Engine Knock

I recently put a new head on my engine after a timing belt failure. (http://forums.tdiclub.com/showthread.php?t=488492)

Initially, the engine sounded "fine" but I'm sure I hear a knocking that isn't supposed to be there. It gets slightly worse when the engine is fully warmed up.

Have a listen:

https://www.youtube.com/watch?v=oqaWCMJP5Aw

I think this is perhaps something in the connecting rods. Wrist-pin or maybe big end bearings.

I suppose the only way I will know for sure is to pull the head off again and remove the pistons. I wouldn't be afraid of putting new connecting rod bearings in it, if that's all it needed, but if the bearing journals on the crank are damaged, then I'd be starting to question whether it's worth the trouble.

The car drives fine, so I'm kind of leaning towards just driving it until it beats itself apart, while I keep an eye out for a 2004-2006 Jetta Wagon.

If your looking at the connecting rod or main bearings, that can be done from underneath...taking the oil pan off and moving the oil pump should reveal those things.
Wrist pins seldom get damaged in my experience.

Easiest thing to do would be pull your oil filter and check the pleats for debris. If that is indeed bearing then you'll find something there.

I'm starting to question if this could be something other than connecting rod bearings. It does sound a little different from what I've heard in the past with known connecting rod bearing noise (on other cars).

My piston protrusions were all fairly normal and the largest difference between two pistons was 0.005".

If I remove the oil filler cap with the engine running the tapping sound doesn't get any louder at all. If it was a bearing I'd expect to hear more noise with the cap off. Or if it was a cam follower, they're right there, so the sound should be very obvious with the cap removed. But no, nothing.

I've had the valve cover off a couple of times and everything looks normal. Injector rockers are properly adjusted and the rollers don't have any flat spots or anything like that.

Good idea to check the oil filter for debris. I'll do that.

Injector maybe? How clean were you during the install? Maybe some dirt got into an injector.

Doesn't sound horrible. Might need some more breaking in?

Sounds good to me? If that is BEW, look at fuel pressures . ALH?sounds like mine.
Cheers

derek5120 said:

Injector maybe? How clean were you during the install? Maybe some dirt got into an injector.

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I think I kept the injectors petty clean. I took them out and stored them in clean fuel while I worked on the engine.

VCDS is not reading any codes so the injectors are at least working well enough that the ECU doesn't detect a problem.

Okay, you guys are going to say I’m stupid, but I reused my injector hold down bolts.

They seem okay, but maybe they’re not clamping the injectors down tight enough.

I’ve ordered some reusable non-stretch type bolts and I’m going to avoid driving until I have those.

Maybe they’ll make no difference, but I think it’s worth a try.

I took out the oil filter and had a look. In the pleats of the filter I basically just see black. I can't see any metal particles or anything like that. I was looking closely with a bright headlamp.

In the bottom of the container that I put the filter in, I think I could see some very tiny particles which could be metal. The filter has 8000km of use on it, so there's bound to be something. It didn't seem like a lot, so I'm not sure what to make of it.

I guess my next steps are to wait for the injector hold down bolts to arrive, put those in, and if that makes no difference I'm going to assume the knock must be connecting rod bearings. I guess they're reasonably easy to put in.

I'll probably leave the main bearings alone for now, if the ticking sound is cured with either connecting rod bearings or proper injector hold down bolts.

Seems fine to me by the sound.

If you still suspect something, pull the sump and check it, its the easiest way to get information, except those 2 F"!#$%ng bolts near the transmission.

I think this guy has a louder version of the same problem: https://youtu.be/2uRbaTdg8AE

It turned out to be an injector for him.

I hope I didn't damage my injectors somehow. I handled them fairly carefully and tried to kept them clean.

Just waiting for my new injector hold down bolts. If replacing those makes no difference then my next step will be looking at the bottom end.

Mike_04GolfTDI said:

I think this guy has a louder version of the same problem: https://youtu.be/2uRbaTdg8AE

It turned out to be an injector for him.

I hope I didn't damage my injectors somehow. I handled them fairly carefully and tried to kept them clean.

Just waiting for my new injector hold down bolts. If replacing those makes no difference then my next step will be looking at the bottom end.

