Ernest Posted December 8, 2021 Report Share Posted December 8, 2021 Hi all Just following up the overheating problem I posted about a week or so ago. I replaced the thermostat this morning but on running the engine the temperature gauge went straight to max!!! A stone cold engine but temp. gauge indicating max temp. So it seems to be a faulty gauge.. I guess it might be the connection to the engine but this seem odd as has been working fine for years. Any suggestions would be appreciated. Best Wishes Ernest Quote Link to post Share on other sites
stuart Posted December 8, 2021 Report Share Posted December 8, 2021 1 minute ago, Ernest said: Hi all Just following up the overheating problem I posted about a week or so ago. I replaced the thermostat this morning but on running the engine the temperature gauge went straight to max!!! A stone cold engine but temp. gauge indicating max temp. So it seems to be a faulty gauge.. I guess it might be the connection to the engine but this seem odd as has been working fine for years. Any suggestions would be appreciated. Best Wishes Ernest Check the sender resistance Stuart. Quote Link to post Share on other sites
RobH Posted December 8, 2021 Report Share Posted December 8, 2021 You probably have a short-circuit to earth on the sender lead. Since you have been working at the thermostat housing I would look there first. It is also possible, as Stuart suggests, that something has happened to the sender itself. Quote Link to post Share on other sites
Ernest Posted December 8, 2021 Author Report Share Posted December 8, 2021 Hi Stuart and RobH Thanks for responses. Please excuse my embarrassing ignorance, but where would I find the 'sender unit'? Best Wishes Ernest Quote Link to post Share on other sites
stuart Posted December 8, 2021 Report Share Posted December 8, 2021 30 minutes ago, Ernest said: Hi Stuart and RobH Thanks for responses. Please excuse my embarrassing ignorance, but where would I find the 'sender unit'? Best Wishes Ernest Underneath the thermostat housing on the left/passenger side. Stuart. Quote Link to post Share on other sites
Tim D. Posted December 8, 2021 Report Share Posted December 8, 2021 By the thermostat housing (where the water pipe comes out the front of the engine to the rad) Tim Quote Link to post Share on other sites
Ernest Posted December 8, 2021 Author Report Share Posted December 8, 2021 Brilliant l! Thanks Stuart and Tim Have just ordered a replacement from Rimmers. It seems that.... as new thermostat and soon a new sender then, if the problem continues I assume it would most likely be a faulty be the gauge. Thanks again Best Wishes Ernest Quote Link to post Share on other sites
stuart Posted December 8, 2021 Report Share Posted December 8, 2021 (edited) 4 minutes ago, Ernest said: Brilliant l! Thanks Stuart and Tim Have just ordered a replacement from Rimmers. It seems that.... as new thermostat and soon a new sender then, if the problem continues I assume it would most likely be a faulty be the gauge. Thanks again Best Wishes Ernest Good luck with that if its come from there, Hopefully theyve sent one thats the correct temperature range. Check the wiring to it as well. Stuart. Edited December 8, 2021 by stuart Quote Link to post Share on other sites
Tom B Posted December 8, 2021 Report Share Posted December 8, 2021 If the the temperature sender fails then I would suspect that it would more likely fail open circuit. As the previous posters suggest it may be better to look for a short circuit. For reference, mine reads 1.812 kOhms in a chilly garage at 8.5C. I would check it against that figure as a starting point. Regards Tom Quote Link to post Share on other sites
RobH Posted December 8, 2021 Report Share Posted December 8, 2021 Before you suspect the gauge Ernest , do a simple test. Unplug the wire from the sender and turn on the ignition. The gauge should read cold. Touch the wire to earth, the gauge should read hot. If that happens then both the wire and the gauge are OK. If the gauge continues to read hot even with the wire un-plugged, there is probably a short to earth somewhere along the wire. Quote Link to post Share on other sites
Ernest Posted December 8, 2021 Author Report Share Posted December 8, 2021 Thanks all for the useful suggestions - Yours does concern me somewhat Stuart.... I view you as the go-too expert of parts quality. Let's hope the standard of Rimmer's parts is now at least adequate. I will definitely try your suggest RobH - it seems obvious when I read your advice but I had not even thought of this. Best Wishes Ernest Quote Link to post Share on other sites
CP26309 Posted December 9, 2021 Report Share Posted December 9, 2021 Not that I have ever experienced overheating with my '6' in over 40 years of use (here and in hot Spain) But I knew when my E Type Jag did...as it turned into a 'Stanley Steamer'! Which was cured with a Rad cap of slightly a higher psi! Quote Link to post Share on other sites
Ernest Posted December 10, 2021 Author Report Share Posted December 10, 2021 Thanks CP26309 But the radiator is cool when the gauge reads hot - it does seem to be the cooling system itself but the way in which temperature is monitored. Best Wishes Ernest Quote Link to post Share on other sites
roy53 Posted December 13, 2021 Report Share Posted December 13, 2021 try without the thermostat fitted Quote Link to post Share on other sites
Mike C Posted December 14, 2021 Report Share Posted December 14, 2021 On 12/10/2021 at 8:51 PM, Ernest said: Thanks CP26309 But the radiator is cool when the gauge reads hot - it does seem to be the cooling system itself but the way in which temperature is monitored. Best Wishes Ernest If the radiator and block are cold when the gauge reads hot it's the gauge. Quote Link to post Share on other sites
Z320 Posted December 14, 2021 Report Share Posted December 14, 2021 On 12/8/2021 at 5:17 PM, RobH said: Before you suspect the gauge Ernest , do a simple test. Unplug the wire from the sender and turn on the ignition. The gauge should read cold. Touch the wire to earth, the gauge should read hot. If that happens then both the wire and the gauge are OK. If the gauge continues to read hot even with the wire un-plugged, there is probably a short to earth somewhere along the wire. +1, Rob helped me with this test to solve my problems earlier this year, thanks again Quote Link to post Share on other sites
Ernest Posted December 14, 2021 Author Report Share Posted December 14, 2021 Thanks for the range of helpful advice. I am working through suggestions. Best Wishes Ernest Quote Link to post Share on other sites
CP26309 Posted December 15, 2021 Report Share Posted December 15, 2021 If it ain't hot...ignore the gauge! Quote Link to post Share on other sites
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