525d engine temp

Hi I'm Wondering could anyone shed some light on this. I replaced the thermostat on my e39 525d last week but the car still struggles to get to temperature. If its left ticking over for a while it does eventually, but on the motorway or im [/align]around 70mph for a while it drops back down around the quarter mark :huh: is there another stat that needs to be changed or was it just a dodgey stat ? With the cold months coming in I don't want it running cold. Any help appreciated thanks.[align=justify]

Is in manual or auto?

Additional air cooling going on for some reason when in motion.

The other thing that occured to me is a dodgy or on the way out temp sensor on the rad.

If it's an auto it has an EGR thermostat which would explain it

Sorry no it's manual. It's really wrecking my head now. Took a spin into limerick on the motorway this evening, and stayed a notch below the quarter. It's running very cold. Could that be diagnosed from a plug in venom? Thanks for the replys lads I'd really love to get this sorted.

Where did you buy the thermostat? Is it genuine. I had the same issue on mine, replaced with a genuine thermostat and never had the problem again. Same on the M5

I can't remember the brand but I'm pretty sure its not genuine. Got it in the local motor factors. Where would I be able to pick up a genuine one?