Lifter/ rocker knock when warm

B6/7 S4/RS4
#21

A few motors under my belt here.

The biggest thing your going to be fighting is going to be the bearings. The crank bearings are very specific to each block and there are 4 or 5 different colors that they can be. So you can’t just drop out the crank and rotational assembly from one motor and put it into the other. Obviously you have to be careful of the rod bearings as well but its not as hard to work with.

I laugh when I hear pro built 4.2 Audi motor. For some reason there just isn’t such a thing. but lots of people say they are. Its a difficult motor to deal with and you get shops that think its an easy job only to find out… ITs crazy. So I would shy off the “pro” built motor unless you take it apart and then inspect things from the ground up.

#22

Justin, how many time have you seen bad crank bearings? I’m thinking I might just leave the old ones in and swap out the rod bearings and rings only. It’s like $240 for new bolts just to install the crank itself. My cylinder walls aren’t terrible so I’ll hit them with some AN30.

The new heads have new cams and almost all new valves. I’m going to pull them apart, have them tested, and probably use them.

#23

Its ultra rare. When I have seen or heard of bad bearings they have been super bad. Perhaps it would be a good idea to take an oil sample if you have it from the motor where you want to keep the crank bearings and send the oil sample out to get tested. That would give you an idea on how much material from the bearings is in the oil. At that point you can kinda see if its normal ware or not and then decide the best path.

#24

Based on how the rod bearings look, I’ve decided to roll the dice and let the crank bearings live on. I inspected every oil passage in the block and head and I have not found a blockage. I’m puzzled as to why the tensioner was flat and the cam adjuster was unlocked when I tore it down. I understand the tensioner may have leaked down but both tested good anyways.

I did use my calibrated palm to test the valve spring pressure on the valves that hit and their neighbors. I found that the center intake valves on cylinders 5 and 6 are noticeably weaker than the others. Is it reasonable to say this has been my noise all along? The progression makes sense in that it started only when warm then onto hearing it all the time. If that’s the case and they were contacting at idle, I don’t know how it didnt do more damage when I drove the car and seen 4k rpm’s.

Anything else I should be looking at or is it safe to say that weak valve springs caused all that racket and made that banks timing values wander from the beginning?

#25

The valve springs could have played a part obviously its so hard to tell.Having the tensioner and the adjuster out of sorts like that could have played a roll and seem to be something that isn’t adding up.

Perhaps inspect the oil pump unit and see if there is anything hideing there that might be a cause for concern.

With the heads. If your able to I would obviously do what you can do run the better set of heads with no issues. Just check to make sure those springs are in good shape as well.

#26

So I’ve rebuilt my original block with new rod bearings, piston rings, and fresh heads. Got everything installed and to my surprise I still have a knock. Swapped the injectors around and it went away for a bit. Ordered rebuilt injectors and that put me back to where it all started. No knock when the engine is cold but comes on when warm. So it is safe to say it’s not mechanical but more a spark knock or pre detonation.

Things of note,
Got a bank 1 lean code after a bit of driving.
Also got a SAI insufficient flow code another time.
Knock sensor voltage is above 3v on cyl. 6 during knock

In troubleshooting the SAI, I discovered that if I run the SAI output tests and start the car the knock is gone for a few minutes. I did this half a dozen times and it worked every time. It appears the car is running lean when SAI is not on and causing the pre detonation. I don’t understand the link.

I’ve chased most of the vacuum lines and only found a leak in the intake actuator. Sealant is curing on that now.

Plugs are in great shape and I’ve moved the coils around but knock remained in cyl. 6.

I’m coming to quite the loss but currently pulling the SAI valves and giving them an ops check and cleaning.

I have no idea where to go from here or how to find out what’s causing the detonation. A/F ratios are a little off but not terrible in my opinion.

#27

Pull the fuse for the SAI and see if that helps. There could be a big leak but maybe one of the valves is broken off the back of the head. The SAI vavles were cracked or broken that would cause issues for sure.

#28

After extensive brain racking and troubleshooting I decided to crack open the timing covers again. At this point the only solid lead I have is bank 2’s cam values wandering and increasing when the knock is present. Bank 1 is running a little lean but not too far off. With the engine installed I pulled the timing cover for bank 2 to check the tensioner I suspected was the culprit. I found that chain and tensioner to both be tight. I did find the main chain loose again. I was a hard decision as all my timing components are less than 20k miles old but I pulled the engine again to have a look at them. I have a new main chain tensioner as well as one off a junk engine. I compared the three in several different ways to try to find differences. I couldn’t find any info on the spring tension and length specs of the tensioner but my results were interesting.

The spring in my tensioner was shorter than the used one and much shorter than the new one.

I used a scale to measure the compression force required to release the lock rod on the piston and found my tensioner at 15lbs, used one at 17lbs, and the new one at 18lbs.

I also filled and submerged each in oil and compressed with my hands to asses the bleed down rate. The findings were right in line with everything else as mine bled down faster than the used one and the new one held almost solid with a lot of force.

I don’t know that anyone has ever tested these to this extent but if this proves to be my issue and this tensioner has failed in under 20k miles then it might be some good info to get out to anyone else in a similar situation. I called JHM and the only new tensioner failure they heard of off hand was new out of the box.

I will post an update with any new info I have and kudos to you Justin for doing as many in-car timing jobs as you have. I’d almost rather pull it. It’s doable for sure but brutal.

#29

SOLVED!!!

Replacing the main chain tensioner resulted in no change. With the engine in I pulled the bank 2 timing cover and started playing musical parts. I replaced one component at a time, temp installed the covers, and ran it until I found the fix. It ended up being the Bank 2 chain tensioner. It visually looked flawless as its only about 20k miles old. I applied air to the port and found that the reservoir side of the tensioner was leaking 3x the amount of air as an old tensioner I have. I’m assuming there’s a pressure relief in there that has failed. It’s been a long difficult road an frustrating that this part has failed prematurely. But aside from crank bearings, I now have a fully rebuilt engine. I appreciate all your help with this Justin and if anyone else needs some help just hit me up. I’ve dug pretty deep into just about everything at this point.

In addition, I did find a cheaper, better alternative to the camshaft diamond washer. It’s a tad bit smaller in OD but has more friction. I’ll try to spread the info if others can do the same.

Integrated Engineering’s EK-FDV2 cam gear friction disk @ $30ea.
https://performancebyie.com/products/cam-gear-friction-disk-vw-audi

#30

FANTASTIC… So glad you came back and gave an update…Stuff like that are so rare to find. It takes real commitment props to you.