faulty sensor ?

Hello I have a 1999 disco td5 whilst travelling on the m40 with cruise con set to 65/70 I suddenly lost power and noticed the temp gauge had shot into the red.I pulled on the hard shoulder and called the greenflag.as I waited I turned on the ignition to my surprise the temp gauge had droped it started and after a quick call to cancel greenflag I was on my way.i experienced something similar last night again on the m40.but the gauge droped and power resumed before I needed to pull over.could this be a faulty sensor and if so would it cut the power.any advice appreciated.

Hi, yes, could be faulty sensor or short on it's wiring, if it happens again make sure the engine is not really overheated, without tester it's hard though but you must feel it's radiating more heat than usual and the top hose is stiffer... the ECU will cut fueling if it gets a signal of overheating

Thanks for your reply I had water escaping from overflow hose on expansion tank.i was advised to change the cap on expansion tank wich I did.It stopped it for a good while but I noticed the other day it was wet in that area and coolnt was quite low.also when I remove cap to top it up you can hear air rush out and coolnt rises leaving no space to fill.a garage changed the coolnt for me maybe they didnt run it with cap off to get all air bubbles out.do you think this might be worth a try.

sierrafery said:

Hi, yes, could be faulty sensor or short on it's wiring, if it happens again make sure the engine is not really overheated, without tester it's hard though but you must feel it's radiating more heat than usual and the top hose is stiffer... the ECU will cut fueling if it gets a signal of overheating

Click to expand...

agree ^^^ plus i would check as many earths and relays as you can for bad connections clean and refit , and while your looking check ECU for oil on the plug ,

it must not run with cap off, the cap MUST be well tightened after the system was properly bled...which means the tank must be unclipped and lifted obove the bleed hole, filled untill fluid comes out there, put back to position, refit partially the bleed screw, rev up the engine above 1500rpm and keep it so untill no bubbles are coming out there then tighten well the tank's cap...the system must work under 1.4 bar pressure so if the cap doesnt keep this pressure the water will start bubleing at 90*C

Ok thanks ofcourse I dont know if the 4x4 place I took it did all that garages seem to charge multiples of £100 for everything. And have little interest in job satisfaction. When you you say dont run car with expansion cap off does this go for runing the bubbles out.do you do as you explained with cap on.?

Ok ill look into all that I did change fuel injector leads and removed oil from ecu when I did that but it was a while ago a year maybe

Ive never done this before where will I find the bleed screw?

Its ok just wached a youtube and was shown bleed screw.asume you do have cap removed when you bleed it thanks for your advice.