Member Since: 10 Dec 2020
Location: Bideford
Posts: 29
FBH dead after recent service - overheating issue
Hi all!
My lovely FBH came out for a good strip down and clean last Sunday, went back in and worked fine... For a couple of days.
Now it won't start at all. Checked with the webasto wtt software, it's showing an overheating error and I'm not surprised, the temperature is permanently stuck at 138c!
I'm guessing the sensor is at fault, and I'm hoping I've been an idiot and pinched a wire or something reassembling, but before I rip it back out again which I'm not eager to do, is there anything else I should try or check?
I've tried pulling the fuse, resetting via webasto software multiple times and checking all connections I can reach without removal or teardown.
Thanks in advance!
5th Feb 2021 7:56 pm
chrisoverson
Member Since: 10 Dec 2020
Location: Bideford
Posts: 29
Found the culprit.. what now?
So I found the culprit.
The coolant temperature sensor (G1 in the workshop manual) should read between 1998 ohms and 4050 ohms at room temperature. It's around 130 ohms.
So I need a new sensor right? I can't find one anywhere, but by some research and going by the workshop manual values, I've identified that it's almost certainly a 2.2k NTC Thermistor.
Now, I don't have one. I'd really love to put the car back together this weekend, so here's my question:
If I just replace this sensor with a resistor for now, then later wire it up to a thermistor and attach that to the coolant system somehow, is that going to matter? It still has the overheating cutout sensor, and as far as I can tell, the burn is not really controlled by the sensor but by using the glowplug as a flame detector.
My temp fix would make the fbh permanently believe the coolant temperature is around room temp. Should I be concerned about safety here for any reason? As it'll only be triggered to run by my command or the car itself, it should never run to the degree the coolant is overheated anyway - It never gets further than a quarter on the temp gauge even after 30 minutes.
Be interested to see what anyone thinks, I'll try not to blow myself up
6th Feb 2021 1:38 pm
rangehelper
Member Since: 04 Nov 2011
Location: Maidstone
Posts: 52
LR004235 the part number that is needed
7th Feb 2021 10:14 pm
rangehelper
Member Since: 04 Nov 2011
Location: Maidstone
Posts: 52
don't experiment, it's your safety!
7th Feb 2021 10:15 pm
chrisoverson
Member Since: 10 Dec 2020
Location: Bideford
Posts: 29
Thank you!
I looked everywhere for this but couldn't find a part anywhere.
I've ordered 2 from the local landy garage - and yes you're right, I did bodge it to see if it would work (which it did) but then chose to disable it to be safe.
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