Hammy Posted February 17, 2006 Posted February 17, 2006 In the process of getting my "new" SE out of hiberantion - The Radiator cap appears in poor condition and I suspect its the wrong one (it may not be deep enough?) - does anyone know what pressure rating the cap should be and what car it originates from ? (i.e what do I ask for at the local motor factors) . Car has X-flow engine with the alloy theromstat extension housing which includes the rad cap. Paul. Quote
stu999 Posted February 17, 2006 Posted February 17, 2006 But.... The alloy thermostat extension (from an early XR2 IIRC) suggests to me that you may not have an expansion tank. Or if you have, that the cap that is fitted is incorrect. If an expansion tank is not fitted, it would be a wise idea to fit one. This will mean fitting a tank as high as possible on the scuttle (but at least higher than the cooling system itself). The pressure cap should be fitted to the tank. Then replace the 'XR2' cap with a plain flat one, and plumb the breather to the top of the tank. This will prevent water loss, and the problem of constantly having to top up the cooling system. If it does have an expansion tank, there actually may be two pressure caps in the system - not good... HTH Stu Quote
Hammy Posted February 17, 2006 Author Posted February 17, 2006 Thx for the replies - I do have an expansion tank but it appears to be a low pressure (overflow type where the vacum created on cooling sucks any displaced water back in) type ( it has a clip flip-top ), so a pressure cap on the housing sounds about right for this installation. Paul. Quote
DickieB Posted February 17, 2006 Posted February 17, 2006 Email me at dickie-b@boltblue.com - I have some photos I can email through to help explain Stu's post. Let me know if you have broadband or not otherwise you could be there a while! Quote
Martin Keene Posted February 17, 2006 Posted February 17, 2006 Thx for the replies - I do have an expansion tank but it appears to be a low pressure (overflow type where the vacum created on cooling sucks any displaced water back in) type ( it has a clip flip-top ), so a pressure cap on the housing sounds about right for this installation. Paul. Correct. I run the same system (if it's good enough for Honda it's good enough for me! and you need a pukka pressure cap on the thermostat tower. A Mk1 XR2 cap will do nicely. Quote
Major Stare Posted February 17, 2006 Posted February 17, 2006 Ive run my x-flow without an expansion tank and have done for over a year now. It maintains temperature a lot better and no probs to date ! If the car over heats, the stat will open and releave pressure to an over flow tank off a Mitsu Gallant. never done it yet ! Quote
stu999 Posted February 17, 2006 Posted February 17, 2006 Correct. I run the same system (if it's good enough for Honda it's good enough for me! and you need a pukka pressure cap on the thermostat tower. A Mk1 XR2 cap will do nicely. If it works, no point in changing it. But look carefully at the design of a Honda (and similar) cooling system, and there will be a decent 'head' of water above the engine (usually incorporated in the radiator), preventing water cavitation/air pockets. A header tank mounted high up does the same. The danger of running a simple 'to atmosphere' tank is that the head of water isnt there... But as I say, if it works... Quote
Martin Keene Posted February 18, 2006 Posted February 18, 2006 Works fine, in fact if somebody else had done without telling me, I'd struggle to notive from the way the engine runs. There probably isn't much of a head of water in the Honda system either, i had a Civic Vti at the time and I couldn't understand you the header tank work so much study was done ans the design copied. I like the simplicity of it, the old system with the header tank has 4 pressurised cooling hoses (2 for the rad, 2 for the tank) mine now only has the 2 for the rad, which has to be a good thing. If it ain't there it can't go wrong/break/fall off/etc... Quote
Davefitton Posted February 20, 2006 Posted February 20, 2006 Hammy do you mind if I Hijack your thread? Could someone please clarify the correct cooling system for me. I have 1700 xflow with a alloy extension on the thermostat housing that has a pressure cap on it (incidently this leaks a little so I need to replace it but with which one?) I also have a expansion tank with a screw thread cap that I don't think is pressurised. My engine never overheats but is it ok and which is the correct pressure cap? Thanks in advance, Dave Quote
Martin Keene Posted February 20, 2006 Posted February 20, 2006 How many hoses does the expansion tank have on it? If it has 2 and the screw cap is yellow plastic then it is the standard Westfield/Ford and it is pressurised, in which case you should have a blank cap fitted to the thermostat housing. If the expansion tank only has 1 hose going to it then it is unlikely to be pressurised, but without seeing it's hard to say for sure. Quote
Davefitton Posted February 20, 2006 Posted February 20, 2006 Martin, Thanks for this, my setup is indeed a yellow capped expansion tank with 2 hoses. What do you mean by a "blank cap"? Dave Quote
Martin Keene Posted February 20, 2006 Posted February 20, 2006 The cap on the thermostat housing should not have the spring on the bottom of it that you would normally find on a radiator cap. If it has it will stop the coolant flowing normally around the system to the expansion tank until the required pressure is a acheived to 'pop' the cap. Quote
John Loudon - Sponsorship Liaison Posted February 20, 2006 Posted February 20, 2006 I'm with Stu999. The thermostat tower would be best having a blanking cap and the overflow pipe from it should go to an expansion tank with a pressure cap. The principle of a pressure cap on the thermostat tower drawing water back in when the temperaturatur cools is good, but in theory it doesnt work on the X/F for some reason and you end up with an air lock in you head. I reverted to Stu's method and fixed my X/Flow cooling issues instantly. John Edit - Mrtin's post immediately above has just changed all this as it now makes me think that his setup is as I'm trying to describe afterall. Quote
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