masiwn Posted April 5, 2008 Share Posted April 5, 2008 my 1800k series will come up to normal temperature on water gauge while idling but once on the move it drops back gradually to zero if I pull in and let the car idle the temperature rises again the fan only cuts in after the temperature gauge goes above 85 any ideas Thanks Aled Link to comment Share on other sites More sharing options...
Mr Locust Posted April 5, 2008 Share Posted April 5, 2008 Aled, the water senders are prone to failure but they tend to make the gauge jump from high to low erratically as the actual temperature changes (at least the three I have changed did). Last time I had one fail, it read high at 80-90degC. I was fortunate enough to have an infra red thermometer in the car which confirmed that the sender was goosed rather than the top hose running at 125degC. Assuming that the gauge moves progressively at all times; has anybody taken the thermostat out of the bottom hose. Ian Green and Silver Roadsport 😬 Link to comment Share on other sites More sharing options...
masiwn Posted April 5, 2008 Author Share Posted April 5, 2008 Thanks the thermostat has not been taken out, The air from the heater also seems to cool when the temp gauge falls does that give any clues could the thermostat be stuck open? Link to comment Share on other sites More sharing options...
Mr Locust Posted April 5, 2008 Share Posted April 5, 2008 Probably a good one to investigate Ian Green and Silver Roadsport 😬 Link to comment Share on other sites More sharing options...
Johnty Lyons Posted April 5, 2008 Share Posted April 5, 2008 the heater is fed by the thermostat by pass cct so therin lies your problem That cct should always be hot no matter wether the stat is open or shut If the heater is running cold then you have air in the system and it will need bled at the upper of the two hoses feeding into the heater jj N.I. L7C AR 🙆🏻 Membership No.3927. Link to comment Share on other sites More sharing options...
masiwn Posted April 6, 2008 Author Share Posted April 6, 2008 Thanks for that, did not fancy having a go at the thermostat do I need to jack the front up to bleed. Aled Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted April 6, 2008 Share Posted April 6, 2008 The air will come out of the highest point, so open somewhere high ! If you raise the front of the car high, you can use the bleed screw on top of rad. Also squeeze J-hose from thermostat - air seems to get trapped there. Do a search in TechTalk - lots of words on this ! 7 related photos Edited by - Stationary M25 Traveller on 6 Apr 2008 09:44:27 Link to comment Share on other sites More sharing options...
Bricol Posted April 6, 2008 Share Posted April 6, 2008 I'm not convinced by the air lock - an air lock to me would lead to overheating. You are getting over-cooling once on the move. When stationary, the temps come back to normal and the fan operates as it should. When it over cools, the heater temps drop - and come back up when you sit still again. I'd go with the stuck/failed stat theory allowing the coolant to be fed through the rad all the time and then there is nothing to regulate the temps when there is some aire flow through the rad - so it gets over cooled. Air lock idea is free to try tho - and a whole lot easier to do than removing the stat. Bri Link to comment Share on other sites More sharing options...
Johnty Lyons Posted April 6, 2008 Share Posted April 6, 2008 Bri I know where your coming from but WHY is the heater cold The engine must be generating some heat especially at top end so the by-pass should be hot Yes/No and if the by pass is hot the heater should be hot I fink Even if you remove the stat completly the by pass goes Hot So there must be summat wrong ❗ Link to comment Share on other sites More sharing options...
Mr Locust Posted April 6, 2008 Share Posted April 6, 2008 Johnty, heater also seems to cool when the temp gauge falls would indicate that the heater does get hot when the gauge indicates so less likely to be an airlock. The heater may just be following the bulk coolant temperature of the whole system. Ian Green and Silver Roadsport 😬 Link to comment Share on other sites More sharing options...
Kevsta Posted April 6, 2008 Share Posted April 6, 2008 Check to see if it is working. Start the car and feel the temp of the return hose from the radiator. If it slowly warms up then the stat is wide open (which it sounds like it is to me). In temperature like today you'd be amazed at how much the rad can cool an engine! Link to comment Share on other sites More sharing options...
masiwn Posted April 9, 2008 Author Share Posted April 9, 2008 Thanks for all the replies I have replaced the thermostat been for a spin and everything seems fine plus I did'nt strip any threads or get help to finish ,dare I try another job or quit on a high Thanks Aled Link to comment Share on other sites More sharing options...
Mr Locust Posted April 9, 2008 Share Posted April 9, 2008 Ian Green and Silver Roadsport 😬 Link to comment Share on other sites More sharing options...
CliffC Posted November 30, 2008 Share Posted November 30, 2008 I have a similar problem with my K-series 1800 but i have only just replaced the thermostat so i assume its OK. One thing i would like to know is: Q. Can you put the thermostat in the wrong way round and if so what problems would you see? thanks in advance CLiff Link to comment Share on other sites More sharing options...
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