jandreas

I can say with 100% certainty that my PCV valve that failed shut, was the root cause of the plug dislodging itself from the oil galley that pressurizes the hydraulic lifters.

The aluminum plug is probably somewhere still "on" your car. Unfortunately the driver's side plugs (at the back of the motor) have a better chance of ending up on the ground, where-as the passenger side will just end up lodged between a cover and the block. I would check everywhere! And if you can't find the plug, I would measure the inside diameter and ask a local machine shop to turn and thread a plug on their lathe for you. And if that won't work and worse comes to worse, buy the rocker shaft, maybe even from a parts dismantler just for the plug.

the_duke

The plug is an oil galley so PCV has no bearing whatsoever on the pressures there.

kishoreh

Giovanni,

Since the plug is not available as a separate part I was assuming if I have to pull the head to replace one of the rocker shafts that I would do this correctly and replace both rocker shafts at the same time on both heads. In my experience with other brand cars at my mileage of 122K is to replace what you can once you have things apart.

I do not know first hand that the cause of this issue is the PCV valve but based on things I have read on this forum and some other searches if the PCV valves on the Audi get stuck or fail it does cause excessive pressure which can cause the seals to leak etc. I am new to Audi engines so I can't attest to anything personally.

If I can find a used rocker shaft and pull the plug and fix it that way or as jandreas suggested to find the part if possible somewhere in the engine bay or have a machine shop fabricate something.

Either way I appreciate the input from all of you.

jandreas

Having blown out that plug twice, I disagree! After the 2nd was when I trouble-shooted the PCV valve failure.

the_duke

There is no crankcase pressure in the oil galley. The dipstick would be pushed out long before crankcase pressure where high enough to start effecting oil pressure.

Giovanni Giovino 6.0+6.0TT

And I can say with 1 million percent certainty that you are wrong, as I said earlier about the crankcase pressure of the PCV system and pressure buildup, ALSO as the Duke stated about the dipstick, do you really think that you could build enough pressure to blow out the plug out of an oil gallery and not the dipstick,
Not to be rude but I don't know what kind of mechanical background you have, but you are 100% totally wrong.
The truth is that the plug fell out, and you probably reused your old plug which again was loose and fell out of place by the 75 PSI oil pressure behind it......

I mean really, think about it...

No disrespect, but are you mechanically inclined or not ?

kishoreh

It has been a while, I finally was able to look at the car again after a year and found the issue was the aluminum plug on the exhaust rocker shaft was pushed out. I purchased a used rocker shaft off ebay and placed it in the freezer to see if the aluminum plug would shrink enough and I would be able to remove easily. I was not able to remove the aluminum plug so I am not sure how the aluminum plug got dislodged from the car if the press fit / interference fit is so tight. The surrounding is some type of steel and the plug is aluminum.

Once I can get this fixed I will document my steps to help others. I also for preventative measure am replacing the PCV Valve even though many feel the PCV valve failure does not contribute to the issue.

target39

I had a similar experience this past winter. The weather got down to 8°F and all of a sudden the car got a low oil pressure warning and started shedding oil all over the road. Fortunately, the engine was not run for long on low oil and I was able to find the aluminum plug caught in a crevice by the EGR valves. It was the driver side intake rocker axle's plug that came loose, which also meant I could access it more easily to press it back in with some finesse. I thought about using thread lock or some kind of sealant but the fit was so tight I did not think it was necessary and so far it has not leaked.

I can't imagine either of the passenger side plugs coming loose due to the plastic covering at the front of the engine, but the potential of the driver side exhaust rocker axle plug coming loose (what happened to you) has me concerned.

One of my ideas involved creating a small rigid bracket that attaches to the plug via its M6 female threading and secures it to the engine/rocker axle via the adjacent allen hex bolt (the one that secures the rocker axle to the cylinder head).

So far, the weather has not gotten as cold and it has stayed put; however, I may implement this solution even if it means simply ensuring that the plug does not get lost in the event it gets pushed out just enough to leak.

As for your used rocker axle and plug, I have some ideas. In order to get it out, I would heat it to at least engine operating temperature (90°C or slightly higher) and then try to remove it via the threading on the plug. If that does not work, quickly temper the rocker axle and plug by dousing it in ice water or submerging it and try again. It may not work the first time but I believe that if the quick heat cycles and the oil pressures cause them to come off on their own, some "simulations" should do the trick.

Once you do get the plug out, some precise, accurate measurements could prove useful if someone decides to recreate one out of a different alloy or simply needs one if they lose it entirely. I tried to take some measurements of my own but unfortunately I did not have access to a precise, accurate caliper at the time. The plug was probably deformed out of specification anyway.

For reference, I took some pictures of it next to a ruler and it seems to have an outer diameter of roughly 10mm or 10.5mm and a length between 13mm and 14mm.

I look forward to your potential solutions and findings as I do not look forward to dealing with the aftermath of this issue again.

kishoreh

target39:

Thanks for the info. I ended up taking the part to a local machine shop and they slowly extracted the plug from the used rocker shaft on their press. The machinist told me the plug is stainless steel. I am having them make two plugs for me from the original. It cost me $75 per plug that included them making the drawings and fabricating the part for me not sure if they are turning the plug or cutting with the CNC machine they have.

They told me it will be the exact dimensions and tolerances as the original plug.

If I had them make a minimum of 10 pieces that price would drop to $40 per plug.

I get the plugs back next week and I will post pictures of the original plug and the new fabricated ones. Hopefully this will work properly and could be a solution for others on this forum.

I think I am going to put some loctite 246 blue /high temp up to 450 degrees F or loctite 2422 blue ultra high temp up to 650 degrees F on the outside of the plug before pressing it in.

Does anyone know how hot the engine gets around the heads?

kishoreh

So I received the part back the dimensions of the original vs the copy was very close. I will test inserting this back into the car and hopefully all goes well. I am going to put some loctite 246 blue high temp.

The stainless steel copy is slightly heavier than the original aluminum so it should be slightly more durable. The machinist admitted he noticed that the original was aluminum but I was fine with the stainless steel.

Also one of the copies needed to be redone as there was a hole at the back of the piece.