Testing the FBH circulation pump.

[navrac]

I've got an FBH with a blown pcb, I can get that repaired but is there any easy way of testing the water pump?

I was measuring the resistance of the glow plug which was fine, but when I measured the circulation pump It measured 10Kohm So I presume its a bit ill.

Or is this normal?

Richard

[FrenchMike]

Originally Posted by navrac

I've got an FBH with a blown pcb, I can get that repaired but is there any easy way of testing the water pump?

I was measuring the resistance of the glow plug which was fine, but when I measured the circulation pump It measured 10Kohm So I presume its a bit ill.

Or is this normal?

Richard

Hi Richard,

It's not normal , you must find a few ohms.

The test is easy;as that's a DC motor,send 12 volts on it and listen !!!

Even better;replace it by a 21Watts bulb and go on for an overall test.

Mike

[navrac]

well this is weird. - it measured 10k ohms and didnt respond to 12V.

So I quickly stripped it down to realise that the coupling from the impeller to the motor was not by a driven shaft but the impeller body was magnetic. So I put it back in the car - rechecked and realised my short to gnd wasn't working on pin 3 - the motor started up and ran fine. So I guess its an AC or pulsed DC waveform being passed to it or my bench supply is playing up!

Richard

[James.uk]

When Jules was testing my FBH water pump he was unable to get a reading on his tester fingy, so he produced a new one he had in stock and tested that, with the same results? Somewhat puzzled and with trepidation he continued testing the other components. When all the tests were completed he finally earthed pin 3 and the FBH fired up and proceeded to work as it should..

We also discovered that the exhaust pipe from the FBH runs dangerously close to the big air inlet pipe, and in my case it was actually touching, so Jules tied it back onto the header tank support..

Having made this discovery we then checked Jules car, and found that the pipes were touching on that car as well!! So again, the air pipe was tied back to the header tank support..

So check your car! you need at least 1/2 inch clearance as the air pipe expands a lot once the turbo kicks in... YOU HAVE BEEN WARNED!!
...

[navrac]

Originally Posted by James.uk

When Jules was testing my FBH water pump he was unable to get a reading on his tester fingy, so he produced a new one he had in stock and tested that, with the same results? Somewhat puzzled and with trepidation he continued testing the other components. When all the tests were completed he finally earthed pin 3 and the FBH fired up and proceeded to work as it should..

We also discovered that the exhaust pipe from the FBH runs dangerously close to the big air inlet pipe, and in my case it was actually touching, so Jules tied it back onto the header tank support..

Having made this discovery we then checked Jules car, and found that the pipes were touching on that car as well!! So again, the air pipe was tied back to the header tank support..

So check your car! you need at least 1/2 inch clearance as the air pipe expands a lot once the turbo kicks in... YOU HAVE BEEN WARNED!!
...

Thanks for that - I will make sure it is well tied back. Just got to find a diesel pump for the fbh and I'll be warm in the mornings - without burning holes through the pipe!

[Jules]

Originally Posted by FrenchMike

Hi Richard,

It's not normal , you must find a few ohms.

The test is easy;as that's a DC motor,send 12 volts on it and listen !!!

Even better;replace it by a 21Watts bulb and go on for an overall test.

Mike

Are you sure Mike!?
The water pump on our Brand new FBH AND our fully remote ZT FBH measure 10k ohms. (both fully functioning)

[James.uk]

Oooops.. Seems I misunderstood the readings Jules was getting...

My apologies gentlemen...


...

[Jules]

Evenin James
The pump has a much higher reading than I expected for a 12volt motor.
Just reread the official FBH service manual and in Tech spec component testing section, there is only limited data.

I can only find a reading for the Glow plug/flame detector of 0.32 - 0.34 Ohms which is similar to Mike's figures.
No Data for the circulation pump


Richard 10K OHMS is normal resistance reading as far as I'm concerned on 3 or 4 known working pumps we've tested.
Mike the FBH Guru can you comment further ?

Maybe it's a Printed Armature or Pancake DC Motor or an Inductance type?

[FrenchMike]

Originally Posted by Jules

Evenin James
The pump has a much higher reading than I expected for a 12volt motor.
Just reread the official FBH service manual and in Tech spec component testing section, there is only limited data.

I can only find a reading for the Glow plug/flame detector of 0.32 - 0.34 Ohms which is similar to Mike's figures.
No Data for the circulation pump


Richard 10K OHMS is normal resistance reading as far as I'm concerned on 3 or 4 known working pumps we've tested.
Mike the FBH Guru can you comment further ?

Maybe it's a Printed Armature or Pancake DC Motor or an Inductance type?

Hi Jules,

TBH,i never dismantled a pump,i know from a troubleshooting tree from webasto :

http://www.google.fr/search?source=i...oogle&aq=f&oq=

simply send 12 DC volts and listen

On my bench,i simulate it by a 21 watts bulb.
so on the car i already tested it by bulb inserted in series .
(bulb glows and pump emits a slight noise.)

Cheers

Mike

[HarryM1BYT]

Originally Posted by Jules

Evenin James
Richard 10K OHMS is normal resistance reading as far as I'm concerned on 3 or 4 known working pumps we've tested.
Mike the FBH Guru can you comment further ?

Maybe it's a Printed Armature or Pancake DC Motor or an Inductance type?

It is probably a similar idea to the CPU fans used on computers. Rather than a commutator switching they use FET switching, which would account for the high resistance when checked with normal meter. Your only way to test them is to put them across 12v and watch for rotation or apply the 12v in series with a bulb or an ammeter.