Originally Posted by RedGray

I've attached a number of files. They describe how to do the timing chain and replace the cylinder head. There are likely some duplicates.

Fwiw, imho, just replacing the head gasket on an M271 does little. Imho, the big problem is that oil cakes up on the valve faces and seats, and the valves and seats need to be fixed.
So, imho, you need to have the head rebuilt, or you need to get a new head.

Originally Posted by RedGray

I'm far from being a scaredy cat.
It's called being an experienced Principal engineer.
Aerospace engineering is different than structural or materials engineer.
As you know, the number of engineering specialties makes the number of medical specialties look like T-ball (For the non Americans: "baseball" for 4 years olds where the kids hit the ball from a rubber-T holding pole).

My main specialty isn't structural. But, I work with a number of PhDs that do have that as their main specialty, and also are gear-heads. I also remember, and I'm still learning, about real-life structural design.
Plus, I've been working on cars long enough to know the difference between "this hack works for now" and "this is the correct way to do things".
Fwiw, I'm a tri-degree engineer -- mechanical & electrical & computer. Still, I've done a wide range of stuff - from specifying custom springs (similar to a car spring), to PWM electronics, to software. There are many products that require that type of breadth of knowledge and experience. Working on an ABS system is one of the most commonly known automotive product. Printers are one of the most commonly known general products.



Fwiw, for example, the method for screwing down the head on a M271 is very specific. A specific pattern in 3 steps - Torque to x-Nm, 90 degrees, then again 90 degrees.

If someone just cranks the head bolt down once, or uses an old head bolt !WTF! - ARG!! , the head and gasket will likely last some amount of time.
But, the engineers that specified the torque to yield bolts and the pattern didn't do it because they were bored. Just look at the JOKE "reliability" of the GM aluminum heads for all of their engines until that POS mismanaged company went under. GM was infamous for doing low-cost cheap aluminum head design (the heads, the bolts, the block holes, the torquing method, etc).
Yet, many people replaced head gaskets, the engine ran for 1-3-whatever years, and they claimed victory and the reason for the re-failure being the design. My Olds Quad 4 (super infamous for mega POS heads) has 12+ years on the head gasket that I redid.

I have 2 cars over 25 years old. My "new to me" 2005 C230K will eventually join my 25+ year old club. That's why I JUMPED on my car when I saw it. It was never driven in the snow. The body/etc is on very good shape.
The engine had an rare occasional cylinder misfire. BFD about the misfire. That's "easy" to fix ( for me , just not cheap or quick).

Where as, a rusted frame, bad body, worn interior, etc would be for me very expensive and cost/time prohibitive.
For a body-work person, they would likely look at buying/fixing a used car the opposite of how I do.

I do things as specified by the manufacture's design engineers and by the ASE (http://www.ase.com/). I have a few friends that are ASE certified mechanics.

If people want to do things by "what they think makes sense", that's their choice. No dealer would hire them or allow that type of work. That alone should say something.

Originally Posted by jaGTAR KAHLON

So I did mine and lined up everything perfectly rotated balancer and checked twice and both cams were off a tooth, realigned and checked twice it was perfect. Start car, no good, remove cover and check again. Both cams are now off a tooth the opposite direction. Meaning they were right the first time. What’s the best approach to realign them? I took of the exhaust sprocket and can’t get it back on because of tension. Take out the tensioner? Pry it? Or pull on the chain? I see you in almost every post I’ve read lol