Miele T4659Ci

[DJB2]

Ok ignore last post. This is incorrect. Have now dismantled dryer as far as I can take it. Fan is directly driven by motor so does turn the opposite way when drum reverses. Everything turns freely. Both belts fully intact. There seems to another fan at the rear enclosed in plastic and I couldn't really see this fully but small belt attached to motor is turning it easily.

Rear felt seal was encased in fluff so this was cleaned up. Front seal clean and front rollers smooth running.

I'm not absolutely certain that rear bearing shell was positioned correctly. A metal bracket on the back panel ensures that the bearing shell can only be central when reassembled but there is an odd plastic protrusion from the shell which looks like it should clip on somewhere but I could not see where. I have placed two metal lugs (one from removable bracket, other from rear case) either side of it to prevent it spinning.

The capacitor is a 7uF so not sure whether to change to 8 or 9uF?

Noted that screws in the back above heater bank have blue sheen to them which you only see in metal that's been really hot. Still don't think that I've found the problem...

D.

 

[zipper]

Replace the 7uf with an 8uf.
The rear fan is a cooling fan, the front fan provides process air. Make sure all the air-paths are clean.
Remove the rear heater cover & heater element, then vacuum any buildup of fluff from the element & cavity.

 

[DJB2]

Will replace capacitor as you say.

As far as I can see all the airways are clear. I've already cleared heater elements of fluff.

Seems to working better now - reverse action seems to be more frequent and lasts longer or maybe just my imagination.

Nearly finished full cycle without groaning noise.

D.

 

[DJB2]

ps will this capacitor do the job?

http://uk.farnell.com/ducati/4-16-10-13-64/capacitor-8uf-450vac/dp/1219055

D.

 

[zipper]

Yes, almost any 8uf will do as long as it is rated 450v or over.

 

[DJB2]

Ok, have been running the machine with side panel removed in preparation for installing new capacitor. Seems to be much better (even before capacitor changed). As previously mentioned, it seems to cycle between normal direction and reverse more frequently and this seems to help keep it cool. I'm convinced that overheating has been part of the problem and I'm still not sure it will cope with a full heat cycle. I tend to always select low heat cycle since even on this setting it still gets very hot. Maybe having the side panel off is allowing heat to dissipate.

New capacitor fitted (8uF) and has so far made no discernible difference but only installed an hour or two ago so early days. Maybe rear NTC is falsely high readings to PCB causing heater to be on too often?

Not sure what to do next.

D.

 

[zipper]

Take a timeout & see how it goes. But first go back into service mode & cancel all the error codes in the log. To do this follow the instructions given earlier to the stage where error codes are displayed...then press the start/stop button for min 5 secs. This will delete all error codes in the log. If you experience more trouble read the new error code & post it here.

 

[DJB2]

Ok thanks, zipper.

D.

 

[DJB2]

Still not working correctly. Groaning noise towards end of cycle still evident.

Here's what I've noticed:

1. Never makes noise when cold and drum turns freely at this point.
2. Groaning noise is associated with what seems to be excessive heat from the dryer and at this point, metal front door almost too hot to touch. Speed of drum (side panel is still unattached) also much slower than normal and when trying to turn drum by hand, it is noticably stiff.
3. Hates higher heat setting. I usually have to select lower temp option on panel otherwise it struggles at earlier stage in cycle.
4. No fault codes so far.

Given that both NTCs are working, I think that there can only be two possibilities:

1. PCB not controlling heater correctly allowing overheating.
2. Inadequate air throughput/cooling from fans.

I've done everything that I can to investigate 2nd possibility and everything seems to be ok.

Does the residual moisture circuit affect the heat control because I suppose if this is not working correctly then it could be to blame?

D.

 

[zipper]

Did you clear the error log as mentioned earlier? If so go back into diagnostics & read out the last error code (if there is one).

 

[DJB2]

zipper

Yes cleared error log and currently no new errors stored.

D.

 

[zipper]

As I mentioned earlier I am still convinced a mechanical issue is at the root of this. Think about it, if the drum can't turn properly then the motor will slow down considerably (but probably not enough to burn it out). If the motor can't deliver enough process or cooling air then something has got to give. Either you pop a thermostat (F2) or it will error out & stop showing an F50, F55, or most likely...an F66 fault in the error log.

 

[DJB2]

Thanks zipper.

So, you think the overheating is end result rather than cause?

D.

 

[zipper]

Yep...that's what I figure.

 

[DJB2]

Some questions for zipper:

If mechanical cause is still most likely, what can I do next?

Are roller bearings adjustable and if so how is this done? As far as I can see the rollers are held in place with a nut and bolt and that's it. Can't see obvious target for adjustment.

How do tell if felt seals need to be replaced? They are intact all the way round but are perhaps evenly worn. Would be surprised if dryer this new (certainly <5 yrs) would wear out such an inaccessible part so early in its life.

Can the internals of the two fans be accessed? They look like they are part of large plastic assembly at the base of the dryer which cannot be easily disassembled without taking all the metal panels off and the motor.

Does the fact that it will run all day long on cold air setting (without noise) not suggest other possible (non-mechanical) causes?

Thanks again.

D.