paulhodgson Posted November 3, 2007 Share Posted November 3, 2007 Guys I need some help, as I am rapidly running out of ideas. Car is an 1993 HPC VX 2.0 Injection, runs well (normally) but is a little prone to coolant issues. Yesterday it overheated after a 20 minute drive when left idling for 10 minutes, no fan cutting in, although the temperature when driving hovers around 80, sometime rises, but always falls back. Tested the fan by by-passing the coolant switch in the top of the rad, and it works fine, so went out and found a new coolant switch this morning, and put it in. Still no fan What else should I look at, is there a water pump issue? how do I tell, top & bottom hoses get hot, heater spews out a lot of hot air, but I am worried that the water isn't circulating!?! Do I just need to get it into a mechanic and get the whole cooling system overhauled? Link to comment Share on other sites More sharing options...
CageyH Posted November 3, 2007 Share Posted November 3, 2007 Top up and bleed the coolant system. Bleed the rad etc. Let it run on idle while it warms up. Check all of the hoses get hot. If mot, you may have a failed thermostat, or the system may not be bled properly. Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
paulhodgson Posted November 3, 2007 Author Share Posted November 3, 2007 Thanks for this, with prior apologies for the dumb question, is the coolant fan switch that screws into the top of the rad also the theromstat, as I replaced that this morning. On the question of topping up & bleeding the system, is this s simple process, I guess you have gathered that I have little mechanical knowledge by now!! Link to comment Share on other sites More sharing options...
CageyH Posted November 3, 2007 Share Posted November 3, 2007 There will be a thermostat somewhere in the cooling system, which is different to the fan switch. On top of the radiator, should be a blled screw. You need to loosen this off, and then top up the system from the highest point (normally thge top hose in the hrater) until water comes out the bleed screw. Then close the bleed screw, and top up the system until you can get no more in. then put the hose on, top up the header tank to max, put cap back on header tank, and let the car warm up. Whilst warming up, loosen the rad bleedscrew. When water comes out, tighten it up. Run car untill fan comes on, or temperature gets high... (hopefully not the latter!). Let the car cool down again. Take the cap off the header tank when the coolant is cold, and top up. Job's a good un Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
paulhodgson Posted November 3, 2007 Author Share Posted November 3, 2007 Thanks very much, wiil go through this tomorrow am and hope it clears the problem, now just need to find the thermostat, to ensure it is working, any tips? Link to comment Share on other sites More sharing options...
Markiebabes Posted November 3, 2007 Share Posted November 3, 2007 Hi Paul, Found this here may help 😬 Mark Car Webshots Here Link to comment Share on other sites More sharing options...
Dave Wilson Posted November 3, 2007 Share Posted November 3, 2007 Don't forget the simple things, the fan is on a fused circuit, check it... Link to comment Share on other sites More sharing options...
F355GTS Posted November 3, 2007 Share Posted November 3, 2007 Paul When you say the Car overheated, what were the symptoms? did it boil over? what did the temp gauge say? it could just be a faulty expansion tank cap releasing pressure too early. Assuming the Car is actually getting too hot and when you joined the two wires of the fan switch together and the fan worked then the switch is faulty, if it still does the same thing after switch swap then I suspect the replacement is faulty too assuming it is of the correct temperature rating and the Radiator is bled correctly. Well worth checking the cleanliness of all connections to the switch/ fan too but thermostat etc etc will not affect the problems you are having only the switch controls whether the fan comes on Mark Link to comment Share on other sites More sharing options...
paulhodgson Posted November 4, 2007 Author Share Posted November 4, 2007 Actual symptoms were no fan, and temp gauge slowly raising to 100+, and then dribbling water from cap on expansion tank. When I changed the fan switch (screwed into top of rad) as i took the old one out, water flowed from the rad, fitted new switch and again ran engine, and again no fan. So, is this a faulty cap that is letting water out prematurely, a failed fan switch (the fan runs when the connectors are linked), or a failed thermostat over and above the fan switch that I have yet to find???. Am refilling rad this morning to check if it needs bled (50% water, 50% anti freeze), and will see what that brings, but I cannot understand why the fan switch repacement still fails to run the fan?? Link to comment Share on other sites More sharing options...
CageyH Posted November 4, 2007 Share Posted November 4, 2007 Sounds like a dodgy fan switch, as well as an expansion tank cap. Are all the coolant hoses warming up? At around 88 degrees, I would expect them to all be hot. If not, suspect the thermostat as well. Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
paulhodgson Posted November 4, 2007 Author Share Posted November 4, 2007 So, refilled coolant, undid bleed valve and a little bubbling, but not much, ran up to speed, and still no fan!!!. Fan still operates when bypassing the switch, so am guessing it cannot be the fuse??. No steam or water from the expansion filler cap, although I did switch off before it got too hot, all hoses red hot, heater blasting hot air, cannot work out why no fan. What else can I try? Link to comment Share on other sites More sharing options...
