running too cool?

[mrdandandan]

Hello everybody,

We've just got back from Yorkshire, van went like a dream except the temp gauge played up a little.
It started on the run back to london, when the temp gauge only rose to the edge of the lower block after a pit stop
It went a little over the mark in queuing traffic, not up to halfway or just past, where it normally would sit. fluid levels all fine, no flashing light either, heaters working, no over heating signs (steam, etc.)
It just seemed like the whole van was operating a bit cooler than normal, got us home quite happily and safely but should I be concerned?
dodgy thermostat perhaps?

dan

[AdrianC]

dodgy thermostat perhaps?

Assuming the gauge or sender pairing haven't decided to have a sulk with each other, then - yep - it's all it can be.

The 'stat controls the lower end of the normal range, the fan switch the upper. If the engine is running below the 'stat opening temp, and the 'stat is allowing coolant to the rad, the 'stat has failed open. Too cool will mean less power, more engine wear, and more fuel used.

[Red Westie]

You really need to determine whether the engine is actually running cooler OR the temp gauge is reading low.
If you allow the engine to idle (engine warm) after a few minutes the thermo switch should click in and 1st speed fan should operate.
Is the air hot coming from the heater blower?
Does the rad fan still work? and if it does, is the temp reading low if/when it does function?

Other suspects: Voltage stabilizer failure on binnacle PCB?
Corroded terminals on coolant temp switch
Faulty temp switch
Thermostat failed open

Martin

[GBHgpJON]

Heh...Got to love T25's......most of the time we worry about em 'overheating'..........
unless of course they're 'underheating'
Paranoia and old VW's go hand in hand......

[mrdandandan]

Thanks for your replies guys, once again i'm amazed by this site and all the top info!

I'm going to let it warm up here as you suggested and look for the fan kicking in (it didn't on the trip but wasn't stationary for long) and warm rad, and clean up all the temp sender connections too before the 'stat is replaced as it seems that might be a problem. Got a spare stat here ready to go in, just want to check before attempting as my old-style thermostat housing looks a little bit old and fragile.
Will report back and thanks again!

dan

[mrdandandan]

Sorted! I cleaned/checked all suggested connections and no result,so, decided to swap the stat ,as cheap to replace, and the gauge is back up fine on the LED, heater working, flashing light on startup, cooling fan kicks in. It was a xxxx of a job though! Upside down fitting in a very tight space, dripping coolant in your face. The stat had stuck itself in a treat somehow...not the best fun really! but done now. Thanks guys

[AdrianC]

It was a xxxx of a job though! Upside down fitting in a very tight space, dripping coolant in your face.

<scratches head> Is it different on the 1.9 to the 2.1, then? I put a new 'stat in ours yesterday and - fubar bolt heads aside - it was quite easy, from above...

[Mocki]

It was a xxxx of a job though! Upside down fitting in a very tight space, dripping coolant in your face.

<scratches head> Is it different on the 1.9 to the 2.1, then? I put a new 'stat in ours yesterday and - fubar bolt heads aside - it was quite easy, from above...

there is a difference between late and early water systems, and age of van may make no odds on that

thought you would have known that AdrianC ?????

[AdrianC]

It was a xxxx of a job though! Upside down fitting in a very tight space, dripping coolant in your face.

<scratches head> Is it different on the 1.9 to the 2.1, then? I put a new 'stat in ours yesterday and - fubar bolt heads aside - it was quite easy, from above...

there is a difference between late and early water systems, and age of van may make no odds on that

Ah...

thought you would have known that AdrianC ?????

Not sure why - that thing outside's the only one to have tasted my blood so far.

[mrdandandan]

It was the early type, face down, attached to the the waterpump - I can see why they redesigned it to be at the top on the later ones. Thermostat was stuck well in too with what had once been an O-ring, so I was gingerly prising it out for fear of cracking the housing...
Another , ahem, lovely, fun job done though - just like doing my heater blower fan... Ouf!

Thanks again