This is an update and FYI to my cooling line thread post.

Here completion of the repair. I did not use a machine shop. I bought two- 5/8"X4" aluminum tubes with .065 wall thickness. I also bought two 3/4"X1-3/4" aluminum tubes with .065 wall thickness. I then sanded down 1-3/4" of the 5/8" tubes just enough for them to slide into the 3/4" tubes. I wanted as snug a fit as possible. I then sanded down the rest of the 5/8" tubes (2-1/4") enough to slide them into the cutoff portion of the heater core nipples. I wanted them to slide in comfortably. When installing them I used JB Weld.

The hard part was taking off .03-.035" off the tubes in order to slide them in, not having a lathe. May seem like a little amount but to do it evenly was tedious. I accomplished this but using a cordless drill and spinning the tubes in the sandpaper.

So far no leaks. The inside diameter of the hose and the outside diameter of the tube is 1.2mm different. I am using a worm clamp and the original clamp and so far no leaks. If it starts to leak I will increase the diameter of the nipple (which I may do anyway) by wrapping it with aluminum foil tape (with a heat spec of >100 degrees C). This will make the hose slide on tighter.

Here are some pics.

 

Damn I could have used this when I replaced my entire core because the inlet/outlet ports disintegrated just like yours.

 

I had the pipe inside the inlet hose crumble on me.
I hacksawed the rough end off where the corrosion started and pushed back the rubber grommit/seal/flange for the hose/firewall.

I found there's more than enough heater core tube under there to reconnect the heater hose to.
Maybe I should have swapped inlet/ outlet hoses too, its only the inlet tube that corroded.

 

This was a great fix! I tried to post pictures of my daughter's A4 repair but the site didn't let me. When I used the JB Weld, I put a bead around the circumference about an inch away from the edge of the smaller pipe so when I pushed it into the larger pipe, the JB Weld will seal any abnormalities caused by the sanding. Do one side at a time (i.e., assemble the pipe first with the JB Weld, let it cure; then apply another bead on the side that will be inserted into the heater core inlet). Don't apply JB Weld on the ends of the smaller pipe. No leaks for two years.

Pipes were not too difficult to find. Found a place based in So. California on line that was very reasonable; I think I paid less than $20 maybe even a lot less than that. Use a drill and emery cloth to reduce the diameter of the smaller pipe. Using two washers, two rubber stoppers, a long threaded rod, and two nylock nuts, I was able to use the drill to reduce the diameter evenly.

John
1998 Audi A4 2.8L

 

That is great... Those that I did above did not fit perfect (both the end inserted and the end that the hoses went on). This was because the pipes I got from a local supplier were off. Could not tell till the did not work correctly. So I drew a schematic drawing of the exact sizes I needed and I included a hose barb on my drawing for the end (to match the original plastic ends. I found someone on ebay and he charged me $40 to machine them to exact size including the hose barb (not necessary to do any additional work on them other than install). Worked perfectly and no leaks that I can see. Had a few leaks in the beginning but not related to the fix - it was the plastic ends that were further in. No way to insert anything that far in so I used JB weld to fix them and so far so good.

 

I have this issue currently. Would you suggest drilling a small bleeder hole? There is a hole in the hose specifically for this. I know any air in the system will collect in the heater core reducing heat.
Also looking to do this possibly with copper tube? (house pipe) Easier to come by where I'm at.

 

I did not drill a whole in the tube since it was already in the Heater Hose. As far as copper tube I would do some research to be sure that there would not be any chemical reaction from the coolant or other metals in the car.

 

Bumping an old thread... Any chance this still available on ebay or your have the details on who did it for you? I have been searching but so far no luck finding any audi kits.

I am in the same situation with broken heater core connections and winter is coming. Fortunately I still have a fairly good core pipe section up to the hose stop bump and then have a 1/4" or so before the damage. It can work if I connect up the pipes but not ideal as I expect it will break more in the future.

I was starting to draw out similar plans and what I believe I would need is about 3 inches (75mm) of length at OD diameter of 5/8" 0.625 (15.8mm) to slide in toward the heater core with a 1.5 inches (40mm) of 3/4" 0.750 (19mm) OD section for the rubber coolant hoses to connect to towards the engine compartment.

Another option I was thinking about would be to purchase a heater core bypass kit from dorman and see if I could sand down the 5/8 sections of the adapters to slide in to the pipe. ICT Billet has an aluminum adapter for 3/4 to 5/8 but it is barbed on both sides and is a bit on the short side.. expecting would need to file it down somehow to fit in the heater core pipe as the barbs are likely greater than 0.625 OD on the 5/8 side so it wouldn't slide in without modification?

 

Found it. The guy I bought this off of on ebay (special order) custom made it for me from my specs. The name of his ebay account is Asheville Metalworx. I checked and he is still on ebay. I would message him.

 

Thank You!