CageyH Posted November 4, 2007 Share Posted November 4, 2007 Another fan switch I would suggest the new one is faulty. Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
CageyH Posted November 4, 2007 Share Posted November 4, 2007 Forgot to say that the fact all hoses are getting hot means your thermostat is working. Did water trickle out of the rad bleedscrew? Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
j passfield Posted November 4, 2007 Share Posted November 4, 2007 I had a similar problem recently, I fitted a new fan swich believing it was the same as removed, further investigation proved it was operating in a higher temperature range, I think the swich you should be using will cut in at 96 degrees and out again at 85. Your original problem of overheating sounds as though the radiator could be partially blocked, you can check this by running your hands over the core of the rad.any cooler areas will be because the water isn't flowing, also it is not unheard of for water pump impellers to fall off but I would expect overheating to happen more quickly than you describe. You also said that originally the temp gauge raised just over 80 and then dropped back, that would indicate the thermostat opening, ie the water has got to, or just above that required for the 'stat to open and as it flows through the top hose to the rad. and cooler air passing through it, so the temp. will drop back slightly. For 3 quid change the expansion cap as a matter of course. Link to comment Share on other sites More sharing options...
CageyH Posted November 4, 2007 Share Posted November 4, 2007 You could also wire in a remote fan switch as a back up. Only dead fish go with the flow....! Link to comment Share on other sites More sharing options...
seventh-heaven Posted November 4, 2007 Share Posted November 4, 2007 If when you by-pass the switch on top of the radiator the fan runs then there are only 2 possible causes of this symptom: 1) The switch is defective; or 2) The switch is not getting hot. As you have replaced the switch already it does not seem unreasonable to initially focus on 2. The causes of 2 above can only really be: 2a) The radiator is not full and there is air between the hot water in the radiator and the switch. 2b) The water is not circulating effectively so no hot water is reaching the radiator. Of course 2b could be due to a defective thermostat or a defective pump but the checks will be the same. You say that you had water out of the switch hole when you changed the switch which suggests that the radiator does not have air. None the less I would check that again to be sure by unscrewing the Allen key plug near the top pipe (assuming same as mine!). Once you have confirmed no air, you need to turn to 2b and check water circulation. When started from cold both hoses to the radiator should remain cold until gauge reads about 80 degrees. There may be a smaller bypass hose from the thermostat housing which should get hot. Once the temp gets around 80 degrees you would expect the top hose to the rad to get hot. You will then be able to feel the hot water spread down the radiator to the bottom and then the bottom hose back to the engine will get hot. If all this occurs before the temp gauge reaches much over 90 degrees that the circulation is fine. Another reasonable test is driving - if the engine does not overheat when it is driving normally then circulation is almost certainly OK. So is the overheat only at stand still. If none of the above reaches a solution then there are only really 2 possibilities - either the new switch is defective or of course it could be the gauge over reading - but then that would again probably manifest itself when in normal driving. Hope that is useful. Andyh Edited by - seventh-heaven on 4 Nov 2007 17:03:17 Link to comment Share on other sites More sharing options...
Bio Posted November 4, 2007 Share Posted November 4, 2007 Have had problems with my vx 2.0 in the past especially with coolant leaks from the expansion cap I have now fitted a round Vauxhall expansion tank and preassure cap and ensured that the position of the tank (still in the front) allows the coolant level to always be slightly higher than the top of the rad to ensure no air is between the coolant level in the top of the rad and the face of the switch The system has been bled carefully (and bled again after a good run) I now have no problems with cooling even after long hard touring John Link to comment Share on other sites More sharing options...
paulhodgson Posted November 5, 2007 Author Share Posted November 5, 2007 Still no joy, new switch still failing, but I have checked all of the points raised above. Engine is fine when running, the temp guage hovers around 80, sometimes rises if in a queue, but always falls back to 80 when driving, so there is not likely to be circulation/blockage issue. Water spurts out from expansion tank filler cap when the guage reads 100, but I have checked the rad by opening the bleed valve as it warms up, and only got a few bubbles before water ran out. Hoses all get very hot, much as described above, top & bottom hoses take longer to get hot, but heater hoses are hot quite quickly. It can only be the fan switch, but this is switch no 3, and I am getting a little irritated. Link to comment Share on other sites More sharing options...
paulhodgson Posted November 10, 2007 Author Share Posted November 10, 2007 Car is now well again (failing cooling fan switch & overheating), had it into Banks Europa who has fitted an adjustable fan switch into the top hose set at 92 - 87 degrees, and the fan now cuts in as required - at last. 😬 Link to comment Share on other sites More sharing options...
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