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MG MGF Technical - B&G low level sensor ?

B&G quote

Price: 8.17 + 1.43 VAT = 9.60 each
Stock No: PCJ000040

Is this for engine coolant or some other liquid or suspension or driver stature or potholes or pleasure or wallet or ?

Someone tell me 'cos I ordered one assuming it's for engine coolant.

D Brunton

Brake fluid?
Tony Thompson

IYWMO (If You Want My Opinion) Stock number could mean a local companys inventory number.
It means nothing to anyone outside the company.
Now if you had a OEM part number, that would be different.



might be the new mgtf model coolant level sensor.
But.. you need the new header tank aswell, if so.
There should be anything in the archives from a recent discussion on the matter.
Dieter K.

I download and installed the catalogue price list and I coud not find any reference to this stock number or description. I also search every part of B&G and it only comes up with exactly as you have posted....nothing else.

Best to give them a tinkle and if not what you want cancel the purchase.


I think it's this what you missed to order additional.

Price: 18.32 + 3.21 VAT = 21.53 each
Stock No: PCF000140

Branko, check online. That's up to date.
Dieter K.

Stop, the PCF000140 is the old expanision tank. Please ignore the number.
Dieter K.

No, Dieter, but that number is correct.

I have just purchased and fitted the new expansion tank which is labeled PCF000140 - perhaps it is now the standard. Just make sure when you get buy the tank that it has the internal float and 'hole' in the bottom for the sensor.

The sensor is PCJ000040 and costs 9.60 from Rover. The tank was 26.08, again from Rover (both prices include VAT).

I have yet to fit the sensor, as I need to test several buzzer/led combinations in situ with the roof down and at speed, to make sure I can hear them!


Tony Thompson

Tony and all other techies

Lateral thinking.

My thought on audio warning for low coolant is to copy an old whistling kettle we used to have ie water boils, exits via steam whistle giving audio warning, additionally steam could be ducted to give positive visual too. I spotted my first boil up using drivers door mirror.

Any thoughts ?

Are there any steam engineers out there?

D Brunton

David, the idea is problematic: the cooling system is pressurised, so any vent that whistles runs the risk of depressurising a perfectly healthy cooling system.

If you are using this idea as a way of highlighting a low coolant level, then you need to ask yourself why is the coolant level low? Usually this is due to a coolant leak somewhere - and if there is a leak, then the pressure contained in the coolant system would have dropped substantially.

Trying to design a 'whistle' would be quite a challenge!

The TF2004+ option of built in sensor would seem to be the best approach.

Might need to pop around to the local dealer whilst it remains open (it's part of the Phoenix chain) and pick up a couple of these bits! :o)
Rob Bell

Well, maybe it's time we all put our coconuts together and came up with a retrofit of a coolent low sensor level.

Something easy to install, inexpensive and effective.


Why bother with any <buzzer/LED combination> ?? On the rare occasion/if ever it goes off, then you have 2 good buzzers under the bonnet called horns which you may need in any case to blast your way onto the hard shoulder.
I must look at the circuit diagrams.
Geoff F.
G. Farthing

>Something easy to install, inexpensive and effective.

Would underline what Geoff said.

... always to late ... ;)

Me's looking foreward to the first MGTF call for help thread.

* A red light according to anything with coolant came off at my TF*
Kicked the accelerator and went home quickly to see what it was..
Suddenly the engine stalled and the damn light still was red.

Or something like that.
Dieter K.

Yes Dieter no amount of clever alarm technology can ever eliminate ignorance or wishfull thinking

Good news though I think? Woke at 3:am put my insomnia to good use and I feel confident that I have solution
that is "Something easy to install, inexpensive and effective"

Watch for my new thread "low coolant level alarm"
D Brunton

The in-law's MG ZS which also has one of these warning lights built in has a warning lamp on the dash (a nice logo showing a water level inside what I presume to be a representation of a radiator, but could be the expansion tank).

That lamp has popped on once or twice, despite the level remaining at a perfectly satisfactory level.
Which begs the question: would a buzzer necessarily be a good idea if the damn thing keeps intermittently going off, scaring the wits out of you inappropriately? I suspect that any such system would soon become disconnected.

A lamp is easier to live with, unless we can think of a way of making the system more selective for a true low water level... (but this will make it less sensitive)
Rob Bell

I was thinking of an outside sensor that you can stick-on low down on the expansion tank. (below the min level)
This sensor needs to sense if water is present on the inside of the plastic casing. When the water level goes down, past the sensor, then a signal will be sent to set off a bright red light and/or buzzer that is in your field of vision in the dash area.

All we need to do is to investigate if such a sensor exists. I'll check out my electronics books.


For Dieter, if he doesn't already have it, the VIn change for the coolant low level sensor type expansion tank and warning light on the instrument cluster is from 4D632424.

Also of interest is that the previous expanion tank has been superceded by the new one so if ordering an expanion tank for any earlier TF or F you are going to get PFC 000140, presumably with a plug for the sensor hole for applications not using or wanting to use this.

