IandelaMare
New Member
Thought I would post a reply as I finally got to the bottom of this having been down the rabbit hole.
I like to think I am a logical thinker and I use tools to diagnose thorny issues for my job. So it’s really annoying that I made a simple mistake which led to weeks of pain.
I first noticed an issue with water temperature when the standard gauge on my Defender 200TDI 90 1993 moved from centre (where it had sat resolutely for years) towards the red end. Had I not just upgraded the intercooler to a front-mounted intercooler, I would have suspected the water temperature sender. But, being a good, logical thinker used to diagnosing issues, I don’t believe in coincidence so I immediately suspected the new front-mount intercooler of restricting air-flow. First mistake.
Second mistake: I upgraded the gauge to a VDO gauge and sender (far superior to the standard one) and then noticed the running temperature on the motorway was 98 degrees C. That’s probably about right I thought – most cars run at 98-105 degrees right?
Just a quick google on the Defender forums to confirm and all’s good.
Defender forums (not this one) universally state normal running temperature as 88-93 degrees temperature (the thermostat opens at 88 and the normal temp climes to no more than 93 they said). Damn! My Defender IS overheating.
Second mistake: don’t verify what you read on the internet no matter how well intentioned it is.
So, I bring forward installation of the AlliSport XL radiator I bought – that will sort it!
But no, still 98 degrees which is when I post on this form the above thread (having first been testy with AlliSport as of course, I know best).
I then book my Defender into James French in Witney who take “Dippy” (long story as to why my Defender is named that and no, I’m not explaining why) for a long run, check the temperature of the hoses etc. and return it to me saying all is fine and (here’s the killer) “98 degrees is centre of the standard gauge by the way” they say.
Surely not: t’inter-web says 93 max.
Partially reassured by the James French technician – shout-out to Jams Frech btw as they didn’t charge me for the check – and being a cynical chap myself, I bought a new Defender 200TDI sender and arranged a small experiment.
Armed with a 12V power supply, some hastily crimped wiring, a pan of boiling water, a really accurate temperature probe I use for cooking, I set to test the sender and gauge.
And what do I observe? The gauge sites dead centre at 98 degrees Celsius.
So, what have I learned about diagnosing mechanical issues on cars? Well, Occam’s Razor says when there are competing theories to explain the same phenomenon, you should always accept the simplest one.
If, at the start, I had simple swapped out the standard sender, I wouldn’t have installed the new radiator, or stripped out the front mounted intercooler and the new XL radiator I had bought, or took my Defender to James French having not driven much for 3 weeks.
To state categorically however, for anyone who has overheating issues (or think they do) – change the sender and don’t listen to people who tell you the running temperature is 93 degrees. It is not. The technician at James French knows and now, after much pain and experiment, so do I.
I like to think I am a logical thinker and I use tools to diagnose thorny issues for my job. So it’s really annoying that I made a simple mistake which led to weeks of pain.
I first noticed an issue with water temperature when the standard gauge on my Defender 200TDI 90 1993 moved from centre (where it had sat resolutely for years) towards the red end. Had I not just upgraded the intercooler to a front-mounted intercooler, I would have suspected the water temperature sender. But, being a good, logical thinker used to diagnosing issues, I don’t believe in coincidence so I immediately suspected the new front-mount intercooler of restricting air-flow. First mistake.
Second mistake: I upgraded the gauge to a VDO gauge and sender (far superior to the standard one) and then noticed the running temperature on the motorway was 98 degrees C. That’s probably about right I thought – most cars run at 98-105 degrees right?
Just a quick google on the Defender forums to confirm and all’s good.
Defender forums (not this one) universally state normal running temperature as 88-93 degrees temperature (the thermostat opens at 88 and the normal temp climes to no more than 93 they said). Damn! My Defender IS overheating.
Second mistake: don’t verify what you read on the internet no matter how well intentioned it is.
So, I bring forward installation of the AlliSport XL radiator I bought – that will sort it!
But no, still 98 degrees which is when I post on this form the above thread (having first been testy with AlliSport as of course, I know best).
I then book my Defender into James French in Witney who take “Dippy” (long story as to why my Defender is named that and no, I’m not explaining why) for a long run, check the temperature of the hoses etc. and return it to me saying all is fine and (here’s the killer) “98 degrees is centre of the standard gauge by the way” they say.
Surely not: t’inter-web says 93 max.
Partially reassured by the James French technician – shout-out to Jams Frech btw as they didn’t charge me for the check – and being a cynical chap myself, I bought a new Defender 200TDI sender and arranged a small experiment.
Armed with a 12V power supply, some hastily crimped wiring, a pan of boiling water, a really accurate temperature probe I use for cooking, I set to test the sender and gauge.
And what do I observe? The gauge sites dead centre at 98 degrees Celsius.
So, what have I learned about diagnosing mechanical issues on cars? Well, Occam’s Razor says when there are competing theories to explain the same phenomenon, you should always accept the simplest one.
If, at the start, I had simple swapped out the standard sender, I wouldn’t have installed the new radiator, or stripped out the front mounted intercooler and the new XL radiator I had bought, or took my Defender to James French having not driven much for 3 weeks.
To state categorically however, for anyone who has overheating issues (or think they do) – change the sender and don’t listen to people who tell you the running temperature is 93 degrees. It is not. The technician at James French knows and now, after much pain and experiment, so do I.
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