FBH misbehaving

Gareth.Richards · 15th April 2018, 08:38

Anyone got any ideas?
Went out last evening to the local shop and the FBH decided to start up (temperature about 7 degrees) I hadn't realised that it was running when I turned off the engine due to all the other vehicles around me in the car park, only on my return did I notice the FBH was running, so drove home and stopped. the FBH was still running, lifted the bonnet and saw white smoke coming out from the air intake pipe! Pulled 15amp fuse 8 and FBH powered down but smoke kept coming for a few minutes.
Any pointers would be welcome

ps. FBH has not been working for some time, Frech Mike repaired the PCB last year, but has been left unplugged until I refitted the ambient temperature sensor (that was missing for some reason) last weekend.

The FBH didn't come on during my outings earlier on in the week though.

HarryM1BYT · 15th April 2018, 09:11

The basic FBH install should only come on, when - engine is running and ambient is lower than +5C. That system uses the alternator output and a thermal switch behind the front bumper. It also should not smoke, so it needs a proper service.

Best guess is that something is over-riding the above. Might there be an optional timer installed, such that it is supposed to pre-heat the car?

Some people have fitted remote controls, to enable the FBH to fire up.

Some have fitted even more sophisticated remote controls, using a mobile phone gadget to fire the FBH up from an even greater distance.

I installed a manual switch, so I could bypass the default system to use the FBH anytime I wanted.

Gareth.Richards · 15th April 2018, 13:20

Quote:

Originally Posted by HarryM1BYT

The basic FBH install should only come on, when - engine is running and ambient is lower than +5C. That system uses the alternator output and a thermal switch behind the front bumper. It also should not smoke, so it needs a proper service.

Best guess is that something is over-riding the above. Might there be an optional timer installed, such that it is supposed to pre-heat the car?

Some people have fitted remote controls, to enable the FBH to fire up.

Some have fitted even more sophisticated remote controls, using a mobile phone gadget to fire the FBH up from an even greater distance.

I installed a manual switch, so I could bypass the default system to use the FBH anytime I wanted.

Basic FBH install, no timers or overrides and came on at over +7C, so maybe needing a good service!
Gareth

HarryM1BYT · 15th April 2018, 13:39

Quote:

Originally Posted by Gareth.Richards

Basic FBH install, no timers or overrides and came on at over +7C, so maybe needing a good service!
Gareth

The +5C switch, is just a mechanical switch/ bi-metal, so not very precise, so that still enabled at +7C is not that surprising. How it could come on without the engine running, is a different issue.

Gareth.Richards · 15th April 2018, 13:54

Quote:

Originally Posted by HarryM1BYT

The +5C switch, is just a mechanical switch/ bi-metal, so not very precise, so that still enabled at +7C is not that surprising. How it could come on without the engine running, is a different issue.

Harry, it came on when the engine started but did not switch off when the ignition was turned off!
Gareth

bendrick · 15th April 2018, 16:18

Quote:

Originally Posted by HarryM1BYT

The basic FBH install should only come on, when - engine is running and ambient is lower than +5C. That system uses the alternator output and a thermal switch behind the front bumper. It also should not smoke, so it needs a proper service.

Best guess is that something is over-riding the above. Might there be an optional timer installed, such that it is supposed to pre-heat the car?

Some people have fitted remote controls, to enable the FBH to fire up.

Some have fitted even more sophisticated remote controls, using a mobile phone gadget to fire the FBH up from an even greater distance.

I installed a manual switch, so I could bypass the default system to use the FBH anytime I wanted.

On that front does anybody actually provide a servicing FBH service?

Mine smokes like Drax power station. I should have clocked that there was something wrong as the seller had the FBH unplugged when I turned up to buy the car but forgot to return to the subject before buying the car. And of course the seller has since insisted that it was fine when he sold the car ( just like he did with the subsequently discovered knackered air con)

HarryM1BYT · 15th April 2018, 16:50

Quote:

Originally Posted by bendrick

On that front does anybody actually provide a servicing FBH service?

