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More work on the W126

Started by TJ 450, 13 June 2010, 09:26 AM

TJ 450

It says in the service manual to helicoil in the event that the threads are damaged. The "a matter of course" part is rumoured on the usual forums.

FWIW, this block I have here has no damage to the threads.

I didn't actually ask Klaus though. I will be back there on Saturday, so hopefully I will remember to ask him then.

I am always concerned about things going awry, as happened with that steering knuckle you had, S Class. One of the Time-Serts installed in my 6.9's water pump housing was skew, but I was able to get away with it.

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

s class

You can get away with it on the water pump bolts because its pretty low torque.  Head bolts, though, like that steering knuckle, would need to be spot-on. 


[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

TJ 450

I picked up the replacement engine yesterday, a high compression version. I have already started pulling it apart, and it came with exhaust manifolds, some CIS parts, AC compressor etc.

Although I haven't checked the camshafts yet, the heads will be replaced with the rebuilt ones from the old engine (still at the shop now). I notice that one of the exhaust valve guides has become loose and shifted downwards... the respective exhaust port is wet with oil because of this. I expect these old heads to be showing signs of corrosion. They were also rebuilt in the past, as they are painted in the same way as the ones now on the 450.

I asked about the threads in the block. The test is to loosen the bolts, then re-tighten to 60NM... if the threads hold then no helicoil/timesert needs to be fitted.

I'll take some pics of this engine soon.

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

s class

Sounds good.  I hope this engine works out for you.  Not to sound negative, but if the heads have already been off before, it probably lessens the chances that the bolt holes in the block will be OK, or maybe you will find they've been time-sert-ed before?  THat would be a bonus. 


[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

TJ 450

#19
Yes, the fact that the heads had been removed before concerned me. Things just went downhill from there, and seized head bolts have meant that the heads have not been removed yet. Rockers and camshafts have severe wear, as did all main and conrod bearings.

Oil sludge was repulsive, with almost resin-like solid deposits around the camshafts... disgusting.

It became clear that the only useful parts from this engine may be the block and pistons, which happens to be all I really need. As the engine was turned upside down, two pistons were able to be removed, and the bores inspected. The two removed pistons are in excellent condition, as are their respective bores visually. The others look very promising. Streak marks are optical only.

My concern now lies with removing the heads. I'm just not so sure how to do this, as the remaining bolts are corroded into the heads all the way up to the bolt heads, which are now rounded out. I'll start by removing the bolt heads by drilling and go from there I suppose.

Main bearing shells were Glyco, dated 1992. Clearly the entire engine was rebuilt post that time.











As a reference for bore condition, this is the unacceptable porosity of the bores in the original block. Surface should be a uniform smooth grey appearance with no honing marks for these alloy blocks.



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

s class

Removing those head bolts sounds like a nightmare.  Do I understand that you are planning to drill off the bolt heads, and get the heads off, then deal with the remaining studs?


[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

TJ 450

It is indeed. Yes, I plan to remove the heads, then extract the studs. It will be difficult because the problem is actually that the bolt shanks have bonded to the cylinder head, it seems.

Hopefully I'll have some success. I'll see how it goes.

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

TJ 450

I removed/drilled the bolt-heads off, but what should I do next? Drill down as deeply as possible, making sure I don't drill into the block?

Even with just these two bolts holding it down, there is absolutely no chance of this thing moving.

Here's some pics;





Tim

PS, I also posted this on various other forums.
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

wbrian63

If you're not interested in preserving the heads, try pinpoint heating the stud with a small brazing tip on an oxy/acetlyene torch. Heat until the bolt is cherry red and then wait about 60 seconds. Then heat again until cherry red. Repeat this cycle 6 or 8 times.

The corrosion between the stud and the head will conduct the heat from the stud into the head, but hopefully, you can cause the stud to swell a bit and crush the corrosion.

You could also try the heating cycle, and when things are nice and toasty, touch the bolt with a candle - the wax should wick down into the stud bore and provide some lubrication. This trick works handily with stuck nuts and bolts, but since you're not attempting to turn the fastener, I'm not certain this will help much.

W. Brian Fogarty

'12 S550 (W221)
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'76 450SEL 6.9 Euro #1164 - parted out

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter V

TJ 450

That sounds like a good plan wbrian63. The heads are past it now for sure, and I broke a valve when I attempted to use (and break) my stud remover. Stripped threads in the block are not a bother either, as this is an engine where a few stripped out upon removal anyway.

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

TJ 450

#25
I removed one head. The other one remains and is secured by three seized bolts. This one took all week and was only held on by two bolts! I didn't bother to take any photos of the head... it was all corroded out, so I don't feel all that bad about the mutilation now. ;)

Should be self explanatory. I would feel sorry for anyone who purchased a car with an engine like this.






Evidence suggests that these marks/scratches are from when metal filings fell in the bore. Some idiot epoxied in the spark plug after they stripped and reamed out the spark plug thread. I have a severe lack of respect for whoever owned the car that this engine was removed from! >:(


That's all for now. 8)

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

s class

Quote from: TJ 450 on 01 July 2010, 12:12 PM
.......I have a severe lack of respect for whoever owned the car that this engine was removed from! >:(

Haha, love your wording.  So after all this, are you still satisfied that this block will be OK to use?


[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

TJ 450

It's not perfect, but it doesn't seem to have any major flaws. Most of those scratches appear superficial.

I'll have to run it by "The Man" to get the final word.

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

WGB

Porsche use the same Nikasil bores and the trick with them is fine wet and dry sandpaper but only one sweep back and forth from side to side - no more - to break the glaze and assist the rings to bed in.

Bill

Big_Richard

Quote from: TJ 450 on 01 July 2010, 07:31 PM
It's not perfect, but it doesn't seem to have any major flaws. Most of those scratches appear superficial.

I'll have to run it by "The Man" to get the final word.

Tim

Look forward to his response - and his actions after selling you this boat anchor for $500 ;)

I suspect he will have no choice but to MAKE it good enough  8)