overheating - took it to a garage and guess what

[ambivert]

Whoever said that I would know more about than them... you were right!

VW specialists too... they seemed to think it was a sensor/dashboard fault and that it wasn't really overheating at all . They said the water would be actually boiling and venting out, and the pipes would be rock hard if the temp was really as high as the gauge implied.

The radiator fan eventually came on too... after about 40 mins... looking good!

But they didn't have equipment for testing the sensor or gauge - so it looks like I will have to do it after all... Found a waterproof digital -50 to +200 C probe jobby (ref 101945 A16) on thermometersdirect.co.uk for £11.75... should do the trick. I guess I'll have to boil the sensor, with it still wired up, in a saucepan on the van stove!

So, can anyone help me, what it the operating temperature (range) for the 1.9 petrol DG ? When the gauge hits max and the red light comes on, what temperature is that?

[Grun]

ambivert,

Here is one I prepared earlier, sorry not much else in Haynes.

http://archive.club8090.co.uk/viewtopic ... ht=#261940

I have only had my rad fan run a couple of times (on the first stage only) and did not have any red flashing light, seem to remember the gauge being just a tad past halfway. (Long time ago now)
Mike

[ambivert]

thanks Mike!

[lhd]

Something i was suprised at is the opening temperature of the thermostat and I think it was something like 97 degrees centigrade so I can see where they were coming from.
In fact I think they are right.
It it were to go much above that you would see steam.
I have known to be wrong once in my life though.
If you leave the van ticking over for forty minutes with no airflow over the rad surely the fans bound to come on.

[lhd]

If the light goes red and the needle maxes out isn't it low water level in the expansion tank?
I cant remember but that rings a bell, if so it would be low water level or faulty water level sensor.

[ambivert]

If the light goes red and the needle maxes out isn't it low water level in the expansion tank?

My water level is fine, I think someone on here may have said that the red light can come on for 2 reasons: water level or temperature... ?

Perhaps bubbles of air or steam could accumulate at the top of the vertical tube inside the expansion tank which goes to the level sensor - this would displace the water away from the sensor, causing it to read a false low level... ?

[Hacksawbob]

red light only comes on when the level sensor is not covered there is no electrical warning of overheating AFAIK only the temp gauge needle.

[Mocki]

the red light will flash for overtemp, and low level, it takes a signal from the temp sender in the thermostat housing AND the level sender in the header tank...... if the gauge is up and its flashing it too hot, if the gauge is low and its flashing its empty, and if its neither its wiring or sender failure........

water boils at 100 degc, but not when under pressure, which is what the pressure cap and headertanik is all about, add the correct coolant mix and it boils at a even higher temp, so unless the pressure drops, or you have no coolant mix, you dont get steam untill much hotter than normal boiling point of h2o

[KarlT]

Whoever said that I would know more about than them... you were right!

Atthummm! he he he!

They like to un-bolt things & bolt new bits on!

'computer says nooo'

[Fritz]

,,,,,,,

But they didn't have equipment for testing the sensor or gauge

In garage speak that simply means 'take it away'


Regards

Fritz,,,,,,,,,,,

PS,,,,,,,

they seemed to think it was a sensor/dashboard fault and that it wasn't really overheating at all

[ambivert]

,,,,,,,

But they didn't have equipment for testing the sensor or gauge

In garage speak that simply means 'take it away'

yeah, thats the distinct impression I came away with! They really didn't want to know!!!

ANYWAY - I HAVE FIXED IT !!! WOO-HOO!!!!!!!!

talk about Occam's razor, out of all the things that could have been wrong with it as the cause of overheating, the simplest thing was in fact that it WASN'T overheating at all. WHY OH WHY didn't I check this first??? Ah well at least I now know how it all works and that I have seriously overhauled the system so will prob never have any problems with it again!

Don't exactly what part of it is f*cked but somewhere between sensor, dash and gauge, there is a fault...

Boiled my sensor in some water whilst it was wired up and found out that the gauge starts moving at about 50c, is in the middle at 73c and hits the red at 94c.

Then, just for an ultimately conclusive proof, I measured the actual engine temperature as it ran (drilled a hole thru my old sensor, the same diameter as the thermometer probe, put it back on the engine, put the probe in, started her up)... and this is what it did:

Warmed up really quickly at first, to about 80c after 10 minutes, 90c after 15 minutes, 95c after 25 minutes, then took ages to get any higher: finally reached 96c after 35 minutes (radiator was warm by this time, as expected, given that the thermostat opens at 95c) I got bored at this point and revved it a bit to make it hit 100c, at which point the radiator fan came on, and the temp went down to 95c in something like 10 seconds! Amazing! it works woo-hoo!!!!!

I just can't believe that van has been sitting there for 3 months with me thinking it was broken... Roll on the summer thats what I say...

Thanks for all your help and support, this could have taken a lot more time and money without it!

Now for another question... seeing as original dashboard/components are a bit hard to find, and probably pretty dodgy anyway... Has anyone tried replacing the dash with something new dash from some other vehicle?

I could do with a tacho on this thing, not to mention a working temperature gauge. Or what about adding those generic gauges from somewhere like motaman, are they any good?