Fiesta Ecoboost - whirring noise

[jakob4maj]

I have a 2017 Fiesta 1.0 Ecoboost with manual transmission and with a mileage of 56.000 km. It was bought used in 2021. Recently, my mechanic performed annual service and a timing belt replacement. Shreds of rubber from the belt was found in the drained engine oil as could be expected from this engine design. When the work was done, the car had a whirring or rattling noise which sounds like a card flapping in wheel spokes.

The noise appears when the clutch is fully released with the car in gear. Not with the clutch halfway and not if it is in neutral. While driving, whenever the clutch pedal is even lightly touched (1-2 cm of travel), the noise stops immediately, and returns when the clutch pedal is again fully released. I can hear the noise in all five gears when accelerating and it follows engine RPMs. The noise disappears during left turns and increases during right turns. It is quite loud when the engine is cold and during maybe 10 km of driving it reduces but never disappears completely. If I take the foot of the gas pedal, it reduces significantly.

Immediately, focus was on the release bearing so this and the clutch was replaced, but it turned out it did not solve the issue. The car has been in and out from the mechanic for several weeks now. During this time, he inspected the timing belt installation and replaced the fuel pump, both VVT wheels, oil pump, and (at least twice) the new oil and oil filter. But also, all in vain. The noise persists.

Eventually, while I was driving the car, the engine warning lamp came on and off and on again. It was checked at the mechanic, and it turned out to be P0017 which can relate to misalignment between crankshaft and camshafts. The mechanic had the car for a week, but the lamp has not turned on again. However, he did find a loose connecting rod bearing on the crankshaft. This could possibly explain the symptoms, but I do not know what to believe now. Why would that show up exactly at the timing belt replacement? I am quite skeptical that this loose bearing can produce that kind of sound.

The mystery of this case is very frustrating and that is why I am reaching out here. Has anyone here any experience of something similar?

 

[Handy Andy]

Owning a manual myself (2018 HB with L4 1.6 NA) - the whirring noise I consider normal - and only heard (it seems) thru the passenger compartment.

So it may be a motor mount onto a shifter (there are two) are not quite positioned correctly in the holster in-between the Battery/PCM and the Ignition Coil.

It looks like a flat bracket tab - bolts onto a ear of the transmission/Engine mating area right by where the Heater, Fuel and EVAP hoses route thru

Part number
8A6Z-7474-C​

This is where those shifter cables route thru and they just may need a tweak in positioning to change the "drag" on the gearshift pivot and control arm. It may help with the noise you're experiencing.

.
Locate that battery and PCM and the Ignition coil
Look between them...

​

For another try and "quieting" try locating the Shifter Arm - in the Shifter assembly on the transmission housing.

Set parking Brake and set shifter to Neutral. No tension...

Remove the Cover...
Locate the gimbals for the shifter cables and release them.

​

Start the car.

Do you hear that noise?

Carefully - by gloved hand (to protect from heat and vibration) and keeping the car in neutral and brake on - gently twist the larger arm for movement and note noises - do the same for the smaller gimbal pivot - using finger pressure - see if you can locate a "zero point" for that whirring noise...pull and push those arms to see if you can zero out that noise or even create it.

As you do this the arm may "jump" this is caused by the synchronizers engaging and disengaging while they spin up or release. So the jump may startle you it's why it's done carefully and let the car just idle to help you locate a zero "float point".

IF the noise is not present with the gimbals (shifter cables) disconnected - the noise is from the shifter cables and specifically the tension on them, It may require you to find "center" in the shifter in the passenger compartment to quiet the noise.

IF that can't be done re-attach the gimbals one at a time noting which makes the most noise - then adjust that cable thru that bracket by sliding it to see if you can change the tension and provide slack.

IF that can't be done you can gently pry up or down on the gimbals fastener brackets - the metal - not the plastic - to see if they can be re-centered to take off tension on the cables to reduce this noise.

It's the best I can offer to solve this problem - I've done quite a bit to locate the least level of noise but it changes by season and even by temperature.

What I found is some of this noise can be fixed but not all...the noises themselves are from the gear lash and slack in the housing - since many of the torque gears - the massive ones, are on the input shaft - these work the synchronizers and also rotate on end-cap bearings - this may be a lash / free-play condition and you might not be able to do too much to reduce this noise.

 

[jakob4maj]

Thank you for sharing your thoughts and ideas and for writing the detailed description. I will inspect those parts you mention.

However, the noise is only present while the car is in motion and in gear. When it idles on the parking lot, there is nothing and even revving the engine there will not produce the noise. When driving, I can step on the clutch (fully or even just 1 cm still with full engagement) and press the gas pedal as much as I want, but the noise is gone. It will only return once I release the clutch completely with the car in one of the gears. In neutral, the noise is not there, no matter if the car is moving or not.

It sounds like a whirring or a rattling that follows engine rpm. Like something stuck in a wheel or like an exhaust leak. It can be heard everywhere inside the car and outside through opened windows on any side.

Before the timing belt replacement, I never heard the noise. It came right after the mechanic had the car disassembled for that job. He inspected the timing belt assembly again and even had the car transported to two other official Ford workshops with no results.

