7 replies to this topic

[aircoolednut]

Hi, I have a 1990 Rover Mini City 998cc. The car goes great, at last (yes on the test track, not the public road of course, I can get it to do the clock , 90mph, even though that is probably only 70mph really). The water temp guage was not showing anything, so I replaced the sensor (termistor) on the engine, did not change anything else, now always shows maximum as soon as I turn on the ignition. I have checked the resistance on the sensor and that seems ok. When I connected a voltmeter from the single cable that plugs onto the sensor and earth, with the ignition on, the voltage shown was constantly changing from 0 to 2V to 6V to 4V etc just jumping all over the place. This has led me to believe that the problem is with the voltage regulater. Just wanted to get some feedback on this and/or any suggestions. The water temperature is correct, run the car for hours without problem, other than it shows the water temp at absolute maximum. I would like to know where the voltage regulator is and where to buy a replacement, if that is the problem.

Many thanks

acn

[taffy1967]

Check this recent thread: -

Click Me

I'm sure the information is pinned here somewhere?

[Dan]

The reading on your voltmeter simply means you were trying to use a low resolution digital DC voltmeter to measure a square wave AC supply. It's also a bridge circuit, the voltage through it depends on the resistance at the end of the cable which is how the gauge works. Sticking a voltmeter on the end of it will always mess it up. Without an osciloscope, you aren't going to be able to make a useful voltge reading off that circuit. You might get a slightly better result by setting your meter to AC.

It's odd that the gauge reads maximum when connected to a sender though. What resistance did you measure from the sender when it was cold? Are you sure it's a Mini sender? What is the fuel gauge doing?

[aircoolednut]

thanks for the reply, the fuel gauge like most mini's does give you a clue about the fuel. The temp sender is new, got it form the mini place in byfleet and looks the same as the old one. Do not remember the restance on the sender, will check it out. All the other stuff went straight over my head, not a techie here, I normally just hit it if it does not work, it that does not work, I use a bigger hammer.

Well if anyone can help me sort out the temp gauge thing, using simple language that I may understand, then please do reply. Sorry to those techies who try to help.

Right thanks all

acn

[Dan]

Simply put, your volt meter isn't going to tell you anything. It's not up to the task of reading the kind of supply the gauges use.

Can you tell us what the fuel gauge is actually doing? Both the instruments use the same voltage stabiliser, if the fuel gauge is doing what it should the problem isn't with the stabiliser. All temperature senders look more or less the same, it being from Mini Speed is no guarantee that it's the right part and fairly often brand new senders don't work at all.

[aircoolednut]

I recently changed the temperature sensor as the temperature guage when the engine was running at normal temperature was not moving up at all (continually showing cold). After changing the sensor and when the engine is cold and I turn on the ignition without starting the car, the temperature gauge will rise from nothing to maximum (i.e. the red line). When I start the car the temperature gauge will stay at maximum regardless of the engine temperature. The fuel gauge seems to work correctly. The engine does not overheat.

Just wondered where the problem lies and how do I check which bit is faulty.

regards

acn

[Dan]

If you remove the lead from the temperature sender and earth it to the engine with the ignition on, does the gauge read hot or even above hot on the scale? To be honest it sounds like you've been sold a faulty sender. Can you measure the resistance of the sender with the engine cold and with it hot?

[Kevin S]

Hi ACN. Did you manage to resolve this issue as I have the very same issue with a 1990 998cc Mini Checkmate. If you did, could you please share the solution. Here's hoping.

Best regards

Kevin S