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2002 Passat, 1.8t GLS Wagon, 160,000 + miles
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Discussion Starter · #1 ·
Hello, Passat Owners. I am new to this forum but have had my 2002 Passat 1.8t GLS Wagon since 2008. I am starting to do as much of my own maintenance/mechanic work as possible to afford to keep it running. I am reaching out tonight for assistance with a noticeable intermittent tapping/knocking sound in my engine bay. I have listened to many engine noises on Youtube and read some posts here on PW but nothing sounds quite like what I am hearing from mine. It only makes this noise when it is warm and then, sometimes, it is quite loud. If I roll my window down, I can hear it when the car is parked. Revving the engine slightly does not stop the noise.

I took it to a local German shop for a diagnosis and they said they tracked it down to the alternator. They recommended replacing the alternator and the belt tensioners (both) for a cost of about $1400. I performed all the replacements myself with great results (Bosch alternator; Conti belt and tensioner kit), but the engine noise is still there. Quite disappointed to say the least. I am posting a video of the sound below to help give the best idea possible. I am still driving the car, but am a little worried to keep doing this with the noise. I have not noticed any symptoms in how the car feels or runs since the noise began. Not sure when it started, but would guess within six months. Car has 163,000 miles. Timing belt, water pump, etc replaced at 137,000. Oil changed a couple hundred miles ago and the oil level is good. Always synthetic.

Any ideas/thoughts would be greatly appreciated. Feel free to ask questions if there is something that needs more clarification.

Thanks!

Here is the video of the engine noise: https://youtu.be/aPPP-Nd0aow
 

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Not being there and seeing the whole thing with the noise is a bit of a disadvantage, but I'll say this, I would not run that engine anymore!
To me, that sounds like an internal noise and serious at that. Something is loose somewhere. Bad connecting rod or something in the valve train.
When you changed the oil, what did it look like? Anything that resembled metallic glitter in the oil or even pieces of metal?
I'd first peel off that valve cover and look at the valve train.

I gotta say it.
You need to find a different mechanic ASAP. Anybody that says the alternator and tensioner are the cause of that noise, hasn't a clue.
You should find that mechanic, rip the wrench out of hands and hit him upside the head with it and tell him your welcome. Sheesh.
 
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I agree, it sounds like something bouncing around under the valve cover. I would also pull the timing belt covers if you can't find anything wrong under the valve cover. You can try a mechanic's stethoscope (or a screw driver to your ear) to pinpoint the noise.
 

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I agree, it sounds like something bouncing around under the valve cover. I would also pull the timing belt covers if you can't find anything wrong under the valve cover. You can try a mechanic's stethoscope (or a screw driver to your ear) to pinpoint the noise.
Ha, I thought of that also, that is a pretty solid clunking noise though. Can't imagine what's flopping around by the cams to make that kind of noise. The frequency of the noise seems like it could be related to the timing because of how slow it's spinning at idle.
To me, that almost sounds like a rod/crank bearing that is gone or a thrust washer that has slipped out of place. Eerily similar to a completely worn out set of crankshaft bearings I had on one of my previous cars.
Obviously only speculation at this point.
 

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2002 Passat, 1.8t GLS Wagon, 160,000 + miles
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Discussion Starter · #5 ·
Not being there and seeing the whole thing with the noise is a bit of a disadvantage, but I'll say this, I would not run that engine anymore!
To me, that sounds like an internal noise and serious at that. Something is loose somewhere. Bad connecting rod or something in the valve train.
When you changed the oil, what did it look like? Anything that resembled metallic glitter in the oil or even pieces of metal?
I'd first peel off that valve cover and look at the valve train.

I gotta say it.
You need to find a different mechanic ASAP. Anybody that says the alternator and tensioner are the cause of that noise, hasn't a clue.
You should find that mechanic, rip the wrench out of hands and hit him upside the head with it and tell him your welcome. Sheesh.
Thanks for the reply and questions, AndreasPassat! I didn't notice anything off with the oil when I changed it--metallic glitter or shavings of any kind. Your comment about something being loose makes sense to me as it sounds like that to me too. Regarding pulling the valve cover as you recommend to have a look around, I have a question: would I need to replace the gasket when I put it back together? I replaced that gasket a few years ago but can't remember if pulling the valve cover damages the gasket.

I am pretty surprised too by the local German shop saying this was the alternator and charging me over a $100 to tell me that! I don't know much about engines, but the more I think about it, it just doesn't make sense! They are a reputable shop too!

