So I'm driving along yesterday, thinking what a great car my old Mondeo has been since I got it.....

[barracuda816]

dont know if its just a vw thing, but often the temperature gauges are horrendously inaccurate!
my T4 will read 90ish (or normal operating temp, half way up the gauge) when my aftermarket gauge is still at 40ish,
or on the girlfriends caddy van, when i can plug in a computer and read the actual temperature, the gauge on the dash is miles out as well

I thought most manufactures did this on intentionally. It’s more of a temp ok gauge then to give an accurate reading. I guess to stop people worrying when towing uphill on a hot day when the temp is high but within normal parameters.

 

[Red'n'Black]

I thought most manufactures did this on intentionally. It’s more of a temp ok gauge then to give an accurate reading. I guess to stop people worrying when towing uphill on a hot day when the temp is high but within normal parameters.

Yep. If you have an OBD adapter the live data shows the true picture.

Personally I'd rather see what's really going on than some sanitised version.

 

[Morrisman]

Sound like you may be low on coolant ?

No, it's well and truly full in the expansion bottle. I did think maybe it is too full, but how that would affect it I can't imagine. Possible there's an air lock, but that probably wouldn't give the same linear temp reading depending on engine load and speed.

 

[Morrisman]

dont know if its just a vw thing, but often the temperature gauges are horrendously inaccurate!
my T4 will read 90ish (or normal operating temp, half way up the gauge) when my aftermarket gauge is still at 40ish,
or on the girlfriends caddy van, when i can plug in a computer and read the actual temperature, the gauge on the dash is miles out as well

It sat at 88-89° for 7 years, which, to me, is a bit too cool. I thought modern engines ran at 100° or over normally, hence the pressurised system. I've seen several pics of dashboards on a Mondeo group, and each one has the exact same temp showing as mine had. It hasn't varied in all the time I've owned it.

 

[Morrisman]

I have just ordered a stat for my Mondeo mk3 TDCI. I have always thought the engine took ages to heat. Yesterday I thought I would look into it so I stopped after driving about 3 miles from cold and felt the top hose which was warm but the gauge had hardly moved from the cold stop, continuing on I was watching the gauge which did increase slightly but nowhere near half way on the gauge then we got stopped, creeping in a traffic jam for 10 minutes and the temp actually came down only to recover when we had a clear road and back around 45/50 mph.

Mine wouldn't warm up just sat ticking over, or driving slow. I could sit with the motor idling for 20 minutes and it wouldn't get to full temp, but if I drove it a while and it hit 89° it would stay there, rock steady, even if I then sat at tickover for a while.

Looking at the 'stat itself I think it is basically normally 'open', and I have an idea that water flows both through the block and the rad when it's cold, but as it warms up the 'stat closes, and shuts off the route through the block and forces all water through the rad, which is back to front to most normal motors.

 

[Erie Fred]

No, it's well and truly full in the expansion bottle. I did think maybe it is too full, but how that would affect it I can't imagine. Possible there's an air lock, but that probably wouldn't give the same linear temp reading depending on engine load and speed.

I never trust the bottle. remove the cap and check the real level.

 

[Morrisman]

I never trust the bottle. remove the cap and check the real level.

That's all there is: the bottle, no radiator cap, it's all modern 'hi tech' stuff, no separate rad filler cap.

 

[bricol]

Sounds like maybe wiring to the sensor for the guage has been disturbed, or the sensor itself has decided to go on strike - couple of my cars have different sensors for the dash and ECU. Might just be an earth connection that should be trapped under a stat mounting bolt.

 

[Morrisman]

Sounds like maybe wiring to the sensor for the guage has been disturbed, or the sensor itself has decided to go on strike - couple of my cars have different sensors for the dash and ECU. Might just be an earth connection that should be trapped under a stat mounting bolt.

If the gauge were doing random erratic things that would be plausible, but to follow the exact actions you'd expect from a stuck or not properly acting 'stat doesn't sound so likely.

I'd be interested to see the list of things the mechanic has been told to do to establish the fault.
I sure hope I'm not expected to foot the bill, as it was working fine when it went in....

 

[voipio]

There's probably a 10mm socket stuck in the thermostat, stopping it from fully closing, though it does need a small "leak" for some coolant flow to get to the wax capsule in the first place, on some designs

 

[DanZac]

There's probably a 10mm socket stuck in the thermostat, stopping it from fully closing, though it does need a small "leak" for some coolant flow to get to the wax capsule in the first place, on some designs

If it turns out it is a 10mm socket, then can I have it back please.

 

[Morrisman]

Well I've been back to collect the car after the second 'stat has been tried.... and the mechanic says it's exactly the same as the previous one.....

I've got the car back and it seems to generally run a bit warmer than it did with the first new 'stat in, but still not right and fluctuates with driving speed.

So, I blagged the original 'stat and the first 'stat the mechanic had tried and have got them on the stove in a pan of hot water.

The water temp was gradually raised, and I checked it with my infra red thermometer gun thing. To my surprise, and satisfaction, the Gates 'stat started to open by the time it was 60c. I whipped it out of the water, and I could blow air through the end.

The original 'stat didn't move until it was up to nearly 80c. At which point the Gates one was fully open.

Oddly enough, after they had cooled to room temp I could still blow a little air through the Gates one, whereas the original one was air tight when it he got down to 70c.

I may have scalded my lips a bit.

We now have a genuine Ford part on order.

It's a strange setup, the left side pipe is closed off when cold and as it heats up and opens the stat moves across to block off the right pipe.

 

[qwakers]

theres no way they should be opening before 80*, so there's your problem...

 

[Red'n'Black]

Good stuff. "One experiment is worth a thousand expert opinions', or something like that

 

[ajlelectronics]

Good stuff. "One experiment is worth a thousand expert opinions', or something like that

I tried that line with an old girlfriend, but still got my face slapped.

 

[Ubique]

Changed loads of those, the body eventually distorts with the heat leading to the seal weeping, there should be no passthrough when closed, the reason it looks 'open' when viewed from the coolant side is that it's a two-stage thermostat to aid emissions being lower, quicker.

 

[dobbslc]

I may have scalded my lips a bit.

We've all done something similar

 

[Morrisman]

Changed loads of those, the body eventually distorts with the heat leading to the seal weeping, there should be no passthrough when closed, the reason it looks 'open' when viewed from the coolant side is that it's a two-stage thermostat to aid emissions being lower, quicker.

The only problem I had with the original was it was leaking coolant, dripping onto the gearbox. The temperature was rock solid when it got to operating temp.
I wish I'd left it well alone now.

The 2 Gates units that were fitted are probably chinesium rubbish snuck into the supply chain somewhere along the line.

 

[roofman]

The only problem I had with the original was it was leaking coolant, dripping onto the gearbox. The temperature was rock solid when it got to operating temp.
I wish I'd left it well alone now.

The 2 Gates units that were fitted are probably chinesium rubbish snuck into the supply chain somewhere along the line.

Why don't we use the same match and burn my vivaro with a snapped cambelt and your mondeo...

 

[Morrisman]

Why don't we use the same match and burn my vivaro with a snapped cambelt and your mondeo...

Any more dramas with it and I'll take you up on that idea.
I'm waiting to see how much the insurance will go up this year, and I may decide I don't really need a car at all.