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6.9 head removal

Started by koan, 18 August 2008, 03:14 AM

koan


Have finally removed and stripped my cylinder heads, only about 8 months after deciding it needed to be done.

Took about 20 hours over three days of unrushed work with a helper. All straight forward apart for a few difficult to get at bolts.

Only one stuff up, "We" accidentally let go of the end of the timing chain after separating it at the split link. Tried fishing for it but I suspect the end is now in the sump. I was thinking about removing the sump to reseal the joint, looks like a definite now.

All the head bolts were tight, unmovable with a normal length 1/2" drive tommy bar, and even with a 3/4' bar about 600mm long it they were close to the limit of my strength.

There isn't enough room to get the exhaust manifolds out with the heads in place, and the manifolds always seem to be in the wrong place and needed much jiggling to get at the lower two rows of bolts. Undoing the mounts and jacking the engine one side at a time would have got the manifolds out out but I'm not too keen on lifting at the sump.

Took a few pictures at various stages and a few showing the unhealthy state of combustion chambers and valves. I'm off to Europe for a couple of weeks on Thursday so I won't get the pictures up till I get back. The heads go in tomorrow so they should be ready when I return, should have transformation before/after shots as well.

koan
Boogity, Boogity, Boogity, Amen!

WGB

Quote from: koan on 18 August 2008, 03:14 AM

Only one stuff up, "We" accidentally let go of the end of the timing chain after separating it at the split link. Tried fishing for it but I suspect the end is now in the sump. I was thinking about removing the sump to reseal the joint, looks like a definite now.


koan

Uh oh - that's why you put a small length of fine wire through the lower end of the chain before you let anything go.

Can't fish it out with a magnet?

Quote from: koan on 18 August 2008, 03:14 AM

There isn't enough room to get the exhaust manifolds out with the heads in place, and the manifolds always seem to be in the wrong place and needed much jiggling to get at the lower two rows of bolts. Undoing the mounts and jacking the engine one side at a time would have got the manifolds out out but I'm not too keen on lifting at the sump.

koan

The 6.9 engine manual says that the manifolds are not removable with the engine in-situ but I new you could prove them wrong. ;D

Quote from: koan on 18 August 2008, 03:14 AM

I'm off to Europe for a couple of weeks on Thursday so I won't get the pictures up till I get back. The heads go in tomorrow so they should be ready when I return, should have transformation before/after shots as well.

koan

Looking forward to the pictures.

Have a great trip to Europe - Business or Pleasure?

Bill

koan

Quote from: WGB on 18 August 2008, 03:40 AM

Uh oh - that's why you put a small length of fine wire through the lower end of the chain before you let anything go.

Can't fish it out with a magnet?


I really don't know how it happened, we've both done the chain separation before. Helper (son) was handing me bits of the split link as they came off so they wouldn't get dropped down the chain box, next thing I see is the end of the chain sliding down the tensioning rail.

Because the chain goes over the tensioner rail and "under" the curved rail I can't even see it. I fished blindly with a bent coat hanger, I'll try a magnet attached to something flexible but doubt I'll get any time in the next few days.

Quote

Have a great trip to Europe - Business or Pleasure?


Business, conference in Scotland for wife all this week, I meet her there and then we go to Italy for pleasure part. I'm sure we'll enjoy it.

koan

Boogity, Boogity, Boogity, Amen!

koan


We managed to fish out the timing chain this morning, with bright light it could be seen through the gap between the lower curved rail and the tensioner rail, some work with bent coat hanger wire did the job.

Relived I don't have to remove the sump before I can turn the engine over.

koan
Boogity, Boogity, Boogity, Amen!

WGB


s class

You are lucky koan.  When I removed and refitted trusty rusty's sump, it must have been the best part of 16 hours all in all.  Two particularly time consuming aspects :

a) disconnecting the 3 fat oil hoses from the sump (rusted on solid) - I lost HOURS on this

b) re-securing the lower bolts that go into the engine mounts.  One of my mounts had lacked its bolt for who knows how long, resulting in it compressing a bit skew.  If I had fitted new mounts, it probably would have been a lot quicker. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

koan

Very lucky and really pleased to have got it out and not have to leave it till I get back.