Roger Parker

Cheers !

did you know I installed a buzzer parallel to the FanFuse after the 15A fuse went ??
Swapped the Fanfuse to 20 Amp aswell.

Worth to follow IMO, cause it gives noise when the Fuse blows _whyever_.
Dieter K.


< presumably with a plug for the sensor hole for applications not using or wanting to use this. >

The whole is a 'blind' one, which goes up inside a hollow pillar on which the float runs up & down. I have yet to wire in the sensor, but, at least, no coolant has dribbled out so far ! :-)



Instructions to fit - no photos I'm afraid

Prior to fitting I pushed the level sensor into the underside of the new expansion tank and connected two wires to it, insulating well with tape. The two wires go to the instrument binnacle so need to be long.

1. Put rear of car up on ramps so expansion tank above rest of coolong system by big margin to save draining cooling system and refilling
2. Undid the two expansion tank bolts connecting tank to body and lifted.
3. Loosened the connectors and two pipes connected to tank. Regarding the top pipe I totally took it off - no loss of coolant. On lower pipe, as I disconnected it, I quickly(!) placed the fast emptying tank over a bowl placed close by. Whilst doing this I kept hold of the bottom pipe to ensure top of it remained above rest of cooling system to ensure no loss of coolant/airlocks getting in.
4. Reconnected the two pipes to the expansion tank and before lowering tank, I refilled tank with new antifreeze. Lower tank and rebolted to body. Checked tightness of pipes on expansion tank. Ensure pipes fully on.

I then threaded the cables through the length of the car via the cabin.

One of the two cables goes to the lamp holder and then the cable leaving the lamp holder goes to a live feed (picked up from Driver's fuse box area (with an inline fuse)The other cable from the sensor goes to earth, again picked up near the fuse box area. The LED light is pushed into the binnacle housing (the black bit above the instruments). The LED holder should not be long as not much space to get the light holder in but easy to drill a hole through the plastic binnacle to hold said lamp holder.

Test by placing clean screw driver on internal float in expansion bottle and pushing down. Light will go on if float pushed far enough down!

Started engine with expansion bottle cap off for a few minutes. Then tightened up cap and ran engine for 10 minutes to get hot. Drove car off ramps, left engine to cool for 20 min and then checked tank level. Drove car around the block (5 minutes), left to cool and then checked level again. No need to refill at all.

Whole job took me 2 hours. Circuit is always live so when ignition off, the light will go on if level falls below half way.

Excellent - many thanks Julian :-)
Dave Livingstone

Interesting that the prt was introduced, and then the low level light. This suggests that there is some concern teh prt is insufficient, or that there is a cooling system design issue which is culminating in HGF after coolant loss.

Was teh instument panel updated to cope with thtis light, or has a light been combined somewhere to make space? Anybody know?
David M

Got a couple of pix of the new expansion tank - thanks Rog - Julian, can I use your instructions for the website?

Rob Bell

Looking forward to the new page Rob - must pop down my local dealer and see if I can get the parts. Goodness knows what they'll be doing soon, it's a family business and has been MGR for as long as I can remember.
Dave Livingstone

Please do use the instructions. Please improve on the English! For info I purchased the red LED from Halfords as small enough to fit and looks great.

Dave, my 'local' is a Phoenix-owned concern - so under administration :o( If Priests have the parts, coulfd you order me a dublicate? Add it to my 'tab'! ROFL

Julian, thanks. Will see what I can do :o)
Rob Bell

Only just caught up with this thread, but as a follow-up to Rob's earlier comment:

>>The in-law's MG ZS which also has one of these warning lights built in has a warning lamp on the dash........That lamp has popped on once or twice, despite the level remaining at a perfectly satisfactory level<<

I also experienced this problem at the weekend for the first time. Easy solution - the push-to-click fit sensor had come out of the bottom of the expansion tank and was moving up and down in the breeze. The XPF guys advised to relocate with insulating tape!

Forgive my ignorance, but presumably the sensor is just a float and proximity detector?

Mike H
Mike Hall


>>Dave, my 'local' is a Phoenix-owned concern - so under administration :o( If Priests have the parts, coulfd you order me a dublicate? Add it to my 'tab'! ROFL

LOL - I was actually too lazy to drive down to Priests yesterday (although I should go down and find out what's happening to them) so I ordered from B&Gs website. I got a call from Malcolm fairly quickly to let me know that he has developed a complete kit to retro-fit this which should be ready in a couple of weeks. It'll include a wiring loom, buzzer (very loud apparently!) and an anti-slosh device that prevents false alarms (level must read low for 15 secs continuously before buzzer sounds). He's going to ship the tank and sensor to me, as ordered, but let me know when the kit is ready and offer it to me less the cost of the tank and sensor.

So, I don't know if you want to do the same? Give Malcolm a call or just order off B&G website.

P.S. He's also got two beginners for the Donington evening for us! If he has the kit by then he'll bring it along.

