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Odd engine noise when started from cold

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This is relatively new but each time I start the engine from cold there is an odd noise coming from somewhere. I have not yet pinpointed where it is coming from and I cant tell if it is a mechanical noise or a plumbing noise but once the engine warms up the noise goes away.

https://photos.smugmug.com/Misc/i-tZ3N6fm/0/37fec75f/1920/TR3 cold start noise-1920.mp4

All engine instruments like oil pressure and temp look normal and there are no fluids leaking significantly more than usual. I removed the radiator cap to see if there was anything unusual going on but did not see anything remarkable. Car has a standard cooling fan, dynamo was rebuilt, water pump was new in 2016.

Anyone recognize this sound ?

Stan

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Could the fan be slightly loose on the pulley ?

Bob.

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Hi Stan,

As it's an irregular "Slapping" and I would suggest that it is at the front of the engine.

I would be looking at slacking the fan belt so you can individually rock each of the dynamo, water pump and crank pulleys. Check each in turn for slop or free movement back and forth.

There are two possible issues to check. 

1 The fan on the dynamo is a sandwiched affair that needs to be tight or the fan will rock against the woodruff key as it turns at idle, rev the engine and it is under load so no noise.

2 The radiator fan probably has metal sleeves through the plastic fan which may have enlarged giving the same effect allowing the fan to slop about. As the engine heats up perhaps it is enough to tighten the slack.

Get yourself a piece of plastic hose and hold one end to your ear and you have the other end to hold around components, as the noise increases so you are nearer to the problem. better still and engine stethoscope which a great old school device. Often times I have used a large screwdriver with bulb to my ear and the screwing end in contact with cylinder head or timing chest good early warning of potential issues.

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I had a strange noise from the front of the engine on my previous 6

turned out i had not fitted the crank pulley fan spacer correctly and it was moving about under the inconsistent load of starting.

has your pulley been off recently?

steve

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Hi Stan,

                very interesting - I have the same/similar noise.

It sounds a little like kettling in the plumbing but the coolant is cold/cool

Or a little like flimsy tin sheet in the sump being knocked against.

It is not there on every cold start.

As it warms up it goes away.

All the mechanicals chech out good and the noise started  a long time after any work was done.

 

Roger

 

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Stan,

This is interesting to me too. I rebuilt my engine about 6 months ago and have only run it on a few occasions for about 5 minutes to check for leaks and suchlike. I got EXACTLY the same noise when I ran it. I was going to ask about it but felt it was a bit difficult to describe. The recording does the trick.

I was really downhearted because, having just done the rebuild, I was certain it was something I had done wrong. (Especially as I had already pulled it apart TWICE due to the fact I'd put some of the piston rings in upside down...)

To me it sounded like a liquid bubbling through pipes, with a mixture of air, somewhere towards the back of the engine, (near the fuel pump), but like Roger says, it has a tapping metallic sheet sound as well.

I’ll be getting the car on the road soon, so it would be nice to find out exactly what the noise is, although now that I hear other people with the same problem I feel bit better.

Charlie.

(Car is a '59 3A)

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It does sound like Dynamo/fan or waterpump flapping to me as well. Does it change with the clutch depressed?

Stuart

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My engine had new pistons and liners, so I assume it would not be piston slap.

To be honest it was the “Gurgling” sound that struck me the most. It was not in time to anything like engine revs. Like sucking up a liquid into a pump, and every so often the level of the liquid would go down so air would be sucked in, and then it would be sucking liquid again. It hinted (to me) something to do with the oil pump pickup, but the pressure remained rock steady, and the dipstick showed ¾ full.

Stan, do you hear more of a "Gurgling" or more of a "Taping"?

Charlie.

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My '3 suffers from piston slap when cold. it is more of a "knock" , & is very regular, not like the noise above.

Bob.

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3 hours ago, RogerH said:

Hi Stan,

                very interesting - I have the same/similar noise.

It sounds a little like kettling in the plumbing but the coolant is cold/cool

Or a little like flimsy tin sheet in the sump being knocked against.

It is not there on every cold start.

As it warms up it goes away.

All the mechanicals check out good and the noise started  a long time after any work was done.

