Temperature Gauge

[Nigel W]

I have in the last 2 days driven my Stag twice for the 1st time. Both time it was for about 30 miles. The temperature gauge settled just above half way, but crept up to near the red on several occasions, but then went down again. Any thoughts gratefully received, I was thinking maybe sensed, or voltage issues. The photo shows how high it went.
photo.JPG

[Nigel W]

Sorry the photo is on its side.

[V Mad]

My neck hurts....aaaaah

No, seriously, you need to find the cause of this asap in case it is a real problem. Hopefully its just a bad earth or dodgy voltage stabiliser. If not, then get the cooling system looked at.

[Nigel W]

Thanks V Mad. What makes me think that its not too serious is that the gauge did go both up and down. Presumably it would not have gone down if it was an overheating problem. I have done a bit of a search and a change of Voltage Stabiliser and sender would appear to be an obvious starting point. I was also very surprised that IR thermometers could be had so cheep, so thats an obvious safety check as well.

[jakesmig]

The fuel gauge is also powered by the stabiliser, does it fluctuate as well?

John

[fool73]

Mine did something similar when I drove it without the speedo in (and therefore without the voltage stabiliser). It was shortly after fitting a new a water pump and I was horrified to see the temp go alarmingly high a couple of miles from home. I turned round to head home and within a short while the temp had gone really low. The temp swung high to low a couple of times before I got home and eventually realised the lack of stabiliser was the cause.

[Nigel W]

I am not sure about the fuel gauge. I must admit that my eyes were glued to the Temp. However, the fluctuation on the temp was quite small, it was always above half way. I will try a solid state stabiliser and see how we get on. I have already flushed the cooling system before I used the car and had a small repair done to the radiator. The repairer flushed the Rad and I have fitted new hoses and I am fairly certain that I have got the air out of the system when filling and rechecking several times. As they say "just because your paranoid, doesn't meant that they are not out to get you!" Thanks for the feedback.

[V Mad]

Just a comment on flushing the radiator. My experience of this is that is a preventive maintenance task that should be carried out regularly, but as a cure for overheating it is usually ineffective. Once sediment has accumulated in the rad, and a row is blocked, flushing does not actually clear it. I have spent ages flushing rusty sediment coming out of a rad, only to find it does not improve things.

A good old fashined rad shop should be able to check for rad blockage with a steam flow test. Using this you can feel the cool areas where the blockages have occurred.

Just my opinion FWIW.

[wilf]

If yours is a MK 2 car, also check you have the correct thermostat fitted (with the foot to blank off the bypass passage when the 'stat opens).

When I finally got around to checking mine, it had the wrong 'stat (no foot) and that gave rise to some occasional weird temperature fluctuations.

[Nigel W]

Thanks Wilf, its a 76. I will keep that in mind.

[Pete]

Without the voltage stabiliser it will give some strange readings as the voltage rises and falls with the revs. I have heard that it is not a good idea to run without the stabiliser as it could damage the temp and fuel gauages but Alan (157.7) could confirm this.

Also, you might have some air in the system? Just a thought.

[Nigel W]

Pete, thanks for that. I may have some air, but I think it is unlikely. I presume there are 2 modes of failure with the voltage stabiliser, it can produce too much voltage, so would over read, or vary output voltage with the instrument read outs changing accordingly. Mine seem to be too high anyway, and then move up and down slightly. To be honest, if the temp gauge had been nearer the middle in the first place I might not have noticed the slight increase. It was just that it was so close to the red.

[KOY 23]

Before you start changing parts and flushing, I would measure the head temperature with a multimeter with a temperature probe, measure by the temp gauge transmitter. The readings of the IR ones rely on the characteristics of the surface being measured, so may mislead you. Only then will you know if you have a problem, which will be down to stabiliser or transmitter, LD sells one that read vertical at 90 degrees.

[Pete]

The voltage stabiliser has vibrating contacts which could fuse, thereby giving you a completely unregulated supply. I'm changing to a solid state one.

[Nigel W]

Because of the low cost, I am going to change the transmitter and stabiliser anyway, which I have ordered from Rimmers today, which I believe is a solid state one, Thanks for that Pete. Koy 23, I am slightly confused could you please expand on measuring the head temperature with a multimeter and a temperature probe? I would be most grateful. Also what is it that LD is selling? sorry to be a bit thick, I am fairly new to stags, thats my excuse and I am sticking to it!