K Series Hose Heater valve to thermostat

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john milner
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K Series Hose Heater valve to thermostat

The joint between the hoses that go between the thermostat and heater control valve is leaking. I have decided to replace these joined hoses for a single silicone hose. I think there are two at present because slightly different diameters are needed at each end and rubber hoses will leak if the size is not spot on. I swapped out the main hoses a few years ago so do not need a full set. My problem is that I am not sure what it is that I need to order. The Caterham site has items that might be right ones or I can probably get one from Classic Silicone Hoses. Any other supplier suggestions for a bent hose that is not in a kit?

Is the hose I am after the longest one with right angle bend in the Classic Silicone Hoses kit?:

http://www.classicsiliconehoses.com/wp-content/gallery/uploads/caterham-rover-k-with-clayton-heater.jpg

Could it be this one:

https://caterhamparts.co.uk/hoses/4737-hose-block-heater-vauxhall-rover-black-silicone.html

Or this one:

https://caterhamparts.co.uk/hoses/1510-hose-block-to-heater-blue-silicone.html

 

 

Something that I have come across in an old thread suggests that there was some confusion in some old manuals as to which hoses went top and bottom at the valve. In my case the thermostat goes to the top and the bottom hose goes to the rail which is the opposite to post #11 in the old thread. I have few problems with airlocks so I am wondering if the confusion could be part of the reason why some people have a nightmare getting rid of airlocks and others do not. Mine is a per Section 9 page 11 of the build manual.

https://www.lotus7.club/forum/techtalk/replacement-cooling-hose-k-series-1800

 

 

 

StevehS3
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Hi John,

I recently ordered one from Classic Silicone Hoses (see photo) but haven't fitted it yet. They explained that they now sell it as one hose to avoid a joint if the heater isn't fitted (like mine) or can be cut in two if the heater is fitted. It has the different sizes on each end and is the correct length.

Steve

john milner
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Thanks but a little confused. I thought the join was to allow each end to have a different size when made in rubber. I am hoping to do away with the join as it will halve the number of clips where a leak could occur. I need to rethink the reason for the join.

StevehS3
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I always assumed that the joint in the rubber hoses was so they could supply the same hoses whether a heater is fitted or not but you are probably right that it was because they are different size hoses.

The hose in my picture is what you want. It is one long hose and has the correct sizes at each end formed into the silicone hose - so no joint in the middle for heater-less cars.

john milner
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Penny dropped about 10 minutes after my last post. If a heater is fitted (as mine is) the replacement hose can be cut so that both the inlet and outlet at the valve can be replaced and not just the bit that I was after. Unless someone comes up with a better idea I'll contact Classic Silicone Hoses in a few days.

StevehS3
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That's how it was explained to me John.

Gordon GWF
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I fitted a full set from Classic Silicone Hoses a few months ago on my K series with heater and the long hose is a different size at each end and replaces the 2 piece Caterham hose so no need to cut it and the join is eliminated.
john milner
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Classic Silicone Hoses are currently unable to supply individual hoses only complete sets for the time being. This situation should not last forever but in the meantime any suggestions of another supplier of single silicone hoses?

Jonathan Kay
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There are good reports of both Samco and SFS Performance (Club discount).

Jonathan

john milner
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SFS were able to supply the single hose that I was after with a substantial club discount. Delivery took just over a week so perhaps these are made to order. Their website does not list it but the part is CHS120.5. The thermostat end is a couple of inches longer than the original and I cut off about six inches from the valve end. Both ends slipped on a lot easier than taking the old rubber ones off so I suspect I will have a week or two of tightening before it is leak free.

The leak I had on the old set-up was caused by the plastic link between the two sections of pipe being deformed (75,000+ miles and 16 years). The bottom hose was barely hanging on and fell off while I was examining it so I am surprised that the leak was  minor.

I did not totally drain the system down but just removed the thermostat end and let it drain until it stopped with the heater valve shut and filler cap on. I lost two to three litres of coolant. Thermostat end was fitted first, then the bottle was topped up until coolant found it its way out of the heater valve, then I stuck a funnel into the open end of the hose and filled that as far as I could before finally connecting the hose to the valve.

Not started the engine yet but I am not expecting any significant problems.

john milner
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Comparing new and old:

 

Deformed ends: