By the time I got there, I was wondering if I'd make it or end up stranded on the roadside. The mechanic there who is quite good with the TR also said lubrication was probably the issue. The car has been sitting a lot as I'm in Bangkok on business for lengthy periods.

Cliff

[foster461]

Yours sure sounds like my screechy sound, and mine started almost immediately after fuelling the car with Shell V-Power, which is what I try to use all the time. But I didn't get as far as you. Today I took the car out and after 30 minutes the engine started to bog down, like it was only running on 3 or 4 cylinders, so I decided to turn back and get it to the shop for repair. By the time I got there, I was wondering if I'd make it or end up stranded on the roadside. The mechanic there who is quite good with the TR also said lubrication was probably the issue. The car has been sitting a lot as I'm in Bangkok on business for lengthy periods.

Cliff

 

Pretty interesting scenario. You can bet that modern fuels are not formulated with mechanical fuel injection in mind and I wonder how the lubricating qualities of the fuel are changing as we add more non petroleum based components into the mix. The metering units have already been adapted for unleaded, perhaps there is a new filling up regime in the offing to stop the moving parts from seizing.

 

Or, given that you have other poor running issues perhaps you just got some contaminated gas..

 

Stan

[badshead]

Yours sure sounds like my screechy sound, and mine started almost immediately after fuelling the car with Shell V-Power, which is what I try to use all the time.

 

I'm a regular user of Shell V-Power (and Optimax before that), but tend to alternate with a tankful of unleaded and Castrol Valvemaster Plus. My MU is quite ancient and not converted for unleaded as far as I'm aware. No lubrication problems so far.