Dirty Den Posted June 1, 2006 Share Posted June 1, 2006 I think I have understood the way in which the K-series cooling system is laid out, but after changing my rad I just want to clear something up in my mind, so this might be a numpty question I understand that the radiator and the expansion bottle are both on one side of the thermostat, with the bypass hose and block on the other side of the thermostat. I filled my car with coolant last night from the top hose, with it attached at the water rail end. Eventually, coolant started to come out of the radiator top hose fixing point. So, I can only assume that either: I don't have a thermostat at all (an ex-RoadSport A) or someone has drilled a hole in the thermostat allowing coolant through even when the thermostat is closed? Have I understood the way in which the K-series cooling system is laid out correctly - i.e. that normally filling via the water rail would not fill the radiator side of the thermostat? Cheers, Den http://www.dens7.co.uk Edited by - Dirty Den on 1 Jun 2006 10:11:13 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 1, 2006 Share Posted June 1, 2006 This sounds right. Sometimes, the plenum has been modified to remove the ball bearing valve for the small hose link to the top of the expansion bottle. This allows a trickle of flow via the expansion tank, but will take a long time to fill the radiator. Link to comment Share on other sites More sharing options...
Dirty Den Posted June 1, 2006 Author Share Posted June 1, 2006 Thanks Peter Den http://www.dens7.co.uk Link to comment Share on other sites More sharing options...
susser Posted June 1, 2006 Share Posted June 1, 2006 I believe the K series cooling system has a fundamental flaw: Any air or other insoluble gasses that end up in the top of the radiator (The second highest point) can't get out again except by the bleed/fill hole in the rad top header. (Small bubbles can be carried down the matrix and out of the bottom hose, then up into the expansion tank.) Every other car that I own has some method of allowing "air" from the top of the rad into the expansion tank, which on my E30 320 looks like a bit of the rad, but isn't. So there. FWIW. And another thing. Air can't swim so won't get down the rad until the rad is full up with air and it then carries through to the expansion tank connection. I'll stop before I start rambling. Link to comment Share on other sites More sharing options...
Lancs Ian Posted June 1, 2006 Share Posted June 1, 2006 I recently had overheating problems and eventually replaced everything, Rad, stat, sender and hoses. The new aluminium rad from Caterham is bigger and has no bleed screw in the top or drain plug at the bottom which was present on the old set up (2000 1.8 VVC). Instead an extra small bore outlet next to the top hose is present which attaches to a T-piece on the top expansion tank hose. This (if my thinking is correct) effectively allows air to pass from the top of the rad direct to the expansion tank. The system seemed easier to set up/bleed and works well with the temp much more stable than before. Link to comment Share on other sites More sharing options...
Myles Posted June 1, 2006 Share Posted June 1, 2006 Every other car that I own has some method of allowing "air" from the top of the rad into the expansion tank, which on my E30 320 looks like a bit of the rad, but isn't. Why do you care? Seriously...? An air pocket in the engine could/would be fairly disasterous - but who cares if there is a small one in the rad? Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 1, 2006 Share Posted June 1, 2006 For once I find myself in agreement with Myles.... 😳. A bit of air at the top of the rad is unimportant. Interestingly, if the rad flows top to bottom there is a greater chance of air getting circulated to the engine. A side to side rad will tend to keep air at the top and this is a good thing. Link to comment Share on other sites More sharing options...
stephen grant Posted June 1, 2006 Share Posted June 1, 2006 Den. Easy way to tell whether you've got a thermostat. What temperatures were you getting at motorway speeds about 3 weeks ago when it was cold and wet? I was getting 45-50 degrees, which is when I decided to put a thermostat in... stephen Link to comment Share on other sites More sharing options...
Colin Mill Posted June 1, 2006 Share Posted June 1, 2006 One thing to remember is that a lot of thermostats have a small hole to allow a small flow of coolant to pass through them. (this is required in more conventional systems to allow the thermostat to 'sample' the temperature of the outflow from the head - not of course strictly needed in the K series system but could explain the effect you mention. As regards the airlock in the top of the rad I suppose it could prevent the fan switch from cutting in at the right temperature but with the thermal conductivity of ali I think it will get close unless the whole of the top tank is empty. I like the idea of the new rad layout though - perhaps a banjo fitting in place of the filler plug at the top of the rad could do the job for earlier machines. Colin Link to comment Share on other sites More sharing options...
Myles Posted June 1, 2006 Share Posted June 1, 2006 For once I find myself in agreement with Myles... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Dirty Den Posted June 1, 2006 Author Share Posted June 1, 2006 Thanks all Stephen, unfortunately I can't answer that question - the car has been off the road recently whilst I waited for my new radiator from Radtec Den http://www.dens7.co.uk Link to comment Share on other sites More sharing options...
susser Posted June 2, 2006 Share Posted June 2, 2006 It's not the damage a small bubble of gas can do that's the problem. It's the issue that the radiator wetted area will be reduced by the prescence of (a) gas. If there is no means of escape for any gas (air) that is introduced to the system, then the standard Caterham rad will end up being full of air, as I stated, and there will be reduced contact between the metal cooling surfaces and the coolant. After all, the rad is there to allow the coolant to dissipate heat and it can only do that (in significant amounts) if it's touching the metal. See And as for you Peter Camichael; Air at the top of a crossflow rad isn't a good thing at all. As far as the radiator's efficiency is concerned. If the rad is half full of air then you've only got half a rad. As above contact comment. So I'll see your "sticking out tongue smileywink smiley" and raise you a "poke with a stick" (like they have on the WSSC site) Bring it on back, 10-4, good buddy, etc etc. Link to comment Share on other sites More sharing options...
elie boone Posted June 2, 2006 Share Posted June 2, 2006 The question is : how much air in the radiator is to much for stopping the fan switch to activate the fan. I agree with Susser, if i would have a K series the first mod. i would do is to put a banjo in place of the bleed screw and connect it to the expansion bottle with a T piece, well i would ditch that horrible piece of plastic and put a nice ali. one in. No 2 would be to put a bleed screw in the heater valve. Link to comment Share on other sites More sharing options...
susser Posted June 2, 2006 Share Posted June 2, 2006 elie Now don't you start with the "if I would have a K series bit" that's like a red rag to a bull if you are a K series fan. I'm not suggesting I am of course, although I might be. Aaaaaaaaannnnnnnnnyyyyywwwwwwaaaaayyyy That's a blinking good couple of ideas there matey, I might hafta get up the garage and have a fiddle. Another little thing wot springs to mind, is that after I've had a cooling system in bits, the expansion tank level always fluctuates more between hot and cold. That must be the air in the pockets, heater, high points etc thats expanding and contracting more than wot water does, kind of thing. Hmmmmmmm Link to comment Share on other sites More sharing options...
Colin Mill Posted June 2, 2006 Share Posted June 2, 2006 "well i would ditch that horrible piece of plastic and put a nice ali. one in" Are you suggesting K series out and duratec in? 😬 Link to comment Share on other sites More sharing options...
susser Posted June 2, 2006 Share Posted June 2, 2006 speaking of which; I've just spent some time at Scholar and I realise that a nice dry sumped duratec is better to look at than 'er indoors. maybe I'll try some of this wife swapping lark, I ought to get at least a set of roller barrels. 😬 Link to comment Share on other sites More sharing options...
elie boone Posted June 3, 2006 Share Posted June 3, 2006 Colin, I only reffered to the expansion bottle. Susser, i am a blue oval fan, the one with AX block and belt drive and a banjo behind me. Link to comment Share on other sites More sharing options...
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