Thermostat question

[chuggers72]

Evening All!

OK so I know the subject of 'overheating' is possibly the most discussed topic on here (and I've put my time in with the wiki and archive) BUT the ol' beast (1986 DG) is running at 3/4 on the temp gauge. It holds steady, go's no higher, drops a little when idling, but still worries me as she used to run 1/2 way until a couple of months ago and does not leave much room on the gauge should a major issue occur!

Over the past year I've spent a bit of cash : new hoses, fresh coolant, new thermostat, new water pump, new rad, new dalek cap , header tank, coolant level sensor...

The fan kicks in but at 3/4 on the gauge and I don't think its runnning overly hot - so its as if everythings normal but the gauge reading has shifted to the left. I think I'm right in saying that if it was over reading then the fuel gauge would do the same but it dosent.

After a few evenings on wiki I reckon it could be faulty temp sensor or thermostat (even though its a new one). Question is, would a faulty thermostat cuase this problem? Surely if it was opening late the temp would still settle down once the waters flowing thro the system ?

All input appreciated

[jes*b]

I have a Jx van that was bought with a 'known head gasket' issue. It was overheating. I did not investigate. I made a few trips, coolant clean. It overheated. It passed the AA sniff test. Two speed fan kicks in. Gauge runs permanently on the 3/4. Although I am planning an upgrade I would be interested to know what could cause the gauge to run high.

Van still ticks over sweet. But has hidden issue undiagnosed

[billy739]

where did you buy the thermostat from??

[Ian Hulley]

where did you buy the thermostat from??

Also where did you buy the dalek cap from ?

ian

[chuggers72]

where did you buy the thermostat from??

Also where did you buy the dalek cap from ?

ian

All parts bought from Brickwerks as advised for reliability (if I hold my hands up the FIRST dalek cap I bought was from GSF however it was obviously buggered from new!).

[andyspanners.21]

Hi
I had similar issues ..... Do you suspect petrol guage reeding is out too? If so it could be voltage stabaliser on back of printed circuit board.... Dont pay rediculous VW price for this part its available from RS electronics for less than £1 Andy

[Ian Hulley]

Dont pay ridiculous VW price for this part its available from RS electronics for less than £1 Andy

RS Components however have a minimum order of £25.00 so look for some tools to take it over that

As with most of this sort of technical enquiry you should ask yourself ... What has actually changed ? What has been replaced since the temp guage suddenly changed position ? Have you fitted a new sensor ? Is it the correct one ? (i.e. people have fitted carb heater switches into the wrong hole on the t/stat housing and wonder why the gauge doesn't work and people swapping from a 2.1 injection to a carb have wondered why the carb heater doesn't work correctly) Do you see my point ?

Ian

[boxer]

After a few evenings on wiki I reckon it could be faulty temp sensor or thermostat (even though its a new one). Question is, would a faulty thermostat cuase this problem? Surely if it was opening late the temp would still settle down once the waters flowing thro the system ?

A thermostat doesn't open 'late' it opens at a set temperature. if it opens at a higher temp it will maintain that temp. It won't 'settle down' to a lower temp.

[ghost123uk]

With all that you have already done, there is not much left to suspect except the gauge itself. It is not a common thing to fail, but it is only a fairly delicate "hot wire" type gauge. To test actual engine temp, you could get a digital thermometer and tape it (with some insulation like foam or summat) to one of the large hot water pipes in the engine bay, the large metal one on the left side of the left head would be good. Then after a good old drive, take a reading. It should be around 88 to 90 degrees Celsius.

Digital thermometers, with a probe on a wire can be VERY cheap off ebay.
I even got a Multimeter for £12 (new) that had a thermometer c/w probe, (plus a load of other "toys" = rev counter, decibel meter etc etc).

[ghost123uk]

Dont pay rediculous VW price for this part its available from RS electronics for less than £1 Andy

RS Components however have a minimum order of £25.00

There's lots of places you can get them. Check in the wiki, then follow the link to good ole ebay

[ghost123uk]

Digital thermometers, with a probe on a wire can be VERY cheap off ebay.

CLICKY


I also9 have one (like on about page 3 of above) that measures inside temp, plus via a long lead, outside temp = so I know when it is near freezing (icy), but you could put the probe on a suitable place on the engine and monitor engine temp

E D I T = LIKE THIS (mine is black )

[chuggers72]

Good info chaps.

I'm fairly sure the fuel gauge is reading ok - its hard to tell though as it swings all over the place

I'm assuming the voltage regulator replacement is a soldering iron job....they scare me!! is it on a pcb behind the dash?

I'm going to get hold of a temp probe and check the engine temp out - can I assume if its running too hot it may well be the thermostat?

[ghost123uk]

Hey, check this out = Brand New Universal Digital LED Water Temp Temperature Gauge

[ghost123uk]

I'm assuming the voltage regulator replacement is a soldering iron job....they scare me!! is it on a pcb behind the dash?

It's easy to check the regulator without removing it, with a multimeter, details in the wiki, just be careful with the probes to not short them against owt they shouldn't. Your looking for 10 volts out from the reg with the black lead of your meter on an earth (metal bit of body !)

Don't know why, but I am going to bet it is not your regulator (fuel gauge seemingly ok)

I'm going to get hold of a temp probe and check the engine temp out - can I assume if its running too hot it may well be the thermostat?

Nope, you cannot really assume that. It could easily be summat else.
You can test a stat if you have a temperature probe, by heating water up in a pan whilst monitoring the temp and looking at the stat for it opening. imho, good idea to test engine temp with the probe as it's easy to do and will point you in the right direction. Don't forget to insulate over the probe a bit as cold air wafting over it will affect it's reading.

[chuggers72]

Hey, check this out = Brand New Universal Digital LED Water Temp Temperature Gauge

I'm liking the look of that - super accurate - no wandering needles!

Am I right in thinking a lot of owners install additional temp meters?