Hello

I am a new kid on the block , I have a 1997 Cabriolet. It has the 2.8 12v engine front wheel drive. I live in Michigan and it is quite cold here. On start up the engine sounds fine. after it idles for a few minutes this exaggerated knocking sound begins. it seems to be on the right front area of the engine. as the car warms up and or it is driven a few miles it goes away. The engine makes almost no noise at all once this scene stops. I plan to take it to a shop but wanted to get some input before someone tries to sell me a new engine. I have not had the car long, it runs smooth and is powerful. It has had the timing belt, water pump and serpentine belt done about 6 months ago. the car has 85K miles on it. My thoughts on the issue are the air pump, ac compressor or perhaps a clogged oil passage. I would appreciate any input.
I can post a video tomorrow on my next cold start if anyone thinks it would help.

 

Well 85 views and no tips.. Hmm .. Maybe I should have bought the Mustang instead ?? :/

 

Could be oil check valve failure, located in the valley pan, allowing the oil to drain out of the head. Also could be a bad lifter that takes a while to pump back up. As you suggested, could be a clogged passage. I'd put an oil cleaner in, run it and do an oil change. You have, of course, placed a long screwdriver against the valve cover and put your ear to it to confirm this is an engine noise? I don't think this is a bearing. You mentioned an air pump. Is this a California car?

 

Hello Hub

Thanks for the reply. I have done the screw driver trick, and it seem to be at the very front of the right side of the valve cover. I had the pulley or bearing thought as the car has only been driven about 250 miles since October and since it has been so bitter cold an angry pulley or bearing comes to mind. And even as it sounds like the a possible lifter consensus among those that have heard think not. But who knows and combined with my total ignorance of VW and Audi engines it really could be anything I guess. I will post the video of the noise in case you care to hear it. Thanks!

 

Ok here is the audio/visual aid. Keep on mind that it takes about 5 minutes of idle before this noise starts, and after another 10 minutes or a few miles of driving the noise stops.

 

Sounds weird. Not a tapping sound so I agree that's probably not a lifter or even oil related. I'm thinking a bad pully or the tensioner is bad. I'd get the plastic belt shields off so that I could look at them. If the front cam bearing was bad, there would be oil leaking out. Could also be the alternator, since that is right below the area you are investigating. There are two different belt routings. One is an updated route so look closely when you remove the shrouds. Go to 12v.org to see them. When the T-belt job was done, the pully should have been replaced along with the waterpump and thermostat, so the pullly and tensioner have been tinkered with. Also, if the mechanic was not knowledgeable, there could be too much play in the timing belt that the tensioner cannot compensate for and the belt is not making good contact with the pulley, and the tensioner is maxed out. In short, the T-belt would be really tight on the drivers side and loose on the passengers side. Let me know what you see.

 

well with the ongoing cold weather I decided to take it to a shop near my home just so a pro could hear the noise and give an opinion. So I got it out of the garage cold and with no warm up took it the mile to the shop and of course the noise was all but gone to a point that no opinion could be given. GRRRR

 

This morning I started the car after leaving it outside overnite. it was 11 degrees this AM. The power steering pump started making a super loud groaning noise worse if I moved the steering wheel. so I shut the car down and went to work in my trusty Saab. After work it was 41 degrees so I took all the covers off with the hopes of seeing and hearing what the problem is. Well I fired it up and the pump was silent and all the pulleys seemed to be turning freely. The fluid is at the correct level and there are no leaks that I can detect. The car has the updated belt routing . The tapping noise in my video started on time @ about 5 mins of idle time. I still can't tell where the hell it is coming from. I drove the on Saturday quite a bit and it ran fine with no noise of any kind. I am truly stumped.

 

Agreed - this is a tough one. When the prior owner had the serpentine belt routing changed to the updated routing, a different belt tensioner is required along with a different belt, to my understanding. Hopefully that was accomplished, but I'd check the part number on the tensioner to eliminate any issue there. I'm still leaning toward the alternator making the noise and I'd be tempted to remove the serpentine belt and run the engine to see. Shouldn't be a problem since the water pump is on the timing belt. The power steering pump, alternator, and AC compressor wouldn't be turning. Make sure the tensioner isn't hitting anything. I think you have two things going on here, as I hear a slight knock on the passengers side that I also hear on my 12v, which I have been reluctant to address. It's a slight tappet sound that we both would hope is a lifter instead of a worn wrist pin bearing in the rod.

 

Try to go to a service dude, is not every failure need to replace the engine. It seems to me , that some cylinder do not work. Does the car have enough power when you drive it?