Eberspacher D4 Heater only runs for a short period. I've checked everything...

HandmadeMatt

HandmadeMatt

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Hi, are there any Eberspacher experts on here?

The History:
It's a secondhand D4 in good condition that was demonstrated on a bench before I bought it. I fitted it to my Mercedes Sprinter campervan and it worked really well for over a week being used and tested everyday.

The symptom:
One night after many hours of heating the heater turned itself off for no reason and we were left freezing. Since then every time I turn it on it starts first time, roars away up to full speed and gets nice and hot. After 12 - 15 minutes it starts slowing down again, it goes down through the heat settings and the pump slows down until eventually it turns off but the blower remains on minimum. This is despite having the thermostat on full all the time.

I removed the heater and have been testing it without any ducting or combustion silencing but the problem persists. I left it disconnected from the power for 24 hours to see if it would reset.

I have also serviced the heater with new gaskets and a new glow plug screen. There was very little carbon build up in the combustion chamber. It all looks as good as new.

The fuel:
I have a good rapid squirt coming from the fuel hose when unplugged from the heater inlet during start up. I have performed a fuel quantity test and get 5.3ml on the first start up attempt, but less on the second attempt. The manual doesn't refer to the second attempt and instructs only to measure the first. 5.3ml is well within the acceptable range. The pump is mounted correctly too. (Angle.)

The overheat sensor measures the correct resistance at room temperature when measuring both sensors according to the manual with a multimeter.

My control panel has a wheel dial on it and one switch. When switched on there are two lights. A green one and a red one. They never change from a solid on.

Nothing has worked.
What is the next thing to check?

This is the controller that I have:


Thanks.
 
HandmadeMatt said:
Hi, are there any Eberspacher experts on here?

The History:
It's a secondhand D4 in good condition that was demonstrated on a bench before I bought it. I fitted it to my Mercedes Sprinter campervan and it worked really well for over a week being used and tested everyday.

The symptom:
One night after many hours of heating the heater turned itself off for no reason and we were left freezing. Since then every time I turn it on it starts first time, roars away up to full speed and gets nice and hot. After 12 - 15 minutes it starts slowing down again, it goes down through the heat settings and the pump slows down until eventually it turns off but the blower remains on minimum. This is despite having the thermostat on full all the time.

I removed the heater and have been testing it without any ducting or combustion silencing but the problem persists. I left it disconnected from the power for 24 hours to see if it would reset.

I have also serviced the heater with new gaskets and a new glow plug screen. There was very little carbon build up in the combustion chamber. It all looks as good as new.

The fuel:
I have a good rapid squirt coming from the fuel hose when unplugged from the heater inlet during start up. I have performed a fuel quantity test and get 5.3ml on the first start up attempt, but less on the second attempt. The manual doesn't refer to the second attempt and instructs only to measure the first. 5.3ml is well within the acceptable range. The pump is mounted correctly too. (Angle.)

The overheat sensor measures the correct resistance at room temperature when measuring both sensors according to the manual with a multimeter.

My control panel has a wheel dial on it and one switch. When switched on there are two lights. A green one and a red one. They never change from a solid on.

Nothing has worked.
What is the next thing to check?

This is the controller that I have:


Thanks.
Click to expand...
I had a D2 with similar symptoms. The overheat sensor gave the correct reading when cold. The D2 will run with it disconnected, so I did that and the prob went away. I then had the confidence to buy a new one!
S
 
Possible problem......

The shut down you are experiencing could be due to the heater thinking it has reached max temp, or overheated.
Things to check..... how long is your ducting? Are there any tight bends, restrictions, constrictions. Has something fallen on the hose and crushed it?? Is there a mouses nest in it?

I had a right angle hood and 6 meters of hose.... this was too much and the heater always shut down after 1-2 hours. I replaced the right angle hood with a straight one and all is well.

Is there reasonable ventilation in the locker where the heater is..... if it gets too warm the heater will shut down... the overheat sensor needs a constant supply of cooling air or it will shut down.

OR....

It could be something way more complex like faulty ECU.....????
 
Alpha22 said:
Possible problem......

The shut down you are experiencing could be due to the heater thinking it has reached max temp, or overheated.
Things to check..... how long is your ducting? Are there any tight bends, restrictions, constrictions. Has something fallen on the hose and crushed it?? Is there a mouses nest in it?

Ditto the above classic symptoms

I had a right angle hood and 6 meters of hose.... this was too much and the heater always shut down after 1-2 hours. I replaced the right angle hood with a straight one and all is well.

Is there reasonable ventilation in the locker where the heater is..... if it gets too warm the heater will shut down... the overheat sensor needs a constant supply of cooling air or it will shut down.

OR....

