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M110 Cylinder Head removal

795 Views 11 Replies 3 Participants Last post by  Ortolani
I’m in the process of doing the head gasket on my M110 engine. All is going ok so far, I’m at the point of lifting the head with an engine crane. Its just not coming loose. I’ve removed:
Head bolts
2 8mm bolts at front of timing chain
Timing chain gears and tensioners
All chain tensioner slide pins
Oil return
Exhaust man. Bolts
Coolant lines and overflow line
All accessories per manual

I have not used a pry bar, it looks risky at this point. Suggestions on what I have missed?
Thanks everyone

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I’m in the process of doing the head gasket on my M110 engine. All is going ok so far, I’m at the point of lifting the head with an engine crane. Its just not coming loose. I’ve removed:
Head bolts
2 8mm bolts at front of timing chain
Timing chain gears and tensioners
All chain tensioner slide pins
Oil return
Exhaust man. Bolts
Coolant lines and overflow line
All accessories per manual

I have not used a pry bar, it looks risky at this point. Suggestions on what I have missed?
Thanks...
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1973 Mercedes 280, 2.8l Automatic
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Discussion Starter · #2 ·
Update, the manual I have incorrectly states there are two M8 bolts. Studying the gasket set, there are four holes that pass through the gasket in that area. Problem solved. I hope this helps someone else.
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1966 250SE Coupe
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Glad you found it. As I started reading that, I was thinking, "Are there a few bolts sort of hidden inside the timing chain area?"

I'm glad you didn't force it and wind up breaking something. Well done!
 

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1973 Mercedes 280, 2.8l Automatic
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Discussion Starter · #4 ·
Yeah thanks, brute force has rarely helped me in these cases. Looks like this engine has been apart, wondering why it blew the gasket…

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It didn’t run great just before the gasket went. Bit of a mess.
 

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1966 250SE Coupe
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There's a lot of glare on that photo, but I don't see a failure of the fire rings, either between each other, or outward to a coolant passage. There is a lot of clogged coolant ports around that rear cylinder. Very common issue with these 6 cylinders, along with rot up inside the cylinder head. I'm sure you'll test both surfaces with a machinist's straight edge, to make sure they're truly flat. If the head has ever been resurfaced, and the cut isn't mirror smooth, that grooved finish will promote a failed head gasket.
 

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1973 Mercedes 280, 2.8l Automatic
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Discussion Starter · #6 ·
I’m sure coolant circulated where it wasn’t supposed to. There was billowing white smoke, black water coming from exhaust, and a big drop in coolant from the rad. I don’t see an obvious single point where coolant got into the cylinder. I checked the underside of the gasket and it’s about the same. Coolant has been everywhere under the gasket around 3,4,5.
The coolant passages have a lot of sludge blocking them. Is this the result from Stop-Leak or some additive?
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cylinder four and five look like they have discoloured exhaust valves. Piston six looks like the carbon has been washed off, on the edge.
 

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1966 250SE Coupe
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178 Posts
Ya, that's a lot of corrosion, and the fire rings on the head side, don't look very happy. There's water/rust damage to #4 cylinder walls, indicating to me that the car sat for a long time with water, not coolant, in that cylinder. I wouldn't be surprised if that head is just a little warped.
 

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1973 Mercedes 280, 2.8l Automatic
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Discussion Starter · #8 ·
Update:
I’ve checked the head and block for visible flaws and found nothing obvious that would cause the problem. The gasket is reasonably intact with no obvious breaks, cracks, or burn through.

However I did see the coolant passages in poor condition with blockages. The coolant has flooded under the gasket. It seems the gasket was done before, (victor reinz gasket) and block may have not been torqued down properly.

I measured the headbolts and I found a 6mm stretch from original. I believe they were reused when they should have been replaced.

Has anyone had a head gasket fail because of bad bolts?
 

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1966 250SE Coupe
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178 Posts
Both surfaces need to be checked with a machinist's straight edge, for being perfectly flat at all locations. There's no way to do this without the proper straight edge. Also, I believe there's a retorque spec, per the gasket manufacturer, which is typically 1,000km (620mi).
 

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1973 Mercedes 280, 2.8l Automatic
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Discussion Starter · #11 · (Edited)
Great work! I need to do this on my M110. Could you let me know how you took the chain off? Did you cut it? Can I remove the head without disassembling the chain Thanks!
I did not cut or break the chain to remove the cylinder head. There are a lot of steps to this, but in summary the chain tensioner is removed, the slide pins for the upper Slide rails are pulled out with a slide hammer. (Radiator comes out for this). The cam sprockets are removed and the cams positioned towards the back. The guide wheel comes out, Cylinder head bolts come out and the head will come off, chain intact.
 

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Your information and steps for chain removal are precious. I didn't conform to information that the current should be cut. I prefer to do the job even if I have to remove the radiator and other parts and preserve the current. Thank you very much!
 
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