Rod Knock (more of a tap) Questions.

I am pretty sure that what I thought was a lifter or injector is a rod bearing tapping. It's on my son's 2000 Jetta ALH with 310K miles....purchased cheap ($1300) a couple of years ago with a tap and a patched up oil pan. Daily driver for him now.

Unfortunately, I did not suspect a rod bearing (sounded like a lifter to me) when we replaced the oil pan shortly after purchase. I would have at least checked for movement back then. But now, after unsuccessfully trying to find the tap up high along with remembering that the pan was JB welded back together by the previous owner I am pretty sure it's a rod bearing.

I would like the car to hold together for at least another year or two as my son will enter college within that window. It is doing fine except for this tap.

Questions:

1. Could I pull the pan and replace the single tapping rod bearing from below without loosening the crank or anything else? I know it is less than ideal, but would this likely improve the situation / reduce tap and risk?

2. What is the thickest oil I could safely run in the mean time? 15W-40 too thick? I normally use Mobil 1 0W-40 in all of our cars.

3. Any other short cuts / tips to keep the car going and minimizing the rod risk?

This is my second TDI...I have 270k miles on my '98 Jetta, and I am pretty good at wrenching.

Thank in advance for all information and thoughts!

Scott

15w40 is fine to run in these cars - it's not much thicker than the 0w40 which will overall be a better oil (synthetic).

one can replace a single rob bearing, providing the crank journal is in reasonable shape.

Lifters are much more common on these engines - rod bearings not very common at all for them to fail - usually an oil starvation issue will take out the turbo long before a rod bearing.

That said, the pan is easy to remove on these cars. If the rod is knocking, you should be able to feel play on the connecting rod.

The only real way to check for sure is to drop the pan and go from there.

Ever since I had a timing belt failure and the exhaust valves hit my pistons, leaving noticeable imprints in them, I've had a tapping sound that I've been trying to track down.

I replaced the entire head, which got the car running again. Then I replaced all the lifters thinking one was bad. That was probably a waste of time.

I also took my oil pan off and inspected the bottom end. I couldn't find any movement in any connecting rod bearings. All felt solid.

My theory at the moment is that it's a wrist pin on one of the pistons. I suspect #4 because VCDS shows a different idle stabilization value for that cylinder and a compression test gave 440, 440, 440, and 430. So #4 was just a touch lower than the others.

I have used pistons and rods on the way from a VW specific auto-wrecker (ordered through ebay). When I get them installed, I may check back here and let you know if it helped.

This is a video of a car that has a knock (maybe a bit louder than mine). See if this is similar to your sound. According to his comments it turned out to be the small end bearing on a connecting rod.

https://www.youtube.com/watch?v=3nkcxJ9bheI

Thanks very much, Windex! I guess to eliminate the lifter possibility, I should pull the valve cover first since it has a re-usable seal.

- If it is the rod with some journal damage, do you think a new bearing would "run in" or just fail quickly? I know you can't say for certain.

Thanks, Mike! Mine sounds kind of similar to the video but a little sharper / more metallic. Mine is easiest to hear standing toward the rear of the car...sound coming off of the ground, I think. Makes me think the tap is down low in the engine. With a stethoscope, I can not find the tap in the head or IP or injectors. And, I loosened each fuel line with no change in the sound. Also, no change at all when I remove the oil fill cap.

I think there is a right oil and it's neither 0-40 or 15-40.

The first thing, I don't know of a 0-40 oil that is intended for diesel use. But if it's not a CH-4 or 4+ API oil, you are not using the right stuff. IT's about soot in suspension in the oil, which a gasoline oil will not do. The 15-40 oil is among the right oils, but an older and heavier oil than is generally needed. We have some who use it in very Southern, hot areas, but not in general, do we agree with that oil.

On to clicking or tapping noises...