Mine smokes like Drax power station. I should have clocked that there was something wrong as the seller had the FBH unplugged when I turned up to buy the car but forgot to return to the subject before buying the car. And of course the seller has since insisted that it was fine when he sold the car ( just like he did with the subsequently discovered knackered air con)

Most of the effort in servicing the FBH, is in removing it from the car to service it and the car cannot be used whilst it is removed anyway [1]. I fully documented how to service it, it is not difficult - see below...

https://www.the75andztclub.co.uk/for...768#post877768

[1] It could be, if a section of pipe were made up to join the missing FBH input, to the FBH output.

Gareth.Richards · 15th April 2018, 21:59

Quote:

Originally Posted by HarryM1BYT

The +5C switch, is just a mechanical switch/ bi-metal, so not very precise, so that still enabled at +7C is not that surprising. How it could come on without the engine running, is a different issue.

Harry
Should it switch itself off when the engine is turned off even if the water has not come up to temperature?
Gareth

HarryM1BYT · 15th April 2018, 22:20

Quote:

Originally Posted by Gareth.Richards

Harry
Should it switch itself off when the engine is turned off even if the water has not come up to temperature?
Gareth

Yes! Stop the engine and the FBH should begin a wind down to being off.

From distant memory - the engine ECU sent out a signal to say 'engine running', which then passed onto the +5C stat, then to the FBH to tell it to run. The FBH then operates under its own control, to ignite, to raise the water temperature reducing its output as it nears its set temperature, then switching off at its maximum temperature.

What you don't want, is the FBH running with the car unattended, generating lots of 'smoke'. The risk then is of someone calling the fire brigade and them busting open the bonnet to extinguish a 'fire'.

sewerman · 16th April 2018, 18:47

Quote:

Originally Posted by bendrick

On that front does anybody actually provide a servicing FBH service?

Mine smokes like Drax power station. I should have clocked that there was something wrong as the seller had the FBH unplugged when I turned up to buy the car but forgot to return to the subject before buying the car. And of course the seller has since insisted that it was fine when he sold the car ( just like he did with the subsequently discovered knackered air con)

Try contacting Trebor or Devilish about servicing they've done a few and have a test rig too

Scott

15th April 2018, 08:38	#1
Gareth.Richards Loves to post Rover 75 Saloon Join Date: Jun 2013 Location: Oswestry Posts: 399 Thanks: 263 Thanked 93 Times in 84 Posts	FBH misbehaving Anyone got any ideas? Went out last evening to the local shop and the FBH decided to start up (temperature about 7 degrees) I hadn't realised that it was running when I turned off the engine due to all the other vehicles around me in the car park, only on my return did I notice the FBH was running, so drove home and stopped. the FBH was still running, lifted the bonnet and saw white smoke coming out from the air intake pipe! Pulled 15amp fuse 8 and FBH powered down but smoke kept coming for a few minutes. Any pointers would be welcome ps. FBH has not been working for some time, Frech Mike repaired the PCB last year, but has been left unplugged until I refitted the ambient temperature sensor (that was missing for some reason) last weekend. The FBH didn't come on during my outings earlier on in the week though.

15th April 2018, 09:11	#2
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	The basic FBH install should only come on, when - engine is running and ambient is lower than +5C. That system uses the alternator output and a thermal switch behind the front bumper. It also should not smoke, so it needs a proper service. Best guess is that something is over-riding the above. Might there be an optional timer installed, such that it is supposed to pre-heat the car? Some people have fitted remote controls, to enable the FBH to fire up. Some have fitted even more sophisticated remote controls, using a mobile phone gadget to fire the FBH up from an even greater distance. I installed a manual switch, so I could bypass the default system to use the FBH anytime I wanted. __________________ Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money. Last edited by HarryM1BYT; 15th April 2018 at 09:18..