Well, it took longer than two days because of my busy schedule and not feeling well for a few days when I could work on it.
But the engine is now apart and it was clearly #6 that was leaking as this was the cleanest piston top.


And as you can see, the combustion area is relatively clean.


Plus, I think I found the reason for the coolant consumption.
Pay close attention to space between the water jacket and sealing area just above the valve.


It doesn't look like a crack, but if it's just a steam trace I hope that it's not too deep and can be planed out.

Does anyone know about Bill's Cylinder Head Service in Phoenix? It doesn't look like he has any web negatives that I can find. Though I can send the head to Metric Motors in L.A., I would prefer to drive it to a local machine shop in Phoenix (if I can feel confident about it).

While taking it apart, every connector on the upper engine wiring harness broke. The wires are somewhat pliable, but the black tubing and connectors are very brittle. Any idea where to get a replacement harness?

Also, the timing chain guides have worn grooves from the chain, so, I think I'm going to replace all the guides too. This means removing the lower chain cover to access them. Anything special I need to know while doing this?

73Elsinore; you asked if I had a shop manual. Well, not the printed Mercedes shop manual used by techs, but I do have a couple of other manuals (Haynes 3253 & the useless E-Class Owner's Bible) plus I do have the 124 Service Manual Library on CD. Is there one in particular that you recommend?

Thanks all for your posts and help...
Michael B.

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

You should post some pictures of the chain guides before you replace them.
They usually never wear out.

Also, if you have the factory service manual on CD, you are in good shape.
Just be meticulous, and read instructions various times to gather the concepts they convey.

The bottom chain cover is fairly easy. Just be careful with the oil pan gasket. Your chances of a leak are much less if it does not get broken in the process. You probably also want to change the front crankshaft seal, which should be inexpensive. You will have to remove the viscous fan mount, which has a little rubber seal and a special bolt to seal in oil. (This is where the belt tensioner "arm mount" bolts to the engine. Follow the instructions carefully for reassembly.

And enjoy! This is a fun rebuild if you're not impatient.

Congrats on getting it apart.

I understand your wanting to go with a local shop, but Metric sees these heads all day long and have done so for years, they know these heads/motors inside and out, and they know exactly what to look for in regard to damage. If you look in your CD manual there are several sections covering internal cylinder head cleaning and repairs (oil galleries cleaning and reseal, etc.). Metric did all these on mine without my asking for it. Another machine shop may not know about these. Not saying they're not reputable, but there is a lot to be said for experience. In my opinion it's worth the shipping and the little extra cost to go with experience and direct knowledge. He will also know to look for the areas of corrosion damage in the head and will weld these areas back and re-machine.

Note the corrosion areas on the block deck between the water jackets. Mine was exactly the same. I was freaked out about this but Metric says this is common (there's your direct knoweldge again) and as long as the corrosion has not proceeded into the sealing area around the cylinder bore you are OK. I had some corroded areas that were about 0.020" deep. I tried to fill them with JB Weld but it didn't hold - too thin.

This will be sussed out when the head is cleaned and inspecyed for cracks. If it's a crack they can weld it and repair it.

The connectors can be had individually from MB and replaced. You need to look at the wires themselves. There is a lot of info on the forum here about the cracking insulation on the harnesses. Do some reading on that before you decide to replace just the connectors vs. the entire harness. Last I heard, the replacement harness is about $900 from the dealer. I do not know if they are available aftermarket. If you are an MBCA member, lots of dealers will give the club discount.

As the other poster wrote, I also have read that they rarely wear out, but mine had pretty good wear tracks in them so I elected to replace mine, as well as the timing chain also. Plus this now gives me an all-new top end on the motor. The front cover job can be a PITA despite what else you read here. It is not easy to remove because it is glued on and it is a registered fit using dowel pins. And there is a chance you will damage the oil pan gasket. When I took mine apart, the oil pan gasket was undamaged, so I replaced the guides, chain, and front cover seal and put it all back together. Then, while working on it one day, I accidentally dropped the timing chain down into the oil pan (it wasn't joined yet) and I was not able to fish it out so I had to pull the front cover off again. Well this time when I pulled the cover, the oil pan gasket self-destructed into a zillion little pieces. The gaposis between the bottom of the timing cover and the top of the oil pan is too thick to just seal it with sealant, so I had to pull the oil pan to replace its gasket. That was a difficult job.

