Webasto thermotop (water) install parts?

[julianf]

Yours for postage, next time I'm at m'y old workshop, god knows when.

Thank you. I'd certainly take you up on that if / when the time comes.

Just to be clear - the control PCB is under the black cover on the unit itself. Some will have an external box on a wire with a screen or the like, but that's (normally) more of an optional extra / add on, rather than the essential bit.

With the right PCB on the actual burner all they need is a simple on/off switch.

Yours may be missing the PCB, but, if you're thinking it should / needs to have, another box, that may not be the case. It may be that all you need is an on / off switch wired in the right place?

 

[julianf]

... I got the pump swapped over to the one that was working years ago and it seems to spin up ok (it was pull down on pin 5, not pull up), but I've got no life from the pcb swap one yet, but that may well be as I'm not using the right pin to try and activate it. I'm tired of it for tonight though.

 

[chrisg3103]

interesting, i have just bought a rover 75 thermotop, the one that doesn't need a can bus signal. going to try retrofit to my Freelander as i like not being cold! can buy brand new kits from aliexpress for about £200 with the remote and stuff, picked up my untested one for 70 which seems extravagant compared to you spending's.
Many moons ago when i had my ZT i dabbled in repairing the pcb's of these, cant remember the values but there are a couple of surface mount resistors under the anti vibration goo on the tall capacitors that rot out. The fix is literal penny's and not too tricky if you can work a soldering iron.

edit - Just found the post - https://www.the75andztclub.co.uk/forum/showthread.php?t=53896

4.7Kohm and 47Kohm, pictures seem to have died though

 

[Barking Mat]

My Volvo 2001 v70, had one built in, but I never figured out if / how it worked, I'd just start thé car on the drive 10/15 mins before I left, job, jobbed.

 

[julianf]

Right, so, despite saying I was done for the night (and clearing up) it was playing on my mind, so I soldered up some more wires and had another go at the PCB swap unit.

All three units have different pcbs, but two of them are clearly the same, with the exception that one is missing one of the transistors (?) that sits under the sprung clip that screws through the PCB (anyone reading this later with the unit in front of them will know what I'm talking about).

As the unit without the transistor also has no pins in the socket where the circulating pump would attach, I assume that the missing transistor is concerned with driving the pump.


Anyway, the third PCB looks totally different from the other two, and it's this one I swapped.

This is the outside of the unit that I'm now dealing with -

Its a rover 75 unit, which I thought were all C, but this one is certainly a Z.

Anyway, post PCB swap, I got some life out of it.

Pin 3 going high kicks it off (again this isn't really a rover 75 unit any more though)

Again, on my other working unit, it's pin 5 going low that gives the action.


All I'm doing now is spinning them up, no ignition. But it's signs of life at least.

 

[chrisg3103]

Webasto FBH Useful Info : 75 and ZT Technical help for all derivatives - 75ZT Community

With the current weather making best use of the Webasto Fuel Burning Heaters (FBH) in our diesels I thought I might just clarify a few ...

www.75ztcommunity.co.uk

Might find this useful regarding the 98570b and pins, even though you swapped the board's

 

[julianf]

Webasto FBH Useful Info : 75 and ZT Technical help for all derivatives - 75ZT Community

With the current weather making best use of the Webasto Fuel Burning Heaters (FBH) in our diesels I thought I might just clarify a few ...

www.75ztcommunity.co.uk

Might find this useful regarding the 98570b and pins, even though you swapped the board's

Thank you.

In truth I didn't even attempt to use the PCB (which is the latter version on that site) as the Facebook seller had clearly been poking about and not bothered to put it back together, I just assumed it was bust or that they couldn't get it to work because of canbus control, however, the website you linked to states the bus is just for diagnostics on this unit, so it would have likely worked fine.

Maybe the need to manipulate two pins simultaneously on some versions is what stumped them? Or maybe it is broken.

If it fires up with fuel tomorrow I'm not sure what the likelihood of me bothering to swap the pcbs back again to find out is... Maybe I will as then I'll have a confirmed good spare if it does work.

Thank you again.

 

[blackolive (Ste)]

You probably know this but the glow plug thing is very low resistance, the unit measures it and if it thinks the glow plug is too high resistance it will not start ticking the dosing pump. Make sure the connections on the glow plug connector are nice and clean and tight. Mine packed in working and a clean of the connector with scotchbrite and contact cleaner sorted it

 

[Barking Mat]

Have you got a pin out diagram for it ?

Should be on / off and temperature regulation I would have thought.

 

[blackolive (Ste)]

Manuals here https://www.butlertechnik.com/technical_library/thermo-top-c-d27

 

[julianf]

Manuals here https://www.butlertechnik.com/technical_library/thermo-top-c-d27

They're helpful, but, as above, there are so many application customisations, that, when it comes to port X1, the "default" / "unbranded" manual is fairly useless.

Ie the pin out of X1 may be as per the manual on that link, but it equally well, may not be!

 

[blackolive (Ste)]

Have you got a pin out diagram for it ?

Should be on / off and temperature regulation I would have thought.

They're helpful, but, as above, there are so many application customisations, that, when it comes to port X1, the "default" / "unbranded" manual is fairly useless.

Ie the pin out of X1 may be as per the manual on that link, but it equally well, may not be!

I know, the troubleshooting manual is useful though as it gives run up and shut down cycle times under various fault conditions

 

[Slowcoach]

Im wondering if a split bush might be a solution. I got sucked into thinking about splitting a bit of 22mm cooper pipe but, if course, that's OD rather than ID, but something like that. Maybe even just a strip of copper bent around as a packer.

Would a slip socket not work? Cut to length required.

 

[blackolive (Ste)]

Found some pics of the inside, feom decoking one. There are a few very comprehensive articles on them on the rover 75 and ZT owners club website/forum

 

[chrisg3103]

Got mine running today, steamy, is a 75 one so just ground pin 3 and fuel pump from pin 6. Using the wrong fuel pump and the fuel tank is a spray can cap, but proved it so it's worth servicing