Head gasket replacement,
Began Friday night by draining oil & coolant
Saturday 8am began - Sunday 2am finish
Lots of prep/replacements/cleaning
Sunday 2:15am 1st fire success, idled 40 minutes, noted engine running hot (100+) w/ heater on (90) but all air going to defroster, possible coolant air lock?
Sunday 8am, ready for 25 mile runner/break in. 5miles in she loses power and I coast in, call tow.
Sunday 9:45? where or what did I do wrong.
No fire (spark) No turn on rotor on bump? Suspecting a slip up or break in timing area, will inspect this tomorrow night.

Any ideas? I am always seeming to be 1 step behind on learning things the hard way

Should have run at normal temperatures on first startup for future reference. If the rotor is not turning on engine bump, that is BAD. Like your chain is no longer connected to your camshaft kinda bad. Cam gear tightened? Tensioner installed properly, and more importantly, correctly loosened? Tensioner guide rail pin fully re-inserted? You won't know the extent of the damage or exact cause until you tear it down. But don't get down on yourself. It's the only way to learn

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http://i193.photobucket.com/albums/z...-RESIZED-1.jpg
1991 300E - 212K and rising fast...

This chain has broke, nicely though.

The brake is on the 3 o'clock looking at the cam-sprocket.

Since its movement is clockwise??? is it impossible to feed the new chain thru now.

Impossible is a big word possibly the right word!

So onto fastlane for a express shipment > new chain

> New guide rails (In&out)

> Any ideas here ______?
i.e. [tensioner, etc]

When fastlane arrives Im sure there will be the link below this post directing me to a reasonable DIY article on replacing the timing chain and correctly finding TDC---
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Again, maybe I'm wrong. But If the chain "breaks" while driving at speed, doesn't that trash the top end (HEAD, PISTONS, & VALVES)? I've never heard of anybody getting off easy with a broken chain. Usually when the guides are broken to the point where the chain is slapping around noisily is when you turn off the car and get it towed before catastrophic damage occurs. And how in the hell did the chain BREAK anyways?

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http://i193.photobucket.com/albums/z...-RESIZED-1.jpg
1991 300E - 212K and rising fast...

The most likely cause for a chain to brake after a head gasket job on an M103 is that the chain tensioner wasn't re-set before it was put back in. When removed, it t must be pushed all the way through the click barrel and then put back in the front again to reset it. It will then find the proper tension via the spring when the cap is put back on. If you don't, and just put it back in the way it came out, it will be at a setting that can over tighten the chain and snap it within a few miles.
Also, as mentioned above, I believe this is an interference engine, meaning, that if the chain breaks while the engine is turning, the pistons will hit the open and out of time valves causing extensive damage to the valves and pistons.

about 5mph when it broke

Even if it was idle, your pistons still collide with the valves when the chain goes, albeit a bit less serious. I would pull the head to inspect damage.

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http://i193.photobucket.com/albums/z...-RESIZED-1.jpg
1991 300E - 212K and rising fast...

Would it be better to pull the head back out as to re-time the cam shaft to TDC. Then crank that 27mm hex on the block to return this to TDC and then re-mating the surfaces. As apposed to pulling the plugs and rotating the cam and cranks individually to get TDC.

You'll need to pull the head. turn the cam until it is at the TDC position (no.1 valves both fully closed and the distributor rotor pointing to the no.1 tower). Then rotate the engine to TDC (piston no.1 at the top of its rotation and the timing mark on the balance aligned with the reference indicator).

But again, as mentioned above, unless you got incredibly lucky, it would be hard to imagine that you haven't at least bent some valves if not marred some pistons as well. Even turning it by hand while its out of time you can bend valves enough to spoil the seating. Though I suppose you usually would, you don't necessarily have to hear or feel anything when it happens either.

I could be way off on this, but, one thing I find strange is that the chain was still draped around the cam gear. I would think that if the chain broke while the engine was turning, it would all end up down around the crank gear and get bound up perhaps causing some other damage. Unless maybe it broke in two spots? and part of it fell down while the other part stayed hanging over the cam gear (which would immediately stop turning). I'd make sure the old chain is the same length as the new one, if it's shorter, you may have some old chain still down in the lower cover or maybe in the oil pan.

the crankshaft pulley has a large 27mm hex on it, my question is there a lock somewhere for the pulley, like a thru pin ? also is this reg. thread not reverse threaded ? Will I need a puller to get it off ?

Thanks if you can answer any of these

there is a special tool you use to lock the crank at the back of the engine..... but you don't need that to get to tdc.

i have the tool..it's not that big of a deal.

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

x2

you need to do this to inspect the damage.

Regular thread. If I remember correctly you don't need a puller on this application. The crankshaft holding tool is one of my favorite tools.

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Jim

2 Bent Valves, one exhaust #6, and one Intake #4

Pistons ok

Not bad. You did get off pretty easy.

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http://i193.photobucket.com/albums/z...-RESIZED-1.jpg
1991 300E - 212K and rising fast...

Sounds like it's time to cut your losses.
As mentioned, a valve can be bent in a manner that is imperceptible to an untrained eye, but will nonetheless cause a sticking valve or poor contact with the seat, resulting in a loss of compression and/or a host of other troubles. You may have damage you're just not seeing.
I would send the head out to a good reputable machine shop, preferably one that has M Benz experience and have it looked over professionally. Besides, you can't just put a new valve in as a replacement. It will need to be seated/checked with a valve lapper and seating compound. The new valves will also need new seals, might as well replace them all (they're cheap) while the head's off, and it's very likely that the head is due for new guides (and possibly springs). A shop will remove all the valves and check them as well as the guides, seats, springs and a host of other inclusive and important things, making sure it's all in spec. Ask them to make recommendations and QUOTE costs before proceeding. It would probably cost in the neighborhood of 375-450 +/- including parts. A small investment considering you'd be spending 100 or so plus all your time trying a short term patch-up job with any further mistakes costing 2-4 times the machine shop (peace of mind) price.

Edited to add: There are other damage possibilities as well that are often over looked. Consider the cam pushing down on a valve while a piston is trying to push it up. This would cause much stress on the cam bearing tower bolts that hold the cam in place. The threads in the head on those tower bolts in an M103 are known to be a weak point and damage easily. A cam lobe is at risk in such a situation too. More reasons to let a good shop look it over.