Cooling System Issues.....

[VW_chris 10]

right, everything works champion, i had a **** load of bother about 8-9 months ago with regards to the fans not cutting in ect, which i solved by disconnecting some wiring harness at the fuse box (traced it back with a multi meter)....

 

anyway, having replaced an abomination of a water pump, i now have another issue, it runs too cold....

 

[ATTACH=CONFIG]82456[/ATTACH]

 

sitting around, on idle, everything works champion, heats up to temp, keeps going a bit more and the fans kick in at the right time ect.

 

when im driving though, its as if the cooling system is too good? it goes no higher than 70 on the clocks... which is no good as its barely off warm up map.

 

any ideas? i have got everything to do a cooling system overhaul today/tommorow, which if anything comes to light, ill report back, i tested the origional thermostat, which was ok, replaced it anyway as it looked ropey as hell, problem still persists. ive bought another themostat, on the off chance euro sold me the wrong one....

 

from there, ill be replaceing the radiator, obv the thermostat, cooling system flush and fresh coolant.

[fendervg 33]

What car and engine? Where are you taking the coolant temp readings from - at the instrument panel coolant gauge, or with VCDS plugged into the ECU? Reason I ask is that they are two different senders.

 

You can test all the senders by putting them in hot water, and the resistance across the sender will change based on temperature. Maybe your thermostat is stuck open? This would lead to it never heating up properly.

[seanl82 23]

Its very common the reading being low on the gauge. Change the appropriate temp sensor (cant remember which colour sorry!) and check out what the ECU is reading too, as that is off of a different sensor.

 

Very much doubt there is anything wrong with any part of the cooling system, so just keep an eye on your oil temps through the MFA, that'll dictate which map is running and have the effect on engine wear.

[fendervg 33]

ECU does not look at the oil temperature or pressure. It's just the coolant temp (blue temp sensor in thermostat housing on VR6) that dictates the switch from cold to hot engine map.

 

There is also an air temp sensor in the inlet manifold and another one on the cat, but they are for a different purpose.

Edited October 3, 2015 by fendervg

[VW_OwneR_85 2]

you need to cross reference the temp reading the ecu is getting using vcds/vagcom software to that of temp gauge , chances are the temp sender for the gauge is lying abit, mine does read slightly lower aswell, what counts is the ecu getting the right temp, failing that if you want to heat it up anyway VW made a grill for the winter which has the slates covered up so the rad doesnt get as much cooling...

[fendervg 33]

No need for the grille. That was for Canada and Scandinavia. There should never really be a problem with a VR getting up to temp as they run hot anyway. Diagnostics software will definitely help here.

[VW_OwneR_85 2]

No need for the grille. That was for Canada and Scandinavia..

yea i agree no need aswell, but i know someone locally that had that grill, i cut the slates out for extra cooling so dont know where you get that info from

[fendervg 33]

I'd say he got it on ebay or second hand or from the dealer - was available to order from VAG until recently.

[seanl82 23]

ECU does not look at the oil temperature or pressure. It's just the coolant temp (blue temp sensor in thermostat housing on VR6) that dictates the switch from cold to hot engine map.

 

There is also an air temp sensor in the inlet manifold and another one on the cat, but they are for a different purpose.

 

 

 

Ok I didn't know that, I stand corrected!

[1xshaunx1 27]

If the blue is for the ecu.

Isn't it the yellow one that was superseded with a back and blue that does the clocks and fans. I'm not totally sure though.

Does anyone know what the electricle bit at the bottom of the radiator does and the other sensor in thermostat housing. Could do with a list of what all three do and what the one in the rad does

[fendervg 33]

Blue is coolant temp for ECU. Yellow is coolant temp for gauge, fan and aux cooling. Radiator is the coolant fan control temp sender. Other sensor in the thermostat housing is for cars with A/C or secondary fans.

[robrado974 1]

The definitive guide to the cooling system on here has everything you need .

[VAG-hag 0]

I'd say he got it on ebay or second hand or from the dealer - was available to order from VAG until recently.

 

Both my storms had the blocked grilles.... Now binned

[VW_chris 10]

totally didnt expect this thread to get the response it has! much appriciated :cheers:

 

after today, having flushed the system, replaced the radiator and header tank, as they were both knackered. still no change.

 

with regards to the sensors in the thermostat housing, i believe they are all working and correct, yellow 4 pin, blue and black. i have replaced them, with no avail, i dont know anyone who has vagcom cabable of reading my car up here near newcastle, its the (old 2 plug) i have an adapter for it, however its been years since i last had it done...

 

its a seriously odd one, the gauge on the dash is correct, feeling the hoses after driving then pulling up, and it feels about right. there not hot hot as id somewhat expect them to be after driving.

 

i mean, this is the thing, i dont know what SHOULD be right, its a very very early late spec corrado, engine no 602. i dont know if its happy running at 70 or not, i can only go off what i know it should be sitting at, and used to sit at, untill i changed the water pump. i know people put low temp stats in ect, the one in mine is an 80 degree stat.

 

i know these lumps run hot, before i swapped the water pump it would be scolding in there, it idles champion as well.

 

stumped :scratch:

[fendervg 33]

Does the hose from the thermostat to the radiator get warm straight away after starting the car?

[Jim 2]

Yeah - wondering if the thermostat is stuck open!

[fla 9]

On a run my coolant temp drops to around 70ish and thats with a new stat, radiator, pump, rad sensor and blue temp sensor. Been like that for a few years.

[robrado974 1]

Mine will sit at 75d on a run . Obviously it rises in traffic , but on a motor way ,it stays at 75 .

[fendervg 33]

Mine varies a lot - the scale on the gauge is not linear anyway. Coolant temp gauges on newer VAGs are calibrated to sit in the middle, bang on, unless warming up or cooling down, for peace of mind. I think people were getting worried when they were seeing the needle move as conditions varied. My VR6 will vary a lot, depending on fans running, moving on open road, or sitting in traffic. I'd only get worried if it shoots up or consistently reads high, and would not consider the older senders and gauges to be a particularly accurate combination - I'd consider them a guideline indication of coolant temperature only. You can always double-check by looking at the oil temperature on the MAF for re-assurance.

[VW_OwneR_85 2]

by the sounds of it you have a cooling system thats actually working ;)

[Portent 0]

On a run my coolant temp drops to around 70ish and thats with a new stat, radiator, pump, rad sensor and blue temp sensor. Been like that for a few years.

 

Mine is similar. I replaced the thermostat this year which improved it a lot (it used to barely register on a run before I replaced it). I think this is relatively normal behaviour.

[Jon_vr6 1]

Deffo thermostat i ran a low temp one for 2 years and it sat at 71 deg when driving. Using lots of petrol decided to replace the stat for a geniune 80 deg one and now sits at 81 deg. So change your stat and job should be a goodun.