Audi Coupe Quattro 2.3 20V - Czech Republic

[Tom_]

I bought it from a regular parts shop, but i can't find any ticket so I can't put it back. It's not damaged noir was installed incorrectly, it's just loose.

edit: what is the part number? Thanks

[Tom_]

I fixed the leaking seal around the water manifold with some TOP GASKET thing from RETECH. It looks like some RTV sealant. Looks like it seals at this moment hopefully, It will stay like that for another 20 years
Have to buy a new master clutch cylinder. There are a ton of manufacturers. Previous leaking ones was TRW, so now considering the Sachs master cylinder as I already have Sachs slave cylinder.
Any experience with any master cylinder brand?

[Tractor Dave]

Sachs were oe supplier for the slave. Very good quality. Just make sure you are buying from a good source.

[Tom_]

Not sure about that supplier. My std supplier doesn't have this on offer.
Supplier have Brembo, NK, FEBI, Delphi, SAMKO

Edit: I was thinking about that leaking clutch cylinder and I decided to make a thread there and put some banjo fitting with the bolt. I think it will be the best option and, otherwise the cylinder wont leak, so it will be useful at the end of the day.

[Tom_]

I will buy a new clutch master cylinder. The thread can't be made there because of the inner undercut.

I also noticed that the bottom half of the rad is ice cold and the hose from the rad and thermostat is also ice cold, even though the engine is around 100 C.

Edit: the bottom part of the rad is now hot and also the pipe is hot. I drilled a small hole to a thermostat to prevent any stuck bubble there. Maybe it helps maybe not...maybe the new flush-out helps the system, but now it seems to be ok.
Also, get a new Brembo master clutch cylinder, hopefully, it wont leak

[Tom_]

The Brembo clutch master cylinder is fitted, no leaks so far, so at least one good piece of news.
The really bad news is the diesel engine block was welded back then because of support for the head gasket and yesterday I noticed there is a coolant leak from the spot where the welder welded that small piece.
I found a picture of that crack. I didn't notice back then when I assembled the engine There was a small crack and more to say, the welder didn't weld that spot so now the tiny amount of coolant goes around the crackdown. I don't blame anyone, I should noticed that back then, but now unfortunately it's a project stopper as I don't have any power left to remove the engine and repair it as I don't drive the car yet
I have to take some time and step back from this project and think about what to do next, as this is frustrating

I was thinking of using some coolant Seal, but haven't experience with that, and not sure if it helps or could possibly cause another problem. Any experience with this type of product? Would it help?

[K Simmonds]

I used K-Seal to fix a minor head-gasket leak on my last 16V MK2 GTI, it worked really very well and held for years of hard use without any issue's, even after I'd changed the coolant.

I wouldn't normally recommend using it on an S2 but given the KR 16V motor is basically a four pot 7A engine I can't see as you have anything to loose.

[Tom_]

Thanks mate, I appreciate it.. You are right; the KR engine has a similar design as our 5 cyl, which is only smaller. So I will try that K seal, hopefully, it will work. Did you change coolant after it was sealed?

[K Simmonds]

That's right stuff, I added it to nearly new existing VAG Orange coolant and left it in the system for at least two years, it didn't cause any problems and worked almost instantly.

A couple of years later I dropped the coolant out to change the radiator as it was 20+ years old and rotting from the outside and generally damaged.

I then fitted a new radiator and reused roughly half the Orange coolant with K-Seal in I'd dropped out as it was only a couple of years old and I didn't want the head-gasket to start leaking again...

I topped the system up with neat coolant to make up for the stuff lost whilst taking the old radiator off and flushing the entire system out with fresh water from a hose pipe while I had the chance. I seem to recall I even removed the thermostat to make sure everything was clear.

I then sold the car a year or so latter and the new owner never complained of any problems.

I tend to use neat or nearly neat coolant in my own cars as it has corrosion inhibitors in it which I can't see as a bad thing plus it has a higher boiling point than water.

[Tom_]

Thanks...I ordered that small 236ml bottle. I think it will be plenty enough as it's usable for around 23 liters of coolant, so maybe I will put only half of the bottle and if it helps?
I'm a little worried that it won't clog the thermostat or some part of the refrigerator or heater. I used a diluted mixture of coolant/distilled water to -30 degrees celsisus.

[K Simmonds]

I'd use the whole one of those small bottles for that fault in your block, you don't want to have keep trying.

I'd want to give the first shot every chance it can to work ASAP and higher the concentration of the stuff is in your coolant more chance it has of working fast.

I honestly wouldn't worry about it clogging anything else, if it didn't do it to my 1986 MK2 16V in two years which was still on it's original heater matrix when I used it I can't see it causing it problems in a system that holds at least another liter or so of coolant which should be at least 50% for -30C.

A MK2 16V barely holds 5 liters and a 7A/S2 with the Aux radiator still fitted is closer to 7 liters.

When I dropped my 75% plus strength coolant out after a couple years and flushed the entire system in both directions the only dirty coolant came out when I back flushed the heater matrix and that wasn't K-Seal just a bit very dark brown filth which I'd expect on any car of that age.

Can you run the car up to full operating temperature currently as I know you have colder winters than we do where you are, and do you have the Aux radiator? It works best if you can get the coolant up to running temperature quickly and keep it running for a while.

If it works and your worried you can always change the coolant in six months.

[Tom_]

I can't drive the car as it on stands, and I don't have that AUX rad anymore, but the car will get up to 98 Celcius with no problems. The stationary idling isn't good for cooling, so it will get to the temp . How long should be on that temp? 5mins at least?

[K Simmonds]

Am guessing the car's probably inside then, as long as you've got decent ventilation for the exhaust and the radiator cooling fan is working properly it shouldn't get too hot to be safe. Have the the heater in the car on full heat with the blower motor on flat out once it's up to operating temp to help with cooling. Keep the blower motor off until the car is nearing at full operating temp so it warms up faster.

Personally I'd like to give it 20 mins at operating temperature to give it every chance of working.

If the engines freshly built what oil is in there currently, are you still at the breaking in stage?

Do you know what the AFR is once it come's off the enrichment cycle with no load? As bore washing a freshly built engine must be avoided at all costs.

[jbrentd]

Hoping that K-Seal will work its magic on the pesky leak!

[Tom_]

Yes, its in breaking stage and there is amsoil breaking oil.
Lambda is 1 (14,7:1). The car is in the garage but at the door side, and i have always open doors to keep venting the exhaust fumes.
the problem on idling is that after the oil gets up to temp 70 deg its quite thin and the pressure on idle is around 1-1,2 bar.

thanks Brent, i hope so