Coolant temp weirdness ...

[S4TAN]

Had an 80 mile drive back from work today .... about half way i inadvertantly glanced at the water/coolant temp gauge and was surprised to see that it had left it's normal 90 mark ... and had actually gone down! (to about 85)

I've never seen this happen before - in any weather (even on colder days than today) ... normally, once it reaches the 90 mark, it never strays either side and just stays rock solid on 90 ... and it gets to the 90 mark within the first few miles of driving ...

I checked the coolant level when i got home - it's fine ...

Anyone ever seen this happen in their own car?

[stimp]

Noticed the same thing in mine recently. Just cruising the other day down a long hill and mine dropped to nearly 70,oil tempp was over 90 still. Takes a long time to warm up at the moment(on gauge), could this be a sticky thermostat.

[UKS4APR1]

I've had same thing after a period of little throttle in cold weather. Soon goes back to 90 after a portion of boost.

S4TAN - How's the average fuel consumption on the K04's ?

[GrahamS4]

Speaking to Doug previosuly coolant temp variation can be a sign of a thermostat or water pump problems.

I'm sure you've had both replaced but I don't think thermostats are renowned for their reliability and as you haven't lost any coolant I doubt it can be the pump.

I'd keep a very close eye, it should go to 90 and stay there as far as I know as you have experienced previously. Mine normally get to a water temp of 90 before I have seen the oil temp guage move and it stays there regardless of cold or heat.

Goning to be a bitch of a labour bill to replace a faulty thermostat though if it is.

[S4TAN]

S4TAN - How's the average fuel consumption on the K04's ?

Ummm... let's just say it's been reduced somewhat! Prior to the conversion I would get around 300-320 miles per tank ... now I get ~250 miles per tank if i drive normally, a bit more (say 270) if i drive with a very light foot (hardly ever on-boost) ... but if i gun the car a lot then probably 220 ...

I'd keep a very close eye,

I assuredly will!

Goning to be a bitch of a labour bill to replace a faulty thermostat though if it is.

Damn! Bloody cars!

[tdiquattro]

Just out of interest my faulty black temp sensor (which is now a nice new green one) would cause the temp AND oil guages to drop to zero once in a while. Everyone should change this anyway if it hasn't already been done imho.

[MarkB]

Had an 80 mile drive back from work today .... about half way i inadvertantly glanced at the water/coolant temp gauge and was surprised to see that it had left it's normal 90 mark ... and had actually gone down! (to about 85)

I've never seen this happen before - in any weather (even on colder days than today) ... normally, once it reaches the 90 mark, it never strays either side and just stays rock solid on 90 ... and it gets to the 90 mark within the first few miles of driving ...

I checked the coolant level when i got home - it's fine ...

Anyone ever seen this happen in their own car?

I would say check and change your temp sender. It's not too hard a job and is the most likely cause...

[KayGee]

Anyone who can use a pair of pliers and a screw driver can do this job. Plus temp sender units are cheap to buy.

[oliew]

mines the same but worse julian, my dash temp reads 65/70 all the time, with lots of boost driving i can get that up to 80/85 , the aircon unit display always says 90 but takes its time to get there...
ive replaced the temp sender and thats not changed anything, doug thought it may be the thermostat thats causing the problem, will change it when i do the k04 route soon.
if you use vag com, there is a block in there that measures coolant temperature i forget which one it is now.
Oli

[boxerdogted]

If your thermostat is faulty the oil temp will also read lower due to the reduced coolant temerature.If the oil is coming up to temperature it is almost certain that your coolant temp sensor is faulty.

[tdiquattro]

I wouldnt bet on that, as I said my oil temp guage was affected as well

[Doug_S2]

julian - you also have the water wetter in the car.

[jimbogrey]

It is possible to drastically reduce the coolant temperature. especially on a coldish day. simply turn the heater on full blast and given normal driving both coolant and oil temperatures will drop. I have experimented with this as a way of reducing temperatures in the engine bay and thus reducing heat soak to a small degree.

[S4TAN]

julian - you also have the water wetter in the car.

Granted Doug - but having done a few long drives with the water wetter in (before last night) it never happened then. It was only last night that this happened - i just thought it a bit odd having never seen it before.

I did have the heater on quite high (as Jimbo says) so maybe that was the cause...

Thanks for the helpful responses all
I'll just keep a close eye on it and see how it goes ...

[ShaneyB]

Sometimes my gauge doesn't move at all. 10 minutes later it will be on 90..?????