850 T5 Auto OVERHEATING ! ! ! !

A week last Saturday, I did a 160 mile trip to Surrey to look at an off road kit car armed with a trusty 4 wheel Ifor Williams trailer hitched on the back, just in case.

I bought the car, loaded it on to the trailer and set off on the return journey.

The weather was if you remember, VERY hot indeed. Anyway, I noticed that the temp gauge went up from it's normal 3 o'clock position to almost a 1 o'clock position, about 5-8 mm from the red. Coupled with this the air con cut out. This scared the hell out of me and all I could see were £ £ £ signs before my eyes. However, just then, the temp went back down to normal and the aircon came back on. Now it fluctuated like this all the way home.

During the week I then thought it best to change the Auto box oil although the diagnostic sockets did not log a fault code, and did a drain and refill as per the Haynes manual, about 7.5 litres of Dexron III transmission fluid.

Then Yesterday I had to do another 250 mile round trip, 125 miles in the morning heat ( no problems ) and 125 in the cool of late evening, ( again, no problems and this was driving it hard and at 75 - 95 mph for about 80 of the 125 miles) But late this afternoon, I was doing a local trip and belting it a little, as a T5 likes to be driven every now and again, and waiting in traffic, and the gauge went up again, frighteningly close to the red again.

What do you think is causing this ? Is it perhaps a faulty stat or a blockage ? Or perhaps a faulty circulating pump ? Should I change the engine oil as well, although this was only changed a couple of months ago (GTX Magnatec Synth)

Any thoughts would be greatly appreciated.




Regards,

Marcel
'95 850 T5 Estate Auto.

[Chris_Rogers]

Two thoughts:

1 sticky thermostat
Why not change it anyway?

2 Cooling fan failing to come on until full speed temp is reached
Run the actuator tests
Note: you have to dis two injectors on turbos.

- Haynes fault code manual shows how.

Thanks for your quick reply Chris,

I will change the Thermostat and coolant at the weekend.

Excuse my ignorance, but what is the Actuator tests you refer to. UI have the Haynes Manual for the 850 but can't find any reference to them.


Regards,

Marcel
'95 850 T5 Estate Auto.

[Chris_Rogers]

The actuator tests allow you to set of a sequence of the ECU running fans, valves, injectors etc. so you can see if they are working.
Be aware that this can dump large amounts of fuel into the engine so it may be wise to leave the car a while since the engine was run for the remaining fuel pressure to reduce, and remove the fuel pump fuse before you run the sequence.

Haynes are clever, they never give you all the info in one manual, I wonder why?

Marcel, I agree with Chris

My T5 is running without a thermostat at present, I need to get a new one before winter. I had overheating like you and the ECU readout pointed to the temp. sensor which was replaced, but the overheating problem persisted. Now I know it's the thermostat, cheap and easy to replace. I wouldn't expect to pay more than £5 for one.

Steve

Steve,

Think again on the price of that stat.

I picked one up yesterday from the local dealers ( Somertons in Newport) and it was £ 20.02 +VAT !!



Regards,

Marcel
'95 850 T5 Estate Auto.

Marcel

The price for a thermostat from your local dealer in Newport would be the same as my local dealer in Cardiff. They're part of the same chain and both are probably expensive. Needless to say I use independents where possible. The price I mentioned is based on what Eurocarparts quote

Regards

Steve

Hiya,

I did a similar distance (165 miles) the other day in my T5 to pick up a kit car, with a 4 wheel car trailer.

The didnt go up, although the Air Con kept cutting out (superheat switch?).

On a recent trip to the south of france (Brighton - South of France & Back in 24 hours!) I never had the air con cut out on me, although I turned it off when slowing down (traffic & tolls). Most of the journey was done at between 100 & 140 mph (the T5 loves it, but my wallet doesn't).

I am thinking of overriding the superheat switch, any comments?


Regards,

[sheerwater]

Great whacking it on the toll motorways with no speed cameras aint it!!!!
Beware however of the French police who used to be in the habit of hiding behind motorwy bridges just before calais only picking up British drivers.
I was the slowest on the road at about 95 when I overtook another British car doing about 90. They pulled him over as he was the easiest to catch!!!!!
PS your problem sounds like the temp sensor sticking and only coming on when it hits very high temps. This would probably also stop the aircon working as the system would not be able to deal with getting rid of 2 lots of heat and wold shut off the aircon. Cheers Nigel