Water Heater - Glow Plug Coolant Heater.

[polar]

I understand the point made about cold engines and emissions.

The coolant heater would be a help in heating the engine up that little bit quicker, but as the coolant passing through it is routed through the heater matrix before it reaches the engine surely any heat will be absorbed by the heater matrix and therefore not reach the engine.

I'm interested in under what circumstances the heater operates, you would assume that if the ECU is putting out a signal to tell the engine glow plugs to come on (3 minute post heat cycle) that it would be classed as cold enough to put the coolant heater on?

Not quite JJ a post heating comes on at a much lower temperature as far as i am aware than the coolant heater. However i never managed to find out what ambient temperatures the secondary heaters fire up - they may rarely do so in the uk. The cylinder heaters help the diesel complete combustion when the engine is cold mainly as we know for emissions and to stop unburnt fuel damaging the cat.    

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[jj9]

I'm not sure of the exact operation of the post heating system on the 2.0 HDI, but I do know how it works on my 1.6 HDI which I would guess would be quite similar?

I know the info below is correct as I have a LED on the dash that is wired into one of the glow plug connections so I can see when they are on 

The post heat comes on for 3 minutes, this happens every time the engine is started from cold (coolant below a set temp) during this 3 minute cycle if the coolant reaches it set temperature the post heat is turned off. (Not sure of the exact coolant set temperature it may be 60 degree C or so)
If the coolant is above the set temp there is no post heat.


Now if the post heat system has the engine glow plugs on for 3 minutes after cold start up to reduce emissions you would think the coolant heater would also be working to get the engine up to temp ASAP to reduce emissions if that's what it is designed to do.

Possibly the power load of 8 glow plugs (4 engine - 4 coolant heater) is too much load at one time.


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[Jed Clampit]

I thought the heater on 1.6 HDI is there to help deice the wind screen in just two or three minute's that the way it work's on mine ??.

[polar]

I thought the heater on 1.6 HDI is there to help deice the wind screen in just two or three minute's that the way it work's on mine ??.

Well i would have thought anything that helps heat the coolant up quicker and gets the heater hotter faster would do exactly that Jed - however i doubt that is the primary reason for a coolant heater more like a nice secondary outcome. I may be wrong though - my piece of junk Ford Mondeo had them and that had a heated windscreen (about the only thing that was any good on the car )

[jj9]

Let's forget whether the coolant heater is fitted with the intentions of helping to heat the engine or to get heat into the cabin quicker as it's irrelevant, what we are trying to figure out is under what conditions it operates.  


I may have to wire another LED indicator up and connect it to the coolant heater so I can monitor if & when it operates.  


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[jj9]

I thought the heater on 1.6 HDI is there to help deice the wind screen in just two or three minute's that the way it work's on mine ??.

If your vehicle is a B9 it will not have a coolant heater like we are talking about and pictured in the first post in the thread.


It will however have an electric heater that is fitted inside the heater housing alongside the normal water heater matrix.

The electric heater heats up electrically so you can get heat into the cabin quickly.


It looks like this :

   


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[Jed Clampit]

Ha i see i knew it had one now i know which one it clear's the screen in two three min good one.

[ghost123uk]

I wish mine had one, would be very useful on these icy cold mornings!

[jj9]

Had a bit of a poke around this morning and found a black box behind the passenger headlight  that has a couple of relays in it along with two 40A Maxi fuses, one of which is blown. (circled in white in picture)

I assume that these, or maybe one of them is the relay & fuse for the coolant heater?

If it is, I think I may have blow the fuse the other day when I was checking out the coolant heater as when I was putting the crocodile clip from the multimeter onto one of the links between the glow plugs I got a spark, I think I must have shorted out the glow plug feed to the body of the heater.    I checked all of the fuses in the engine compartment fuse box and the one inside the car at the time and they were all ok but now I've found this one blown.

I don't have a spare fuse of this type so I'll have to get one.

[jj9]

Progress...

Ok, got a new 40A fuse and put it in, started the car up with the multimeter connected to one of the heater plugs of the coolant heater, initially there was no voltage present but after a few seconds the voltage showed up.

The information display in the car showed an outside temperature of + 8 degrees C so not freezing cold.

The coolant heater remained on until the coolant temperature reached approx 70 degrees C on the gauge.


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