Correct dimension for brake fluid reservoir hose


I would like to replace the two hoses that go from the brake fluid reservoir (1974 S2, LHD). Does anyone know the correct dimensions (inner and outer) for these two hoses? The item number according to the Part Catalogue is C20072. I believe the inner diameter is approximately 8mm or 9mm.

Thank you for your help!

Best regards,


I think it’s 7x13mm and you have to make sure that it is glycol (brake fluid) resistant. There should be plenty of hoses on the market. Tin foil or plastic will work wonders for your paint.

1 Like

While you’re at it, replace that reservoir with one from a Mitsubishi.

1 Like

I say keep it original unless it breaks.

Why? If the cork float sinks and fails to tell you you’re out of brake fluid, you could end up with a totalled car or worse. Against that, what is the value of keeping it original?

Could you recommend a Mitsubishi part number or vehicle model?

Thank you David!

I measured the thin end of one of the “pipes” from the reservoir and it measured 7.8mm, so 7mm seems correct. I have learnt that the correct type should be EPDM.

Do you mean for protection it while I drain the fluid?


I replaced the reservoir cap and the sensor earlier this year…


I check frequently and the float won’t sink immediately. I get it though, I‘ve read about it.

The early style reservoir also measures 7.8mm and I checked with a 7mm hose I had laying around and it seems to fit. Maybe an 8mm would work but not so sure. EPDM should be the correct type.

Yes, to protect the paint work - tin foil is pretty good to catch any spills and it doesn’t move easily.

The issue with the Mitsubishi reservoir is that the fittings are 10mm I think. So the thing to do is buy some 10mm hose with the EPDM liner, and buy perhaps a foot of 8mm hose with the same liner. Cut an inch of the 8mm hose off, peel the outer layers off it, and install just the EPDM liner over the fitting on the master cylinder. Then install the 10mm hose over that and clamp it.


in my car the reservoir looks exactly like yours! Bright white cap and yellowed can container … why? Because the container is dead safe and healthy and a mess to replace without damaging the paint below, and the cap with the brake fluid sensor is usually shot and needs replacement which is as simple as cooking water. Failure mode is a short resulting in a permanent lighting of the brake warning light. Take it seriously, replace the cap and rest assured about a functioning brake fluid level indicator …

All the best


75 XJ6L 4.2 auto (UK spec)

I‘m thinking he has a new cap now. Early XJ have a different reservoir, but similar sender and I couldn’t find one at the time so I adapted a wine cork and made a copper tube to fit because the aluminium had disappeared completely. Works fine now and a NOS spare is waiting for the day that will never come.

Correct. The bright white cap is the new cap that replaced the old rusty cap which based on the colour match with the reservoir, was probably from when the car was new.

The function of the cap and the indicator light on the dashboard can be tested by pressing the small metal pin on the top of the cap under the brown rubber cover.

Best regards,


Yes. I do that every other week, checking if it comes back up swiftly :slightly_smiling_face:

Sorry, David,

that was exactly what I was trying to get at with my description. The common failure mode is the metal part in the cap holding the sensor vanishing and causing the warning light to illuminate.

The part is only delivered as a complete set, and I bet that many XJ drivers, like Marc and I keep the new white can in a shelf, go on with the original part and replace only the cap.:slight_smile:



75 XJ6L 4.2 auto (UK spec)

That’s what must be happening - Kirberts XJS solution is a good alternative I think.
I did like making a new float and „tube“; cost slightly more than a bottle of wine, wine included. :slightly_smiling_face:

I don’t know if the copper, lead and tin hold up better. Brake fluid is due in a year…

I actually managed to buy only the cap from SNG Barratt, SNG Barratt UK | Keeping your Jaguar on the road

I also see that it is possible to only get the sensor, SNG Barratt UK | Keeping your Jaguar on the road

Just thought I would mention this in case someone needs to replace the sensor and finds this thread.


1 Like