Confusion over temp gauge.

[BertieWells]

Iv never been convinced my temp gauge works properly ... here's why:

On start up the red light flashes for a few seconds then goes out.
After driving for a few minutes the needle progresses up to the end of the first "fat" white section.
I believe at this point the needle should be around the half way point? (hence why i think it may be faulty)
Up until today i thought this was as high as it would go and that it was faulty but today i drove up a steep hill at low speeds and the needle went up almost to the half way mark. Fearing this meant disaster i parked up quickly instead of going on to the parking spot i had intended to stop at a minute or so further ahead.

I will upload a picture tomorrow to help this make more sense.

What do you think? Faulty or could it be an after market gauge with a different scale.

Thanks

Rob

[lloydy]

normal is dead centre, around where the led is. it could be that your thermostat has failed open and the engine is running cold. you could check if your rad gets heat from initial start up

[BertieWells]

It does seem to get warm almost straight away ...

[lloydy]

Looks like you have a stat change in your immediate future then.... Bonus is that it's only a cheap part. If your diesel it's a pretty easy job, petrols look a bit more involved

[BertieWells]

normal is dead centre, around where the led is. it could be that your thermostat has failed open and the engine is running cold. you could check if your rad gets heat from initial start up

How will this negatively affect performance?

But before i order a new one, how can i check this is the problem?

[pionte]

Rob, what engine do you have ? It would really help people wanting to offer advice if they could instantly see , put it in your signature at the bottom.

although the same principle applies to diesel engines, I am mostly talking about petrol below.

The thermostat does a very important job, its sole purpose in life is to promote quick warm up of your engine. This is important for 2 reasons, firstly engines don't work well when cold... they have an optimum working( water ) temperature of 95-100 degrees , when cold the fuel doesn't mix well with the air, it clings to the side of the inlet tract and will run too weak, to over come this the mixture has to be compensated and more fuel is needed . This higher fuel to air ratio will have a " washing" effect on the side of the cylinder bores, robbing it of vital lubrication from the oil , over time this will greatly increase the wear on them and inevitably the longevity of the engine.

Secondly with the higher fuel to air ratio your MPG will be greatly reduced, costing more money !


As lloydy said, the thermostat itself is a cheap part, but .... the water cooled engines came in 2 different versions of the water cooling, early and late.The early system ( upto about 1986) has the thermostat housing at the front of the engine attached to the water pump and is made from cheese ( sorry aluminium ) The later type is located at the back and made from plastic.

The early type has a very nasty habit of welding itself to the water pump and self destructs when trying to prise them apart ( sledge hammer is often the only way ! ) These housings are as rare as hens teeth ....

to check if the thermostat is working, start the engine and locate the thermostat housing, hold the pipe on the engine side of the water system , and the pipe the other side going to the radiator, what should happen is the side before the housing will get hotter very quickly , one it reaches 85 degrees the stat will open allowing the coolant to flow through and on to the rad, if both sides warm up at the same time then the stat is stuck open. They can stick shut, this causes overheating issues very very quickly.

Good luck .

[AdrianC]

How will this negatively affect performance?

If the 'stat has failed open, then the engine'll rarely get up to working temperature, increasing wear and decreasing performance. It may also increase fuel consumption.

But before i order a new one, how can i check this is the problem?

Given how cheap they are, I wouldn't sweat it. First thing I do on any new purchase is a very full service including coolant change and thermostat.

But a bit of basic diagnosis can help you figure it - take the front grilles off and, as the engine starts to warm up, see how long it takes for the rad to get hot. If the 'stat is open, you'll feel warmth as soon as the gauge starts to move. If the 'stat is working, it'll remain cold until the gauge reaches "normal". If you've got an IR thermometer (tenner off eBay) you can check that the temperature at "normal" is really about low 80s degC.

The temp gauge is a very inexact science. It just transforms an electrical resistance into movement. That resistance comes from the sender reacting to coolant temp. Any poor connections, or a dodgy sender, or a gauge that's getting old - all will change the relative position of needle to temperature. The important thing is what's "normal" for YOUR VAN.

If the 'stat is behaving, and it's just a low-reading gauge, then the next question is why the temp rose so much. Is the fan working?

[BertieWells]

Rob, what engine do you have ?

Im 99% sure its the 1.9DG. Thanks for taking your time to explain that!

But a bit of basic diagnosis can help you figure it

After a 2 minutes or so of ideling and a short burst of 2-3k revs for a few seconds you can just about start to feel the radiator warm up. it doe this even though the indicator has barley moved.

So from what you guys have said it looks like the thermostat has jammed open ???

[lloydy]

Yup
Infact I'd even have a bet that the previous owner may well have removed it..

[BertieWells]

Because he didn't want to replace it?

[pionte]

Because he didn't want to replace it?

if it failed shut and you are stranded somewhere the its a good tip to remove it, some people wrongly think that its not required, and that you will get better flow rate and cooling if removed.. what age is your van ? like I said, early metal housing's can be a pig to get apart, later plastic ones can crack but are readily available.

http://www.brickwerks.co.uk/index.php/t ... -2-1l.html" onclick="window.open(this.href);return false;

http://www.brickwerks.co.uk/index.php/t ... -5cyl.html" onclick="window.open(this.href);return false;

[BertieWells]

Its a 1985.

Thats cool, you wouldnt recommend buying from jusk kampers @£9.50?

[pionte]

Its a 1985.

Thats cool, you wouldnt recommend buying from jusk kampers @£9.50?

I trust Brickwerks 100% with their quality, they only sell what they would fit. Im not sure what make it would be, it could be that the JK one is the exact same one, but trust me on this, If yours is the early metal type housing and it hasnt been out for a while , you wont want to do the job twice... I took my engine out in the end to do the job properly, ( I did the exhaust manifold studs as well ) Its not a 10 minute job to do, hence why they changed the complete water system. You may well be lucky and all the bolts come out.

[ghost123uk]

If you've got an IR thermometer (tenner off eBay) you can check that the temperature at "normal" is really about low 80s degC.

I have just ordered one of these from Amazon ( LINK ) at only £8 and with lots of good reviews I have a variety of uses for it, but I too want to check my stat is operating at the correct value. My temp gauge sits a bit low (at around 1/4), but mine stays there regardless of conditions, so mine is either a sender (or gauge) issue, or the stat is opening too early. This device will let me find out which and enable me to replace the correct part with no guesswork involved.

[BertieWells]

Apart from anything it looks F****** COOL!!

Ordered haha

Thanks