Dave Livingstone

The retro-fit kit sounds ideal Dave - does Malcolm give any indication as to likely costs?

Perhaps Donny will give you more opportunity to chat with him :o)
Rob Bell


>>The retro-fit kit sounds ideal Dave - does Malcolm give any indication as to likely costs?

He said that their target was sub 100, which doesn't sound cheap considering the costs of the tank and sensor. However, he assured me that they'd spent time discussing this with Powertrain and had come up with a solid solution.
Dave Livingstone

The kit sounds interesting. What was the lead time? Was it the couple of weeks and it will be available, or they expect to have the design complete in a couple of weeks? 100 does seem a bit high considering the parts used though.
David M

Ouch. 100 quid? I think that a DIY solution is more tempting...

Over to all-round electronics Guru, Will, for a suitable damper circuit to reduce false-positive reporting! :o)
Rob Bell

you mean like a cap, resistor and a comparitor....

Now I wonder where I might have seen a circuit like that before!!!
Will Munns

Can you let me know if the circuit is made or broken when the tank gets empty? (and I'll add it to Dave's circuit as I have a spare comparitor!)
Will Munns


Assuming you talking of the standard tank & sensor, the circuit is 'made' when the coolant level drops.
Tony Thompson

Cheers, that makes things easier.
Will Munns

To get some idea of the new tank, have a look at the following pictures. The quality is poor - they are web-cam shots - and the tank is off a 25 or 45 !

However, apart from the mounting lugs, intended to fit to the rear bulkhead of a front engined car, the tank is otherwise identical. The proper tank is a direct swop for the original MGF/TF one.

The photos show also the sensor itself and, if you look really carefully on one of them..... :-) can see the float through the cap hole!

I'm not sure if you can buy the connector for the sensor from Rover, but its the same as the one on the coolant temp sensor - AMP 347882

Tony Thompson

Will, could you let me know your circuit diagram, I'll have a go at making it as well :o)
Rob Bell


My B&G order arrived today. I can see where the sensor should go. It looks like a simple press-fit, but I can't seem to do it! Am I just too weak or is there a knack?


Hopeless DIYer from Amersham
Dave Livingstone


If it's the same as the ZS, it's a press-fit.

Mike H
Mike Hall

I thought the same. It does fit but you need to push VERY hard!!Infact I used the palm of my hand to bang it in but a small hammer will do it as well. God knows how you get it off again!!!

Thanks Julian - you gave me the courage to press really hard :-) As you say, I can't imagine it coming out!
Dave Livingstone

>>God knows how you get it off again!!! <<

I can assure you that the one on the ZS has (had?) a tendency to come out all on its own - hence the addition of some insulating tape!

Mike H
Mike Hall

I don't want to sound like a miserly Scotsman but I will anyway (actually I feel strangle compeled to must be the Gordon Prudence Brown effect) . . . . ahm . . 26 poonds is an awfae money tae spend fur a wee hole like yon
D Brunton

Very interesting thread.
As I need to order the items to be mailed to the far south Ill appreciate your precise advise:
Whom to buy from?
What to order -stock numbers-
Many thanks
JM Vega-P.

Looks as though the B&G website is a good bet for you:
Rob Bell

To pick up on Rogers posting - my TF has a VIN of 4D633140, and it hasn't got a low level indicator expansion tank or sensor fitted. Wish it had!

I have just spoken to Tony at B&G's, they have a prototype running at the moment, he's not sure when it's ready for production.
I'll have an update, hopefully, from Malcolm tomorrow.

Adrian Clifford

I've just had it confirmed by Malcolm Gammons that the water level sensor is performing well.

The details are that it should be ready for sale and delivery in 3 to 4 weeks, they will take orders straight away, but no money as of yet.

It should retail at about 99.99p, although the first 100 or so should be about 80.00p.

The kit consists of everything you will need, expansion tank, cap (the new one is pressure tested), buzzer, wiring etc.

It should take a reasonably competent DIY'er about one hour to fit, with very simple fitting instructions included, no loss of water from the cooling system should be experienced as long as the hose is held high enough.

It is suitable for F's and TF's (incidentally, it will also fit Mk1 and Mk2 Elises as well)

Labour would be about 40.00p if done at B&G's.

Anything else give B&G a call on 01462 490049 (P.S. I'm not on commision just passing on the details as there is considerable interest)

Adrian Clifford

I've now fitted and tested my new level sensor, and can definitely confirm that some form of damping / slugging of the signal is required. 99.9% of the time it's okay, but the odd tight bend or bumpy road triggers the led & buzzer. Whilst this provides a constant 'self-test' facility, I don't think I can live with it. :-))

My circuit is simply a in-line fused 12v supply fed to the paralleled led & buzzer and then though the car to the sensor. The other line from the sensor goes to ground.

Got details on your "cap, resistor and a comparitor" maybe ? Is it variable ?


Tony Thompson

This thread was discussed between 16/04/2005 and 30/04/2005

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