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Post by lagain on Jun 26, 2015 20:03:21 GMT
Do you use the overflow pipe? The expansion bottle sits on the near side just behind the radiator and is connected to the overflow pipe with a long section of rubber pipe. I have a blanking cap on the radiator and the pressure cap on the expansion bottle. The bottle is 'see through' so easy to see the level of the coolant. It has never overflowed.
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Post by Phil Nottingham on Jun 26, 2015 21:45:04 GMT
Same set up on our 1972 S3 Land-Rover except its not a see through tank. The standard cap is used which has a one way valve as with the P5B to allow coolant (or air) back into the rad when it cools down to avoid a vacuum collapsing the hoses which is sometimes seen on P5B's (and other cars) when the wrong cap is fitted
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Post by enigmas on Jun 26, 2015 23:40:14 GMT
Phil said,
The explanation is a bit confusing Phil. If the radiator cap has a small valve at it's centre it functions by virtue of a vacuum. The system will only function correctly if free of air otherwise purging occurs due to steam pressure in a hot engine not hot coolant. As the coolant heats up it expands and takes up space, hence the need for an air space in a non recovery system. All older style cooling systems with vertical flow top tank radiators were filled to within half an inch of the filler cap in the past and gave no issues but did require checking occasionally.
With a recovery system the radiator is filled to the top and a dual valve cap used. The large one being operated by system pressure (for example 7 - 15 psi, depending on the system design) and the small one functioning under vacuum when the expanded hot coolant in the system 'cools down' and is drawn back into the radiator from the expansion bottle. This is quite obvious when the system is functioning correctly as the coolant will rise in the expansion bottle with a hot engine and fall when the engine is cooling down. An expansion bottle needs to have the coolant transfer tube/hose submerged in the coolant within the bottle. It acts like a syphon so can be mounted lower than the radiator as Steve noted. The system works equally well on both vertical and cross flow radiators and can be adapted to any system.
The other earlier type had a purge tank. A cap was fitted to the radiator for topping up but it did not have any valves it was there merely to seal the filler on the radiator. The overflow hose was firmly connected to the filler tube and connected to a small purge tank which had a normal style radiator cap. This allowed the radiator to be filled to the top. A small amount of coolant was in the purge tank and the tank was mounted above the radiator core. The purge tank has it's inlet underneath and is merely an extension of the radiator allowing for coolant expansion. This method is not a recovery system and the purge tank needs to be above the radiator to function correctly.
If hoses collapse due the suction induced by powerful water pumps and/or recovery systems internal radiator hose springs can be fitted. Quite a number of vehicles have these fitted from the factory.
The recovery system is in my opinion the least maintenance intensive and most effective when setup correctly.
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Post by cyf on Jun 27, 2015 14:43:07 GMT
Interesting
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Post by guidedog on Jun 27, 2015 15:22:27 GMT
My Cyf I you found it interesting. Can I go back sleep now. It's all over my head.
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moonchariot
Rover Rookie
Preserving P5B - 846-00117-C
Posts: 40
Location: South Australia
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Post by moonchariot on Jun 30, 2015 8:58:46 GMT
The top of the manifold is a high point, Cyf, so air would become trapped there. The small nipple near the top, and the hose connected to it, allows any air to escape into the top of the radiator and from there into the expansion tank. It also would allow a small flow of coolant to keep moving out of the top of the manifold to stop stagnant pockets developing, causing localized hotspots. But the air bleeding issue would be the main reason. A very sensible solution to the problem. Don't ask me what I think about the methods used on my 406.
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Post by Warwick on Jun 30, 2015 11:22:06 GMT
Indeed Mike. Now that's a coincidence. It's a 1998 SRDT sedan with 450,000km on the clock, and on its last legs. It was passed on to junior when he got his licence a couple of years ago. We're currently in the process of buying a replacement; a 2001 HDi with a modest 330,000km.
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