Brake Pressure Bleeding Master Cylinder Cap Adapter

[Scott52]

I have a pressure bleeder and the caps in the kit are all screw on mainly for European cars.

Our master cylinder reservoir caps are a bayonet style a bit like a radiator cap. Unbelievably the Vendors can't tell me which of the SP Tools adapter caps will fit a Navara. One or more of the caps below will fit but not even SP Tools can say which one. They provide no dimensions or no photographs of the cap underside. One seller said to buy the part number advertised for Nissan (which one of the three?) and if it didn't fit get a cap from a Wrecker and drill hole and make my own. I've already been down that path and it doesn't work because the cap is not rigid enough. Once pressure is applied the cap lifts and the air escapes.

I feel they're in breach of Australian Consumer Law as they can't guarantee to provide the correct part that's fit for purpose. You wonder how these businesses will survive.

So does anyone know which of these caps will fit the master cylinder reservoir on a Thai built D40?

The other option I was investigating was Aliexpress: https://www.aliexpress.com/item/4000994646687.html?spm=a2g0o.cart.0.0.260438dak5CqNW&mp=1

I'm pretty sure S02 will fit our D40's as the internal diameter of the cap matches. S02 is the middle item in the bottom row in the picture showing the cap undersides.

When I scale the photograph and measure .... S14 looks like the same diameter as S02 but there's no measurements provided. These people make it hard for Customers with scant information.

 

[Scott52]

Australian Online Car Parts were helpful because they actually sourced decent information to allow me to make an informed decision. Part Number SP70821 will fit my 2011 Thai build D40.

I've posted the pdf documents here for members to reference which caps will suit their Navara or any of their other vehicles.

 

[Scott52]

Well I ended up purchasing the alloy cap #2 from Aliexpress. It fits like a hand in a glove and is good quality. It's a clever design as the smaller knurled portion of the cap tightens on the central shaft thereby compressing and expanding the o-ring for a robust air tight seal. That feature probably makes it better than the SP Tools item however I haven't tested it so shouldn't judge. See the photos above for cap #2 underside.

The supplied 90 degree fitting is removable and conveniently the threaded centre shaft has a 1/8 BSP female thread so I purchased a barbed fitting to replace the air fitting supplied.

I made an effective pressure bleeder that works very well. I bought one of these for $6.98 from Bunnings: https://www.bunnings.com.au/aqua-systems-2l-garden-pressure-sprayer_p3368550

I drilled an 11.80 mm hole (I didn't have an 11.50mm) and installed a tyre valve so I can set the pressure. With about 500ml of brake fluid in the sprayer it takes about 30 pumps to get 15 psi which is about what you need. I've found anymore than 20 psi tends to stress the reservoir.

After you remove the spray nozzle the nipple will take a 3/8 BSP fitting so it's pretty easy to install a barb on the outlet. I made the hose long enough so the pressure vessel sits on the bullbar. The Champion plastic packed fittings from Repco cost me $32 which was more than the cap at $20.02 delivered. So all up it was about $60 for a good pressure bleeding system.

Now I've proved the concept I'll buy another pressure cap from the same Aliexpress vendor that fits my car and van. They're Euro style that screw onto the reservoir.