Power steering fluid leak from reservoir

[Orlando St.R]

Hi everyone. My car suffers from leakage of PAS fluid from the top of the reservoir, either from the cap or the seal round the reservoir lid. Both are newish and in good condition. I keep the PAS fluid level just below the top of the filter, so there is plenty of room for expansion. However, I'm wondering about the cap.

When I installed my power steering setup, the reservoir did not come with the original cap/dipstick, so, not having an original to examine, I fitted one of these non-pressurised radiator caps, which has a rubber seal under the cap and no apparent means of venting:

non-pressurised radiator cap 1.jpg (131.59 KiB) Viewed 1839 times

non-pressurised radiator cap 2.jpg (75.88 KiB) Viewed 1839 times

I say 'non-pressurised' because that's how they're described by suppliers. But, presumably, as the PAS fluid heats up, it will expand and, even if you have air at the top of the reservoir, that will become pressurised and have nowhere to vent to. So, I wonder if the fluid is being forced out of the reservoir under pressure.

I wondered if anyone has any experience of this issue and/or what caps you are using on the reservoir and whether these have a rubber seal.

[JCS]

Rob

I have an identical set up and experience the same problem. In fact, although it would seem easy to trace, that is not the case. Even a wipe around with fingers after a run failed to show up the culprit first time.

I eventual fitted a flat type circlip 2.050 inch outer diameter some 0.045 inch thick under the rubber to provide more contact pressure.

I shall be at the 20/49 meet on Thursday and I have placed one of these circlips in each car, so if you appear you can have a circlip. You probably realise that you need a split type of ring to be able to thread it under the cap rubber.

I am assuming you have no objection to using a Rolls-Royce axle circlip on a Jaguar <smile>


Norman

[Orlando St.R]

I'm glad it's not just me, then, Norman. And I'm glad your engineering brain has applied itself to the problem.

Yes, I'll be there on Thursday, so I'll gratefully accept your very kind offer (and buy you a beer in return). Since my reservoir seals are already Rolls Royce items, I'm completely relaxed about another RR part on there!

[Glyn Ruck]

Oh boy! Something to look forward to. I use a similar cap. A hand cut Vellumoid gasket on the lid & a Studebaker tappet cover rubber seal on the centre "bolt". So far no leaks.

[Orlando St.R]

Oh boy! Something to look forward to.

It's great for rustproofing the LH chassis rail. Just not so great for the garage floor or the radius arm rubber bush (that's where it comes out)!

[cass3958]

Oh boy! Something to look forward to. I use a similar cap. A hand cut Vellumoid gasket on the lid & a Studebaker tappet cover rubber seal on the centre "bolt". So far no leaks.

That is not very original Glyn. A Studebaker!!!! Points being removed from your scorecard as I type.lol.

[Glyn Ruck]

Oh boy! Something to look forward to. I use a similar cap. A hand cut Vellumoid gasket on the lid & a Studebaker tappet cover rubber seal on the centre "bolt". So far no leaks.

That is not very original Glyn. A Studebaker!!!! Points being removed from your scorecard as I type.lol.

LOL ~ I might tell you to the casual eye the Stud part looks identical to the RR part. My restorer is really a Studebaker man.