Glyn Read Posted June 20, 2009 Share Posted June 20, 2009 I wonder whether anyone has any ideas about why my engine overheats. I recently had a full service at Caterham factory including fitting new water hoses. On driving home the car overheated. I rigged up a wire to keep the fan on permanently and returned the car assuming the therm. switch in the radiator needed replacing. This they duly did and I set off again. The same thing happened! It overheated even with a new sensor switch.Any ideas of where do I go from here to cure the problem would be greatly appreciated. Link to comment Share on other sites More sharing options...
Myles Posted June 20, 2009 Share Posted June 20, 2009 Well, on the move, the fan-switch is irrelevant. Unless driving in extreme conditions, the standard rad should be sufficient above - ooh? - 40mph - to keep the engine cool - as long as the waxstat that physically controls the flow of water from the rad into the engine is happy. Why do you think it overheats by the way? Does the expansion-tank fill or overflow? Does the fan come on in traffic? Or are you just relying on the water-temp gauge? The standard temp-sensors used by Caterham are (well, were) desperately unreliable. I, personally, went through at least half a dozen (no joke) before changing all of my temp instruments to SPA gauges. Each time the standard sensors failed, they did it in a different way. Some fluctuated, some read high, some low. Make sure the symptoms are genuine before you start addressing 'the cause'. 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester Racing 7s Ecosse™ 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Glyn Read Posted June 20, 2009 Author Share Posted June 20, 2009 Thanks Myles. Forgot to say it only overheats in traffic otherwise runs at indicated 85. The header tank appears to be full. The fan sometimes comes on in traffic at an indicated 100 but takes a long time to cool the temp. Other times it kicks in at about 90 and the engine cools much quicker. Would an air lock affect it if the system was not refilled properly? Link to comment Share on other sites More sharing options...
Myles Posted June 20, 2009 Share Posted June 20, 2009 The header tank appears to be full. Full-full? As in to the cap? That's not good. Could be as simple as a duff pressure-cap - there was a period (back when Rover actually existed) when the parts-desk would send you round to the engineering-bays to get your new cap tested as the QC was so bad... Try another cap. Search techtalk regarding bleeding the system - the general recommendation is to get the front of the car up in the air - but squeezing the major hoses helps. Someone will probably mention possible head-gasket failure, but let's get the basics out of the way first. Replacement expansion-tank caps cost a few quid. 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester Racing 7s Ecosse™ 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Glyn Read Posted June 20, 2009 Author Share Posted June 20, 2009 Miles Many thanks for your help. Really appreciate it. Will try your suggestions. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 21, 2009 Share Posted June 21, 2009 Big chance there is an airlock in the system. CC not always so good at removing air from brake or cooling systems !!! Link to comment Share on other sites More sharing options...
Englishmaninwales Posted June 21, 2009 Share Posted June 21, 2009 I agree with S25T. Do a search, loads on how to refill the coolant. Link to comment Share on other sites More sharing options...
jackb_ms Posted June 21, 2009 Share Posted June 21, 2009 A PRRT may be the way forwards Before fitting a PPRT the fan went on at 85 and temperature went down to roughly 75 when the fan stopped. Leaving the car stationary with the engine on was always a worry for me. I've finally fitted a PRRT to my VVC and from the stationary test the coolant stay at a rock steady 80 degrees even after about 1/2 hours. Jack Emily, The Very Yellow 21 Link to comment Share on other sites More sharing options...
Glyn Read Posted June 21, 2009 Author Share Posted June 21, 2009 Many thanks Folks. Very grateful for all the advice. I will go for a proper bleed of the system before trying another new thermo switch!javascript:insertAtCursor(document.postpage.message,%20' *smile*') Link to comment Share on other sites More sharing options...
Glyn Read Posted July 1, 2009 Author Share Posted July 1, 2009 Just an update. I returned the car to Caterham and asked for the coolant to be changed and another bleed of the system. This time the coolant is pink in colour and has not moved from the header tank max level. The fan also comes on as per spec. So the advice was spot on. Bleed the system before changing the rad sensor. Once again many thanks for all the help. Link to comment Share on other sites More sharing options...
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