Strange whirring noise under bonnet

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Tilleypops425
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Strange whirring noise under bonnet

Post by Tilleypops425 »

Hi
I took out my beloved Morris Minor for a spin yesterday just a short hop 30 miles all round just to warn her up. I haven't driven her yet this year due to current situation.
I'm wondering if anyone can shed any light on a problem she seems to have under her bonnet.
When slowing down or going around a corner there is a loud whirring sound almost like something is spinning , this then disappears once driving on the straight road and accelerating.
Any help greatly appreciated.
simmitc
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Re: Strange whirring noise under bonnet

Post by simmitc »

Welcome, glad to hear that you're out and about again. Are you sure that it's under the bonnet - could it be from the front wheels?

If the car has been standing, there could be rust on the brakes. Do you have the standard drums or converted to discs?

Jack up each front wheel in turn, observing normal safety precautions. Spin the wheel and gently apply the brakes - do you hear the sound. Check for wear in the bearings at the same time - is there any play or roughness?
myoldjalopy
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Re: Strange whirring noise under bonnet

Post by myoldjalopy »

As above - or take the car for a spin and when about to slow down or corner, disengage gears into neutral, switch the engine off and see if the sound appears or not (no need to worry about steering locks on these old cars 8) ). If it is still present then 'probably' something to do with the front wheels. If not, it might be fan belt slipping (though this usually make a squealing rather than whirring - but some noises are sometimes difficult to describe).
Last edited by myoldjalopy on Mon Aug 03, 2020 12:16 pm, edited 1 time in total.
Edward1949
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Re: Strange whirring noise under bonnet

Post by Edward1949 »

Good advice above.
Could also be buzz from exhaust contacting underbody upon deceleration. This would fit with the noise disappearing under acceleration.
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Re: Strange whirring noise under bonnet

Post by Chipper »

Also check your gearbox-to-gearbox crossmember retaining cable; if worn, loose or frayed, there is the possibility of the fan moving forwards into the radiator under braking, as the entire engine and gearbox moves forwards on their mounts. :o
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Re: Strange whirring noise under bonnet

Post by Matt »

Sounds like wheel bearing noise to me!
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Tilleypops425
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Re: Strange whirring noise under bonnet

Post by Tilleypops425 »

Hello everyone!
I begin with an apology. After posting my 'whirring noise problem' in August 2020 I must have been kidnapped by Aliens who then wiped my memory before depositing me back on planet earth as I have no clue what happened to me that I didn't reply. :o I must have appeared very rude to you all for not replying. Apologies again.
Regarding the whirring issue all the brakes were changed and the issue has now been resolved.
However I now have a different issue.
My husband had to move her one morning to get his car out whilst rushing to work. Unknown to me in his haste he left the keys in the ignition in the on position. I only found this out days later and she was as flat as a pancake! Assuming it was a dead battery we charged it then tried again to start her... no joy. We were told we should try changing the coil. We did this but still no joy.
Could it be the starter motor has been damaged? This was my next line of investigation.
I promise I will reply this time!!

Maddie.
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Re: Strange whirring noise under bonnet

Post by philthehill »

Leaving the ignition on will not damage the starter motor but will cook the coil.
Try changing the condenser (as well as the coil) and check the coil/distributer wiring as it might have burnt out.

myoldjalopy
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Re: Strange whirring noise under bonnet

Post by myoldjalopy »

OK so, with a fully charged battery, does the engine turn over as normal but without firing up, or will it not even turn over? If it turns over briskly without firing up the starter motor is OK. If it won't turn over at all it could be the starter, or a connection/earth fault (as Phil says above, some of the wiring may have burnt out), or the battery itself. Its possible that the battery was on its way out and draining it right down killed it off. But let us know whether the starter cranks the engine over or not first.
Tilleypops425
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Re: Strange whirring noise under bonnet

Post by Tilleypops425 »

Hi there

Thanks so much for your advice. Yes the engine does turn over rapidly but doesn't start and after a few goes just dies.
We didn't look closely at the wiring but certainly didn't see any obvious signs of burning. I had suggested to my husband that it could be the battery that we had killed it but it was charging ok and reaching a full charge on the reader its about 4 years old. The condenser is something we didn't know about so could try they if wires are ok.

Maddie.
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Re: Strange whirring noise under bonnet

Post by oliver90owner »

First thing to check is whether there is a spark at the plugs. There may be other issues - such as a fuel blockage, fuel pump issue, fuel quality (unlikely), etc.

If the battery discharges quickly, its capacity is likely seriously reduced, its output voltage may be reduced (even though it turns over the starter motor OK, initially). It will certainly be more sulphated now, than before this mishap.
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Re: Strange whirring noise under bonnet

Post by myoldjalopy »

Maddie, you say that "the engine does turn over rapidly but doesn't start and after a few goes just dies." Do you mean after trying to start a few times with the engine turning over OK, the starter then fails to turn the engine over? If so, it sounds like the battery is unable to hold and deliver its requisite output. That in itself may cause starting problems. If I understand you correctly, I would get the battery checked out and if it proves to have failed, try again with a fresh battery. If it then won't fire up, we should go down the route suggested by 'oliver90owner' and check for sparks.....either at the king lead or the plugs. But if the battery has failed, that may be where your problem lies.
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Re: Strange whirring noise under bonnet

Post by StillGotMy1stCar »

Does the fuel pump tick as normal when you turn the ignition on.

Just a theory but I reckon an SU pump could be damaged by being left on with a low voltage as the battery runs down, not enough power to make the contacts go overcentre leaving the solenoid coil energised and overheating it, an electronic version might be more susceptible to damage, overheating and destroying the switching transistor.

