E320 CDI Heater Auxilliary Pump

[dieselman]

There are 2 thermostats listed for your car 87 deg and 92 deg. I have to say i thought 80 was the running temperature for 320cdi in a 210 but obviously not.

87-C UP TO ENGINE: 30024536
92-C FROM ENGINE: 30010848

 

[panason1c]

It hadn't ocurred to me to try to revive it, I will have a go - nothing to lose!

That's exactly what i thought....nothing to lose!

Also, i served my apprenticeship during the earlier years when the first priority was to repair where possible rather than replace regardless!

 

[47p2]

I never knew I had a problem with my temperature as the needle of the gauge was sitting smack bang in the middle. This would be the normal position for most vehicles, but in typical Mercedes style they have to be different.

Keep us posted as to how you get on with your project

 

[Griffo]

Well I had a go - when I stripped the aux. pump it was completely rusted up inside!

Firstly, the electrical end - the brass bush that the 'axle shaft' (excuse my terminology!) ends in, was siezed onto the shaft and the brushes were almost worn out. Also the commutator was black!

The metal plates around the outside of the 'windings' (sorry again!) were very rusty, as were the two half-magnets that they turn inside of.

The ball race that the shaft goes through into the outer magnet (front), which drives the impellers, was siezed also!

All in all, a terrible mess and the whole thing was locked solid!

I was determined to have a go though, so I carefully introduced WD40 and rust-penetrating oil to the siezed bushes and bearings and eventually managed to separate the parts and get the shaft rotating freely.

I cleaned everything up using wire brushes, emery paper, oil, etc. I then carefully re-assembled it. The shaft was spinning quite freely by hand but it couldn't be called 'smooth and quiet', I believe the front bearing is fairly bad.

Anyway, I connected it to a battery and it worked - how good is that?? It's now back on the vehicle and running but not very smooth and quiet. Frankly, I doubt it will last very long and, sadly will have to be replaced.

However, for those who are inclined and whose pumps haven't had the ingress of moisture that mine must have had - this is well worth undertaking as Panason1c has proven. If one as bad as mine can be resurrected, one with just worn bushes and dirty commutators (most of those that pack-up, I suspect), would be fairly easy to repair.

So that's the current condition of my Aux. Pump and my duo valve is sort of working, thanks to PTFE tape around the valve stem seals plus small sections of cocktail sticks (wound with PTFE tape) sealing the insides of the tops of the valve stems! Bodger - me?, how dare you!

Bottom line is, sadly, I need a new duo valve, a new Auxiliary Pump and (I suspect) a new gearbox mounting, so a few pounds to be spent, but I've learned quite a bit!

 

[Griffo]

Dieselman - thanks, I will check my engine number to see which I should have. Certainly looks as though it needs changing though.

 

[Griffo]

87-C UP TO ENGINE: 30024536
92-C FROM ENGINE: 30010848

My engine number is 61396130028250. So I'm puzzled. Did you mean 92 C from 30010848 up to 30024536, then 87 C from 30024536? In which case mine would fall in the 87 c range??

 

[Bolide]

As these parts are subject to revision, and the recommended part may change retroactively, I'd say you need a 92 degree stat as your engine number is greater than the 92 From: number

Nick Froome
www.w124.co.uk

 

[mlawson]

Residual Heat not working

I have read this thread with interest. I have a W203 C220 CDIwhich has a similar problem, but it appears to be electrical. When I activate the REST function I can hear the air vents change position and the fan goes to a low speed, but after a few minutes all I get is condensation building up on the windows. Closer investigation revealed that the auxillary coolant pump was not working.

I checked the voltage across the pump (with REST on) and it was 0v. I have checked ground continuity to one side of the pump (ok) and measure about 13kOhm resistance between the 12v end and ground (with the pump disconnected). So far I have been unable to trace the wiring back, but believe it goes to the SAM module on connector M15.

The next thing I tried was powering the pump independantly, just to see if it worked. I powered it from a separate battery and I can feel coolant circulating in the system. Also, when I activate REST the condensation doesn't build up.

Therefore, I conclude it must be a problem with the pump control circuitry. The pump is obviously working, but is not being activated for some reason. I do not know why.

I have checked battery voltage, 12.9v - so should be ok.

Is there a fuse or a relay that drives this pump?
On WIS the wiring diagram doesn't show any and the 13kOhm resistance suggests it is transistor switched.

BTW - the mercedes dealer thought it was because the coolant preheater wasn't working. Apparently they checked the pump on STAR and it worked fine, but quoted me about £300 to check the preheater (located behind the starter) and another £300 if I need to replace it and wanted the car for 2 days. However, I am not convinced this is the problem or is necessary as the pump never works, irrespective of the coolant temp. Also I thought surely it should be possible to check the heater is working by measuring the current it is consuming (or not).