It could be something way more complex like faulty ECU.....????[/QUOT

Ditto the above classic symptoms
Click to expand...
 
HandmadeMatt said:
but the blower remains on minimum. This is despite having the thermostat on full all the time.
Click to expand...

That is a "control idle" state rather than a shut down, the heater believes it has exceeded or reached the set point temperature on the dial and is sampling the incoming air temperature, it would normally fire up again when it senses a drop in air temperature but as it is not it is highly indicative of a faulty temperature sensor (not overheat as that would cause a true shut down) or an ECU issue. The basic resistance tests can be misleading, unless hooked up to EDITH so one can monitor the change in resistances over time they are not indicative of what is actually happening during operation.
 
Last edited:
I believe you can over ride the safety cutouts and run it without. If it runs OK, you could then re connect them and hence find which one is stopping it. Can't give detailed directions but there is plenty of info on the le tonkinois web site (strangely).
 
ghostlymoron said:
I believe you can over ride the safety cutouts and run it without. If it runs OK, you could then re connect them and hence find which one is stopping it. Can't give detailed directions but there is plenty of info on the le tonkinois web site (strangely).
Click to expand...
That was my belief and I did it. A manufacturer rep gave me a hard time about revealing that, but I argued that doing it on the bench as a trouble shooting regime was justified!
S
 
Indeed, I do it myself for confirmation, I do have a temperature probe attached to my test bed though and would not leave one unattended when doing that test. It is even more of an issue with later heaters made after the new EU certification requirements for overheat protection.


skipper_stu said:
That was my belief and I did it. A manufacturer rep gave me a hard time about revealing that, but I argued that doing it on the bench as a trouble shooting regime was justified!
S
Click to expand...
 
Alpha22 said:
Possible problem......

The shut down you are experiencing could be due to the heater thinking it has reached max temp, or overheated.
Things to check..... how long is your ducting? Are there any tight bends, restrictions, constrictions. Has something fallen on the hose and crushed it?? Is there a mouses nest in it?
Click to expand...

My ducting is only a couple of meters total. There are three vents, two permanent and one closeable but I've not really closed it ever.
There's two 90 degree bends just done with the ducting. There's also two Y pieces that separate to the vents.

The problem persists even on "the bench" with no ducting though....
 
The heater wouldn't run with both plugs removed from the ECU, it simply didn't do anything.
With the green one plugged in and the blue on left out the heater did fire up but then shut down again after 7 minutes.

So, I'm non the wiser and don't know what to try next.
Any help would be greatly appreciated.
Thanks
 
you can do a fair test on the heat/flame sensor but temperature is critical.

I hold the sensor against a warm body part which I assume is at blood heat and check the resistance against the spec. It seems to work and will certainly identify a sensor which is way off spec.
If I have a good ECU you can borrow it to try if you want.
 
pcatterall said:
you can do a fair test on the heat/flame sensor but temperature is critical.

I hold the sensor against a warm body part which I assume is at blood heat and check the resistance against the spec. It seems to work and will certainly identify a sensor which is way off spec.
If I have a good ECU you can borrow it to try if you want.
Click to expand...

I'm pretty sure that my temperature sensors are within the resistance range. I used a thermometer to maintain a twenty degree ambient temperature and left the heater to equalise at that temperature for over half a day and then took my measurements.
That's very kind of you to offer an ECU. It would be nice to eliminate that from the checklist if it's the next thing on the list. I'm in Surrey though...
 
HandmadeMatt said:
The heater wouldn't run with both plugs removed from the ECU, it simply didn't do anything.
With the green one plugged in and the blue on left out the heater did fire up but then shut down again after 7 minutes.

So, I'm non the wiser and don't know what to try next.
Any help would be greatly appreciated.
Thanks
Click to expand...
Ive found out that when they start doing weird things then the ecu starts to come in to the frame. Take Pete up on his offer.
S
 
pcatterall said:
12 or 24 volts I have either. I can post, I will insure it so it could be £10.
Cheers
Click to expand...

Thanks mate. I'll send you a PM.
Having spoken with Butler Technik they have recommended upgrading my controller to a digital one that will give me fault code readouts. It's a good idea.
Should I do that first? (It does mean spending money on a heater that's not working, that's my only reservation.)
 
Guys,
Once resolved how could I ensure that the fault doesn't repeat? Does my installation sound reasonable? If it is the problem is ECU failure just bad luck?

(There are two permanent vents and one closing one (although I'm yet to close it.) There's a total of 3.5 meters of ducting and two "Y" pieces to distribute to the vents. All the ducting is the same 75mm diameter. There are two 90 degree curves made with the ducting (not an elbow piece.) The ducting is insulated.)
 
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