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  #1  
Old 12-25-2007, 10:21 AM
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606 head removal

I found my mysterious coolant leak finally, yesterday afternoon when I had the intake manifold off (for GP change). Coolant seeping down the block from the HG on the back corner of the engine, by the oil filter.

My Christmas present? I get to change the head gasket. Yay!

Is it possible to do this without disrupting the timing? I saw some photos somewhere where the cam shafts were locked into place using a drill bit (or proper MB tool if you have that) into a hole in the front of the head. Then the cam sprocket was zip-tied (with multiple ties) to the chain. At that point, you can unbolt the cam sprocket and remove the head but timing remains intact.

Is this a valid procedure?
Any bolts or other hardware that isn't reusable?
Any tips on this job for a first-timer?

Big Thanks in Advance.

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  #2  
Old 12-25-2007, 11:18 AM
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First-timer?

Is this the first headgasket job you've ever done or just first one on a 606 motor?

I just finished this on my '82 320i and I'll just caution you to check and recheck the cam timing BEFORE spinning the starter motor. Turn motor by HAND.

I locked everything in place (I thought) with zipties (camgear and chain) and indexed the distributor to #1 TDC, and STILL managed to get a tooth off! Couldn't figure out what was going on (crappy running) until compression gauge readings revealed 90-90-90-90. Put everything back RIGHT and compression went up to 155-152-155-155.

I was lucky to have no bent valves. I dare say that had it been a 606, my day would've been ruined.

I also seem to recall that the camgears on the 606 have timing marks. I'd recommend getting a hold of a copy of WIS and seeing what needs to be done as far as indexing them, the crankshaft, and the injection pump. Your margin of error here is pretty slim.
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Last edited by deltajetfixer; 12-25-2007 at 11:23 AM.
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  #3  
Old 12-25-2007, 12:33 PM
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Quote:
Originally Posted by deltajetfixer View Post
Is this the first headgasket job you've ever done or just first one on a 606 motor?
First time on a 606 motor (or any MB for that matter).

FWIW I've done HG's and about a dozen timing belts on VW TDI motors, so I'm quite familiar with the precision required in aligning the crank, cam, and IP. I have all the special tools to lock the IP and lock the cam on a VW TDI, even the special computer to check / fine tune the timing - just don't have tools or procedures for a mercedes 606.

I do have the service manual on DVD disc. It calls for the use of numerous MB special tools so specifically what I'm asking about is any tips or tricks to doing the job without the special tools. Any recommendations are appreciated!

Is the chain mechanically tensioned (like a timing belt)? Or is it like the Porsche 911 motor where the chain tensioners are hydraulic, and operate using oil pressure i.e. when the motor is not running, there is only very minimal tension?
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  #4  
Old 12-25-2007, 04:31 PM
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Work Carefully

The main special tool you need is the special socket to undo the cylinder head bolts - there's another recent thread on here that talks about the tool you need.

The cams are held in using 12 point bolts - if you only have 6 point sockets, you might struggle.

You'll need to rig something up to remove the guide rail pins - I used some M6 studding and some washers and tubing to pull the pins out. I took the opportunity to replace the chain guide.

The chain is tensioned using a hydraulic tensioner that's on the left hand front of the engine. You'll need a large spanner or socket to get this off. I used a vice to squeeze the old oil out of the tensioner, and a valve spring compressor and a baked bean tin full of new oil to get the new oil in - the method is described in the manual.

I was quite paranoid about dropping things into the void where the timing chain runs - there are a couple of smaller bolts between the head and block down there.

Tie-wrapping the cam sprocket will work well. I also removed the vacuum pump, and wedged the chain against the injector pump sprocket. But, the guides run so close, it's difficult to imagine the chain coming off.

There's a measurement procedure given in the manual to allow you to check if you need new head bolts - typically, if the head hasn't been off before, they'll be OK to re-use.

When you have the head off, I would recommend that you check all of the onlet valve head heights. On my OM606, the inlet valves on the rear cylinders had sunk - to the extent that they weren't sealing. This is what motivated me to remove the head in the first place.

I did mine in April 2007, and in the interim, there have been a couple of people on here who seem to have the same valve problem - it's worth checking. While the head's off, putting a couple of new seats in isn't a large extra expense if they have sunk a bit.

