Timing gears: (cam gear). One mistake I made was not turning the engine to TDC before starting this process. So, with a 27mm socket/ratchet, turn the engine over by hand clockwise until you are at TDC. (marked on the crankshaft). To be sure you’re at TDC, look on the back of the timing gears. There are small “doweled” holes that you lay an allen wrench (on the top surface of the head ) and slide into these holes. This is TDC. So, make sure the crank is on TDC before you loosen the chain tensioner. I didn’t do this. Thankfully, Arthur Dalton sent me a pdf of this procedure. My mistake: I marked the chain at both cam gears, and then once on each chain rail. I thought this was enough – or the right way. When I reassembled the engine later, with the new head gasket, I lined up my marks thinking I nailed it. Thankfully, Arthur sent the pdf, which explained the procedure. I then checked my timing with the TDC/allen wrench method in the back of the timing gears, and I was a tooth off. So, off came the tensioner and the cam pulley. And I reset the timing. Thanks, Arthur.

I can’t explain it any better than Steve Brotherton’s article. https://www.continentalimports.com/ser_ic100345.html - an excerpt from the article: “I’ve described how to get the sequence of assembling the gear on the intake cam right a number of times over the phone. The easiest way for me to explain it here goes like this: Forget the chain for the moment and place both cams on their doweled marks. Take the intake gear and turn it clockwise, looking straight at it from the front (don’t move the cam). In this position, the cams are on the marks, the crank should have stayed there from first disassembly and, most importantly, the cam, while in its mark, is retarded in the adjuster. If the chain were in pieces, you could just drape it over and pin it and you’d be set. It can’t be assembled in this way, since we don’t break the chain in the operation. This example is conceptual to describe the effective positioning of all parts. During actual assembly, you must get the chain on the gear, have it pulled tight on the driver’s side and be sure that the cam is retarded to match the concept above. After becoming acquainted with the cam timing arrangement, remove the exhaust gear. Probably one of the toughest issues can be the removal of the pin from the driver’s side guide rail (see Photo 7). This pin is often difficult and must be removed to get the head off. We use a small slide hammer of our own manufacture. The center of the pin is threaded, and it can be pulled with a bolt and various cylindrical spacers such as the socket in Photo 8. The chain should be hung with a piece of shop wire, and the tensioner should be removed.”

Once I went through the process, Steve’s explanation made perfect sense. So, make sure the engine is at TDC (not just the crank harmonic balancer), and check the position of the doweled marks on the back of the cam gears. I would next loosen the three bolts holding the cam gear on the exhaust side of the motor. Easier to do this with the chain tensioner in place. Once loosened, you can remove the chain tensioner (27mm). Make sure you see the MB cd manual explanation on this (thanks, Arthur!). Now, the chain will be quite loose on either side, where it falls off the cam gears toward the crank gear. I then removed the three bolts in the exhaust-side cam pulley, and removed the pulley. The chain didn’t really want to move out of the way for me to pull it off both cam gears. So I removed the small positioning collar on the passenger side cam gear (small, single bolt in the center of the cam gear). You’ll notice the “center” of the cam gear moves to the left/right (advance/retard). This is ok. It’s very important, per Steve’s writeup, that the cam is retarded in the adjuster when you put the chain back on.

Cylinder head: First, you’ll need to remove the wiring harness, or at least move it out of the way. No need for me to explain the hazards of that here. And original wiring harness (brittle) will never survive what you’re about to do. With the plug wires and all engine sensor/attaching points wiring unplugged, you’ll need to remove the wiring plugs from the fuel injectors. They just squeeze together and pull up and off. The point is, you’ll need the harness out of your way.

Ok, there is a specific order to loosening/torquing the head bolts. I recommend you see the MB manual. Your new head gasket set will also have a cheat sheet that repeats this order. Remove the head bolts. You will need a special XZN 12-point socket. You can get a set of these (think the size is 12m) at pep boys, or on ebay. With the timing chain off, and the other items/attaching points previously mentioned, removed, the head should come right off. You’ll get water can other garbage down in the cylinders. Just use clean shop towels or a mitivac pump to suck the water out (and the cylinder head bolt holes – in the block). I used a razor blade gasket scraper and a fine scotchbrite pad to remove the gasket material from the head surface. I also removed the “soft” ridge at the top of my cylinder walls. The walls looked great (98k) – cross hatched, just like from the factory. I also used a fine/long file on the block surface --- to make sure it was totally flat with no gasket buildup. I then blew the cylinders with compressed air, and wiped them down with a clean, lint-free rag soaked in oil. With the engine block ready for the gasket, I then placed the gasket on the head --- make sure you set it down correctly --- and covered the block over with a sheet until I was ready for the head.

Regarding the cylinder head, you need to be careful scraping it off, as it’s alumimum. I did use a fine wire brush/drill on the carboned combustion chambers and bottom of the valves. And then blue all the debris out by putting compressed air in the intake/exhaust ports, blowing it out out. Of course, the cylinders with the valves closed, this really didn’t matter.

Torquing down the head bolts is nerve wracking. Recheck the torque specs, but I believe that the first stage is 41 foot lbs. And do them in order – turn the radio off, and don’t stop for anything. It’s EASY to forget where you are. I did it once. I waited about 15 minutes between stages. Second stage, I used a ½” ratchet and a breaker bar, and I tightened the new stretch bolts 90 degrees, or ¼ of a full turn. The third stage, I did the same thing. Nerve racking, to say the least.