Will do the sump at some stage as I pretty sure there's some seepage from the join, and do the three hoses at the same time.

s class, I remember you saying the flange for the hoses had to come off but can't recall if you said anything about the A/C compressor and lines.

koan
Boogity, Boogity, Boogity, Amen!

s class

I had to dismount the compressor - (refitment of which is a bastard too).  I kept the A/C pressurised, but I had to deflect the line that runs in front of the sump as much as possible.  Remember though that my car is LHD, and the routing is different of the A/C.


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

koan

Not getting much done, have my heads back but still no pictures taken.

I did get the valve springs tested today, had to convert Newtons and mm to pounds and inches for the old Repco spring testing machine.

Surprisingly all 16 pairs of springs were with in a couple of pounds of each other and were right in the middle of the range given in the manual. Not bad for 30 year old springs, must be be quality steel.

Also been cleaning up the top of the block and the pistons. After weekly applications of WD40 for about a month quite a bit of the carbon on the pistons wipes off, scraping with a bit of hard timber breaks up what remains and a bit more WD40 finishes the job. Piston tops are clean but not shiny.

I've been greasing the top of the bore and bringing up the piston to TDC before the cleaning. Hoping this is sufficient to prevent bits of carbon getting stuck between piston and bore. Oil feeds and drain holes are taped over.

Waiting on a few parts, gaskets and 32 new valve collets. Don't know if the collets needed replacing but I managed to jam a couple removing them and cost is under $50 for the set.

koan
Boogity, Boogity, Boogity, Amen!

s class

Good progress.  How badly carboned were the piston faces - do oyu consider this cleaning with WD40 has been essential?


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

koan

Quote from: s class on 17 September 2008, 12:52 PM

Good progress.  How badly carboned were the piston faces - do oyu consider this cleaning with WD40 has been essential?


I've put a few pictures of block, heads and valves up here (Garage > koan's bits > Engine Work). Some pistons had more carbon some less.

Essential ? Probably not but I don't think I could allow myself to put it back together in that state.

koan.
Boogity, Boogity, Boogity, Amen!

koan


6.9 Exhaust manifold gaskets are no longer a stock item, have to come from the classic center, up to two months and about $40 each, eight required. The two months is not a problem but $40 for something that should in the single figures seems a bit steep.

There's a place Melbourne which can make up gaskets to any shape out of various materials, usually for liquids and gasses. They have a material, I think Aramid was the name that should be suitable for exhaust gasket use, 1.6 mm thick and suitable for high temperatures, and about $3 each.

Should I go the $3 or the $40 route?

Share your thoughts (am I being stingy?).

While cleaning up various parts today I came to the valve rotators (rotocaps). Would have thought they would have some preferred direction of rotation but they seemed happy to rotate either way with no sign of ratcheting or friction. This was without the pressure of valve springs, just by hand, maybe they behave differently under pressure

Is there any test or check for valve rotators?

koan

Boogity, Boogity, Boogity, Amen!

WGB

I would have thought the rotating action would come from the wiping motion of the cam follower as it pivots as well as any rotational movement from the spring as it is depressed.

M-B engines never gave that much trouble before rotacaps were fitted - it was just a little bit extra to help longevity in the valves I thought.

I guess if all 16 are the same that is the way they are supposed to be.

I have been trying to find my S-class book which mentions when the rotacaps were commenced but cannot find it at present.

Bill

TJ 450

#13
Hi Koan,

It sounds like your making good progress. Regarding the gaskets, I would go for the cheap option providing it's the correct material. The standard ones are quite thick and compress considerably when the bolts/studs are torqued up which is worth noting.

I'm missing the spacer tube for the far LHF cylinder head bolt on my car. Would there be any chance of a pic of yours? 8)
I need to make one up as they are apparently NLA.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

koan

Had another look at the gaskets after posting the query, they are metal both sides and with a gasket material filling, and what looks like a compressable sealing ring around the hole.

Very tempted to go the $3 route but it would be slightly annoying (!) if they don't work out given the manifold won't lift out with the heads in place.

Quote from: TJ 450 on 21 September 2008, 10:38 AM

I'm missing the spacer tube for the far LHF cylinder head bolt on my car. Would there be any chance of a pic of yours? 8)
I need to make one up as they are apparently NLA.


I'll measure and take a couple of pics of it.

koan
Boogity, Boogity, Boogity, Amen!