You'll needa set of injector pipe clips, they're really brittle. Don't think of not replacing them if they fail - your injector pipes will fail from fatigue in short order. If your engine doesn't have a turbo, you may find that you need to damage the rubber/plastic crankcase ventilation ports in the inlet manifold, and so, it's worth ordering a set of these before you need them. Also, as you'll disturb all the thin leak off pipes from the inkectors, it's best to fit new ones.

It's an excellent opportunity to check the condition of the engine wiring harness. I found mine was badly deteriorated, and I've now got a new one to fit, which I'll be doing sometime over the next few days.
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  #5  
Old 12-25-2007, 07:33 PM
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Thanks for the nice writeup Mr. Cruncher!

- I pulled the intake manifold yesterday and replaced all 6 glow plugs.
- I've already replaced the injector return lines with viton.
- The CCV piping did indeed tear at one or two of the nipples where it meets the intake manifold, so I need to order a new one of those.
- The injector pipe clips are mostly broken, so I need to order some new ones.
- I've already ordered a full set of new head bolts, so I won't be re-using them.

I do have the "triple square" sockets, (they're also used on VW TDI cylinder heads).

Tomorrow I remove the fuel lines and valve cover and hopefully the head after that. I'll report back with some photos. Wish me luck!
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Last edited by lupin..the..3rd; 12-25-2007 at 07:40 PM.
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  #6  
Old 12-26-2007, 08:55 PM
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Quote:
Originally Posted by Number_Cruncher View Post
You'll need to rig something up to remove the guide rail pins - I used some M6 studding and some washers and tubing to pull the pins out. I took the opportunity to replace the chain guide.
Is there more than one guide rail pin? I see one looking down into it. I was able to pull this one easily using an M6 bolt, washer, and a socket. I ran the bolt through the socket and into the pin and simply tightened the bolt - pulled the pin right out!

The plastic guide rail feels "free" now, I can wiggle it around 1/2" or so in any direction so it doesn't feel like there are any other pins.

The plastic rail won't come out though. It feels like it's caught on something? I peered down in there with a flashlight and I can't see any other pins, nor can I tell what it's catching on.

Can anyone shed some light on this? I'm stuck at this guide rail and might just call it a night...
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Last edited by lupin..the..3rd; 12-26-2007 at 09:03 PM.
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  #7  
Old 12-27-2007, 10:49 AM
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There are 2 guide pins; one obvious one, which forms the pivot for the serpentine belt tensioner spring; and one less obvious one, directly beneath the top hose outlet stub.


In return, could you confirm a point for me about vacuum pipe routing? There are two valves fastened under the inlet manifold, which control the resonance flaps. Does the white/green vacuum connection go to the 2 forwards pointing ports, with the black, atmospheric, connector to the 2 rearwards pointing ports?
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  #8  
Old 12-27-2007, 11:09 AM
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Quote:
Originally Posted by Number_Cruncher View Post
There are 2 guide pins; one obvious one, which forms the pivot for the serpentine belt tensioner spring; and one less obvious one, directly beneath the top hose outlet stub.


In return, could you confirm a point for me about vacuum pipe routing? There are two valves fastened under the inlet manifold, which control the resonance flaps. Does the white/green vacuum connection go to the 2 forwards pointing ports, with the black, atmospheric, connector to the 2 rearwards pointing ports?
this webpage may help you with the resonance crossover valve connections:

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=210020&M=606%2E912&GA=722%2E438722%2E600&GM=717%2E446&CT=M&cat=19T&SID=14&SGR=170&SGN=09
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  #9  
Old 12-27-2007, 01:40 PM
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Thanks for the web link. It's very helpful.

If the schematic shows the valves in their correct orientation relative to the engine, then that's how I currently have the pipes plumbed in.

I've searched the site for resonance valves, without finding anything appropriate - does anyone know how and when, under what engine operating conditions these resonane valves should operate? I'm thinking of running some thin wires and leds, so I can tell when the vacuum solenoids are energised, but as yet, I wouldn't know if they were working correctly or not.
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  #10  
Old 12-27-2007, 03:32 PM
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Quote:
Originally Posted by Number_Cruncher View Post
There are 2 guide pins; one obvious one, which forms the pivot for the serpentine belt tensioner spring; and one less obvious one, directly beneath the top hose outlet stub.
Crap, that's what I was afraid of. I did notice that one after looking at it again - it's thoroughly rusted and mucky looking. Time to play with the brake-kleen, liquid wrench, and heat.

