Water Temp Sender Woes!!

[Feel]

Where is this coolant manifold on the diagrams?

I had an AMK Engined LCR. Over the 4 yeas I had it the Coolant Sensor went first, I replaced with a green top (rich running), then the prongs scaled up in the header tank (three beeps).

Then I had the gauge go funny. I did a load of reading and found it had a diferent sender unit, can't remember the links now. Whilst it was still funny, I was on a RR day at Awesome. Jim commented that the gauge was funny, that it was a common fault on the 1.8T and that it was a fairly big job because of the position of the sender in the thermostat housing which is under the inlet manifold, LH Side (from the front) and because you had to drain the coolant. Car was due for a service anyway, so I let the garage do it. They confirmed it was a big job as they had to drop the coolant.

Whatever. If your gauges are duff, change to a green top and see if it fixes it Much easier job to do the green top, and it doesn't matter who's right or wrong if it gets fixed.

 

[traumapat]

Phil... if your right then lots of peeps on here are misinformed.

the green top sensor tells the ecu engine wise the coolant temp. so if this fails it would show on vagcom and you`d run badly?

the header tank sensor only gives 3 beeps or nothing depending on level of coolant.

the dial itself is controlled by a sensor in the thermostat housing. is the same sensor that would alert you to overheating? the only warning comes from the gauge reaching 120... so if mines sitting at 80 most of the time am i likely to show only 110 in the event of a wp faliure...and get no alarm?

ive an oil temp gauge as a back up so im not overly worried. just be nice to understand how this works?

 

[Feel]

Phil... if your right then lots of peeps on here are misinformed.

Hey, it wouldn't be the first time. I've posted this info several times in several threads to do with the same subject

the green top sensor tells the ecu engine wise the coolant temp. so if this fails it would show on vagcom and you`d run badly?

Yes, this is the main culprit for the VAG-COM error about the car running rich. I'll look the specific error up in a bit.

the header tank sensor only gives 3 beeps or nothing depending on level of coolant.

Yep.

the dial itself is controlled by a sensor in the thermostat housing. is the same sensor that would alert you to overheating? the only warning comes from the gauge reaching 120... so if mines sitting at 80 most of the time am i likely to show only 110 in the event of a wp faliure...and get no alarm?

Yep. Re-Overheating, not entirely sure, but I think so. I think you're right, you'd get no alarm, but actually, I think the gauge would just sit around 80 and would get up near 120.

 

[traumapat]

thanks phil.

it fits to some extent as vagcom shows nothing and car is running better than ever.. yet the dial is sloppy.

 

[Cupra_UK]

An update: I flushed the coolant last night with water and added some G12+. Just to recap, I didn't ever have a problem with this. I ended up needing to do this because I tried to install the new green temperature sender without the O-ring (as it came without one) so lost all the coolant.

Flushing the coolant is an easy enough job. Would be easier if you didn't have to remove the under tray though. You can find the tap fairly easily but its quite difficult not to get wet... best thing is a small pipe running from the nozzle to a drain, etc.

Anyway, I changed the coolant, let the car reach normal temperature, let it cool down and add coolant as needed. I didn't get a change to drive it last night but this morning it needed a little more of a top up. Checked under the car and no wet patches so assume it's still finding it's way round??

I've been on a 5 miles drive after bring the car to normal engine temperature this morning and the gauge seems to be behaving itself. The problem previously was kind of intermittent so perhaps this its still early days.

I should be doing some longer trips this weekend so will keep an eye on the gauge and the coolant levels. First impressions suggest it's been fixed but I will report back later... fingers crossed.

Over and out.

 

[Bosher]

The green ECT sensor (G62) has 2 sensors in it, (hence the 4 wires to it) one is for the ECU and one for the temp gauge. So you can have a dodgy signal going to one and a normal signal going to the other. This is what I have, (gauge is fine, intermittent fault to ECU).

