CharlesElliott Posted October 14, 2003 Share Posted October 14, 2003 For my own interest and education, can anyone point me to a diagram of how the cooling system works in the K series? (the water circuit that is, rather than the electrical circuit associated with the cooling) Charles --- My Caterham Academy 2004 Diary Link to comment Share on other sites More sharing options...
V7 SLR Posted October 14, 2003 Share Posted October 14, 2003 I can describe it if you'll bear with me. Stand on the passenger side of the car and face the exhaust side of the engine. The coolant EXIT rail is above the exhaust. The coolant exits the engine (head) towards the back of that side. Under the front of the throttle side is your thermostat. Coolant enters the engine at this point. Now, when the engine's cold and the thermostat is closed, coolant exits the engine as aforementioned and travels around the BACK of the engine (through the heater if fitted) and into the thermostat through that narrow pipe. When the engine is hot, the thermostat opens and bleeds coolant in from the radiator through the thicker piper. The amount of coolant that circulates is dependent upon the amount the thermostat is open, which in turn depends upon how hot the coolant is. Essentially, coolant travels in 2 ZEROS. With the index finger on your right hand draw a circle anticlockwise. With the index finger of your left hand do same but clockwise. Synchronise them and that's how the coolant travels around the engine. Any good? Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Edited by - V7 SLR on 14 Oct 2003 21:07:58 Link to comment Share on other sites More sharing options...
CharlesElliott Posted October 14, 2003 Author Share Posted October 14, 2003 Thanks - I think I've got it. So the implication of that is that if you don't fill the head circuit specifically (with the thermostat cold) as I didn't there is no water in it and no way of water getting into it until the thermostat opens. Is that right? How does the pipe that exits from near cylinder 1 into the expansion bottle fit into it? Charles --- My Caterham Academy 2004 Diary Link to comment Share on other sites More sharing options...
V7 SLR Posted October 14, 2003 Share Posted October 14, 2003 Well, no not exactly. The only "tap" is the thermostat, and that's on the inlet side. The exit side is open at all times therefore if the head is empty originally it'll fill from the exit side. The pipe from the throttles (near to cyl no 1 entry) is intended to bleed air out of a known high point in the head, allowing coolant to flow in from elsewhere (the exit when you're filling the system). Also, there is a small 4mm hole in the flange of the thermostat. This is intended to allow hot coolant from the "heater" circuit to pass over the wax pellet and open the thermostat more efficiently when in use. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
CharlesElliott Posted October 14, 2003 Author Share Posted October 14, 2003 Thanks for this. So when the thermostat opens the flow of water from the head circuit 'pulls' water from the radiator circuit into the head - is that right? The implication of this is that the radiator circuit is not pumped directly. In normal use, would you expect coolant to flow from the throttles exit? How about if you had the front of the car jacked up? (when I was doing this to bleed the system, there was a fairly steady stream from this outlet). Charles --- My Caterham Academy 2004 Diary Link to comment Share on other sites More sharing options...
V7 SLR Posted October 14, 2003 Share Posted October 14, 2003 Well the pump is within the engine, so when the coolant exits the head it takes a path proportional to the least resistance. If the thermostat is open then more coolant will be pumped into the radiator, pushing coolant out the other side and into the engine. The throttle exit has a ball valve inside to prevent coolant bleeding from here. Air would get past because that would mean coolant flowing in. However, a lot of "tuners" drill this out as it has been known to stick closed. Better to have it bleeding coolant out into the header tank than to stick closed. The amount is really very small. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
CharlesElliott Posted October 14, 2003 Author Share Posted October 14, 2003 Thanks - I think I've got it now, although you've now got me worried about whether the ball valve is working properly as from memory, there was a pretty full scale flow from the throttle exit into the expansion tank. Charles --- My Caterham Academy 2004 Diary Link to comment Share on other sites More sharing options...
V7 SLR Posted October 14, 2003 Share Posted October 14, 2003 Well, if it's open then that's a good thing. Only worry if you get no flow. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
Peter Carmichael Posted October 14, 2003 Share Posted October 14, 2003 Trying a different perspective to maybe add something... There are two circuits and they have a common segment - the run through the block. The pump is in the common segment, so the pump pumps both circuits. The proportion of flow distributed between the two circuits depends on the opening of the thermostat and the comparative resistance to flow of the open (small) bypass pipe vs. the resistance of the radiator and the thermostat. The small pipe up to the expansion tank is a self-bleed. It is on the high pressure side of the pump, but has a jiggle valve at the inlet manifold end. If there is coolant at the valve it shuts off and there is no flow. If there is air at the valve it opens and the air vents. In practice this valve is a pain in the t!ts and you can get rid of it entirely with no ill effects. If you do this there is a steady stream of coolant up to the expansion tank. [i can see that while I have been writing this Charles and Nig have moved it on a bit] Link to comment Share on other sites More sharing options...
V7 SLR Posted October 14, 2003 Share Posted October 14, 2003 Happens to me all the time. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
CharlesElliott Posted October 14, 2003 Author Share Posted October 14, 2003 Thanks Peter - the pump explanation does help as well [i'd assumed until put straight that the pump was external to the engine and I just hadn't found it yet]. So if I'm getting a stream of water from the throttle exit either there is air still venting along with some coolant or the valve has failed. Charles --- My Caterham Academy 2004 Diary Link to comment Share on other sites More sharing options...
Peter Carmichael Posted October 15, 2003 Share Posted October 15, 2003 If you are getting a stream of coolant it is no bad thing and is preferable to having the valve "working". If the stream is uninterrupted there is no air in it. Air bubbles appear as a pause in the flow (unless the valve is trying to get in on the action). Link to comment Share on other sites More sharing options...
CharlesElliott Posted October 15, 2003 Author Share Posted October 15, 2003 Thanks both - this is great and I think I have a clear understanding now. I'll keep an eye on the throttle exit out of interest. Charles --- My Caterham Academy 2004 Diary Link to comment Share on other sites More sharing options...
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