Is my thermostat knacked?

[steve_earwig]

Sounds more like something's up with your air con

[Welly]

Once it gets up to 90 it should stay there!

Sounds like thermostat to me! it's the first thing I changed when I bought mine - just for peace of mind really.

And your performance will be down when it's running cold.

[teamster1975]

Sounds like the 'stat to me too if it's not maintaining engine temperature!
I guess there could be an airlock but that'd be sorted when you changed that 'stat anyway.
The amount of people you've had tinkering with your car recently anything is possible soops!

[rapport25]

Hi Supa its the thermostat.

I replaced it when I had new coolant and flush around 3 months ago. Also when I had my cambelt a month ago i had new water pump and cambelt kit fitted If its due a cambelt change the water pump as well.

[ddoherty406]

The same question has been in the back of my head. Ive a 96 1.9td and the heater no longer gets hot. It gets slightly warmer when im on the motorway but still not very hot at that. Could this just be the heater matrix? the car engine temp still sits just below the 90 mark unless im sittin in traffic for a while. Is it a big job replacing it? Always happens in the winter?

[steve_earwig]

Sorry, that's normal for my 2.1. Weird that it heats up once it gets moving though (and I have a feeling it should still be putting out warm air but I'll shut up now).

[jasper5]

If I'd read this in a VW forum, I would have said water pump, very common on VW Golf and variants, they use plastic implellars on their pumps, always breaking.

Thermostat is the first thing to replace, could always try bleeding first though.

The water loss could be a slow leak from the pump.

[mjb]

I'd be more inclined to say it's just in need of a bleed - should be a pipe coming through the passenger side of the bulkhead with a bleed nipple on top. Stick the n/s on the kerb with a cold engine, top up the water, then undo the bleed nipple cap until coolant starts coming out

If it were the 'stat stuck open, you'd eventually get warm when idling, but driving (especially at speed) would cause it to get cold. If it were stuck closed you'd be overheating...

jasper: 406 water pumps are metal... (ps anyone want to buy one along with a cambelt+tensioner for an XU10J2TE? )

[steve_earwig]

If it were the 'stat stuck open, you'd eventually get warm when idling, but driving (especially at speed) would cause it to get cold. If it were stuck closed you'd be overheating...

Looks like I get to take the paper bag off my head

jasper: 406 water pumps are metal...

I was wondering about that myself, it would be very unusual for it to happen to a 406 but then Supa's car likes doing that sort of thing (I reckon as the temp sender's at the top of the engine it would read hot hot hot).

As the car's loosing water I reckon air locks are favourite : air lock in thermostat housing - nothing for the sender to measure, air lock in the heater pipes - no flow of hot water. Once the engine speeds up it forces the air locks around. Makes sense.

[jasper5]

Yeah, I know they are metal on the 406, I was just comparing the fault to a common VW fault.

Wouldn't hurt to try bleeding first, costs nowt

[mjb]

jasper: 406 water pumps are metal...

I was wondering about that myself, it would be very unusual for it to happen to a 406 but then Supa's car likes doing that sort of thing

Point. It'll probably end up being the switch for the boot light or something equally daft ;)

[mjb]

Wouldn't hurt to try bleeding first, costs nowt

Dunno, I ended up buying loads of tyre valve caps to replace the nipple covers I kept dropping due to freezing/scalded fingers... Think I've still got 4 or so spares in my toolbox

[steve_earwig]

The ones on my D9 are tyre valve caps

[mjb]

I can't help it if my car has "issues"

Aww... I'm sure all you need is a nice big hammer to threaten it with and it'll behave - works for me

[steve_earwig]

Did you try the bleedin' thing yet?

I just thought, the boot light switch is a tilt switch, perfect for making a bomb...