Which radiator cap

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janz
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Which radiator cap

Post by janz »

Wanting to replace the radiator cap on my 1964 English Moke as I felt coolant was passing to easily into the overflow pipe, I discovered that the cap doesn't reach all the way to the filler neck seat.... so that's why I keep losing coolant! :o Bit of research reveals that Moke still has the (probably) original Coventry branded radiator in it with the long filler neck. I have found a 4 PSI rated long filler neck, but I still lose some coolant on longer trips.
Anyone know what the correct rating should be?
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Wally2
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Re: Which radiator cap

Post by Wally2 »

Hi JanZ, Had to replace cap on mine for the same reason. My cap was 10PSI and in the Leyland workshop manual it states 13 psi so thats what i've put on. Everything seems ok now. Chap at the local spares shop even measured the depth to the sealing face on the rad before selecting the cap.
Cheers - Wally 2
Chris
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janz
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Re: Which radiator cap

Post by janz »

Hi Wally2, that sounds like a normal length radiator cap. THey tend to be rated from 10 to 15lbs. I might be wrong but the long neck caps are lower pressure like 4 or 7 lbs. I haven't measured it exactly but the long filler neck is about 8mm or so deeper to the seat. Long neck Coventry radiators were fitted to 848cc Minis built before 1965 and are rated at 7lbs max operating pressure. My radiator cap is rated at 4lbs. I hazard a guess that a 1964 Moke would have the same as an 848cc Mini, but so many things were 'variable' in those days, I want to be sure. Putting a cap with too high a rating could damage or blow the early radiators as well. If you measure yours.... I'll measure mine :lol: Jan
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Wally2
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Re: Which radiator cap

Post by Wally2 »

janz wrote:Hi Wally2, that sounds like a normal length radiator cap. THey tend to be rated from 10 to 15lbs. I might be wrong but the long neck caps are lower pressure like 4 or 7 lbs. I haven't measured it exactly but the long filler neck is about 8mm or so deeper to the seat. Long neck Coventry radiators were fitted to 848cc Minis built before 1965 and are rated at 7lbs max operating pressure. My radiator cap is rated at 4lbs. I hazard a guess that a 1964 Moke would have the same as an 848cc Mini, but so many things were 'variable' in those days, I want to be sure. Putting a cap with too high a rating could damage or blow the early radiators as well. If you measure yours.... I'll measure mine :lol: Jan
Hi Jan, you may be correct, mine looks a 'normal' depth, it measures 25/32" in old money or 19.5mm. The Leyland manual just states 13psi for all mini mk1 & 2 848cc and 998cc.
Chris
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janz
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Re: Which radiator cap

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Hi Chris, Took the English Moke out today - actually topped up with coolant but forgot to measure the neck depth. May do so tomorrow. I was diverted by the fact that I had two different sealed beam headlights at different wattage. I decided to replace the weaker one only to find my headlights and dipped beam not working :x So it was out with the Fluke and the wiring diagram (original one in the supplement I add 8) ). Dropped the dash, buzzed it all through to the front - no continuity. Turned out to be a slghtly dodgy bullet to bullet connector on the 'supply in' to the floor mount high beam switch. Must have caught the loom whilst driving last Thursday night. It's not easy manoeuvring a size 11 boot between clutch pedal, gearstick and high beam switch :roll: Final result - lights work, but still not replaced the weak sealed beam :?
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janz
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Re: Which radiator cap

Post by janz »

New radiator cap arrived today - FRC64 or GRC101 - anyway, it's the 7lbs long neck type. It's 34mm from top of cap to bottom of spring. Researching the radiator in my Moke, I found that Coventry Radiators were bought out for the 1st time in 1965. Radiaters then became 'Associated Engineering' Prior to that in 1964, rads had the Covnetry label on them. My Mokes says:
Image

Can anyone coroborate that? I have found on the web, but that's not always correct. I think my 64 Moke has the original rad in it :D
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Wally2
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Re: Which radiator cap

Post by Wally2 »

Hi Jan,
Having trouble with my rad cap again! The new one is letting water past it and into the overflow pie and ending up all over the inside of the wing and under the car. I've ordered a 15lb one from tinternet, I think, for whatever reason, that the cap is just not sealing properly. Wether this is a fault on the rad itself or the caps I just dont know. Will try the new one when it comes and let you know, unless anyone else has any ideas?
Cheers
Chris
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Tim
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Re: Which radiator cap

Post by Tim »

The cap is meant to let water out if the pressure gets above the rating of the cap. Often what happens is that after you fill the radiator right up, the hot water doesn't have any headroom to expand into. It has to go somewhere or something will pop, so the cap lets it out. Once the first lot of water is lost there is some headroom in the top tank and you should find that the overflow stops.

Tim
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Re: Which radiator cap

Post by Wally2 »

Hi Tim,
I fill the rad up to the level indicator (a wire hoop about 1/2" down from the neck). After I've lost some fluid the level ends up not much above the rad core. I'm due to change the cylinder head soon and while doing that I will pipe in the heater I've fitted, this will add capacity to the cooling system and may aid the problem.
Cheers
Chris
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janz
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Re: Which radiator cap

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Hi Chris, much the same with mine - 7lbs cap (long neck) and on a warm day, 100 miles is enough to let sufficient water go to bypass to drop an inch below the fill marker (well brass block above the core). It's certainly about 1.5 to 2 pints (oooerrr look - metric mixed with toes, knees and elbows) of coolant gone. I keep a 2 litre bottle with me pre-mixed now. Was at Castle Combe. Some vendors said a higher pressure long neck cap didn't exist, some said a 13lbs one was available, but not on the day :roll: - Anyway, autumn is here so fewer rides out in the 64 - however...FUD is out lurking though. And soon it will be duvet for winter - but first... MOT. Will buy the 64 a 13lbs cap for crimbo :lol:
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Wally2
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Re: Which radiator cap

Post by Wally2 »

Hi Jan, Well tried the 15lb cap but its just a smidgin shorter than the 13lb so it doesnt seem to seal right, tried it with a large 'o' ring in the bottom of the rad neck but once warm out the fluid comes, so gone back to the 13lb and trying it with less water in. Wouldnt mind but its not exactly hot weather either!
Chris
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