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!
EDIT 12/03/09: I answered an email asking about the best way to remove the main radiator. I am reposting my reply here:
The main radiator isn't a horrible job, but you will
probably bark some knuckles and swear a little. I decided to write up what I did
- I will post it on my webpage, but here is the first draft:
Drain the cooling system by pulling the bottom rear hose and remove the upper
plastic air inlet cover. Remove all the hoses from the rad and let the rad drip
for a while.
Remove the upper rad mount/ brace entirely from the rad and the front sheet
metal.
Remove the foam piece on the fender side of the main radiator. Underneath you
will see the outer nut for the side rubber mount, which is easy to get to with a
box end wrench. Remove the nut.
The rad fan housing is attached to the radiator sides in four places - two 6 mm
bolts per side. The inner bolts are accessible with a quarter drive ratchet from
the rear if you are patient. You can remove the single Allen bolt securing the
hydraulic hose brace (the steel bar near the fuel pressure regulator) if
you need more room. Access to that bolt is tricky because the engine mount
interferes. I replaced the looooong brace bolt with a regular (shorter)
hex bolt so I could install it easier. When the inner fan housing bolts
are out, the inner plastic air inlet duct also comes free from the rad.
The outer two fan housing bolts are easy - get to one from the top and one from
underneath the car. Remove them and you should be able to push the entire fan
housing assembly rearward a little. If you need more room you can remove the
screws for the windshield washer
reservoir and the coolant tank. The carbon canister comes free when you
lift up the coolant tank. Then you can push the plastic parts around as needed.
You don't need to disconnect any hoses. It will be MESSY under the hydraulic
tank - clean this glop and the tank exterior before reassembly.
Remove the AC condenser bolts and carefully pull the unit forward a little. The
lower part of the coils is poorly supported and may already have pulled away
from the fins like mine did. Be careful!
At this point the only thing holding in the rad is the lower mount. Crawl under
the car and remove the lower nut. Wiggle and lift up on the rad and you will be
able to get enough room for a large adjustable pliers in there - unscrew the
rubber mount from the rad. This frees up the bottom plastic inlet duct piece,
which is normally sandwiched between the rad and the mount. Leave the lower
rubber mount lying in its bracket for now. See….
http://www.spokanister.net/images_web/Audi_Coupe_Quattro/Primary_Radiator/Radiator_primary-008.jpg.
With patience and some tongue biting I was able to remove the bad rad through
the available space. Be careful with the new one to not damage the fins. My
Chinese made rad came with a drain port which has a simple rubber nipple and
hose clamp. This is a pain in the butt to work with, so I installed a 1/4
brass ball valve using 3/8
heater hoses to make servicing and flushing the system easy.
Most likely your hoses are junk. If so, you need to replace them, which takes
some time.
The small formed hose going from the bottom of the rad to the coolant tank is
expensive (US$60+ from the dealer) - I used a universal heater hose with a 90
degree bend at the top, and a reducer coupling and straight heater hose near the
bottom.
The large J shaped hose going between the top of the rad and the thermostat
housing is readily available in the aftermarket, but it most likely will NOT
fit, since it doesn't have the enlarged ID needed for the thermostat end. Use
the OEM part from the dealer!
The tri-hose from aftermarket suppliers works fine. Plug off the part of the
tri-hose going to the secondary rad IF you have removed that part, and also plug
the upper rad port to the secondary rad using a section of the old hose and a
plug. You definitely do not want to connect the unused hoses together, or they
will bypass the main radiator (not good!).
Reassembly is straightforward - replace
hose clamps and rusty hardware as needed.
Good luck.
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New dec 03, 2009 |