faulty temp sensor?

[Ricky]

I have a problem with my temperature gauge, for example, I went to the petrol station today, pulled in, the temp was at a normal 80. Put £20 in so only took a few minutes, started the car and the temp was just above 90. Pulled out of the garage and the needle dropped rapidly to normal again, like as quick as it drops when you turn the car off..

Anyone had a similar problem? Think I may either need to look for a bad earth or the sensor is dodgy.

[andywhy]

Could be heat soaking through from other parts of the engine causing it especially if you've been on boost before coming in to fill up. As long as it drops I wouldn't be too worried just yet, but keep an eye on it. And if you have been on harsh boost, idle for at least a minute before turning off to let the oil and turbo cool a bit. I normally drive easy the last half mile from home before turning off if I was going there.

[Ricky]

I was only plodding along beforehand, just driving to work. Either way, the temp would not drop that fast.

thinking about it, I have a bad earth I temporarily fixed the other day, where the glow plug relay earths behind the battery, I didn't do it very tight so it could be that playing up.

[andywhy]

Certainly could be, give it a proper fix

[cwspellowe]

Could be an airlock?

Mine does it intermittently once from cold then behaves normally. Hits 90, then drops to 75, then stays below 85 forever

[Ricky]

Well i'm 90% sure it's electrical, the temperature goes up when the lights are on, goes down when they are off, and the needle wavers up and down!

When driving normally, like I was in 4th doing 45ish, no load on the engine as such, and the temp rose to 90, then I got to the roundabout and it dropped to just over 80, then soon after was at 90 again. I really do hope it's not HG, there's a fair bit of pressure in the top pipe but not crazy, will bleed the system again to eliminate airlocks.

[andywhy]

If it moves when you turn lights on and off then it sounds like an earth fault or other wiring fault somewhere.

[puglove]

Could be an airlock?

Mine does it intermittently once from cold then behaves normally. Hits 90, then drops to 75, then stays below 85 forever

For ever you say..... Didi it stay below 85 on the way to fcs last year????

[Ed Doe]

II had the issue on the 6 when I changed the loom. Check the video below for my symptoms!

https://www.dropbox.com/s/e7s29dpy7ja6db....54.27.mp4


It also went up massively when turning on the heater rear window. Ended up being the gearbox earth not bolted down. Yours is probably corroded if you've not touched the loom/earth potins recently....

[Ricky]

Well I've fitted a new engine recently, all earth points are tight, but the whole loom is in a bad way. When it didn't start last night I earthed the battery to the engine with a jump lead and used the other jump lead from positive to the plugs for heat and it started fine. Going to fit another earth to the gearbox to sort that out.

[Ed Doe]

Forgot to say my other issue was it started like shit, cranked really slow and took a while to catch with the earth as it was. So your symptoms are pointing more and more to earth issues...

[Ricky]

Think it's all sorted, just need a new relay because mine has a snapped connection. For now I will have to heat the plugs manually until I get a new one.

Got a new negative battery terminal connection, with two new beefy earth wires, one to the engine and one to the chassis. One of the wires is the sort of size I would use to put the battery in the boot so it's more than up for the job! Haven't driven it yet so can't comment on the temperature, but fingers crossed it wasn't overheating..