Thermostat or Temp Sensor...or both.

[Johnny50]

I did start a thread a while ago, and at the time it sounded like it was the Thermostat, due to reduced fuel consumption etc...but recently its been fine, and now its playing up again.

Typical example was lastnights drive home.

Car warmed up to 90degrees, after 30mins driving, fairly fast/motorway, it dropped all the way to 60degrees, then drove for 1 mile at 35-40mph, and it jumped up to just under 90degrees, then another mile or so, it went all the way to just under 60 again.

Should i just replace both to be on the safe side ?
It's not like they're expensive.

Thanks

[biomulv]

Shot in the proverbial - waterpump breaking up?

[ap0gee]

Originally Posted by Johnny50

Should i just replace both to be on the safe side ?
It's not like they're expensive.

Would be my first port of call - get the pack from the stealers / factors rather (ebay seems to only sell the sensors IME) and it's only 30 quid or so plus an hour or two of your time. Much better to get that out the way before looking at the pump, and at least it'll mean you're OK for the next few years regardless of whether or not it was the problem. I'd say a pump breaking up would show as a gradual tendency to overheat IMHO...

[AwesomeSarah]

Mmm
No I would not say water pump
The temp goes up the faster you go as it cannot keep up due to some of the impellas breaking up
As you said , temp sensor and thermostat not that expensive , I would do both to start with
Check to see if there is a block in coolant
Be carefull though and dont let the temp go too high
Sarah

[Johnny50]

Thanks.
The temp has never gone above 90, ever. I sat the car running for about 20mins after a run, and it never pushed above 90.

Water pump was done along with the belt just over a year ago.

[AwesomeSarah]

Have you the old style sensor in (black)?
If you have it is worth doing that anyway as they are prone to go faulty
Sarah

[Johnny50]

I certainly do.

I'll go for the green ( i think it's green)

Cheers ears.

Oh, anyone got a definate asnwer on wether the thermostat is easy or hard to fit ?

[AwesomeSarah]

Hi
Thermostat is quite easy
Sarah

[mackdaddy]

Thermostat is 5 mins even for a DIY disaster like me.
Mine had same symptoms - feared water pump - which was fine.
New sensor, 90 rock solid.

[olit]

My car had the same symptoms - but went a step further.. It started running at 3-4000 rpm after start up, and kept running at that speed :-(

It was the temp-sensor. Takes 2 minutes changing. It was the black one, now green. :-)

JAN

[Johnny50]

Ta muchly mackdaddy

[Neily Weely]

I concur - the thermostat is relatively easy to change. Given the nasty plastic housing the typical fault is one of the lugs that holds the thermostat tight in the housing breaks and allows the stat to move. Net result is coolant always circulates through rad - regardless of temp and car never gets warm.

Typical method of test= Take car for a run, temp gauge bareley moves. Stop car, turn ignition off and then on - temp gauge risies to correct level. - Start engine and proceeed to drive - watch temp gauge start to fall back to original position.

No real alternative other than changing the housing - especially as trying to remove reervoir pipe can end in plastic shearing off!!!!

Dont forget to get a couple of llitres of Comma Red Extreme Antifreeze at the ready- for refilling!

[VRSPhil]

I thought the thermostat on the 1.8T was a sod to change? It certainly doesn't look very easy to get at to me.

It sounds like the sensor to me.

[fatty5000]

Originally Posted by VRSPhil

I thought the thermostat on the 1.8T was a sod to change? It certainly doesn't look very easy to get at to me.

I heard this as well

And yes it's the temp sender you liar