Quote:
Originally Posted by Number_Cruncher View Post
In return, could you confirm a point for me about vacuum pipe routing? There are two valves fastened under the inlet manifold, which control the resonance flaps. Does the white/green vacuum connection go to the 2 forwards pointing ports, with the black, atmospheric, connector to the 2 rearwards pointing ports?
Edit: I just took a peek and forgot that I had replaced most of the vacuum tubing last year. I used black silicone tubing, so I no longer have the colored stripes.
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Last edited by lupin..the..3rd; 12-27-2007 at 05:11 PM.
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  #11  
Old 12-28-2007, 10:46 AM
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Quote:
Originally Posted by Number_Cruncher View Post
Thanks for the web link. It's very helpful.

If the schematic shows the valves in their correct orientation relative to the engine, then that's how I currently have the pipes plumbed in.

I've searched the site for resonance valves, without finding anything appropriate - does anyone know how and when, under what engine operating conditions these resonane valves should operate? I'm thinking of running some thin wires and leds, so I can tell when the vacuum solenoids are energised, but as yet, I wouldn't know if they were working correctly or not.
pimpernell here, 96e300d, another poster provided this information....hope this is helpful



Resonance Intake Manifold: From CTP to 2550 rpms, both 99/2 (Intake Line Flap-middle of long intake pipe on top) & 99/4 (Intake manifold flap) are closed. From 2550 rpm to 3350 rpm, 99/2 opens & 99/4 stays closed. 3350 & up both are open.
* In viewing a 124 chassis 606 engine, the above was true.
* In viewing the 210 chassis 606 engine that I am working on, I found the opposite happening from 2550 to 3350. 99/4 would open and 99/2 would stay closed. All electrical connections seemed factory. I swapped the vac lines at the swithover valves, Y22/6 & Y22/7, to generate the operation the book calls for and the car runs much better and more pep.
You might know the Mercedes HHT showed 99/2 opening when it really was 99/4 opening before the swap.
* Here's the kicker, another 210 Chassis 606 rolled in for an oil service and it was doing the same thing. I don't know if I have found a true MB foul up or not.
Could this community with the 210 Chassis 606 engine look to see how there resonance flaps are working? This is very hard to put into print and know if I have described what I have found in an understandable way or confused everyone.
Thanks, Michael
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Old 12-28-2007, 12:55 PM
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Thanks pimpernell - that's really helpful info.

From the quick tests of the vacuum valves I did the other day while replacing my engine wiring harnes, I suspect that my system is wired up incorrectly. I'll get hold of some 12v LEDs in town tomorrow, and wire them up so I can see what happens as I drive.

Thanks again!
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  #13  
Old 01-05-2008, 12:33 AM
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Made some more progress tonight. Upper chain slide rail is out. Cams and cam tower are out. Oil filter housing / heat exchanger is out. Had to also remove the starter to get to the oil filter housing bolts. Exhaust is unbolted.

Everything is now disconnected from the head - all that's left is to remove the 26 head bolts and off it comes!! Waiting for my 10mm "triple square" socket to arrive from Snap-On and then "off with it's head"!
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  #14  
Old 01-05-2008, 12:37 AM
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Some photos of the disassembly in my too-crowded-and-full-of-junk garage.

I'm replacing a bunch of "might as well, while you're in there" kind of parts. All the coolant hoses, thermostat, ground strap, some more fuel system O rings (with viton), glow plugs (all 6 came out easy, none broken), temp sensors, etc. Everything is 10 years old at this point so "might as well".






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  #15  
Old 01-05-2008, 09:13 AM
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Hey lupin,

Thanks for posting your progress and taking the time to take pictures along the way. It's really going to help all of us 606'ers with our own inevitable cylinder head removal - whether it be a head gasket, broken glow plugs, timing chain/tensioner/guides, valve stem seals, etc.

What is your current odometer reading? I think I would like to be a little proactive with my engine and perform all of the above repairs before it is 'required'. What else are you planning on replacing while you have the head off? This is my first diesel so I am unclear as to what else is recommended if the head has to come off anyway (ie. clean the prechambers, valve lap, new oil pump)

P.S. I am nervous looking at the one picture you posted with the camshafts on the very edge of your table - do me a favor and put them somewhere where they cannot be damaged!

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