Temperature Gauge only works over 70mph!

Hi all, I should start by saying I have NO mechanical
Knowledge! My garage has changed the sender but
still the gauge doesn't move until I go above approx 70mph! As I slow down it falls back to nothing. I can't find any other thread mentioning this problem so thought you guys may have an idea?? Thank you.

Hello,

How very strange.
Does it move when you turn the lights on? Mine had a bad earth and would hit the red when I turned the lights on. Then go done when I turned them off.

Is your car 100% std?

Cheers

Don't take any more photos of it.
I would suggest that if the temp gusage is affected by the speedo there might be some wire's touching or similar. Although how often do you need a temp gauge?

Sounds like a bad connection, as suggested probably the earth and if I'm reading your speedo correctly it's quite a high mileage vehicle. In which case it's probably never been touched from new (or needed to be).

Thanks all, it definately only moves with the speed, not lights, indicator etc. The connection was rewired just before Xmas in the hope of an easy solution A new Turner recon engine was fitted in 2013 & has only seen 30k miles if that is relevant?
(a friend took the photo from behind - no safety issues - after the garage refused to believe me! )

I'd agree with everything that the other members have already said.
As @neilly asked, "is your car 100% standard?" What is that little red indicator light on the top of the dash for?
As @goonarmy said, "Don't take any more photos of it." In fact don't touch your mobile phone at all while you're driving. Not only will you upset the Old Bill, but a lot of members here too.
As @Nigel-S said, "Sounds like a bad connection". Either a connection which should be made but isn't or a connection which shouldn't be made but is. The only way to find it unfortunately is to physically examine the circuit and correct any faults which might be found.

Ok thank you, no easy fixes then. I will go back to wiring. When I find the fault I will let you guys know in case it comes up again.
I don't really like the patronisation mind you. As already stated, a passenger took the photo which was entirely safe & within the law so there is no reason for any members to be upset. Thanks

More the fact your doing 70 in a tratter Was it being towed

Look at it from another angle, does the heating blow ok at idle and at speed or does that change? Could be something to do with pressure. Is there a working thermostat in it?

Doo said:

Look at it from another angle, does the heating blow ok at idle and at speed or does that change? Could be something to do with pressure. Is there a working thermostat in it?

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Interesting you mention that because it stopped working when it was REALLY cold & it wouldn't start just for the day. At the same time it knocked out the blower switch (still had heat though so assume thermostat ok?). No change at idle.

I'm guessing a wiring issue. The sender is normally variable resistance negative feed to one part of the gauge and + to the other. That means as the engine warms up, the resistance in the sender changes and allows more volts through (in this case the negative feed to the gauge) so the needle climbs to indicate a rise in temperature.

Therefore, the sender needs a clean - feed. Now either you need the engine to body earth connections sorted out or perhaps you have a poor + feed frpm the alternator that is only coming on song as the revs build. I wonder would it work at, say 40mph in 3rd gear? Easy thing is to get an alternator health check. You can get them at Halfords foc and they give a print out. Have the voltage regulator checked out.

LadyLandy90 said:

Ok thank you, no easy fixes then. I will go back to wiring. When I find the fault I will let you guys know in case it comes up again.
I don't really like the patronisation mind you. As already stated, a passenger took the photo which was entirely safe & within the law so there is no reason for any members to be upset. Thanks

Click to expand...

No its not safe. The patronising tone is very well deserved.

Be interesting to know if it's engine speed related, try the same engine speed in a lower gear cos that might point towards the alternator

Marmaduke said:

Be interesting to know if it's engine speed related, try the same engine speed in a lower gear cos that might point towards the alternator

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Errmmm.... isn't that what I said?

Doo said:

Errmmm.... isn't that what I said?

Click to expand...

What? You want me to start reading what other people have typed?

Yeah @LadyLandy90 what he said

Fookin hell, I didn't realise the 70,80,90 etc numbers did anything!

70 ?? whats that?

When you get to 70, does the needle suddenly jump to the position shown? Or, does it slowly climb to that position over the next minute or so of travelling at 70mph? I used to have to do 55 to 60 for about 12 miles for my temp needle to climb up a bit. It dropped straight back down when I slowed down. Thermostat was stuck open.

If the other gauges behave oddly too, it could be a wiring fault, if not I'd say you need a new gauge. It's a pretty simple thing.

And shouldn't this be in the 90/110 section?