If your chain guides have not been replaced, the updated replacement guide on the tensioner side is wider than the old one. That means the timing chain must be loose when you reinstall the cover otherwise you can't fit the cover past the new, wider guide. &^%$!! Found that out the hard way.

Make sure you disassemble the chain tensioner and clean it out good. You have to reset the ratcheting mechanism when you reinstall it or else the chain will be too tight and you will bust a cam when the motor starts. The manual tells how to take it apart.

The CD manual is what you need and that is what I was referring to. It is just a crummy scanned electronic version of the paper manual. I suggest you go to this site and download the index to use with the CD manual - it makes it MUCH easier to navigate through the CDs:
http://web.mac.com/dakota/Mercedes/Indexes.html
The E Class Bible has its place in the literature for this car as a reference book and for the owner who wants to do some of his own maintenance. It was not intended to be a manual a la Haynes.

Hope this helps - let us know how it's going.

I think your guy in AZ could be just as qualified. If you're reasonably sure that he does good work and knows the m104, you should go for it....just know your tolerance for resurfacing the head's mating surface. Did you measure your chain-stretch before you removed the head?

Called Bill's Cylinder Head Service in Phoenix yesterday and asked Don if he knew Mercedes heads. He said, sure. I asked, specifically the M104 engine? He said no. I then explained this engine is the DOHC in-line 6 cylinder and he said he didn't know that it was called the M104. Ok, I'll give him that since a man can't know everything. So I talked about the blemish on the deck of #6 and he said he could pressure test it, but didn't suggest he could repair it. I felt ok about that conversation, but made another call to Metric Motors in LA.

While talking to the guy at Metric Motors, I immediately felt he knew his business as he espoused confidence and knowledge of the engine. The minimal estimate to clean, inspect and test the head is $740. Slightly more if it needs any valves or springs. I mentioned the blemish on the deck of #6 and he said he has seen that before and though these heads don't usually crack, they do sport these blemishes from time to time, however usually near cylinder 3 & 4, especially if it overheated. To my benefit, this engine didn't overheat. It ran up over 100*C for short periods here in the desert, but never overheated.

So, all that said, I will be sending the head to Metric Motors in L.A. Two days travel time, to and fro, plus 3 days in the shop. About a week from now, I will have the head back and hope to have the lower half ready for the head. Any suggestions relative to cleaning and inspecting block surface area? I have done this a dozen times on domestic cars, but never to an MB.

Now to find a blanket to wrap it in and a box for shipping as this was the recommended way to pack it.

More later as the saga continues.
Michael B.

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

why is he charging $740 to pressure test, clean and inspect the head? WAY to much....

unless he is doing some seal work on it, you are paying too much..

I sent my head to a machine shop that does the m104 engines. he cleaned it, pressure tested it, and even lapped one of the valves for $85 .....something in your quote is not right......

__________________
1993 300E, 2.8 M104 .....

Well, I don't know exactly why it's so much, but what I have heard from others is they DO know this engine and DO ALL the engines for the Mercedes dealers in the LA area and also DO many engines for the a Mercedes classic car club. I think this also includes the valve springs.

$740 is half the price of an exchange head ($1450), so I thought it was a deal! $85 for doing your M104 head? Dang man, that's cheap enough to send it twice, with overnight shipping. Can he weld the head if necessary?Does he replace the springs? Does he put new guides in it? I will call them again to find out exactly what I get for $740. Can you disclose who this guy is that is leaving all this $$$ on the table?

Also, can someone else tell me why I should spend an extra $655? Plus more if it needs valves or welding?

Thanks!