Before you start digging into an engine without knowing where you are going, it may help to listen from both the top of the engine and the bottom. A big screwdriver to the ear and against the valve cover will usually allow you to figure if the tapping is coming from the valve cover area, although it probably won't pin it down to a specific lifter. Removing the cam will allow you to determine if a cam follower is collapsed or worn.

If you go under the car (at least on jack stands) and the tapping, knocking noise is louder from under the car, you are going to drop the oil pan.

Rod bearings can be rolled out. I'd start with the #3 rod and see what the bearing material looks like. That is the most stressed rod. Any wear sign,like copper showing or discoloration, wear in the middle third of the bearing, is sign to replace bearings. The journal should look smooth and shiny, with not coloration or wear lines. If the bearings have wear, for example, front right, lower left, that is indication that a rod is bent. The rod should be checked for length and straightness and replaced. That requires cylinder head removal.

A knocking noise can also be rings and cylinder wall damage. Without pulling the head, you can get a small snake light with a pea bulb to run up into the bottom of the engine to see how the cylinder walls look. It's not a very easy thing to see without the right lighting. We have seen that Horrible Freight has a cheap snake light with a single AA battery that works quite well, inexpensively.

If you see any lines in the cylinder walls, you got trouble and that is the knocking noise you are hearing... a ruined piston, rings and cylinder wall. Pull the engine and fix it.

Shortcuts? There are no shortcuts. There is the right way and every other way is the wrong way (less than right way?). If there is rod bearing journal wear, the usual best way is to pull the engine.

There are a lot of tricks to making a TDI engine go back together for the long term. There are plenty of mistakes to make it run for the short term. If you need some extra guidance, let us know.

It certainly is aggravating trying to pinpoint this type of noise. In my case I'm basically rebuilding the whole engine to fix it! I don't mind doing it, because you can't buy anything new that compares.

Mike_04 Golf,

We have consistently spread this word, but here it is again.

Rod length and weight, especially on the older engines, is WAY OFF. We usually see as much as 24 grams weight difference (usually 8 grams) between rods marked with the same number, say '65' The point is, just because it says whatever number, does not make it the right weight or LENGTH. From the shortest to the longest stock rods, there can be a difference of .040", when .004" is the difference between head gaskets.

We recently got an engine that was cobbled together with a bunch of junk. The one rod was obviously replaced and when we did our initial cleaning on the cylinder head, we could see the impression of the engraved numbers from the top of the piston, etched in carbon onto the piston. WAY TOO CLOSE!!! He's just plain lucky there wasn't piston/ cylinder head contact.

So, just getting a rod that says a number isn't so close as you might hope. We measure between the big end, bearings out and the wrist pin end, bushing in, and find the closest distance on BOTH SIDES of the rod. We also check on a flat plate to see if they are warped. We try to get all rods within .002" of each other. We do quite well.

In order to match a rod length, we require that the straight rod from a reciprocating set be sent to us to match for weight and length. All our rods are weighed and measured for length. It would be nice if you could just measure just like us, but that will not happen. It becomes a 'feel' thing.

Thanks for the info Frank. The rods and pistons I got are a matching set pulled from a 2004 Jetta. They aren't just a bunch of cobbled together rods from various sources on Ebay. (I communicated with the vendor to find out where they came from, etc).

The vendor has 100% positive feedback, and they do accept returns. I'm hoping they wouldn't sell me junk.

They had many high resolution photos and everything looks good. The black coating on the sides of the pistons is not worn off (I think that's a good sign), and the tops of the pistons don't have any unusual dents or anything to suggest they've struck a valve.

This is the set I purchased: https://www.ebay.com/itm/04-05-Vw-Jetta-Golf-Beetle-1-9-TDI-BEW-Piston-and-Rod-OEM/283004629803

Thanks, Frank. I appreciate the info. I hate to be looking for short cuts, but lots of competition for time and money lately within my family of 5.

