AAH 2.8v6 engine loud tapping noise

Posted: Mon May 25, 2015 5:50 pm

Hi everyone, this issue is likely to have come up many times before but I couldn't find an answer on the forum so am posting a new query. I have a 98 cabby 2.8v6 AAH engine with auto box. I had the cambelt, water pump and a full service done about a year ago and I've done less than 400 miles since it was serviced. I'm planning to her back up and running in time for summer and started her up today to keep the oily bits moving and was suprised to hear a loud tappetty noise coming from the drivers side of the engine.

Before I parked up last October the car was running sweet and has only covered 80k miles in its life. I had to jump start the battery as it was totally flat and checked the oil and it was as clean as a whistle and full. Temp, oil gauges read normal and I'm thinking its likely to be the Tappets that are causing the noise. I let the car run for 10-15 mins to warm up and revved the engine but the noise remained. Not sure what had caused this issue may be due to the car being laid idle for 7 months. I'm keen to get the car sorted in time for audi in the park in August so would appreciate some advice from more mechanically minded forum members.

Thanks in advance Nomadic1

Posted: Tue May 26, 2015 7:52 am

It's quite common on these engines. You'll find that the oil has drained out of one or more of the hydraulic lifters. Try taking it for a drive, it might be fine with regular use. If not it's not all that expensive to replace them and I'd recommend replacing the check valves in the cylinder heads at the same time to ensure the issue isn't related to the oil draining from the cylinder heads.

One thing I will say is that mine had always sounded tappety when started but would quieten down and was like that for years until one day a lifer failed and it sounded horrendous all the time, I replaced all the lifters and it was perfect for 2 weeks. It then went back to being tappety all the time although nowhere near as bad as it had been, I've never investigated further and just lived with it so can't be sure of the cause but suspect the lifters just aren't great quality.

Posted: Tue May 26, 2015 7:34 pm

Thanks for the reply A80QAAH, I've done some research and also established the problem could be caused by a blocked or loose oil suction pipe in the sump or issues with the oil pump itself. I'll try running the car in a few weeks once it's back on the road and will post the solution to this irritating problem.

Thanks again!

Nomadic1

Posted: Sat May 30, 2015 7:38 am

unlikely, if it was running ok before. you just need to let it run until it clears itself, can be up to 15 or 20 mins apparently. which is not going to happen if you didnt know that, obviously..

first time I heard it, it scared me too, but after watching the guys at Audi not caring in the least starting it up (after a key loss meaning trucking the car to them) and was told by the technician "perfectly normal after a long stand"

Posted: Sat May 30, 2015 8:45 am

Thanks for the replies to my post. I let the car run for almost 25mins (10 mins longer than my previous attempt) and within that time the tappety noise had gone completely:-) tried it again two days later and no noise! I'll continue to run and warm the car a couple of times per week until she's back on the road in mid June. Next job fixing remote central locking on the car!

Posted: Sat May 30, 2015 9:05 am

yea there you go. it doesn't sound "perfectly normal" at all does it, but it is.

so unless you know, you turn it off and call a mechanic not let it run until it either destructs or cures itself lol

I dread to think what mine is going to sound like when i start it up and all 12 of them are doing it (full top end rebuild currently)

Camped on the site Joined: May 01, 2011 Posts: 314

Check valves in the heads you say? Where are they located and are they hard to replace? I have a Tappet rattle that goes away not long after starting but if the oil is not sitting around in the head I'd prefer to fix it too !