I'm helping a friend with his 2001 Audi A4 1.8 quattro, and he's having several problems with it. When he was getting his oil changed, he said the technician showed him where a vacuum hose had come undone, and the piece that connected the two had deteriorated. I have a pic of it, it's circled in green. I looked at a vacuum diagram, and it looks like some sort of check valve. I wanted to know:

1. the purpose of this check valve
2. can I buy a universal one at auto parts store, or do I need to buy a specific one for this Audi mode;

One of the problems he's having is a nasty diesel sound. From online research it looks like it's probably an issue with his secondary injection. Could this simple check valve be the culprit?

I really appreciate the help. Thanks

[IMG]local://upfiles/24859/6AEFA5063DA446C28CFB87781C1A65B8.jpg[/IMG]

 

it's just a generic check valve, autozone or advance isn't going to have it. there are several of them within the engine bay, but they're all the same valve, you could go to the audi dealer and pay $50 for one, or get it from ECS for $28.

If the hose was completly dis-connected then that's a major vacuum break and is a pretty big issue, espically with a turbocharged engine.. If the nasty diesel sound you're refering to is the ticking noise, then it's normal, all german cars have valve-train tick.

 

Thanks for the reply. Any idea what the part number is, ow where I can find that info?

Also, the diesel sound is really bad, like when it idles, it sounds like rocks in a coffee can and you can hear it 50 feet away. I've heard it's fairly common for the secondary air pump to go out on these. I was hoping maybe just fixing this vacuum line would solve the problem.

Thanks

 

it's probaly not the pump, the secondary air pump is all ecu controlled, you'd be throwing a code if it were bad.

ecs lists the part number as #058 905 291, but if you were to show it to any VW or audi parts guy he'd know what you were talking about. they have an off-branded one for $18.95 and the genuine audi branded for $25.55

does it come and go or is it on all the time? I used to have the same kinda sound in my car it would come and go at idle, and it turned out to be a bad muffler, as the problem disappeared after I put in my milltek exhaust. The stock muffler had a bunch of soldered holes in it from the 8 years of salted roads.

 

Would this generic check valve not work?

http://www.partsamerica.com/ProductD...egoryCode=3110

I was always under the impression that a check valve was just a simple plastic valve that only allowed the air to flow one way.

 

whatever works would be okay, the only concern is the barb size which makes it difficult to find I found out in most local parts stores. Or maybe it was just me. I think it might matter if the valve is designed for the increased pressure from a turbocharged engine, but I don't know the answer on that one.

 

For the diesel sound, I would guess it's probably a leak in the exhaust headers.

 

Diesel sound could also be cam chain tensioner. Mine went and sounded like what you describe at idle, sucks for your buddy if thats it.

 

ya def sounds like Mcgovs'. the vacuum problems are easy to fix compared to the cam chain tensioner.

 

ya the cheapest I could find the tensioner anywhere was about $650 and saw them as high as $800. If he needs the tensioner he might as well do the tb, wp, ect. My mech did the maint items for cost of parts only since he was already in there forthe tensioner.