I'll pull the valve cover and see what I find. Might be a few days before I can get to it, so stay tuned.

Thanks again!
 

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Discussion Starter · #6 ·
I agree, it sounds like something bouncing around under the valve cover. I would also pull the timing belt covers if you can't find anything wrong under the valve cover. You can try a mechanic's stethoscope (or a screw driver to your ear) to pinpoint the noise.
Hey, PZ. Thanks for the ideas. Just thinking about this: can I run the engine with the valve cover off to better see/hear the possible problem? Since I don't have a stethoscope, the screwdriver idea might work for me.

Thanks!
 

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Discussion Starter · #7 ·
Ha, I thought of that also, that is a pretty solid clunking noise though. Can't imagine what's flopping around by the cams to make that kind of noise. The frequency of the noise seems like it could be related to the timing because of how slow it's spinning at idle.
To me, that almost sounds like a rod/crank bearing that is gone or a thrust washer that has slipped out of place. Eerily similar to a completely worn out set of crankshaft bearings I had on one of my previous cars.
Obviously only speculation at this point.
Hoping this is not the case, as it sounds either very expensive/time consuming or likely the end of my Passat :cry: I'll start with the valve cover then work my way to the timing cover and see what I find.
 

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Pull the timing belt cover at the front first. You can run the engine with the top timing belt cover removed. Unless it is a new gasket (like only months old), then I would replace the valve cover gasket if removing it. No, you should not run the engine with the valve cover removed. Oil will get everywhere.
 

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I don't know much about engines...
That's fine not everybody does. Nothing wrong with not knowing about cars.
What really ruffles my feathers is these so called ASE Certified mechanics that are supposed to know a thing or two use that as a ploy to draw in unsuspecting clients and then they get robbed blind.
Whatever happened to the honesty factor?
 

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Hey, PZ. Thanks for the ideas. Just thinking about this: can I run the engine with the valve cover off to better see/hear the possible problem? Since I don't have a stethoscope, the screwdriver idea might work for me.
Thanks!
Yes, as said above, start with the upper timing belt cover. If it's not there, then go for the valve cover, but watch for oil splatter. I've seen people put cardboard on the sides and back of the head to minimize splatter, just don't let it touch the hot catalytic converter.

Hoping this is not the case, as it sounds either very expensive/time consuming or likely the end of my Passat :cry: I'll start with the valve cover then work my way to the timing cover and see what I find.
The real issue is when it goes quiet because it jammed the valve, piston, or crank. I've seen some of those engines.
 

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I would first check the timing belt tensioner pulley bearing. ( And that is not far from the mechanics diagnosis)
 

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Discussion Starter · #12 ·
Finally getting a chance to update you all on the situation with my Passat and that engine noise. After hearing your thoughts about the valve train and talking to a friend on the phone who has worked on this car before, I did the screwdriver sound test with the longest one I had (mentioned by PZ) and narrowed it down to two places. (see attached image with the valve cover on and two red circles). The part of the engine where the engine code is etched on is where the sound was the loudest. After talking to this friend (a mechanic), we thought it might be the VVT actuator and so I replaced it. Bit of a bear to get the old part out and ended up needing to buy an aluminum VVT compression tool online from 034 Motor Sports (I somehow broke the plastic one that came with the new part as many people seem to do) to complete the job. Took days as a result. Got it all back together yesterday and took it for a spin to make sure the timing hadn't somehow been altered (I checked and rechecked this before putting everything back together). Drove fine; no dash lights, etc... and the noise is exactly the same as before. 😔

So, I am back to square one. The cams looked fine when I was in there. The cam chain looked fine. The engine is pretty discolored, but imagine oil can do that over the years. Seemed a little dirty as well. I replaced the valve cover gasket as VAGguy recommended as well. Oh... found that someone had stripped the head of one of the cam seal retainer bolts previously and it would not allow me to unscrew it. Probably whoever did the timing belt the last time. Why would they (a shop) use this bolt if they damaged the head! Had to drive to the local Audi dealer (25 minutes away) to get a few new bolts just to be on the safe side. Getting that damaged bolt out was... stressful! Accidentally broke the tip of the extractor off in the bolt! Long story.

Next place seems to be the timing belt area as Tomvw mentioned. I am at a point where throwing parts at this doesn't seem to be logical anymore. The timing belt was last replaced in 2016 and not even 30,000 miles ago. Belt looked fine when I took the cover off. Hard to see much down there as the space is very narrow.

