Hello everyone and thanks for having me on the forum!

I own a Discovery I 1995 petrol V8 which is still running beautifully considering it has been kept in the Bahamas for the last 20 years (which is definitely a challenging environment), so I am treating it in the best way possible to keep it in shape.

A recent problem that occurred is a sudden overheating, where the gauge shoots up almost to the red area and the oil pressure lamp starts to flicker(!). I of course stopped the car immediately when it happened the first time and shut it off. After letting it cool down overnight, I refilled some coolant (there was a little bit missing, but not a lot) and drove it slowly to the local garage (without any problems).

I then had a new water pump installed and all the hoses changed, as well as the temperature gauge, which also makes the extra fans in front now kick in regularly, which they did not do anymore before - instead they switched on and off with in a second repeatedly.

I hoped to have the problem solved, but unfortunately the same symptom came back recently. The thing is, the overheating takes place so rapidly - from slightly too warm to the red zone within 10 seconds - that I suspect some clog, that will suddenly make the water flow stop completely - would this be a sensible approach? I am now driving it very defensive with constantly monitoring the termperature, and it has not done it again yet, the temperature is always in the perfect spot - but I keep my bike now in the trunk in case it does it again. I certainly don’t want to lose this car to some overheating issues in the wrong moment, so I will give it to back to garage in a couple of days. I was wondering if you‘d have any suggestion for the mechanic what to look at. You know, it is an island situation and he is a good guy, but there certainly is not Land Rover dealership in this remote island…;-)

Thanks!

 

I assume you are looking at the temp display in the dash. Mine does the same thing for the last year and a 1/2....DO NOT trust the gauge on the dash! they are usually wrong. When my gauge was pegged, I checked the hoses under the hood and they were warm, not burning hot. I also noticed could squeeze them (not much pressure) and I even got the nerve to open the coolant tank and stick a finger in and it waas lukewarm at best (180 thermostat on a cold snowy night) Needless to say, after replacing the fans, water pump, thermostat (a number of times), temp sending units (both), and a radiator, it still does this occasionally. I now use an infra-red thermometer to check the temp of the coolant and the gauge on the dash has a post-it note over it. I suspect there is a wiring issue in the dash. I don't believe an engine can heat up and cool off that quickly.

But yours may be different.
these things are bad for trapped air bubbles and that can get the temp gauges confused so check that first

 

Wiring problems could cause that. A short circuit of the sender unit can also cause the dash gauge to spike high. Corrosion could cause a short to ground at the sender. Super simple job to change the sender (the one with only one wire). Last time I checked it cost less that 20 bucks for a new one.

 

Thank you both very much for your answers.

In my case, the cooling water got actually really hot, when I opened the coolant tank a tiny bit I heard the water starting to boil inside, so I closed it off immediately - and it does not cool of quickly after that. Also, what does make me worry is that the oil control lamp starts to flicker red, so I do suspect there actually is something wrong in that moment.

It never occurred again in the days after, but I have to say this might be due to the fact that I drove her very carefully from that moment on, never pushing her too much. I dropped the car at my local car repair guy and described him everything that happened, so he‘ll take some time and start to investigate what might be the cause.

I‘ll keep you posted about the results - thanks so far!

 

If your oil light flickers at the same time as the temp gauge fluctuates it may indicate a common electrical issue, like a poor common ground.

 

...or the oil also got so hot it thinned out and couldn't support oil pressure.

 

Yes that’s possible but it sounds like the indications are momentary excursions. If it was so hot that the oil thinned that much I think the indication would not be only a flicker. I’m definitely no expert on this though.

 

If you're relying on the stock temperature gauge in the dash unfortunately that is how overheating will always present. It is essentially a 3 step gauge that will read "cold"-"okay"-"overheated". (terrible design for a car that will die if overheated by hey it's a land rover) Most people running D1's on this forum recommend an OBD2 dongle that will allow you to monitor the temperature more accurately in real time. In addition most people run at least a 180 degree thermometer instead of the standard thermometer, some I think even go for 160 thermometers but I have not tried that. Highly recommend at least the OBD reader, get one that reads to an app on the phone and you can monitor exactly what temp the ECU is receiving. Mine has gotten as high at 206 without the gauge on the dash even budging so I find it invaluable especially when climbing hills during the summer, etc.

 

I think 96 was the first year with OBD2. My 94 doesn't have it. It does have a LR code reader built-in, so there might be a way to tap into that circuitry. Maybe I saw a thread on that topic?

I placed a simple K-type thermocouple at the T-stat outlet, ran the wire into the cab, read it with a hand-held multimeter. A bit clunky, but simple and effective. Read around 210 deg F when it was 109 outside last summer, idling in a parking lot with A/C on. My meter does data logging, so I can read high and low temps recorded during a drive.