W124 320CE Engine Loom replacement

[fredbenz]

The original engine loom on my 1994 320CE needs changing. I've read that the job is relatively straightforward if done carefully and methodically and that the job can even be done in around a couple of hours.
Having examined the existing loom in situ I have to say that it is very very snug between the battery compartment /area and where the loom comes through the firewall. Rather worryingly there is a lot of cabling squeezed in that confined area as well as rigid metal pipework and hoses too. I don't think that I could extract the loom without significant dismantling of the plastic that is tight behind the firewall [where I believe the pollen filters and heater blower live]. I can't recall anybody ever mentioning that they had to remove these things though, in order to change their engine loom - hence this enquiry. I'de be grateful for some help please on the optimum way of extracting the loom from this model.

Regards

Steven

 

[grober]

[YOUTUBE HD]kz6K1v2R13Q[/YOUTUBE HD]

 

[coupe addict]

Take all the plastic and rubber gubbins out, it will be quicker in the long run. This is your golden opportunity to change the pollen filter, a worthwhile job but one for which most people feel that life is too short. If your heater fan rattles, change the motor at the same time - it's a trivial job with everything out, and an unbelievable bore otherwise.
Steve

 

[bolide]

It's not an awful job but the knock sensors are really difficult to get to. You'll need two people for that bit

Nick Froome

 

[fredbenz]

It has been a dull and damp day here in darkest Wiltshire so I took the opportunity to make a start on extracting the engine loom. Good news is that removing the 'plastic and rubber gubbins' behind the firewall has indeed made enough room to get the loom out between the firewall and battery compartment - thanks very much for such sound advice. Having removed the plastic and rubber gubbins there is no sign of any pollen filter [car is 320CE registered 1 Jan 94] or even a filter housing in the area of the wiper and heater blower so I assume that it doesn't have one. Also, having exposed the area under the wiper, I've had a good look around & it seems to me that the casing surrounding the heater blower is in effect a ventillated box that is pop riveted to the scuttle............ is the motor likely to be accessed through the cabin?

Being new to Mercedes I have to say what a pleasure it is to work on something with real build quality [nothing broke during the dismantling].

regards

Steven

 

[coupe addict]

Pollen filters are aircon only I think, and obvious visually if present. Fan should be visible to you at this stage, with simple bolt fittings (provided that your arms are long enough). I believe some early models had access from the footwell, but not yours I think.
Steve

 

[bolide]

W124 fan access is always via the engine bay. The heater box goes through the firewall and the fan assembly is on the engine bay side of it

AFAIK the fan in footwell story comes from another MB model

Pollen filters are on some cars and not others - I don't think it's related to aircon

There are more variations in the fan / pollen filter / fan housing / mounting / retaining clips assembly than in any other W124 part I've seen. The fact that a fairly large proportion of cars had aftermarket aircon makes it hard to predict what you'll find. Each car is different

Nick Froome

 

[fredbenz]

Thanks to all who have kindly offered advice which has been very valuable indeed. Seems I have been fortunate because on my car the knock sensors have leads permanently attached making their actual disconnections from the loom some distance away from the fixings on the block and hence quite easy to do by comparison! Anyway the loom is safely out of the car and nothing got damaged.
It has been suggested that I remove, inspect and lubricate the heater blower while I have the opportunity............here I'm probably not so fortunate, as my car doesn't have the central strap fixing and single motor arrangement with twin squirrel cages, it has two separate blowers each independently and heavily enclosed [much in the way that jet engines on aircraft are]. Space is tight and visibility poor in the area and I simply can't fathom how to detach each of the these blowers from whatever their fixings are [suspect that the fixings must be either underneath each blower or otherwise on their side where they each touch the firewall. Even the electrical connections appear to be under the twin blowers. Has anybody got experience of this set up? If so advice would be welcome please - I don't want to break anything and suspect that a trial and error approach just might. Incidentally the outer casing that the heater blower occupies is unlike any I've been able find images of anywhere - perhaps proving the wisdom of Nick Froome's comments on the numerous permutations across the model range.
Thanks for your patience which is much appreciated.
regards
Steven

 

[hotrodder]

Post a pic of what's visible and someone may recognise the set up you have. As Bolide said there's loads of variations in this area with w124s even with 'factory' aircon and lots of them had aftermarket/dealer fitted systems some of which can't be got at without taking the dashboard out or being a bit brutal... How to bodge-up a w124 fan with after-market aircon - Mercedes-Benz Owners' Forums

FWIW my '93 has factory aircon, the heater box is Behr and it has no provision for pollen filters. The twin cage squirrel fan motor is Bosch but that doesn't mean any twin cage Bosch fan fits for example...

Mine uses the lower style, the top one won't fit unless the cages are swapped over and even then the motor shafts are different lengths, one side too short really

 

[fredbenz]

Ah ...............the fog is lifting. I've been looking for factory fit aircon not realising that aftermarket W124 aircon was so common and hotrodder has prompted me to widen the my search. The 2nd picture within the post from robparker, that hotrodder has kindly provided a link to, is the very same heater blower outer casing that my car has and it seems that casing is a non aircon one. I've managed to track down the datacard for my car and aircon is absent from the list - this looks conclusive to me.
From what I can see on my car the twin blower arrangement I have is definitely different to that shown within the 3rd picture of robparkers post and I'm becoming resigned to the potential that my blowers might, after all, be fixed from within the cabin. For the present nothing actually compels me to have to get the blowers out, they work fine, so I'll probably just apply a little ATF to the motor spindles [which will be a laugh as I'm no contortionist] within the limits of what is accessible.
Getting back to the engine loom itself, I'm having a loom made up by Simon Lambert of Sileck who has received favourable comments from other W124 owners that Simon has helped. I'll let you know how it goes.
regards
Steven

 

[bolide]

If you want to get at the fans from the passenger compartment you'll have to remove the steering wheel, radio, ashtray, centre console, heater controls, heater switch assembly, dash switch assembly, airbag, lower dash, dash, vent pipework, heater bowden cables and heater water pipes

And degas the a/c and remove the a/c pipework from the evaporator

Then strip out all the trim in the engine bay above the heater box to allow you to get at any fixings on the firewall

Then you have to remove the heater box from the firewall and extract it through the car. Then you may be able to get at the fans

The fans are on the engine bay side of the firewall. Accessing them via the car interior isn't a good idea

Nick Froome

 

[hotrodder]

The fans are on the engine bay side of the firewall. Accessing them via the car interior isn't a good idea

Nick Froome

Did you see what Rob Parker had to do to access the fans from the engine bay in the link i posted? I would have done a similar thing rather than rip out the entire dash but unless Rob missed a trick you'd like to share it seems pretty clear that with at least some of the aftermarket set ups the airbox was bolted or rivetted from the dashboard side of the bulkhead i.e. cut the thing open to get at the fans or take the entire car apart

 

[fredbenz]

I promised an update after the engine loom was removed, rebuilt and re-fitted. Thank to al who provided earlier responses - much appreciated. The engine loom was sent to Simon Lambert at Sileck who rebuilt the loom with much attention to detail evident. The cost was less that £400 including delivery and the loom fitted like a dream, a real testament to Sileck's fine work and clearly an exact reproduction of the original. The car fired up immediately to my great relief.
Simon even put a couple of 'flags' with written directions on 2 connectors that I had found not connected to anything when removing the original loom.
I've found Simon to be very helpful indeed, he clearly has a fondness for and wealth of knowledge on the W124.
I hope that others in the same predicament I was in find this helpful.

Steven