E320 CDI Heater Auxilliary Pump

[Griffo]

I have a 2000 E320 CDI with defective heating (luke warm, at best). I have read somewhere that the duo valve system has an auxilliary pump driving it and wonder if this may not be working? I have tried disconnecting the power to the duo valve, which I think should result in maximum heat, but it's still luke warm.

Any thoughts please?

 

[Ellsy Tanners]

If your car is a 211 then you will have a faulty eletronic shut off valve.

 

[230K]

Hi

Year 2000 will be a 210.

230k

 

[panason1c]

I have a 2000 E320 CDI with defective heating (luke warm, at best). I have read somewhere that the duo valve system has an auxilliary pump driving it and wonder if this may not be working? I have tried disconnecting the power to the duo valve, which I think should result in maximum heat, but it's still luke warm.

Any thoughts please?

The engine not reaching its normal working temp of at least 80 degrees (due to a defective thermostat) is one reason for a lukewarm heater..........

 

[television]

The engine not reaching its normal working temp of at least 80 degrees (due to a defective thermostat) is one reason for a lukewarm heater..........

I agree here this is the first thing to check

 

[Griffo]

Thanks for the replies. Yes it is a 210. The dashboard temp. reading is 80 degrees at normal running, should I trust that?

 

[Griffo]

When you say -'the first thing to check', can you please say if you mean there is a way to check if it's stuck open, or do you mean - change it anyway?

I presume that I should ignore the dashboard reading?

 

[Griffo]

I'm told the operating temperature is fine at around 80 degrees, so doesn't look like it's the thermostat.

Apart from the duo valve, there are two other components in the engine bay, that appear to be linked to the heating system. The top hose going forward from the duo valve, goes down to another item (looks like an 'old-style' electric fuel pump), mounted on the O/S chassis leg. Is this the Auxilliary Pump??

There is a hose running from that to a large item mounted on the inside of the wheel arch - what on earth is that??

I have photos of these items but don't know how to attach them?

 

[panason1c]

I'm told the operating temperature is fine at around 80 degrees, so doesn't look like it's the thermostat.

Apart from the duo valve, there are two other components in the engine bay, that appear to be linked to the heating system. The top hose going forward from the duo valve, goes down to another item (looks like an 'old-style' electric fuel pump), mounted on the O/S chassis leg. Is this the Auxilliary Pump??

There is a hose running from that to a large item mounted on the inside of the wheel arch - what on earth is that??

I have photos of these items but don't know how to attach them?

The auxillary pump wouldnt affect the output from the heater, it is there to continue circulating the coolant around the engine for approx a ten minute period after turning off the engine, this helps the engine to cool down 'evenly'.........The pump also works in conjunction with the 'Rest' function (if fitted) by using the residual heat from the stationary engine via the coolant to keep the passenger compartment heated for a limited period of time.

My aux pump had previously failed but it had no detrimental effect on the efficiency of my heater as the main source of coolant circulation is by the engines water pump.

 

[Dunhamkid]

Its the booster heater, which is electrically powered. The tank on the top is the vacuum tank

 

[Griffo]

Thanks for the reply.

Its the booster heater, which is electrically powered. The tank on the top is the vacuum tank

What does that do please? Is it likely to be a possible suspect for my problems?

I am experiencing great difficulty in getting any specific guidance on this problem - it seems the heater system is an area of 'mystery'!

 

[Dunhamkid]

The booster heater is an element type heater (I think) that heats the engine coolong water up when the outside temperature is below 7°C as CDi engines do not warm up quickly due to their efficiency. You can switch it off by means of the switch next to the ashtray. I'm not sure whether mine works or not but maybe I have to alter the heating controls to max before it operates?

 

[Griffo]

Ah, yes, I have a switch inside the ashtray - I've not noticed any speed-up in getting the engine to working temperature. I have certainly noticed that this car takes ages to get to 80 degrees, whereas my old E280 (124) used to start giving warm air after about 1/2 mile of driving!

I am completely lost on what to do to try to get my heating working properly. I get 'reasonable' heat if I disconnect the wires to the duo valve but totally irratic and pretty poor heat when the wires are on. Sadly, nobody seems to know what the problem might be! I certainly don't feel inclined to do what the garage suggested:- change the duo valve, then if that doesn't work, change the dashboard controls (and hope that fixes it!).

The cost of all that is probably enough to persuade me to get rid of the car!

 

[Griffo]

One last try ...

Yesterday, I stripped the duo valve (again) and re-assembled it after thorough cleaning. I got the car up to about 60 degrees and the top hose going to the duo valve was quite hot. However, the bottom hose was cool and both of the bottom hoses at the rear (going to the heater?) were cold. Furthermore, the hoses in and out of the Auxilliary Pump and the Booster Heater were all cold.

This clearly can't be right and putting the wires on or off the duo valve seemed to make no difference.

Surely someone out there must have some idea(s) what is wrong .. please?

 

[JEZ.S320L]

Its the booster heater, which is electrically powered. The tank on the top is the vacuum tank

The heater booster has nothing to do with heating the engine up. It is an independant unit that warms up the INTERNAL temperature of the vehicle.

 

[Griffo]

The heater booster has nothing to do with heating the engine up. It is an independant unit that warms up the INTERNAL temperature of the vehicle.

Oh, I see, thanks. It's obviously not working though (like the rest of the heating system!), as the hoses to/from it stay cold. Pity, it might make the cabin bearably warm!

From the number of threads about defective heaters (and the apparent lack of successful remedies) it seems this is a big flaw with Mercs. My old E280 (W124) was brilliant, this car is a big disappointment.

 

[JEZ.S320L]

Oh, I see, thanks. It's obviously not working though (like the rest of the heating system!), as the hoses to/from it stay cold. Pity, it might make the cabin bearably warm!

From the number of threads about defective heaters (and the apparent lack of successful remedies) it seems this is a big flaw with Mercs. My old E280 (W124) was brilliant, this car is a big disappointment.

The heater booster is an independent heater that runs off diesel - hot or cold hoses have nothing to do with its operation. My understanding, is that it is situated near the passenger headlamp. On mine, it works perfectly - especially when the outside temp is around 8C or below, the temp set to max and the blower to 3 or 4. Toasty warm in a couple of minutes

 

[Griffo]

In that case I'm even more baffled. The item I'm referring to has a hose coming up from the auxilliary pump and is mounted on the inside of the O/S wing. I would attach a photo if someone would kindly tell me how to do it?

 

[JEZ.S320L]

In that case I'm even more baffled. The item I'm referring to has a hose coming up from the auxilliary pump and is mounted on the inside of the O/S wing. I would attach a photo if someone would kindly tell me how to do it?

When you say 'auxillary pump', can you explain a little more please?

If you can hang on, I'll go and get Television to see if he can shed some light on it.

 

[230K]

Hi

The auxilary pump is the little electric circulation pump that circulates the coolant around the heating system. Sounds like its stuffed. If it is not making noise pull the plug off it and make sure its getting power if it is and its not pumping its defo stuffed.
The one on the wifes 124 is gone too, quite expensive from memory thats why i never replaced hers. Her engine sometimes needs revved to get heat to the inside if for example the car is sitting in traffic for long.

230K