odd temperature behaviour

[bigjode]

odd temperature behaviour - possibly solved.

My 2001 LC is not staying at 90c as it should (on the dash guage) (note - once warm, these cars are meant to stay at 90, not drop and not increase)

the background o the problem is this:

1. changed coolant temp sensor 5 times in the last 9 months as I had the EPC come on every 2 months with the mapped cooling system error.

I therefore have all of these greentop sensors now and the problem repeats itself on all of them. I also dropped the tip of the coolant sensor in a cup of hot water and it read the temperature fine.

2. when first driving, it starts to warm up, as soon as i cruise on mway it drops to 60 or 75, when i just sit idleing it warms up again.

3. the readout on the climate control display (the "secret" one when you press recirc then up) shows the temp rising steadily to 90 and then it stays there, but the guage readout, and vag com readout give a different figure - where does the climate control get its figure from? - its not the green top coolant sensor as I unplugged this and the climate control display still reads normally.

Now the change in the cars temp seems to coincide with driving style too much to just be a fault in the wiring to the sensor, or the sensor itself. If so, its a major coincidence how the the fault appears when the engine is coolest from the cold air whilst cruising at mway speeds (note - as soon as i put my foot down on the mway, it heats up again)

so that leaves a fault in the cooling system itself, possibly being the thermostat sticking open and constantly cooling

I guess I have kind of answered my own query as to wht the problem is likely to be, but what I want to know is if anyone has had a similar fault and it been anything other than coolant sensor, as every temperature related problem usually ends up with "it'll be the coolant sensor".

 

[goble]

have u had it read on 5051 or vag -com could be just the dash panel insert gauge itself that is faulty.check it through 17 and 01

 

[Degudodger]

I'm experiencing the same thing with a 1.8 20V Toledo. Both sensors have been replaced with green tops but the temp display is still flitting between 85-90c.

 

[bigjode]

I'm experiencing the same thing with a 1.8 20V Toledo. Both sensors have been replaced with green tops but the temp display is still flitting between 85-90c.

Both sensors?

I know of the greentop, 4 pin one that goes in one of the coolant pies just to the right of the engine. Where is the other one?

Do you mean the one in the expansion tank (big ball shaped bottle where you top up the coolant)?

 

[bigjode]

took the thermostat out today - I was gobsmacked to say the least.

A picture is worth a thousand words:

A reguar thermostat:

My thermostat:

I don't where the rest has gone TBH, whether it was never there, or whether its stuck int system somewhere, or whether it fell out when all the coolant started flooding out?

In any event, its safe to say I need a new one!

 

[goble]

is it stuck down the pipe??? have seen it b4 on polo's

 

[bigjode]

which pipe would we be talking about? I stuck my fingers into the hole on the in the engine where the tsat usually sits and could feel anything except a flat metal disc type thing - i thought that was meant to be there but may its not?

 

[bigjode]

I've thoroughly checked the coolant pipes where the tstat comesfrom, and there's no way the missing piece of the tstat could have gone toward the engine side, as the waterpump (brass one) wouldn't let it pass that way, and it couldn't go up the pipe going to the rad as 1. The top half of the tstat itself was blocking it, and 2. the pipe bends about 45 degrees and the missing piece would have got stuck there.

I'm beginning to think its been like this for ages - when i first got the car in feb it used to cool down on mway for no reason. Through summer it stopped doing it but then it was warmer, now it reoccured but worse (bacuase its even colder out) so it leads me to believe its not a recent thing.

Oh, on another note, I broke my dipstick tube, are these replaceable, and would it cause oil pressure issues being broken?

 

[goble]

tube can be replaced yes
oil pressure issues being broken???
do you mean low oil pressure???
ps the part of the stat must be in there

 

[bigjode]

Yeah i mean low oil pressure because the system isn't sealed anymore? I don't know how pressurised the oil system is meant to be, if at all.

As for the Tstat piece, i'm thinking 2 things - 1. It was broken when I bought the car (I have had this dodgy temp behaviour since day 1 of my ownership but seemed to go away over summer and return)

or 2. the piece was in there and gushed out with all the coolant and has now dropped down in the engine bay somewhere (along with a load of my tools!)

It couldn't physically fit through the system in either direction as there are many bends and restrictions etc.

 

[matt_s]

When you say dip stick tube, do you mean the metal tube or the little orange plastic bit? The plastic bit is about £1 form GSF or ECP or possibly a little more from a dealer.

 

[goble]

god youd need some force to snap the metal insert!

 

[bigjode]

yeah its the plastic one. its filthy so can't see how it fits but i presume it must be quite easy then

 

[goble]

yer just push it down then it clips into place,but normall quite hard to get off sometimes run a hacksaw blade down the side of it to split it in half

 

[bigjode]

cheers!

 

[silver surfer]

seen this type of thing before people remove stat because engine runs hot .but some times you get hot spots in the engine as the stat works as a resistance in the water system .so they break the stat up and put the bit you have back in to maintain water flow through out the engine

 

[bigjode]

seen this type of thing before people remove stat because engine runs hot .but some times you get hot spots in the engine as the stat works as a resistance in the water system .so they break the stat up and put the bit you have back in to maintain water flow through out the engine

Could be. The water pump has been replaced, so it was obviously overheating at one point. Maybe before they discovered that the pump was knackered, they tried that to remedy the problem.

Not wise though with these cars, as the car thinks its cold all the time and runs rich.

 

[Degudodger]

Hmmm, i think I'll be getting a thermostat tomorrow from the local Skoda garage as my local Seat stealership is about 15 miles (plus i can't be arsed). According to Etos the thermostat is located on the block and it looks to be an easy job, is this the case and is there anything i need to be aware of.

The car in question is a 1.8 20V toledo - AGN engine.

 

[bigjode]

If its anything like the 1.8T, you have to move the alternator out of the way to get decent access

 

[cupra-c_ya]

I have had the problem with the temperature gauge going up and down, just thought it was the temperature sender? I have just bought the green top sender to fit, if it is not this and the thermostat where abouts is this on the LC?
thanks