Click to expand...

thats different engine than yours, but your video does not sound bad

While driving mine sounds similar to that last video. At idle it's not so bad.

It doesn't seem to matter if I'm accelerating or coasting in gear, the noise is there.

Well I got bored and took off the oil pan. I found absolutely nothing remarkable. I tried moving the connecting rods around and they’re solid on their crankshaft journals. I can’t wiggle or move anything.

There was no debris of any kind in the sump. The pick up was clear of debris as well.

I think it’s safe to say I don’t have a bottom end problem.

Since the head, cam, and lifters are all brand new and were shipped to me assembled and ready to use I doubt anything is wrong with them.

This has to be something related to the injectors. I am hoping that when I replace the stretch bolts that will improve things.

Did you use new copper sealing washers when installing the injectors?

aja8888 said:

Did you use new copper sealing washers when installing the injectors?

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Yes, I put a new seal kit on each injector.

Is there anything special about the rocker shafts? They both looked the same to me. There isn't a left and right one is there? I was moving them to a new head so I didn't keep track of what order they were in.

Faulty hydraulic lifter? The noise seems to be at camshaft speed (1/2 engine speed). Disconnect the pipe from the air cleaner and listen for that noise in the inlet tract.

Mako said:

Faulty hydraulic lifter? The noise seems to be at camshaft speed (1/2 engine speed). Disconnect the pipe from the air cleaner and listen for that noise in the inlet tract.

Click to expand...

Okay, I'll give that a try when I have the car running again. Right now I have all the injector rocker bolts out and the injector hold-down bolts loose. I'm waiting for non-stretch type replacements to arrive in the mail. (For rockers and injectors).

I have the valve cover off while I wait for those bolts so maybe I can try to spot a bad lifter just by looking. The engine hasn't run for a couple days, so I suppose all the lifters will have "deflated" for lack of a better word. Maybe I can turn the engine over and look for an unusual wear pattern on one of the cam lobes or something. If one is much different than the others, that may be a clue.

The replacement head may have sat for some time after manufacture. I wonder if a lifter could just sort of become stuck or collapsed.

To be honest, the sound DOES sound like a lifter. I just don't want to believe it because it's all brand new.

Well, after installing new bolts for the injector rockers and injector hold down wedges, the engine sounds a little better.

So I think the sound I’m hearing has something to do with the injectors. I adjusted the rockers according to the method Franko6 suggests in which you line up the intake lobe with the middle of the roller on the injector rocker, then tighten the adjustment screw until it bottoms out, back it off 180 degrees, and then secure the lock nut.

I might redo that adjustment with a dial indicator, but I don’t expect that to make any difference. I trust Frank’s method.

Anyway, I don’t think anything is wrong, just different. After driving the same car for fourteen years, I’m very attuned to any changes.

Was this a oem head? Did you get from a trusted source? There is a guy that goes by Prothe that sells Chinese junk that will wreck your engine.

joep1234 said:

Was this a oem head? Did you get from a trusted source? There is a guy that goes by Prothe that sells Chinese junk that will wreck your engine.

Click to expand...

No this is a newly manufactured AMC head from a reputable vender. (IDParts).

I've driven around a bit today and the sound is basically still there. I've inspected everything I could, and I can see no mechanical reason for the sound. Lifters and cam look fine. There are no unusual wear patterns on the cam lobes suggesting that maybe something is wrong.

I'm starting to think there may be some issue with my injectors. I did take them out of the old head and put them in the new head. During this process I did things like wipe them with rags (thinking I was cleaning oil and stuff off them). I'm not sure how sensitive they are to this kind of thing.

If I had to guess, I think it might be just one injector. VCDS shows that the #4 injector has a different idle stabilization number than the rest. Three of them were hovering around -0.07 to -0.12 mg/stroke idle stabilization. #4 was more like +0.28. It is consistently a little different from the other three. I'm not sure if that's typical or not.

Another thing I've noticed is the sound is almost non-existent when the car is first started, and driven gently. After the first time I accelerate a little harder and therefore increase the fuel demands, the ticking gets worse, and will stay that way for possibly quite a while. Sometimes it will seem to quiet down after another period of gentle driving.

Once it starts doing it, it'll still do it when costing in gear, like down a hill for example. No fuel would be injected then, but could a screwy injector still make noise?