When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So the other day my wife noticed some pink fluid under the car in her parking spot..... Yep that's antifreeze. I did some investigating and found the nipple on the top of the expansion tank had a hairline crack on it. Just enough for the fluid to leak out of. I tried just gluing it with fiberglass epoxy (surfboard repair product) but that didn't work. So the next step was to cut off the nipple, drill out the hole, and I installed a brass fitting. I covered it with Plastic JB weld epoxy. So far no leaks. The new tank is on its way but if anyone else has this problem this is probably the only way to temporarily fix your leak.
I forgot to take before pictures just a final one.
Very good. Audi actually had a factory fix for their 1980's radiators where a similar nipple was prone to cracking. A brass fitting was tapped into place and an epoxy-type material was added to seal the joint. It held several years for me. On the expansion tank, I'd use it for a few days until a new tank was delivered.
Expansion tank failure is one of those Audi-isms that have been around for a long long time.
The Brass nipple fix for radiators was a temporary one at best. Glad to hear you got a few more years out of it. The plastic end tanks used on their radiators started to get brittle after about 10-12 years and progressively got worse until they failed completely.
I suppose this thread could be also titled "The joys of owning an older Audi".
It held until the radiator failed where the plastic, I mean "Engineering Grade Composites" side of the radiator separated from the aluminum when the vehicle was about 13 years old. Yes, replaced it with a new genuine radiator.
I just finished replacing mine...should have been at most 30 minutes to do. But, as my luck would have it, one of the threaded sleeves that one of the two top 10mm bolts screw into was broke, so I couldn't remove the bolt even after holding the threaded end with vise grips or anything else I tried. Cut it off, replaced the tank. I guess after 8yrs plastic breaks down between the heating up and cooling down. Found mine for $58 from partsgeek, took 2 days to come in. Good luck!
I did exactly the same thing... Mine started leaking again around the threads after a few days. The JB weld doesn't seem to bond well to the tank. It got me through the short term until I bit the bullet to buy a new one.
The nipple might be a bit more difficult to tackle, but I have over 10k+ miles on the JB weld repair on my tank, although the crack is on the side of the tank. JB Weld is an amazing product. It's rated at 500*F so that's way more than what it will experience.
With an adhesive that strong, I would like to point out that poor surface preparation is more likely to cause failure rather than the adhesive itself.
Once the tanks start to crack it is time for a new tank. First the nipple goes, then the larger hose fitting at the bottom usually followed by the low coolant sensor. I just don't mess around with repairing the tank. I just buy a new one and I am good for another 10+ years. Adding a brass nipple is good for a quick fix while waiting for a new tank, but that is it.
One of my expansion tank connectors had cracked and crumbled after 11 years ('09 A8L 4.2L). I just wanted to provide some pictures of what the bottom connections look like to help others who are going to do the job. There are three bolts to remove, 2 at top, and 1 next to engine. There is large hose and the connector for the level sensor at the bottom, which are accessible once the bolts are up and you wiggle it out an inch or two. Most of the time went into sucking out old coolant, then straining it to put it back in, and of course ... fishing out a socket and extension that fell into engine bay.
Last edited by Sci-fi_Wasabi; 10-09-2020 at 04:38 AM.
Just went through this. I noticed I had a slow leak from a cracked hose nipple that obviously wasn’t going to get any better. My local dealer had one in stock for $100 which was fair for the OEM part.
Despite it having a 2017 manufacturing date, the new part still had G12 (coolant type) stamped on it which amused me, despite that stuff being discontinued 15 years ago.
Old leaking bottle:
Anyway, I noticed that my car had the TSB done where they put Silicate cartridges into the coolant bottle. Supposedly to prevent heater matrix scaling which the G12 silicate heavy coolant protected against. As G12 was outlawed for environmental reasons and they went to G12+/G12++/G13 low/silicate free coolant, cars designed for straight G12 still had to have a source of silicates in the coolant system. So the workaround to get the necessary silicates into the coolant when doing a change with the newer silicate free coolants was to pop these silicate cartridges into the coolant bottle. Supposedly they’ll last the life of the car and don’t need to be changed again, even with subsequent coolant flushes.
This was apparently only an issue for early cars as they modified the heater matrix internal coating so that silicate free coolant could be used without problems.
Suffice to say, I fished the 4 cartridges out and will put them in the replacement bottle. I could buy new, but as they’re supposedly lifetime, and running in the same coolant as they came out of, it didn’t make sense to spend another $50 on replacements.
07-18-2015, 08:23 AM
expansion tank quick fix DIY
Mine started leaking again around the threads after a few days. The JB weld doesn't seem to bond well to the tank. It got me through the short term until I bit the bullet to buy a new one.