Roger

 

^ If relevant..,   I had the same sort of kettle-boiling noise on my old Jag.  To me it was really worrying as it implied somewhere was locally boiling water rather than being cooled by it.  

I reasoned that must be caused by no circulation at some point  ..so an airlock,  which was most likely attributed to the car's bulkhead mounted heater matrix (it being higher than the engine or radiator on that particular car), or to the top pipe leading to it.  I removed a pipe to that and filled it by hand - and there was air in there.  However, I had also found the wrong thermostat valve was fitted and that partially obstructed the bypass route, so I also corrected that.   And as that (1966) car never had an expansion tank for the radiator / cooling system,  I fitted one.  

The issue went away, but Tbh I cannot say if it was refilling the heater matrix, changing the thermostat, or it now having an expansion tank (which prevent the loss of water when it expanded, and so avoid air being sucked into the cooling system). 

Anyway I hope something in the above may be of help in identifying your car's issues.      

Edited by Bfg

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Thanks for the above

I don;t think it is local boiling as it is only present on initial start up from cold.

I have changed the thermostat for a summer one - I will have to listen to hear if the noise has gone.

 

Roger

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I reasoned the localised boiling occurred because when first started and warming up there are hot places in the engine,  but the thermostat was still closed and the flow rate on tickover was minimal.  When things warmed up and the thermostat opened, even if just a little, then the faster engine revs / pumping rate would sort things out.  

..Just a theory like !  

Edited by Bfg

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2 hours ago, billy l said:

Take the fan belt off and try it then, Cheers, Bill.

 

That's what I'd do but if the issue is with coolant circulation it might still go away if the water pump wasn't turning.

Do you have a bellows thermostat?

Tom

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Stan,

I have exactly the same noise on my 3a.  It appears a few seconds after start up and disappears once the engine is warm.  If you have one of those stethoscope things (or a piece of dowelling) and place it on the sump lip at the bottom of the block you will hear it clearly and it seems to come from the front.  I have even gone as far as to drop the sump to check bearing clearances with Plastigage and they were all spot on, as is the end float.  In the end I gave up looking.  Oil pressure is good, I don't have a fan having replaced it with an electric one, and it doesn't appear to come from the water pump.

Let me know if you ever find it pls.

Rgds Ian

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6 minutes ago, Ian Vincent said:

Stan,

I have exactly the same noise on my 3a.  It appears a few seconds after start up and disappears once the engine is warm.  If you have one of those stethoscope things (or a piece of dowelling) and place it on the sump lip at the bottom of the block you will hear it clearly and it seems to come from the front.  I have even gone as far as to drop the sump to check bearing clearances with Plastigage and they were all spot on, as is the end float.  In the end I gave up looking.  Oil pressure is good, I don't have a fan having replaced it with an electric one, and it doesn't appear to come from the water pump.

Let me know if you ever find it pls.

Rgds Ian

Hi Ian,

    you may be getting close.  Could it be the timing chain tensioner (thin metal flapping about) scuffing against the cover/block when cold.

As it warms up and changes shape the sound goes.

 

Roger

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Hi Roger,

I don't think it is scuffing against the timing chain cover because I have put my stethoscope against that and there is no sound other than the rustle of the chain.  It could be the block though.

Rgds Ian

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Only just catching up on all this... before I listened, my first thought was same timing chain but that’s a real ‘ticking noise’ that I never picked up ( engine bay all looks immaculate by the way!) from the clip

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Out of the blue I occasionally had the same sound on cold start.

It disappeared after I had the sump of to fix some leakage issues on the gasket.

While having the sump  removed, also exchanged the thrustwashers and oilpump-filter. The filter was damaged, guess it was slapping to the inside of the sump.

Robert

image.jpeg

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Robert, you could be on the money with that suggestion, but what causes it to stop when the engine warms up?

Rgds Ian

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Thanks for all the great suggestions and diagnostic ideas. The weather was dreadful today, rain and 50 degree F temps so we opted to go get our second Shingles shot instead. Tomorrow looks better for getting into this noise a bit deeper and I do have a stethoscope and some poly tubing.

Stan

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