RS2 Overheating problem

[BosnianS2]

Hello Friends,

I currently live in Germany and have purchase about 2 months ago 1994 RS2. Two weekends ago I was on the way to friends house to do timing belt service on my RS2 when after attempting to accelerate aggressively engine blew a head gasket and naturally it overheated. I took the head off, had it checked for flatness, however it needed to be machined and that was done. I assembled the head back on the motor and replaced also following:

Timing belt (Audi original)
Water pump (Audi original)
Thermostat (very good German aftermarket brand)
After run temperature switch
cooling fan temperature switch on radiator
Engine temperature sensor (on back of cylinder head)
All gaskets (Victor Reinz)
New cylinder head bolts (Victor Reinz)

After assembly everything seems to be fine as long as car is driven normally and then as soon as engine sees little boost it starts to over heat until coolant starts to boil. Cooling fan seem to operate properly but it does not seem to be able to cool the engine down because. Both fan speeds work. I have spend whole day today trying to figure this problem out and no luck, therefore i would appreciate if some of you guys can give me little input. I almost suspect cracked head, but i never heard of 5 Cyl. head to be cracked before.

Any help would be appreciated as I am totally out of ideas.

Thanks

[spink]

5 cylinder heads do crack I am afraid,are the coolant pipes getting hard when engine is hot?

[A80Avant]

check if the radiator is half blocked with old coagulated coolant.

i had a similar problem and the car had a radiator which was half blocked

[BosnianS2]

The hoses get hard when engine is hot but not extremely which I think is normal. But if these heads are know to crack (which i did not honestly know) then maybe i may have a problem because problem seems to show up only if i give enough gas that boost starts to build up. I will check the radiator also, but I have to say while replacing head gasket everything seem to be pretty clean.

Thank you guys for input

[spink]

You can try this,kits are quite cheap (20-30 euros)

http://www.youtube.com/watch?v=oYQHkWVULn8

http://www.youtube.com/watch?v=ypIEfSIyZDQ&NR=1

[popdemonic]

well,i'd say just starting from something basically.Have you ever checked if your reservoir cap holding the pressure?
if it broke,your car will be overheated.check your T-stat if it's correct orientation once you installed it.bad viscous
coupling is most likely the culprit if you never been replaced it.We just can't look at it while it's working and tell
if it's fully working.clogged up Radiator is also good time to be checked if the ex-owner used the tap water in the
cooling system.you stated if you give it a boost and car overheated.it looks like your cooling system is insufficient for
additional heat builds up.i'd start with something very easy.reservoir cap,aux fan speed low or hi,T-stat orientation,
viscous coupling fan,readitor.i had been experienced this issue for a foe months and it ended up with the freaky
coolant temp gauge.I still have not get it fixed since it 's the wiring issue.I used the aftermarket gauge ta[ on the console instead.

[prj]

Might be stupid question, but did you bleed your coolant system properly when you restarted the engine?

[BosnianS2]

I want to start by saying thanks to your replies and there are no stupid questions, so there
One of you guys are talking about viscous clutch and I thing that you have this car mistaken for URs4, they have viscous fan clutch but RS2 don't, RS2 has only electric fan.
I also played around bleeding system for hours , but it still overheated so I am pretty certain that it is not air in system. What really puzzles me is the fact that if i drive it where there is no boost generated or very little temperature seems to be fine, therefore i almost believe that boost somehow ends up in cooling system and car starts to overheat. I am really suspecting cracked head but it will have to wait until next weekend and I will try to to cylinder leak down test and see if i find anything.

I really appreciate your guys help

[popdemonic]

I want to start by saying thanks to your replies and there are no stupid questions, so there
One of you guys are talking about viscous clutch and I thing that you have this car mistaken for URs4, they have viscous fan clutch but RS2 don't, RS2 has only electric fan.
I also played around bleeding system for hours , but it still overheated so I am pretty certain that it is not air in system. What really puzzles me is the fact that if i drive it where there is no boost generated or very little temperature seems to be fine, therefore i almost believe that boost somehow ends up in cooling system and car starts to overheat. I am really suspecting cracked head but it will have to wait until next weekend and I will try to to cylinder leak down test and see if i find anything.

I really appreciate your guys help

Oops! I totally forget Your car is RS2'd Car.You didn't pressure test on your head once you had it off for resurface?everytime when i remove the head,i'll send it for the machinery shop for pressure test.some hairline cracks is difficult to be noticed.
let me know buddy if you sorted it out.

[simon20vq]

I have bleed many cars and non compare to the s2/rs2 for being a right pain in the ***! I would double check for an air lock in the system. If the head was cracked it would not make any difference if you ran boost or not as long as it was up to full temp. Have you fit the thermostate in the right way? Or remove it completely and see if things are any different.

[BosnianS2]

Hmmm, so these cars are pain in but to bleed? Well there is still hope then, cause it would really suck if the head is cracked. I also wanted to ask can you give me more details about thermostat being in the right way? I know that if thermostat has small hole on the flange , that has to be oriented to 12 a clock position, but is there anything else that i am missing here?

[Billman]

it is easy to put him upside down i think!

[BLAMM0]

hi there, so my 3b engine also started to overheat, this happened after i changed the main radiator to a Nissens one, because the old one started leaking. now i get 100-110C when cruising and some boost. Tried to bleed it like 5 times now, changed the lower thermo switch for the fan, changed the main thermo switch (3 pins). the fan now blows at the second speed also, before the replacement of the radiator thermo switch, it only came up sometimes and on low speed. what else can i check? we've also changed the water pump, the thermostat, i guess we put it in the right way

[BosnianS2]

Ah you seem to be in same boat as I am, so probably as some of the guys here suggested we have airlock problem. I will work on my car this weekend and if i come up with something I will write it up here. However I realized that my new thermostat does not have small opening like original from Audi, so I am thinking i should remove it and drill small hole in flange area, and orient it at 12 o'clock position, so hopefully this helps. Did you also put in original thermostat or aftermarket?

[BLAMM0]

by the way, i have disconnected the auxiliary radiator, now only the main radiator has remained, will check tomorrow, maybe i have something not tightened correctly, but guess not. water pump original, metal blades. thermostat also for audi, by part number, if you drill that hole, take a picture or something, that would be helpfull getting crazy with this, by the way, unplugged the hose from heater matrix, coolant is flowing out - no air.
tommorow i'm making a fan bypass switch.