I'll add a few pictures to give a look at the engine. Noticed that cylinder 1 and 4 were wet looking under the spark plugs and the plugs themselves were a bit corroded. Ideas? Cylinder 2 and 3 were dry/seemed free from carbon buildup. Is the discoloration of the valve/cam area normal from the engine oil?

I await your feedback and thoughts. And thank you all for chiming in so quickly and honestly! This is my first time in a forum; I can see why they exist!

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Watched the video again.

I had roughly that same sound and frequency in an ATW 1.8T Passat I had a while back. It was a an extra car, so I never really looked into it much. It eventually went away without any intervention.

Under that valve cover looks a little cruddy. This is mine after 176k hard miles on 5w40 synthetic since new at 5k intervals.



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Did you put the old plugs back in or replace them?
Manual or auto trans? Mine was manual.
 

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I suggest you don't run it again until you have checked the timing belt roller bearings.
If a Tb roller bearing is making that noise, I would expect bent valves or worse very soon.
 

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Discussion Starter · #15 ·
Watched the video again.

I had roughly that same sound and frequency in an ATW 1.8T Passat I had a while back. It was a an extra car, so I never really looked into it much. It eventually went away without any intervention.

Under that valve cover looks a little cruddy. This is mine after 176k hard miles on 5w40 synthetic since new at 5k intervals.

View attachment 103357
Did you put the old plugs back in or replace them?
Manual or auto trans? Mine was manual.
Your engine looks quite a bit cleaner than mine! I was a little surprised to see so much grit in my engine, especially on the exhaust cam side. Mine is much more stained. I had an oil sludge issue with this car many years ago (very expensive to have fixed) and that might be reflected in the color of my engine being stained so much and being so gritty. The under side of the valve cover was really bad as well--cleaned it as best I could.

I put the old plugs back in for now but will plan to change them out when I figure out what this noise is. They are really spendy as well! It's an automatic transmission. I have had the fluid changed twice during ownership (I know they say it supposed to be lifetime fluid, but I have heard from others that it is a good idea to change it to prolong the transmission's life--too expensive to replace!). I love the automatic trans, but hope it continues to last.

Just curious... that sound in your other car's engine: did it get stronger over time before it resolved itself? And any memory of how long before it resolved itself?
 

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Discussion Starter · #16 ·
I suggest you don't run it again until you have checked the timing belt roller bearings.
If a Tb roller bearing is making that noise, I would expect bent valves or worse very soon.
Thanks, Tomvw! I'll try to do a screwdriver test to see if I can isolate the sound to the timing parts/roller bearing. It's sitting in the garage and I am driving my wife's car for now. Just wondering if the intermittent/non rhythmic nature of the sound and only coming on when warm fits with the more rhythmic nature I would expect from the timing parts? Nothing about this sound makes sense to me, but I guess that shouldn't be too much of a surprise as I have a lot to learn about cars/engines and how things all work together. Thanks for the recommendation. I'll let you know what I find. If it is the roller bearing, would you recommend just doing a whole timing belt component change rather than just that one part? It was last done in 2016 and about 27,000 miles ago.
Now that I am thinking... the belt seemed to be slightly forward of the teeth on the exhaust cam wheel; just slightly but it caught my attention. Hmmm...
 

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As far as I can tell from the video, that noise is consistent with a bearing about to seize and/or fly apart.
I suggest you at least do a visual check of the TB roller bearings before starting or cranking the engine again.
 

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It's probably not the case here, but the water pump in my AWM made sounds similar to that as it was going out.

I know you changed it just a few miles ago, but try your stethoscope screwdriver closer to the water pump just in case.
 

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If it's noisiest at the front, I would pull the alternator belt and a/c belt and see if the noise stops. If not, I would remove the timing belt covers and check the water pump and tension damper pulleys. Have you checked the oil pressure?
 
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Discussion Starter · #20 ·
As far as I can tell from the video, that noise is consistent with a bearing about to seize and/or fly apart.
I suggest you at least do a visual check of the TB roller bearings before starting or cranking the engine again.
Thanks for the suggestion, Tomvw. I pulled the TB cover and checked the tensioner pulley bearing and did a stethoscope test. Normal noise there. Nothing matching the knocking sound. I have been driving this car since then (about the last 1.5 months) and nothing has changed. Considering to pull the front clip off and replace the whole TB system/waterpump, but not really excited to do that if it isn't the problem.
 
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