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

I am no expert on this, but cleaning, pressure testing, and checking are not really DOING anything when it comes to these heads. if he is going to dig into it, and take things apart, or rebuild it then the quote will make sense...other than that, something is not right....call them and ask...

other more experienced members will have a better insight on this than me...

__________________
1993 300E, 2.8 M104 .....

If you read the info on Metric's website, the $740 is for a 'basic valve job': disassemble, clean, inspect, surface the head, install new guides and seals, cut new valve seats, grind/face the valves, clean and reseal the oil galleries, blah blah.

Mine was $1150 out the door which included shipping both ways. I had the basic valve job, plus a lot of problems. All my exhaust springs were out of spec and had to be replaced. I had one pitted exhaust valve and I had corrosion damage that had to be welded up and remachined back to spec. They sent me back all the bad parts so I could check them if necessary. The one pitted valve had a single pit about 1/32" in diameter so that tells me they did a thorough inspection, at least on this valve.

You just can't go wrong with these guys. Every indy shop owner I know uses them and has done so for years. This is their mainline business. If these were Ford 351 heads or early Mopar heads, then sure, I'd use my local shop.

Oddly, I can't go back to when it happened and tow it. I can tell you however that by the time I realized it had hydrolocked, the engine was running. My first thought was dead battery, but on the 2nd or third try, the engine rolled over and started. It wouldn't have done me any good to stop the engine at that point and call the tow truck, because if there was going to be any damage, it would have already been done.

That said, I have the head off now and can see the piston tops. Mechanically speaking if it had bent a rod, the #6 piston (where it leaked) would not have been as high as the #1 piston whilst at TDC. So, I'm pretty confident I didn't bend a rod. I suppose I could measure the stroke to be absolutely certain.

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

Thanks 73Elsinore! After talking with the guy on the phone, those were my sentiments exactly. Going into this I said I wanted confidence knowing that once I put it back together, I wouldn't have to take it apart again for a very long time.

I am taking my time and am not rushing this job one iota. This is why I bought another 300CE to drive while my angel is in the shop. Stay tuned! More after this commercial break and station identification.

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

$740 if he is going to do a valve job along with cleaning regrinding doesn't sound too bad. I paid $230 for all that, but I provided the valve guides + stems...based on what I am reading on his expertise, it may be worth the extra $100 having somebody who genuinely KNOWS that head very well.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I don't doubt the shop's qualifications or knowledge but I think at $740 your paying a hefty premium for a reputation. Is shipping included at least?? I would think any reputable machine shop that does a lot of European engine work would be well qualified to do a 80s-90s mercedes 6 cyl head.
I sent mine to a local guy who does most of the work for the MB, Volvo, BMW, VW, Porsche, and etc dealers around here. He did a thorough job, said I'd save some $$ if I stripped it down to the valves and springs and also told me if I could get the parts cheaper than him to go ahead and supply them, which I did. He cleaned and surfaced it (in spec), Checked it for cracks, installed guides and seals, tested the springs. Not sure if he removed the oil gallery plugs before cleaning. Anyway, I think it was about $265 total. Car is running free of leaks and as good as ever with 220K.
I would easily pay a little extra for competent, expert work and good service, but that seems a little high. All that said, if your okay paying somewhat extra for the peace of mind, go for it.

Quick question...

The crank bolt seems almost impossible to get off without an impact gun. I locked the crank with two longer bolts after taking off the belt pulley and pulled with a breaker bar until my back told me to stop. I'm thinking I need a longer breaker bar and will get one today. Hopefully that'll do it. According to the manual, it is 370 nm (270 ft lbs) tight.

One thing I wanted to make sure of was that the bolt is in fact "right-hand" thread. I'm not mechanically (or electrically) inept and understand the "righty tighty, lefty loosey" thing rather well, but was hoping someone could confirm my suspicion. 03-3420 doesn't confirm either way.

For some that may question why I'm taking the Vibe Damper off, I'm replacing the chain and guides while she's apart.

Thanks!

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

When you did the head job, did you check flatness of the block with a straight edge & feeler gauges? It won't matter a hill of beans how good the head is if your block is warped.

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.