Q for those with Webasto Thermo Tops

When you start the Thermo Top itself (with the engine not switched on) does the Webasto Heater's Water-Pump have enough pressure & flow to visibly flow coolant water into the engine bay coolant reservoir?

Reason I ask - Webasto Trying to diagnose why my Webasto Thermo-Top C heating system fires up, gets really hot on the Heater's exhaust, then after a few seconds of highest heat, switches to a cool-down and switch-off cycle - I can't see any of the orange anti-freeze coolant flowing into the coolant top-up reservoir, so wonder if the pump is broke or bunged up.

What if your engine is running? Eg. Start webasto then mid startup cycle turn on engine. There should be enough coolant flow through it from the engine to give you an idea? Is it a new install?

You may have a dodgy glow pin. Short answer is the webasto changes its function once the heater is running. On start up it ignites the fuel but once running it monitores the resistance of the pin to check it's still hot enough to ignite the fuel. As yours is getting hot and then cutting out, it sounds like it's not detecting properly.

Check out daimlerkiwi's reply (#7) in this link http://forum.landrovernet.com/showthread.php/201160-04-Freelander-Fuel-Burning-Heater-PCB-Repair

Cetane said:

What if your engine is running? Eg. Start webasto then mid startup cycle turn on engine. There should be enough coolant flow through it from the engine to give you an idea? Is it a new install?

Click to expand...

It's the second-in-a-row I bought from fleabay, that is the sencond 'reconditioned' job from East Europe - the ones that come with the new wiring looms and a cheap chinese fuel pump (I fitted a used good Webesto fuel pump).

A cope of times when I have been driving with a hot engine, and switched on the Webasto, I have found the Webasto kept itself going and only went on the cool-down cycle when I parked up and switched off the engine.

Starting the engine from cold with a reset Webasto, no, it just fires up, the fuel pump ticks, the Webasto exhaust gas gets very hot, at which point it clicks off to a cool down cycle with lukewarm exhaust and purges white smoke.

Can you folks with working systems, please confirm if the Webasto Water Pump on it own (engine off) can circulate coolant up into the plastic Coolant Expansion/Fill-up bottle ?

Thinking of buying a water pump off the auction sites, but they are not cheap.

Again, I really would appreciate if any of you folks who have a Thermo-Top heater, would check if the Heater's Water-Pump alone (engine off) can circulate the coolant water up into the expansion/filling-up bottle. Mine doesn't, so I am wondering if the Water Pump has packed in.

Well, went ahead and bought a new Water Pump.

The Webasto (after a Lockout Reset) now kicks into life, the car's cabin fan comes on (the Webasto is also wired to work as a Parking Heater) I hear the familiar heartbeat of the Webasto-branded Dosing Pump clicking away (tested- it spits the fuel good and far)

The Webasto Heater, it builds up to, then stays on at full heat (by feeling the Heater's exhaust gas on my hands) a lot longer, just like it is working normally as a Parking Heater.

I can hear the Water Pump this time whirring away strongly.

I get my hopes up...

Then sadly, the sound of a Relay clicking behind the cabin fuse box (cabin fan being switched off) and it switches to the familiar smoky cool-down switch-off cycle.

Back to the drawing board. Working fast with Winter just a few days out...
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What is confusing me, is that I have 2 of these Webasto Thermo Top C units. Both bought as fully recon'd units. Despite swapping them over (using same ancillary components), the problem of the early switch-off is identical. I have replaced the Fuel Dose Pump with a good working Webasto unit, replaced the Water Pump with a good working Webastp unit.

I have not yet replaced the original Clock/Timer/Off-On unit that came with the original Webasto Heater (the original Heater itself was scrapped). Could the Clock/Timer unit in any way be switching the unit off when it gets going?

Just wondering on the next step - test-bed the lot in the shed?

....another question... The Lockout Reset Procedure - it mentions removing and replacing the "main fuse" a few times, then also mentions removing and replacing "Fuse F2" - my Fuse F2 (20 Amp) is in the Engine Bay fuse box - should I be removing the biggest of the 2 cabin fuses that link to the Clock/Timer when it says 'main fuse"

Well I took it off the Freelander and stripped it all down in the shed.

I set it up as a crude test-bed. When switching on, I get the water turning over nice, but the Combustion Fan stays on at a very high speed, bloiwing cold air. No signal to the Doser Fuel Pump.

Stripped it down. Not as much coke as I thought there would be, quite clean.

The Glowpin registered zero resistance (a short ?).

Strangely enough, when connected directly to 12v, the Glowpin does seem to work, it glows a lovely red colour.

If I connect a 12V 5W bulb parallel across the Glowpin terminals, I understand that may 'fool' the system to keep it working?

Is this right? If the 5W bulb will do this, would that be a sort of permanent fix if I can site the 5W bulb somewhere safe and easy to replace?

Well I connected the little 5W bulb across the GlowPin terminals.

On switching on the Heater, the light comes on for around 1/4 second then goes out.

The Heater system remains the same state on not working.

The PCB looks very different from the images on French Mike's original repair article.

Not showing well on the photo, this (Reconditioned?) unit PCB has a thick layer of laquer-like varnish all over everything.

Think all I can do now is risk a new GlowPin and see if that works.

Hope you folks don't mind me talking to myself ;-)

Now with the first proper sub-zero temps, the Heater won;lt even begin a fire-up procedure. Just the cabin fans switch on, no life from the Webasto.

The Webasto looks hungrily at my wallet. Now looking into alternatives as pre-heaters.