W124 blower motor advice

[John Turner]

It is that time of year when problems with heater blower motors regularly get posted! I have searched old posts and realise the problem I have is common in enough in W124s (mine is a 1996 E300TD). The blower motors has been erratic, coming on some time after beginning a journey, and sometimes failing to come on at all. The blower has now stopped all together, although a slow current of hot air will still come through the vents while driving. The blower motor in my car was replaced in 2004 by the previous owner and so the current unit should not really be failing. There are some excellent guides to removing the blower motor eg: (http://www.mercedesshop.com/Wikka/W124BlowerMotor/show?time=2006-08-14+13:38:32become problematic)
but the job is quite a big one, involving removal of the wiper motor first, though relatively logical and requiring no special tools. I am prepared to have ago to save labour rates, but a new blower motor and the squirrel cages around the fans are expensive - too expensive to order one and have it ready should a failed motor be the problem. The usual problem seems to be worn brushes and a dirty commutator, and from all accounts, the chances of getting the motor going again after removal and a clean seem good. Other than the obvious (blower motor unplugged at bulkhead behind dash - observable under bonnet just above fuse box) or a blown or misalingned fuse (Fuse no 12 apparently can get hot and the contacts deform), the only other problem seems to be a failed regulator. Obviously I do not want to do the job twice, but without somewhere dry, I do not want to leave the car dissassembled should I have to order new parts and wait for them to arrive. I would be interested to hear how other people have got on with this repair, or whether they have left it to the experts? Is there a good success rate in getting the blower motor going again, if so, has anyone any advice / tips?
Thanks
John

 

[Bolide]

If the motor bearings are shot then a complete replacement unit is the only fix. Take the unit out and see how much play there is in the shaft. It runs in simple sleeve bearings so the shaft just wears away. If the fan is noisy it's probably fairly worn. Normally they rumble at high speed when worn

If the bearings are OK, unsolder the brushes leaving as much of the lead in place as possible. Source some brushes with the lead coming out of the correct face, file them to shape, fit them & resolder the connections. I've been told you should braze these & not solder them as solder will fail when the unit gets hot - I don't know the truth of this. Then test & refit the unit. Be careful when testing as they pull a lot of current on starting and generate a lot of torque

Before you remove the fan, disconnect the feed wires and put 12 volts across it. If it's good it'll spin up at high speed. If it won't start, give it a flick. If the brushes are worn it'll normally start with a flick

It's not a big job. All you need is a medium posidrive, an allen key for the wiper arm and a 10 mm socket for the wiper motor bolts. You may be able to get brushes from a Bosch Service Centre when you've removed the motor and have the part number

Don't forget to lubricate the bearings before you refit the fan. Also clean the fan housing, hoover out the underbonnet ducts, clean the rubber trim and the base of the screen, replace the pollen filter and fit a new front wiper blade. You know you've beeen meaning to...



Nick Froome
www.w124.co.uk

 

[Blobcat]

As for the solder you can get high temp solder for this type of application

 

[television]

As for the solder you can get high temp solder for this type of application

Very true, you also need a high temperture iron otherwise the joint will be dry and that's no good.

Malcolm

 

[Blobcat]

I took that as read, soldering iron rather than the clothes type is also useful.

 

[John Turner]

Many thanks Nick for your very helpful and detailed reply, and to Blobcat and Television for your additional advice. The blower motor was rumbling while intermittent, almost as though it was rubbing on the housing and this might well be a symptom of worn bearings. I will investigate the current cost of a replacement unit prior to beginning the disassembly, although looking at my car's file, I note it had a new blower motor (at a cost of £161.56 exc Vat) only 3 years ago, and so I am very surprised that it should have failed so soon, unless fitted out of true. This is in the 1996 W124 E300TD. I also have a 1989 W124 250TD which has always had a much stronger blower motor - nothing short of producing a tornado round the car on full position!
Regards
John

 

[Bolide]

I'd be interested in knowing the part number of the motor

Nick Froome
www.w124.co.uk

 

[John Turner]

The invoice for the failing blower motor does not give a part no, unfortunately (just 00001) which is odd because everything else does have one! It was fitted by a reputed MB specialist rather than the main dealer. The MB job notes indicate the unit will be a Siemens/thermal since the car has no air conditioning, which I think required the Behr blower motor. As far as I can tell, the Mb Russia site suggests that my car should have Blower part 0008308208. It will be interesting to see what is in there!
Regards
John

 

[stereo]

On the blower motor for the 300ce without a/c,does it have just one cage or two cages,side by side kind of confused,help please

 

[John Turner]

One I think. I have the new part but have not fitted it yet.

