Can the patient be saved ? FOD identification help please B8 A4 2.0 TFSI

   #41  

Jack@European_Parts

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TIME & TIMING!

Mike it's the one thing we/I can't buy!

I just like to play and I'm off to teach today, going into play Scirocco fuel system now and maybe spend a couple hours on my disks.

Last week I verified I am right about something, now have to try next idea I'm dreaming for hysterical hysteresis fun!
 
   #42  

Samz09

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You are kind of missing the point.

Two things are happening when a cam has floated on the sprocket.

1. It has effectively broken the "press fit" hold from sprocket to cam and the float permits a move that doesn't show or possible under load not install visually!
( The only way to know is to press off and verify or if it was prior marked showing clear deviation )
2. Notches on cams will appear as if in proper spot/location and link count checks to lock bar causing the deception.
3. If you painted sprockets that were already floated on press fit & on damaged engine there is no point of that right?
4. Exhaust cam with lock bar or without and irrelevant to sprocket location since notch is at 12 o'clock position anyway on each cam!


Samz09 thank you for engaging!
The problem i'm having is, this would be much easier explained in person, face to face ha. I follow the points you're laying down, i'm trying to word this hypothetical failure scenario as clear as possible for others to see because i know you already do.

1. The paint method, by painting you are not using, checking or following timing marks. Therefore you're assuming all timing is good when swapping a adjuster. Point here is you wouldn't know if something else had happen/shifted
2. And this is what id like to hopefully word correctly.
-Yes 12 is where the notches should be. With them at 12, there is the link count. That number corresponds to "starting" the count at a given link in relation to the notch, and "ending" the link count in relation to the other notch. So If a gear had shifted, your link count may still be good if the shifted gear moved 1/2 a tooth lets say. So lets stick with 1/2 tooth gear shift. With the bar set, cams at 12 so notches line up with cam cap windows, and one being even 12 and the other off to one side more as i think it usually is. The location of your first link count start point to the last, will not match the location of the last link count location with the adjuster filling all the chain slack. Now this is to say its 1/2 link out, because i'm sure maybe someone will say it. If the gear happened to perfectly shift a full tooth length then i guess what i just described would be irrelevant because it would all match.

However i did not consider, so thank you for it, and actually solid point from you about engine load. Because yes the press fit is compromised at this point and say a 90% engine load or higher rpm can further break it loose and cause major damage.

I think i worded it right for the most part, but still feel like i'm missing some things. But id have to say you understand what i'm trying to say lol

(edit) clicked your link after writing this, and the picture is there, start point and end in relation of the gear to the notch, that's what i was trying to point out would be different if a gear had shifted!
 
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   #43  

Jack@European_Parts

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At this point many of the older engines which support the same sprockets have possibly suffered an incomplete inspection.
It would be wise when dealing with any car that has such historical evidence of this to inspect the press fits.

And you should charge for it!
Just an FYI on race engines, with stronger springs or shims, I weld the sprockets to the cams to be sure it's not going to move.
I also do this to TFSI adjusters too & which are problematic for the same issues with that stupid round pin that shears under load & so it can't deviate.
 
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