This morning I have tested the wiring and traced them using VAG wiring diagrams. and IMO this sensor does both the gauge and the ECU... also i've looked @ a m8's ibiza and another m8's Cupra this morning.. same sensor just slightly different position.

The two probes in the water bottle are just a level sensor.

 

[Muttley]

Feel wrote

Where is this coolant manifold on the diagrams?

Coolant manifold is my own description, it is the piece of metal pipework bolted to the right-hand end of the cylinder head. Three hoses go from it to the cabin heater matrix, the top of the radiator and to the oil cooler, and the green or black sensor assembly screws into the top of it. This is what you have under the bonnet, yes?

This sensor assembly has two separate temperature sensors in it, feeding the ECU and the gauge independently.


I had an AMK Engined LCR. Over the 4 yeas I had it the Coolant Sensor went first, I replaced with a green top (rich running), then the prongs scaled up in the header tank (three beeps).

Then I had the gauge go funny. I did a load of reading and found it had a diferent sender unit, can't remember the links now. Whilst it was still funny, I was on a RR day at Awesome. Jim commented that the gauge was funny, that it was a common fault on the 1.8T and that it was a fairly big job because of the position of the sender in the thermostat housing which is under the inlet manifold, LH Side (from the front) and because you had to drain the coolant. Car was due for a service anyway, so I let the garage do it. They confirmed it was a big job as they had to drop the coolant.

The thermostat housing is indeed under the inlet manifold, next to the water pump. The thermostat sits in the block, and is held in place by the housing which has a dome-shaped cover and a large pipe, to which the lower radiator hose is attached. You can't miss it.

Now the diagrams I'm looking at are the same for all the 1.8t engines and show no electronics in the thermostat housing. It will be easy to tell - if there are any wires or connectors attached to the thermostat housing then there is a sensor in there. I'd be surprised if there is, though, it doesn't make any sense to add another sensor specially to the AMK engine, and ignore the one in the standard package.

Whatever. If your gauges are duff, change to a green top and see if it fixes it Much easier job to do the green top, and it doesn't matter who's right or wrong if it gets fixed.

I don't want to send people hunting for a sensor that doesn't exist, or alternatively give them bad advice about the green-top sensor.

 

[Feel]

The green ECT sensor (G62) has 2 sensors in it, (hence the 4 wires to it) one is for the ECU and one for the temp gauge. So you can have a dodgy signal going to one and a normal signal going to the other. This is what I have, (gauge is fine, intermittent fault to ECU).

It might have two sensors in it, the valver might use both, but the 1.8T doesn't use it for the gauge. Did you know that the MAP sensor also has a temperature gauge in it? That one's not used either.

This morning I have tested the wiring and traced them using VAG wiring diagrams. and IMO this sensor does both the gauge and the ECU... also i've looked @ a m8's ibiza and another m8's Cupra this morning.. same sensor just slightly different position.

It might do on the valver, but it doesn't on the 1.8T. The sensor might be the same, but is obviously used differently.

The two probes in the water bottle are just a level sensor.

Yeah, I know. Three beeps. We've already said that.

 

[Feel]

Coolant manifold is my own description

Good description, was just checking if you got the name from the diagram

This sensor assembly has two separate temperature sensors in it, feeding the ECU and the gauge independently.

Disagree. Gauge isn't fed from this sensor.

I don't want to send people hunting for a sensor that doesn't exist, or alternatively give them bad advice about the green-top sensor.

Neither do I. What we need is for someone to have it fixed/fix it and report back (like I did), rather than just keep posting the same contradictory opinions at each other

 

[Muttley]

Okay. I'd be really grateful if someone with an LCR would go and look at their thermostat housing and tell us if there is an electrical connector on it. All my evidence, from Seat workshop documentation, says there isn't - but the only way to be sure is to look at the real thing. A photo would be even better, of course. I don't know how easy it is to see the housing on an LCR - it's simple enough on my TDI110, without even taking the engine cover off.

