For MB board: Ok, these are my notes on the head gasket replacement for my 98k ’95 E320 M104 engine. Now before you pull the head or any of the other components described in my writeup, I recommend you print out the head gasket replacement, upper timing cover removal, timing chain tensioner removal and engine timing (lining up the cam gears with the crank on TDC) from the MB repair CD. I also recommend you print Steve Brotherton’s excellent writeup. And above all, go slowly and use common sense. I didn’t always do this, and made a couple mistakes that could’ve sunk me. Oh yes, – and remove the negative battery cable from the battery.

http://www.peachparts.com/Wikka/M104HeadGasket

You can pull the head one of three ways.
1. Head only: unbolt the intake and exhaust manifolds from the head
2. Head + exhaust manifolds: (M104 has two manifolds – three cylinders each) - unbolt the intake manifold from the H-pipes, and the intake manifold from the head
3. Head + exhaust manifolds + intake (unbolt the exhaust manifolds from the H-pipes, and the remove the fuel lines, coolant line, vacuum lines, electrical connext and losen the hose clamps attaching the upper portion of the intake manifold.

As I was primarily on my own (tough job – requires a strong back or two to hoist it out the engine compartment), I opted for method #2 – left the exhaust manifolds bolted to the head. If could do again, I would rent/borrow an engine hoist/chain, and pull the manifolds while still on the head. My neighbor helped me pull the head/exhaust manifolds out of the car. I climbed in the engine compartment and installed it myself without help.

A few thoughts:

Front cover: I’m really a pro at getting this off and on quickly. It’s VERY simple, and you don’t need to remove the serpentine belt. I always do in this order. First, loosen the fan shroud. Then, drain the coolant at the crossover pipe connection just above the AIR pump. Then, pull the switchover valve (two 13mm bolts), and move the electrical connections to the side. Also the connection to the AIR pump. I then remove the black engine lift hook (two long hex bolts) right next to the switchover valve (these are the items hidden behind the black cover (front of the engine), and pull the engine lift hook. You can then remove the large coolant hose in the front. Two hose clamps. From there, it’s very simple to remove the coolant crossover pipe – single hex bolt holding to the block, and the small bolt holding it to the thermostat housing. With the pipe out of the way, pulling the fan is simple. I use a piece of angled steel rod – bent for this need – I think it’s ¼” that I can slide in to the groove behind the cooling fan pulley. With this in place (the rod), with the other hand, put an allen wrench into the hex bolt on the cooling fan. Turn clockwise until the rod “locks” down the fan pulley. Then loosen the cooling fan pulley by loosening the bolt counter clockwise. With the fan out of the way, I would suggest removing the valve cover. I won’t explain that process – it’s an easy task. With the valve cover off, you can pull the timing cover. There are six bolts that hold it in place – you won’t be able to remove the lower bolt on the passenger side – just unthread it and leave it loose. Also, remove the bolt holding the belt tensioner “shock” absorber. The upper timing cover will now come off. Careful – I use a flathead screwdriver on the passenger side first, then on the drivers side. There are a couple pry points. Don’t try and pry anywhere else. A rubber mallet may also do the trick. Once off, I remove the “pin” attaching the timing chain rail on the driver’s side. I use a long bolt / washer and a socket. Tighten down the bolt into the threaded pin, and as it gets tight, I turn clockwise with a ratchet on the bolt, and with the other hand, pulling outward toward me with the socket. This will ease out the pin. I recommend putting a clean rag between where the timing chain drops/hangs nto the block. You don’t want to drop any nuts/bolts/tools/dirt down here!

Intake manifold: removing the intake manifold (first time attempt) was a major pain. Especially the last/bottom bolt against the firewall. There was a bend/tab on the end of the fuel rail which totally obstructed access to the bottom bolt. I recommend if you remove the intake (or, if you’re comtemplating replacing the water pump), you get a few variations of 6/7mm (can’t remember the size – think it’s 7mm) hex sockets, allen wrenches and extensions – stubby hex sockets ¼” ratchet “wobble/flex” extensions are key. Embarrassed to admit I had to get a sawzall out and carefully remove this tab (attached a small wiring harness). There are two large vacuum lines that attach to the bottom of the intake manifold (next to the third cylinder intake port) – one hose goes to what I think it the throttle body, the other, to I believe the power steering pump area. My hoses were hard as a rock, and when I tried to remove them from the intake, I **broke** the two vacuum outlets/ports on the bottom of the intake. The rubber hose, over time, had fused to these ports. So, I had to drill out the two broken connections in the intake and tap them for the two brass fittings I bought at Home Depot. The hose outlet to the front of the intake needed to be approximately 3/8”, the one to the back (to the throttle body), is smaller. I then used Jbweld, after I threaded in the new brass ports, not only to rebuild/seal up broken sections around the ports, but to further seal up things around the brass fittings. Kinda cheesy, but it worked. I do think now that I could’ve removed this broken section from the bottom of the intake (it’s double layered, and seems to be designed to replace), but I was running out of time. You might check with the dealer on this. However, I **strongly** recommend if you pull the intake, you consider cutting these two vacuum hoses in half. And with the intake in hand, or at least bolted to the head, you can properly remove them from the intake. After that, I unscrewed the fuel filer cap and removed the two fuel lines (I think the ends were 17mm). You’ll need to loosen the two top clamps on the large air intake hoses that go from the top portion of the intake manifold to the bottom. Then, only a couple small vacuum lines and one electrical connector in the center of the upper intake. You can also loosen the mounting screw for the oil dipstick, and pull the dipstick up and out of the block. Really sounds like more than there is.

Exhaust manifolds: Very simple – just unbolted the two manifolds halves from the header pipes. Four bolts in all. One you get to from the engine compartment, the other three, easily from underneath. The EGR tube is simple to remove. I pulled the ERG unit from the right cylinder head by removing the two nuts on either side, and then the single mounting nut. With the intake/head off, it’s kinda easy to remove the EGR tube for cleaning or replacement (one of the mounting bolts at the throttle body is a bit tough). Mine wasn’t too coked up, but I definitely cleaned it out. The coked end was at the throttle body, where the harshest bends are. Make sure to loosen the transmission fluid dipstick mounting bolt/nut, at the back of the head on the exhaust side. Also, there is a hard liquid line that runs to the center of the head, between? The two exhaust manifolds. I simply unbolted this (single bolt/nut) from the block/head, and I believe I loosened it below the manifold too. IMO, not worth removing all the manifold-to-head bolts.

(continued in next post)