Coolant loss...factory built sportster

[Sportster-Green]

hi all,

my sportster , powered with a rover v8, has been bult by Marlin.

they used a radiator from a BMW, with original BMW radiator cap and a separate expansion bottle, mounted at the bulkhead, routed from a T-juntion inside the upper cooling hose

the cap here:

http://www.ebay.co.uk/itm/Neu-Original-BMW-Kuehlerverschluss-Kuehlerdeckel-1-2-bar-E30-E28-E24-E23-Z1-4379047-/200958968267

Number on cap: 4379047

the cap has a valve which opens at 1.2bar.
when the valve openes coolant passes through recesses in the thread of the cap.

the cap at the expansion tank opens at 1.6bar.

the car runs stable with 80degrees during cruising, inside town it goes up to 92 degerees, when the fan cuts in and brings it down to 85

as, for certain reasons, i want to remain the higher pressure the questions is:

is there a blanking cap for the BMW radiator existing or a cap with the same geometry but higher pressure?

[Sportster-Green]

Re: Coolant loss...factory built sportster

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[greatoldone]

Re: Coolant loss...factory built sportster

Hi - I don't think that there is an OEM blanking cap for the BMW radiator, but you can make one like I did here:



I cut the pressure relief valve out of the standard cap, and then made a new gasket out of rubber so that the cap seals on the outer part of the radiator filler, rather than the middle one as it originally does. This means that the return from the radiator goes from the old radiator overflow back to the header tank:

http://www.greatoldone.co.uk/blog/2008/5/6/watertight-at-last.html

Cheers

Jason

[Sportster-Green]

Re: Coolant loss...factory built sportster

good idea....i have now closed the valve on my cap with windscreen adhesive and will give it a try.

if this fails, i will do the same as you!!

thanks for the great idea!!

meanwhile i have also removed the blanking-cap in the upper cooling hose:

i used a 32mm alloy hose joiner with a 1/8"NPT thread, screwed in a hose barb where the overflow-hose is connected to.
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clean and neat solution.