1991 Audi Coupe Quattro Primary Radiator Replacement Woes
I took the original aluminum primary radiator to a local shop for testing, and I was told it is junk due to an internal leak. I had a heck of a time finding the correct radiator. These do NOT fit:
Silla 9998A - the dimensions appeared to be right on, and it was a great price! The unit that came was way wrong, intended for an Audi 80 I think.
Silla P1090 - the catalogs say it will fit, but it too is wrong!
My local Schuck's (Checker) Auto Parts guy surprised the heck out of me by finding this - US$150 and a Lifetime Warranty! The third time was a charm and this one fit fine: Ready-Rad 431256 at CSK Auto It has plastic end tanks and a copper/ brass core. All these aftermarket rads are Chinese made. They seem to have acceptable quality, and they are cheap.
Compare the Audi aluminum radiator to the Ready Rad 431256.
The Audi rad uses floating brackets for attaching the plastic fan shroud and inlet cowling.
The Ready Rad uses fixed nuts brazed in place on the core sides. I had to slot the plastic side cowl (the piece that runs past the hydraulic pump) holes about 3/16 inch to get them to line up properly.
You do NOT have to remove the fan and all the plastic to change the radiator! This view looking down at the fan and shroud shows the lower radiator rubber mount unscrewed and lying loose, trapped between the steel support bracket and the lower front plastic piece.
Close-up - this is the key to removing the rad without disturbing the fan and side cowl. Once all the other rad supports are removed, lift the rad about an inch and unscrew the lower mount from the bottom of the rad and let it lie in place. This method works great and saves a lot of time and busted knuckles!
Since the secondary radiator was completely trashed, and a replacement is around US$300, I decided to bypass it completely as many CQ owners have done.
I used a 1 inch alloy plug (Plug, 1" w/ Retaining Nipple) from 034 Motorsport to block the three way hose and secured it with an aircraft Adel clamp and stainless machine screw.....
...and also the top fitting on the new rad,
I added all new hoses (except for the firewall heater hoses) and also a 1/4 inch brass ball valve for a quick drain.. I flushed the system four times to remove the green Prestone and re-serviced with Pentosis Blue. All better!
Original article can be found here
