Blue Sensor? Yellow Sensor? Thermostat?

[jpowell79 0]

Hey guys,

 

I've been having an issue with the Corrado getting pretty hot (especially when sat in traffic!) often up to 110 degrees plus.

 

It tends to drop back down to 100 degrees or so when driving normally, and down to maybe 90 when on the motorway.

 

Now I don't have any steam or anything coming from the engine......but the coolant level seems to be dropping (having to top up ever 3-4 days) so am guessing theres a small crack or leak somewhere.

 

Found a good thread about rplacing a thermostat housing here: http://the-corrado.net/.archive/forum/viewtopic.php?f=1&t=55166&hilit=thermostat+housing with tips how to replace the housing, so have just ordered a new housing, seeing as it could most likely do with a replacement anyway!

 

My questions are:

 

1. What does the blue temp sensor do? and how do I know if my one needs replacing?

2. Same question for the yellow temp sensor! :)

3. I've heard debates about getting a 70 degree or 80 degree sensor - seeing as I mostly do motorway driving, does that mean I should ge the 80 degree one??

4. based on the problems I've described, does it sound like replacing the thermostat/housing/sensors and checking for any cracks in pipes and leaks around o-rings will resolve the issue with the cooland level dropping??

 

Sorry for being a complete div.....I really am a novice when it comes to car engines (but am enjoying the learning curve as I go along :) )

[Reggit 0]

From what little I know :0

 

The blue sensor supplies the engine temperature to the ECU so it can work out fuelling

The yellow sensor supplies the dash gauge

There's sometimes a 3rd sensor in there, i think it's for the air-con and fitted but not used to some non air con cars.

 

The 70 or 80 degree sensor you are talking about is actually the thermostat. I would never fit a low temperature one to a standard car, they would just cause it to run cool and possibly mask an underlying issue. I'd just get a normal one from VW.

 

Can't say if replacement of that lot would sort your coolant loss out as obviously it depends where it's leaking from.

[andy 0]

Yes don't get a low temp thermostat, VW designed the VR6 to run at the temp set by a standard thermostat. If your engine is standard in other respects, don't bother.

 

Your temperatures don't sound massively high, a bit maybe but not drastically so. Mine sits at 100 plus on the motorway, approaches 110 in traffic and 90 ish if just pootling around.

 

You need to sort out the leak though, that has to be the priority!

[vagman 0]

On with the same job mate! Hope you get the help you need. But after reading over the cooling thread i decided on a low temp stat from awesome GTi, aswell as everything else for the cooling system. I wont be driving the car much in winter so hot summer days are in order thats how i came to make my choice! Dont get me wrong, i am no corrado wizz but from the info i have gatherd so far its not the best design cars out there.

 

For instance........

"QUOTE" kevhaywire

Yep, because you can only get 2 of the 3 bolts off the thermostat cover in situ and it's a real nuiscance.

 

Everything on the VR is like that though, have you noticed?

 

1 - Main water pump, you can see all 3 pulley bolts, but can't quite get to the 3rd, jack the engine up.

 

2 - Thermostat - can get 2 bolts off, not the 3rd, off with the whole housing.

 

3 - Upper chain tensioner pad, you can see where it clips on and wiggle it about etc, but can't quite get to it, off with the gearbox.

 

4 - Offisde front wishbone bolt, you can see it behind the sump, but can't quite undo it, jack the engine up

 

5 - Lower intake manifold, you can see the last bolt sat there behind the alternator, but can't quite get to it, off with the alternator

 

6 - You can see and undo the bottom alternator bolt, but can't pull it out because the inner wing's in the way, jack the engine up.

 

7 - And so on....

 

Bloody car

 

But maybe they got the stat right, and the complex after thought of the whole cooling system itself! All i will say is once all the work is done and after a few miles of monitoring the temp gauge's i should not have to sit with one eye on the road and one fixed to my temps this summer when i decide to open it up a little, or get stuck in traffic!

[jpowell79 0]

Ok after looking through the "cooling thread" sticky..... I realise theres an issue with the fans.....seems like only "stage 3" fan works.....ie when it gets to 115degrees the big loud fans kick in :(

 

So I have a coolant leak and a fan issue! :gag:

 

I've had this car for less than two months and already its become the least reliable car I've ever owned!

 

Still wouldn't change it for the world though! :D :D

[jpowell79 0]

ok well I managed to eventually get the thermostat housing out..... the seal rings around the edges have completely worn away (you can see the bit of the rubber dangling down in the pic!) which will hopefully explain the reason I am losing coolant fingers crossed!

 

 

The seal around the plastic that holds the thermostat itself has also withered away so will need replacing

 

 

 

I popped the thermostat itself into a pan of boiling water and it opened and closed ok, so guess it should be ok, but the rubbery seal around the top of it is looking a bit battered (not sure if you can make it out properly in the pic below - its a bit of a manky brown colour) - can i buy this seperately or do I need a new thermostat??

 

 

Anyone know how I can test the blue/yellow temp sensors are working correctly, now they are out the car?