erheating fixed but dash gauge still in the red? HELP….

Overheating fixed but dashboard gauge still in the red? HELP....

I am quite new to this forum so please go easy. I'm in the UK and have a manual 2000 328ci which has recently been causing me some problems and I would appreciate any technical help.

Last week the temperature gauge on the dash suddenly went all the way into the red. I pulled over as quick as I could after I noticed.

Here were the symptoms:
Radiator reservoir was full of water as normal,
no visible water leaks,
pump was pumping as the little jet at the top of the reservoir was jetting,
no bad noise from the pump,
no white smoke, no loss of power,
all belts in place, hoses okay,
hoses hot/warm to the touch without excessive heat or pressure.
Top hose hot,
bottom hose not getting hot, and radiator not getting hot to the touch.
Oh and the electric fan (Manual car) was cutting in and out so that seemed to be working too.

The roadside recovery towed the car to my local independent garage. They found a fault code on the thermostat and replaced it (costing £170/$280 inc labour). The computer they plugged in to the car, tells them the water temp in the car is running at normal temperature. The car is NOT overheating and running fine.

However the gauge on the dash is still displaying full in the red. I start the car and within 5mins the gauge creeps all the way round to red.

The garage says that they now think it could be a) A faulty instrument cluster or B) another temp sensor sender which is apparently under the inlet manifold and very difficult to access without removing the inlet manifold. The garage say they can't replace the instruments as they haven't got the right equipment to re-code the clocks etc. They see no fault codes now.

Any thoughts, advise or help would be really appreciate. Was the thermostat really faulty? Should the other sensor be replaced? Do the instruments clusters fail? HELP?????

I love this forum and the really knowledgeable people who post - so please help me....

A quick update – the problem is still exactly the same.

In addition to the garage replacing the thermostat I have just replaced two of the sensors.

The water temp sensor in the bottom hose that goes into the radiator – 13621433077

And

The temp sender (oil/water) that sits behind the oil filter – 12611710509

But the problem is still exactly the same. Start the car from cold and watch the dashboard temp gauge creep slowly (4-5 mins) all the way off the scale in the red. No other warning lights or buzzers sound.

HELP – someone must know what I should look at next. Many thanks to whoever can help me…..

If the radiator wasn't getting hot, that does sound like the thermostat--it wasn't letting water go through it. The top hose will still heat up just from being fairly nearby, or maybe there was a tiny bit of water going through the thermostat...I would have replaced it, too. And I'd even guess that was still the problem if the computer weren't damn sure it wasn't...still, I'd try to check.

It sounds like the gauge is reading correctly. Check your hoses and radiator again as it climbs--see if you can feel the radiator start to get hot when it reaches normal temp. Just check it every 30 seconds or so and keep track of what the needle is doing and how it feels.

Sounds like the temp sender in the block is bad. I think the sender near the oil filter is the oil pressure sender? Did you check realoem?

Thanks hummer - yes next thing for me to replace will be the temp sensor in the side of the head under the inlet manifold towards the rear of the block.

There are in fact two sensors near the oil filter housing – one is a temp sensor and one is the oil pressure sender (I have already replaced the temp sender here).

Replacing the temp sensor under the inlet manifold is a much bigger job, requiring the removal of the inlet manifold to access it so I will take it into a BMW specialist tomorrow to get this done as I don’t have the time. Fingers crosses this will solve this problem.

I took the car to an independent BMW specialist (P&R in Hays, UK) and they ran a computer check and all the sensors seemed fine, so they thought it must be a fault with the instrument cluster. The removed the cluster, and re-coded it (basically reset it) and this solved the problem. The temp gauge is now functioning perfectly normally.

I am please it’s working again, but I was told that the fault could re occur and that if it does then I would be best buying new clocks from BMW with zero miles on so they could be coded to my car.

Fingers crossed this problem won’t ever come back... I also have no idea what caused the problem – any ides guys? I had tried fitting LED rear number (licence) plate bulbs. Any link?