sharkey964 Posted December 22, 2016 Share Posted December 22, 2016 Theres a bit of a story behind this one,so bear with me. Last May whilst in the Pyrenees my 300tdi started running a bit hot,not off the scale,just touching the red area on the gauge. So me thinks,thermostat is Fubared,so I took it out.All good,once warmed up gauge reads normal. I have run it al the rest of this year with the thermostat minus the middle which I punched out.I read somewhere it's not good to run totaly without a stat. Now the werather is much colder,I thiught I'd replace the Thermostat.So,motor warms up nice & quickly now,but not long after reaching normal operating temp it rises to just under the red.If I turn the lights or fan on the temp gauge goes right up into the red immediately. So, I'm thinking something electrical,I have changed the temp sensor & stat.Do you think bad earth,& if so where would you suggest I start looking? Thanks a lot guys. Marc. Quote Link to comment Share on other sites More sharing options...
Peaklander Posted December 22, 2016 Share Posted December 22, 2016 I don't know exactly how the gauge responds to the volts across it from the sender; I can guess but I don't know. So if it were me I would eliminate everything and connect the gauge direct to the sender ( if it isn't already) and apply a connection directly to earth from the appropriate terminal on the gauge. Then I'd hopefully know what's really happening Also I'd try to borrow a little IR temperature gauge and point it at a very hot area that's water cooled to check that the real temperature isn't more than about 90 degrees Quote Link to comment Share on other sites More sharing options...
Kevm Posted December 22, 2016 Share Posted December 22, 2016 You can't just connect it direct as there should be a voltage regulator inline somewhere on the back of the instrument panel, it should be supplying a steady voltage to the fuel and temp gauges, does the fuel gauge fluctuate also? This sort of thing is handy to give some indication of spot temps.http://www.ebay.co.uk/itm/Racetech-Motorsport-Temperature-Test-Strip-Sticker-116-154c-Pack-of-10-/291301023312?hash=item43d2e4de50:g:dPMAAOSwBahVDZ~g Quote Link to comment Share on other sites More sharing options...
sharkey964 Posted December 22, 2016 Author Share Posted December 22, 2016 Just a quick update on this problem. Turned out to be the earth strap from the battery to the chassis/transfer box. Cleaned it up & re fitted,up to yet gauge has not gone above normal/vertical. Thanks for the ideas & all your imput fellas.Much aprechiated.Marc Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 22, 2016 Share Posted December 22, 2016 i had the same on my 300tdi. mine just needed a crimp and a clean on the sender stud. The earth had already let me down, see tech archive how to spot a bad earth. Quote Link to comment Share on other sites More sharing options...
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