If you are interested in the 0W-40...the guys over at bobistheoilguy.com are pretty high on it for non-DPF diesels....

https://www.mobil.com/english-au/passenger-vehicle-lube/pds/glxxmobil-1-0w40

I have been using it in my AHU for about 11 years and well over 100k miles. So far so good. I switched from Rotella 5W-40 because of better cold start flow.

Thanks again.

Scott

I don't think you need to be worrying about cold weather flow in NC as much as us northerners...

As to whether a new conrod bearing will help (assuming you find a problem with it), it again depends on the condition of the rod journal - if it is excessively scored, then the new conrod bearing will only delay the inevitable.

It's worth noting that different possible causes have differnt noises - top end (lifters) noises occur at half frequency to bottom end noises.

Also, conrod bearings and wrist pins tend to change severity or go away entirely when the source of ignition for that cylinder is removed. That you cracked each injector line with no change in the noise is interesting...

Is there any chance you can make a video of the engine running and put it on Youtube so we can hear it?

This may seem a bit left field, but are you sure your IP is 100%? A while back I had a knocking noise that sounded like it was coming from the motor, but it was not.

I have a spare IP from a trusted source....because I am NOT sure my IP is OK. I have to do the timing belt this year, so I plan to tackle the IP at that time....possibly along with cam and lifters. What inside the IP typically starts ticking?...cam plate/rollers?

I am just so amazed and frustrated at how hard it is to isolate / pin-point this tick.

Thanks again everyone. I started another thread about what I saw when I inspected my lifters.

I've never really had an issue isolating knocks / taps on an engine, but it helps to have the proper tool.

I use something like this: https://www.tenaquip.com/product/ge..._JViDycnTG8kMEjP00s3oKj-5MZrI5mBoCpKcQAvD_BwE

a combination of listening using the hose and the probe has always allowed me to find the source of hard-to-find noises.

I'm using the nuclear bomb option to fix my ticking sound. I received all my parts in the mail yesterday, including connecting rod bearings, main bearings, rings, gaskets, etc, to go along with my replacement pistons and connecting rods.

It will be hilarious if it still makes the sound after I rebuild the engine.

https://www.youtube.com/watch?v=aCbfMkh940Q

OP- Because the oil pan apparently failed, I would simply install new rod and crank bearings. When I had to do mine, it turned out to be much easier than I thought.
Let me know if you'd like the instructions I used (from QuickTD, saved my butt)

Windex, that's exactly what I have...no success. Thanks, though. I think that part of the problem is that this tap is similar in nature to an injector click just louder?....so, it is easily masked or misdirected.

I am seriously thinking of getting some large piece(s) of foam that might block noise from the IP or head or vice versa.

If you are using the probe to "touch" suspect areas for the knock, it shouldn't matter that something nearby is noisy - the sound will only transmit from the point of contact.

Just keep touching the probe to various parts of the block when / where the noise is occuring - the noise is coming from the loudest place.

SO, last night we changed the oil and ran directly from Diesel Purge and did a lot of listening with my mechanic's stethoscope for any changes. Nothing really chanced the tap, but I THINK the tapping is actually from 2 of the 4 injectors! I am a little embarrassed to admit it.

Last week, I cracked the injector lines one at a time while my son was listening at a short distance (easier to hear/distinguish the suspect tap at a distance.) He did not hear a difference, but if 2, not just one, are tapping, his lack of experienced listening might have made him miss it.

With the stethoscope, injector #1 sounds best...a mild clicking with each open and close. # 2 is similar with a little louder click on close. #3 has a MUCH louder tap....and it seems to coincide with the tap I hear as I approach with the stethoscope in my ears drowning out the "normal" noises. #4 has a louder tap than than 1 & 2 but not as loud as 3, but #4 also has a like a double tap...like the needle is bouncing a little?

I think I will pull and inspect and clean these nozzles. I replaced my AHU nozzles last year, so this is very do-able. Before investing in nozzles, I will look for something obvious. I might also swap 1 and 4 to make sure the sound follows the injector.

Thanks for patiently giving me feedback. I will keep y'all posted.

Scott