 

[Handy Andy]

Have the mechanic inspect the CV axles, the left one is the shorter of the two, but the right one has a carrier (carriage) bearing used to keep the vibration of that axle down - this may be that noise.

Have him put it on the hoist and check that bearing and the clamp over it - if turning the right-side tire generates the noise - that just may be it.

Else the main problem would be the clutch and alignment to the plate - did you have the clutch bled at the bell housing to see if there was air trapped inside? (Bent finger or air pocket in the slave ( at the clutch)) Best to do this when it idles so the vibration of those fingers can be detected by how the fluid trapped in the slave "bounces". Use a clear PVC hose and let it rise above the Master brake cylinder to work much like a bourdon tube to see if the fluid changes levels. Observe how the fluid acts as it bleeds out during this idle. It SHOULD be a steady or slightly positive flow (meaning it drips but not a gusher) and rises to about or just above the level of the reservoir the pressure of that bounce then signals work needed on the clutch system - if there is no flow whatsoever, then the line might be kinked or the piston at the foot-pedal is not retracting all the way - so the port from the master which has all the fluid to send to the slave can be opened and let more fluid in to displace that which "stays behind" in the slave cylinder as the clutch media wears down. The lack of fluid can also signal a delay in the refill of that slave cylinder so it cannot rest evenly on those clutch fingers - making that noise - which would make sense and fit the facts of how you press on the clutch pedal - and quiet the noise.

 

[Handy Andy]

To help, this noise may be also part of a pilot bearing that is going out, but this only works when weight or load is placed on it, so since it goes silent - means the pilot bearing is ok, else it would squeal and groan from having to bear a load,

Since it is not doing that (per your posts) that means it may have free-play in it. Free play is due to wear and is a tiny sleeved bearing and that you can't fix unless you replace the clutch with it - it's buried in the clutch pack. The Slave cylinder simply presses the fingers to move the clutch - but it needs a pivot point moving with the Clutch - so the Pilot bearing bears that load and lets the shaft spin.

By letting it do that it lets you shift gears because the shaft doesn't have to connect the engine - the pilot bearing merely moves the clutch - it acts like a sleeve but is a fulcrum point to make the pads engage the flywheel or get pulled away and let the flywheel spin at it's own speed while you make the gearbox shaft spin at another to engage the gears.

The noise is from the pilot bearing loosely rattling away on the opposite side of clutch - opposite of that slave cylinder, then when you press the clutch that slave slides those fingers and makes the pilot bearing take on more load reducing that noise.

For more read... This site talks about two types of bearings you may need to talk to your mechanic about this condition

So the noise is an indication of worn parts, doesn't mean immediate failure - but does mean that a new clutch may be necessary in the near future. Depends on how hard you drive and the number of miles left on those pads - which can be forever onto as soon as tomorrow night after the party.

 

[Handy Andy]

As you diagnose this, one of the things I know from my own experiences are the types of noise you get and how it stops when you either engage the tranny or disengage it (freewheel slowing to a stop)

Now, if you hear the noise then ever so slightly press the clutch in - and the noise disappears, then that is something in the clutch and it's assembly. More than likely it's a slack/rattle free-play from the fingers, the slave itself - or the clutch pilot bearing that is INTEGRATED into the clutch plate (you can't remove it or repair that bearing). In these cases - it's cheaper to just replace the clutch. Why? - because it may have defective parts and there's a greater change of damaging the transmission from continuing to use it.

IF the noise "spins down" and is now silent even with the engine running - then the noise is from the transmission - and the various bearings involved. One of the main bearings is the one that is the main bearing where the transmission-side input shaft goes into the main gears inside - this one also can make a "shake" feel you feel thru the steering wheel when the RPM is high and there's a lot of torque from the motor. IF the shake is felt more and more often, the transmission will have to be replaced. The housing is cast and the bearings are press-fit - so if the transmission housing has to handle too much torque or rapidly applied force, that housing will distort and the bearings won't last long afterwards - its' at the mercy of that now deformed housing to hold everything together.

 

[jakob4maj]

I appreciate your effort!

Right after the noise was dicovered, the mechanic did replace the clutch and the throwout bearing. He was so sure that this was the problem that he offered to do it for free if otherwise. So, eventually it turned out that he had to do it for free!

Every time I touch the clutch pedal ever so slightly, the noise disappears and returns when I release it again. It does not spin down. It goes away and comes again instantly. Like an on/off switch. Even while I do this light press on the clutch (1 cm or so) and then press the gas pedal all the way, the noise will not return. It is only there when the clutch is fully released and the transmission is not in neutral.
In roundabouts, the long left turn (in gear and not touching the clutch) will make the noise reduce a lot, close to disappearing. Perhaps the shifting of weight does something similar to when I touch the clutch pedal?

I cannot feel any shaking at any time that I can relate to the noise.

What makes this case so difficult is the fact that it came right after the timing belt replacement. Both the mechanic and I have tried hard to make the connection between that job and the source of the noise but so far, it has been impossible to do so. If he made a mistake with the timing belt, he would have been happy to correct it for free just to close this frustrating case.
By now, I think he gave up, took the loss and moved on.