 

[kieran]

Good description, was just checking if you got the name from the diagram



Disagree. Gauge isn't fed from this sensor.



Neither do I. What we need is for someone to have it fixed/fix it and report back (like I did), rather than just keep posting the same contradictory opinions at each other

Feel, are you sure?

I've had the temp guage problem for a long time now, the guage would sit at 0 during normal driving and randomly shoot up to 90, then go back to 0, sometimes it wouldn't work at all, and sometimes it would work fine. Other time it would float at a random temperature between 0-90, but never go above that.

I bought the green sensor today from GSF, apparently they sell quite a lot of them. Also picked up a new O ring and cost around £20 in total.

After reading your replies on here, i was lead to believe this sensor does not feed the temp guage on the dash.

However i took out my old black sensor today (from the 'coolant manifold', the sensor with the 4 wires coming out of it held in with the C clip), and replaced it with the new green one, and now my temp guage is working perfectly.

Just thought i'd post that up for anyone having the same issue, as it has fixed mine (2003 Leon Cupra R, 1.8T AMK engine which is for sale by the way!)

EDIT: This is a picture of the sensor i changed today (Picture taken by 'petay_pan')

 

[Feel]

Well, there you go, maybe I am wrong - all I know is the green top didn't fix my gauge problem and Awesome, plus a few others told me there was a different sensor in the thermostat housing. I had that replaced by a garage and the gauge worked fine.

 

[Bosher]

I'm gonna change mine during the week. I'll post a pic of it so ppl can see where it is on a 16 valver.

 

[petay_pan]

Thanks for the pic credit .

All you can't see in the picture there are 4 wires coming out of that sensor, was taken on my 52 plate Cupra, 1.8T AUQ for anyone that might be thinking this is a Cupra R problem only.

I will have to get over to a parts place and see if I can pick a sensor up and see if it sorts since it sounds like its simple/cheaper than Mr Feel's suggest so worth a try first for the sake of 20quid.

Thanks for the feedback Kieran.

 

[traumapat]

jurys still out for me. after searching vortex ive found a thread were the green top didnt sort the gauge and goes on to do the tstat.

 

[Cupra_UK]

Another success story here. 140 miles round trip today and temp gauge behaved as it should. Warmed up to about 80 as revs drop to idle and then to 90 after a minute or so of driving. I'm convinced this sensor feeds the gauge and is what causes the gauge to play up.

 

[traumapat]

it seems strange this has been solved by changing the thermostat, the green top and the sender unit actually embedded in the cluster/dial itself.

it seems to depend on the model. lots of info in all cases except the last on vortex

intrestingly the gauge sits at 90 as designed but even if it reads 80 or 100 it will still read 90. it was changed to this to stop customers worrying why each car sat at a different temp if the temp falls outside certain paramiters then the gauge will show it.

 

[Cupra_UK]

By the way... how often should I keep checking the Coolant level after having changed it? I've checked it twice and both times it's been slightly low. So only topped it up to the top line - thought it would have settled by now?!

 

[Feel]

it seems strange this has been solved by changing the thermostat, the green top and the sender unit actually embedded in the cluster/dial itself.

Not sure if this is a mis type - but to be clear, I'm talking about a sensor that's in the thermostat housing, not the thermostat itself.

 

[Cupra_UK]

By the way... how often should I keep checking the Coolant level after having changed it? I've checked it twice and both times it's been slightly low. So only topped it up to the top line - thought it would have settled by now?!

Ok, getting a little worried now. The coolant needed a top up again this morning. Could this just be air in the system coming out?

I have to be honest I didn’t let the new coolant run through with the bleed 'tap' open for very long because I was worried that I may not having enough coolant. I couldn't see any drips under the car after I did the full change and let it run until warm. I think it's unlikely that I've left the tap open slightly or not closed it properly as the way it's designed, it takes a minimum turn to open or close it.

Should I run the car with the top for the expansion bottle off? There was never a problem with loosing coolant before and I haven't made any changes or touched any of the pipes.