Does anybody have any thoughts or guiding light on this as it is one of those niggling faults that is getting at me - particularily at this time of year.

Many thanks in anticipation
Mark
W203 C220 CDI (2002).

 

[Griffo]

mlawson

I probably can't help you much (at all?) here, as I have been trying hard to get answers myself. When my 'indie' was having a look, he established that there was no current going to my pump, which for a brief moment gave me hope that it might just be that causing the pump to not work.

He located and changed a 10 amp fuse, in the main holder (inside f/o/s wing panel in engine bay) - No 4 on my vehicle. Could this be the problem with yours?

Best I can do , hope it helps.

 

[mlawson]

I had a quick look on WIS for your model and I can see a fuse 4 rated at 10A, the M13 pump also appears to be controlled via a relay. However, on mine (W203) there is neither a relay or fuse on the wiring diagram.

I have traced the wiring to connector M15 pin 4 of the front SAM & fusebox and there is nothing between this and the pump (i.e continuity is present <1ohm). The fuses number 43 to 65 on this, I have checked those that I can visually and those I haven't appear to have notihing to do with the aux pump or AC system when I look at their function on WIS.

Assuming there must be a fuse somewhere, I assume it must be driven direct from the AC controller, which will be fused.

I will be taking my car into the dealer to have a central locking motor replaced on Wednesday, while it is connected to STAR I will ask if they can spend half an hour or so on it and see where it goes.

If I end up having to replace the AC controller or SAM I will probably leave it be, but for the sake of a loose connector or perhaps a hidden fuse somewhere along the line it would be worth having it fixed. I did disconnect the AC controller a while ago when I retroffited SatNav but I don't think REST was working before then anyway so it won't be that.

I think I am starting to waffle.

The alternative of course would be to just construct a homemade timer to just switch the pump on for 30 mins after shutdown. Did it a while ago for a coolbox controller but it knackered my battery so a redesign would be in order.

Hope you get your problem sorted.

Finally, Happy New Year.

Regards
Mark

 

[panason1c]

Just worth mentioning that on my 2002 ML the ecu blower/cooling fan which is situated in the fuse box under the bonnet works in conjunction with the aux/rest pump.......i noticed that after engine shutdown and the aux pump turns off after its 10 minute cycle... the ecu cooling fan turns off with it!

That suggests to me that they are both switched from the same source..........

Worth a check to see if your ecu fan is operative .......if my theory is correct then that won't be working either.

 

[Griffo]

Back to the thermostats for a moment, if I may. I've been giving this matter further thought - once the thermostat is fully open (at normal engine temp.), surely from that point on, the temperature is controlled (ultimately) by the electric fans, in warm/hot weather?

So even if my thermostat is wrong and opens fully at too low a temperature (ie; 80 C), on hot days the operating temperature should rise to the point where the fans cut in (in traffic for example)? I don't remember seeing my temp. guage reaching as high as 92 C last summer; I'm sure I would have noticed if it did.

I'm sure I'm missing something fundamental here - straighten me out please?

 

[maddog]

Back to the thermostats for a moment, if I may. I've been giving this matter further thought - once the thermostat is fully open (at normal engine temp.), surely from that point on, the temperature is controlled (ultimately) by the electric fans, in warm/hot weather?

So even if my thermostat is wrong and opens fully at too low a temperature (ie; 80 C), on hot days the operating temperature should rise to the point where the fans cut in (in traffic for example)? I don't remember seeing my temp. guage reaching as high as 92 C last summer; I'm sure I would have noticed if it did.

I'm sure I'm missing something fundamental here - straighten me out please?

The fan on your car is on a viscous coupling and is spinning all the time so its unlikely the electric fan will cut in if everything works as it should or even if the thermostat is stuck open.

If you thermostat is knackered so is mine and mine has been like it for 6 years

 

[panason1c]

once the thermostat is fully open (at normal engine temp.), surely from that point on, the temperature is controlled (ultimately) by the electric fans, in warm/hot weather?

I'm sure I'm missing something fundamental here - straighten me out please?

The engine temp is controlled by the thermostat.
The operation of the thermostat is variable......it is constantly varying the flow of coolant around the engine to maintain a consistent engine temperature of around the 80/90 degrees mark by opening or closing in varying degrees.

The electric rad fans come into operation when the engine reaches a predetermined temp usually because airflow through the radiator is too low (ie....when in queuing/stationary traffic) to cool the engine which would otherwise overheat even with a fully open thermostat.

 

[Griffo]

Thanks, pretty much what I believed already. However, my point is about "the predetermined temperature" for the fans to operate. Surely, this temperature level is set only a few degrees above optimum (normal running), to avoid damage.

If this is so, it seems that quite a few people here (most?) are finding their cars running around 80 degrees, which suggests their fans are cutting in around this level, when required. Isn't that an odd coincidence?