3B strange cooling issues :(

[gad3n]

hi guys, sorry that my first post is a problem ... i recently got my S2-3B in mint condition then drove it a few days and took the engine out did a complete engine rebuild with forged rods and all best components.

Engine started from first time and works like a charm no noises no smoke .. just perfect... then temperature goes to 90 fans kick in and all is fine. But when i take it for a drive on the highway temp slowly starts to drop to a little over 50 degrees.
Thermostat was my first guess - changed 4 - one Behr two Wahler and one unknown and problem persists. Changed all temp sensors - no change

When i pull over on the highway and touch the hose from the thermostat to the lower part of the radiator it is completely cold so thermostat is closed so how is the car overcooling ?

please help i really like this car but is driving me nuts

Best regards - Hristo, Bulgaria

[Drummer87]

My car does this, fan kicks in around 90. When at those temps take it for a nice cruise like on a motorway to bring the temp back down.

It's all down to outside temperature and how much flow you got going into the bay. Also with the aux rad taken off my car I see big drops in temp when driving.

[gad3n]

when the car was bought from germany it came to my country with driver ... 1500km. temp was at 90 degrees all the time ... something happened after that

[Drummer87]

Strange I thought these cars go up and down with temp read outs depending on how your driving it, where and when. Also outside temps. Maybe the stat was stuck

[gad3n]

outside temp is 12 degrees right now ... termostat is completely shut and car still sowly cools down

[rs200]

audi s2,rs2,200 20v have same "problem". s4&s6 don't have it.
this is normal. don't worry

acept one thing. radiator must be hot everywhere, try to put hand on it when they get 90C. must be hot . if it's not, than your radiator is bad. must be changed.
do you have 2 radiators? big with fan and small behind the grill?
both of them must be hot !

[gad3n]

car has two radiators both brand new and original .. both get hot ... just didn't think that this temperature drop is normal otherwise the car is awesome it has completely stock look and interior just KW inox adjustables

this is how it came ... with the dirty messy engine bay ... now all is shiny


thanks for your opinion it is a bit of relief

[Tony Stark]

Where exactly is the needle sitting? Is it a genuine thermostat?


First mark above 50 is 85 degrees.

Have a read of this thread and see post #15 here: http://www.s2forum.com/forum/showthr...ht=needles+sit

hth

[stocious]

Is the wiring at the plug of the MFTS on the water manifold under intake ok, mine were brittle and broke with a touch, coolant gauge had mind of own till I fixed it! Also I think I read on here that the MFTS should be shrouded with rubber pipe ect.. To keep moving air from cooling sensor! Seen as the engine was out and wiring was disturbed is check the MFTS to be sure

[UrS4boy]

MFTS Info

Is the wiring at the plug of the MFTS on the water manifold under intake ok, mine were brittle and broke with a touch, coolant gauge had mind of own till I fixed it! Also I think I read on here that the MFTS should be shrouded with rubber pipe ect.. To keep moving air from cooling sensor! Seen as the engine was out and wiring was disturbed is check the MFTS to be sure

Agree that the MFTS might be the issue, i.e. a perceived drop in temps when, in fact, all it well. The rubber boot that goes over the MFTS is not just there for looks, it is there to stop the MFTS from being air cooled.

Here is some MFTS info for gad3n to read: http://forums.quattroworld.com/s4s6/msgs/22584.phtml

[driftin jo]

Do you have access to vag com ? If so just see what the ECU is seeing when the gauge is reading low, it uses the temp sender on the back of the head so is not affected by gauge sender.

[gad3n]

MFTS was replaced and wiring fixed .. that didn't changed nothing

post 15 here http://www.s2forum.com/forum/showthr...ht=needles+sit explains a lot ... neddle is on 90 degrees on idle and if it moves a little after it fan kicks in and back to 90 ... on highway drops to where is marked 87 degrees on picture ... thermostat has 87degrees marked on it

all my previous cars were spot on 90 degrees that is why i was worried

next thing to fix is annoying brake warning (Brems licht goes on and off all the time and beeps)

i even wrapped MTFS with heat wrap to see if it changes something but no effect

i will hook it to vagcom tomorrow when i get my cable ( borrowed it to a friend )

[UrS4boy]

MFTS was replaced and wiring fixed .. that didn't changed nothing

Does your S2 happen to have the automatic climate control?

[gad3n]

Yes it have retro climatronic

Sent from my GT-I9100 using Tapatalk 2

[UrS4boy]

Yes it have retro climatronic

Well, if you set it up properly, with temp sensor in the coolant line to the heater core, then you can access Ch.51 of the Climate Control Diagnostics which is the coolant temp.

http://12v.org/urs/Climate%20Control%20Channels%20&%20Codes.pdf

General AAN Thermostat Info (might be of some help):

http://forums.quattroworld.com/s4s6/msgs/21881.phtml