head gasket change...need help with chain guide bolt

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mindingthepotol

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Nov 6, 2009
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doing the head gasket on my 2.6 190e and i have come across a problem with the chain guide bolt.

it looks as though it has been sheared off inside itself.

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any advice as to how i can remove it..... this is the first headgasket i have done on a 2.6 merc.

i have been following the guide for the 3.0 engine in the how to section, but would like some help on this matter.

thanks

mark
 
that is a very tricky one. what we can see here is a tap that has been sheared off inside the rail pin - oh dear, someone HAS been clumsy! looks like a small crack in the rail too.

i will think about this one. drilling it out will not be possible, as taps are way too hard to drill. possibly it could be unscrewed with a hammer and delicate punch, but most likely it has been sheared when the torque became too high so that is doubtful. possibly you could move the rail forward far enough to get a hacksaw blade behind it and saw through - if doing this, ensure plenty of rag is used to stop swarf getting in mischievous places.
 
Would it be possible to destroy the guide around the pin. Then grind two small flats on the pin back from the front rim by (say) 6mm then get molegrips on the pin and into these flats, then somehow attach to a slide hammer. (note to OP...this is how the pin should be removed normally)

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again, if i was to destroy the guide... can these still be obtained from mercedes..
 
the plastic guide is obtainable, but would require front case removal to change, this is not a small job! the pin is also available, and could be extracted from the head when the head is removed - this is what i would do (saw off as above post).
 
Having said that Alexander: the guide is knackered and really should be renewed anyway despite the difficulty. It is split and the pin hole is elongated. (maybe that's intended?) Is there more than one pin holding it?

edit. The EPC shows two pins so probably you're right. It is easier to saw it off. :doh:
 
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On the OM605 there are two pins holding the guide, this is the top one in the photo using stud/socket to extract the pin (it's a friction fit)

If both pins are removed you can slide the guide out.

What I would try and do here is to remove the second pins lower down (if its there) and then unbolt the sprocket attached to the cam shaft, hopefully this would allow you to remove the head with the pin still in.

If you have a chain tensioner to the left remove this also, this will give plenty of slack on the timing chain to manoeuvre.

Worth a try but may not apply to your engine.

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ahh, ok - if the tap hasn't gone all the way through I would try and get a hacksaw blade in-between the head and the plastic guide.

Might take some time but they are only mild steel and quite soft, this way you dont have to remove the front to replace the guide.

Should be easy enough for a work shop to extract it once the heads off.

You would need to be careful of swarf/filings dropping into the timing chain cover.
 
ahh, ok - if the tap hasn't gone all the way through I would try and get a hacksaw blade in-between the head and the plastic guide.

Might take some time but they are only mild steel and quite soft, this way you dont have to remove the front to replace the guide.

Should be easy enough for a work shop to extract it once the heads off.

You would need to be careful of swarf/filings dropping into the timing chain cover.

that is a good idea, wish i had thought of that ;)
 
Yes, I think Spock's idea is the way to go - a good wad of grease under the area should prevent any swarf dropping into the abyss, and will be easy to wipe away after the head has been taken off.
 
ahh, ok - if the tap hasn't gone all the way through I would try and get a hacksaw blade in-between the head and the plastic guide.

Might take some time but they are only mild steel and quite soft, this way you dont have to remove the front to replace the guide.

Should be easy enough for a work shop to extract it once the heads off.

You would need to be careful of swarf/filings dropping into the timing chain cover.

If you do that how do you get the rest of the pin out?
i would have thought you would try and keep the pin intact so you can grip it with something
 
If you do that how do you get the rest of the pin out?
i would have thought you would try and keep the pin intact so you can grip it with something

Once you have the head off the car, it's quick, cheap and easy work for a machine shop to drill the remaining stub out (or at least to thin the walls so it almost falls out!) - they can bolt the head onto their machine and drill square and true easily - while the head is in place on the engine, it's a difficult job to do by hand without risking damaging the head.
 
yup, it would be easy to drill, thread and pull the stub out. i doubt the broken tap could go in that far so that would not be a problem.

thanks for the appologies n/c, also, go easy with me and the cosworth job on the other side please!
 
great minds do think alike, but then fools seldom differ. i just got there first david, i am sure the solution is obvious to you too.
 

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