If it still ticks then pretend you haven’t read this as it is OK and check for a spark :D

Regards John.
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Re: Strange whirring noise under bonnet

Post by oliver90owner »

Possibly buy a battery before checking for a spark? Never, on my shift!
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Re: Strange whirring noise under bonnet

Post by simmitc »

Maddie, do you have a multimeter? It's very useful for diagnosing faults. They are cheap enough these days and worth getting one.

All good advice above. I would check:

Charge the battery. Disconnetc the charger and leave battery to stand for a few hours. Check what voltage is present (using meter). If less than 12 volts, change the battery.

With headlights switched on, does the starter motor still spin the engine quickly? If no, change the battery.

Remove the centre high tension lead from the distributor cap, leaving the other end in the coil. Wedge the free end about 1/4 inch from good earth point. Get an assistant to operate the ignition switch. With the engine spinning, is there a bright spark between the end of the HT lead and the earth point? If no, then you have an ignition problem, if yes, then we can move on to other checks. Replace the lead in the cap!

Remove the petrol pipe from the carb and place in a container suitable for petrol. Switch on the ignition, but do not attempt to start. Does the pump operate freely and discharge petrol into the container? If no, then replace the pump. If yes, then we move on to other checks. Replace the pipe and pour any discharged petrol back into the tank. Take appropriate precautions with this test - no naked flames, no sparks, plenty of fresh air etc.

Try above and report back.

Leaving the ignition on will not damage the starter, but will drain the battery and could damage other components, depending on whether the ignition and fuel pump points were open or closed at the time.
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geoberni
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Re: Strange whirring noise under bonnet

Post by geoberni »

simmitc has pretty much said it all, well enough to be getting on with, because these points need covering first.

As myoldjallopy has said, 'What exactly do you mean by
"the engine does turn over rapidly but doesn't start and after a few goes just dies."
Such a phrase means different things to different people.

If the battery has been charged but cannot spin the motor over for more than a minute or so, then it's Duff, probably old age or perhaps warped plates from being left to over discharge.

Many old batteries will retain Voltage, but not retain their capacity to give the current required.
I've recently treated Basil to a new battery because his old one would read 12.6 volts or so, even after standing a few hours, but could no longer provide sufficient cranking capacity.

But I certainly wouldn't fork out for a new battery without proving it's duff.

You've obviously got another car at the premises, because that was what caused the problem initially.... so have you tried Jump Leads?
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myoldjalopy
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Re: Strange whirring noise under bonnet

Post by myoldjalopy »

oliver90owner wrote: Tue May 04, 2021 6:53 am Possibly buy a battery before checking for a spark? Never, on my shift!
But if the battery is goosed a new one is needed anyway. That's why I said to get it checked out, not to randomly buy a new one 'just in case'! :roll:
Tilleypops425
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Re: Strange whirring noise under bonnet

Post by Tilleypops425 »

Hi everyone

Wow what a lot of great advice amazing! Thankyou.
I have a strange feeling it's the battery. So will check that first.
Sorry for not making myself clear I will try again...so I try to start her after charging for a few hours. She goes through the motions of trying to fire up so you get the engine making a trying to start noise but it doesn't and then the more you try eventually there is no engine firing up noise any more just a click and a whirring noise as though the charge is exhausted and she hasn't even got enough power to fire up anymore.

I'm heading for the battery I think we do have one of those meters so I will show this to my husband and we will test it first.
I did think that maybe a selonoid had burned out due to being over heated as one of you previously mentioned.
Anyway I'm on the case armed with all of your excellent knowledge.
I will let you know how I get on it's my husband's day off tomorrow so we should be able to work on her in the afternoon.
Watch this space...!

Maddie.
oliver90owner
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Re: Strange whirring noise under bonnet

Post by oliver90owner »

myoldjalopy wrote: Tue May 04, 2021 11:09 am
oliver90owner wrote: Tue May 04, 2021 6:53 am Possibly buy a battery before checking for a spark? Never, on my shift!
But if the battery is goosed a new one is needed anyway. That's why I said to get it checked out, not to randomly buy a new one 'just in case'! :roll:
And I suggested a quick check, costing nothing - maybe not even removing the battery from the car, and certainly not transporting it anywhere to have it checked. If there is a spark and fuel, there should be no reason why the engine should not start, if the starter spins the motor over at a good speed - at least immediately after charging. If the engine starts, the battery can be addressed later. Simple enough?
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Re: Strange whirring noise under bonnet

Post by geoberni »

Hi
Just to review some of your comments for clarity, ours and yours.
so you get the engine making a trying to start noise
Is that just the engine turning over on the Starter, i.e just constant turning and nothing else, or is it actually giving the occasional kick as it tries to 'fire' ? I'm assuming just the former.
just a click and a whirring noise
For your benefit/knowledge, that is the Starter motor turning over but with insufficient speed and battery power behind it to engage the Starter Bendix gear onto the flywheel and turn the engine over.

If it's possible, I would really try and use a set of Jump leads from your other half's car; preferably without removing his battery from his car, because then you'll have to find Radio Security codes ... :wink:

Just a point on Battery Charging, it's easy to get the Terminal Voltage up from 12v to 12.5v, but what you need is the 'cranking current'.
If you've got a fairly standard battery charger, it's probably about 6 Amp capability. That'll take some 8-10 hours to give a decent charge to a 'flat' battery. If you're only charging for a few hours, you'll not get enough 'ommph' into it to get a decent chance of starting.
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