 

[stereo]

Thanks John,i previously checked the link on this thread but didn't relise that was for a 300ce with a/c,went to the breakers and refused the motor cos it only had one cage,i soon called back and will collect tommorrow,it's getting colder,thanks again

 

[John Turner]

Update on blower motor

I replaced the blower motor on my 1996 W124 300TD today. As others here have indicated, the job was straightforward. My car does not have AC. It did take me about 4 hours, but that involved a lot of careful cleaning of all parts, locating replacment missing screws/bolts and an attempt to get the old motor working. I had already ordered a new single fan Behr blower motor (Mercedes part #124 82033 42 at £161.18, from Euro Car Parts, Part #219220240, Behr #910 01328 - this time some £40 cheaper than the dealer, but often my dealer is cheaper than ECP.). This new motor was identical to the blower motor that came out. The old motor had a very dirty commutator and even after cleaning with electrical contact cleaner, it failed to work. The brushes looked OK though dirty. The bearings seemed OK but were a bit rusty, and there was corrosion on many parts of the blower motor which was surprising.
My car differed a fair bit from the descriptions given in:
http://www.mercedesshop.com/Wikka/W124BlowerMotor/show?time=2006-08-14+13:38:32
In particular, there were no metal strips below the windscreen, and the seals around the wiper assembly were integral and did not come away as individual pieces. Also, the motor was a single fan unit and not a double fan unit.
The well below the motor contained shards of broken glass, no doubt from the removal of a previous damaged windscreen. A number of screws and bolts were missing. I suspect these lost after a window replacement since a number of components were incorrectly fitted. I am beginning to wonder whether my blower motor had failed (it was after all only 3 years old) because of water ingress resulting from poorly fitted components by a windscreen fitter. I took a lot of care to put it all back together correctly. It was satisfying job and I have saved myself a very large labour bill - although my work rate will never get me a job as a Mercedes Mechanic!
John

 

[Bolide]

For other people reading this thread:

The metal clips on the windscreen seals were only on early cars. The later ones just press in and take a lot of cleaning before they'll fit properly

There is more than one design of the plastic assembly under the windscreen. The most brittle bits are the two white plastic clips that secure the outer sections to the centre

I haven't figured out why some cars have a dual fan and some a single. But aircon cars seem to have the double one

A telescopic magnetic probe is very useful for retrieving the nuts & bolts that inevitably drop into the fan housing, and a vacuum cleaner with a long nozzle is handy for removing all the grit & bits of leaves that find their way in there

Final thing to do is to replace the pollen filter that should sit (in two parts) on top of the fan assembly and in between the two halves of the case

Lots of fun...

Nick Froome
www.w124.co.uk

 

[John Turner]

Thanks Bolide, and thanks for earlier advice.
I am relieved to know that my metal strips were not missing! The plastic ducting parts for wash water & rain run off screwed directly onto the bodywork under the window using self tapping screws and brass clips. There are holes unused closer to the wiper mecahnism. My white clips were good, although one was loose and free, and I cannot fit it - I think the projection it fits over on the underside of the ducting is mishapen, and I do not want to force it and break it. I'll try another day. I agree that cleaning the window seal is essential to get a tight fit. My car had no pollen filter despite being a late model - I hope that this is normal and nothing is missing -please advise! (my car is a W124 300TD 191 - late95/early96). I managed the whole job without dropping a nut - that is why it took me so long! With one fan, there is a lot of free space in the well. I understand that the twin fans are on air conditioned models. The fan blows well and is appropriately variable, although it takes a while for hot air to come through after start. My W124 250TD is much faster to blow hot.
It is amazing how much more solid the 1989 W124 estate is than the 1995 W124 - small things like thickness of plastics, number of fittings (eg the metal strips under the window) and so on. No doubt reductions in weight / emissions and costs are the reason.
Regards
John