Friday, December 20, 2013

Audi A8 Crankcase breather Hose Improvised Replacement

I bought a car at the Auto Auction on Thursday.  It's a 1999 Audi A8.  It's a lot of car, but it spoke to me and I had to have it.  Unfortunately it has a few issues.

I've got a number of trouble codes that point to a vacuum leak.  I pulled off the engine covers and started poking around.  I found that the crankcase breather hose between the cylinder heads has taken on the consistency and structural integrity of an overcooked spaghetti noodle.
The Audi Part number is [URL=""]077-103-221-E[/URL].  The local dealer price is $180.00 and has to be shipped in.  Even worse, it's the weekend before Christmas, so the correct replacement part is at least 7 days away.  I'd like to fix it before then. 

I've discovered that Auto-Zone Heater Hose Part number 80416 "Dayco/Hose (Lower)" can be trimmed to an acceptable fit for replacement.  It costs $10.99.  I was originally concerned that the hose would collapse under vacuum, but in initial testing that has not been an issue.  If it becomes a problem I will insert a length of 1/2" ID Convoluted Tubing (the stuff you use to organize wires into neat bundles) in the long section.

To install it:
  • Remove the engine covers over the valve covers with 4 5mm cap head allen screws.
  • Remove the 4 cap head allen screws for the center engine cover.
  • Remove the two worm clamps, one near the oil filler cap, one on the passenger cylinder head. 
  • Pull the hose off.  If it's rotted like mine it will come off in pieces.
  • Trim ~2 inches off the short end of the AutoZone part.
  • Test fit it on the oil filler cap end.
  • Test and Trim the  appropriate length from the passenger cylinder head end of the hose.
  • Install the hose with new worm clamps  Note: These are a -tight- fit.  I could not use the OE clamps and had to use flat clamps from AutoZone.  I had to push them into place with a screwdriver.
  • Tighten up the hose clamps.
  • Replace the engine covers.

Here is a terrible picture of the completed installation.

I hope this helps someone else.


Anonymous said...

Nice!I have 1999 audi a8 quattro also. I took off the covers last night to change a few ignition packs and found my vent hose to be disintegrating and with a large hole in it. I will try your version of replacement. Did you notice anything different after you changed it? my email is

Elizabeth Greene said...

Yes, after changing it the engine went from 12 trouble codes (including misfires on every cylinder and a system running too lean error) to 1.

I'm happy with the repair on the front hose, it works great. The rear two hoses don't really fit right, and I would prefer to have the correct parts for them. The cheapest I was able to find them was around $85 each. I'm hesitant to spend that unless forced.