Engine rebuild questions (280E)
 

Hi to everyone on this forum. My name is Imanol Alamillo and currently live in Mexico. I own a 1980 280E Mercedes that has been through several failures.
The car used to drive great and we used it a lot in travels and whatnot.
All the ordeal started when driving at highway speeds and reaching a work zone. A semi bumped a traffic cone (those big ones :cool: ) and under the car it went, busting a transmission cooler line and spilling oil everywhere. A shop on the side of the road managed to fix the line and refilled the trans.
Since then the car started acting weird, will upshift fine but would not downshift (had to stop completely to engage first gear again and so on).
We decided to go to a transmission shop to have it checked and they took it for a test drive. Long story short, they revved the engine several times and all of a sudden bam! the engine made a horrible sound and died.
Upon disassembly the woodruff key on the exhaust cam was sheared off and valves hit pistons.
I teared down the whole engine and already changed rings, bearings, valves, guides and valve seals along with all the gaskets and seals to have a healthy engine again.
The catch is that the intake cam sprocket went missing so I got a new one from MB. The only problem is that it doesn't have the timing mark :confused:
Do you guys know how can the timing be set correctly without it?
Anyway! Some pictures to show the progress so far.

http://i982.photobucket.com/albums/a...1_192001-1.jpg

http://i982.photobucket.com/albums/a...901_192012.jpg

http://i982.photobucket.com/albums/a...901_192036.jpg

http://i982.photobucket.com/albums/a...106_155537.jpg

http://i982.photobucket.com/albums/a...108_204113.jpg

http://i982.photobucket.com/albums/a...108_204207.jpg

http://i982.photobucket.com/albums/a...109_121201.jpg

http://i982.photobucket.com/albums/a...109_121225.jpg

http://i982.photobucket.com/albums/a...117_174609.jpg

http://i982.photobucket.com/albums/a...117_174613.jpg

http://i982.photobucket.com/albums/a...117_194640.jpg

No first hand knowledge on rebuilding the M110 but here are some good links for you.

http://www.w123gassers.com

1984 W123 280E refurbishment and top-half engine rebuild (PICTURE thread) - Mercedes-Benz Forum

In some respects the intake cam marker going missing is good news! If you look in the factory service manual for the W123 / W126 there's a section for the M110 engine that has a chapter for checking the camshaft timing. This is chapter 05-215. It concerns the position of the intake cam lobe over cylinder #1 with respect to the crankshaft position.

This is often referred to as the "2mm lift" method and is frequently discussed for diesel engines. Whilst there is lots of documentation / internet how to's showing the method on single cam diesel engines there isn't all that much (if any?) for the twin cam petrol engines.

Thanks for the replies guys. I really appreciate it.
So what I have to do is set piston #1 to TDC, exhaust camshaft sprocket with its mark lined with the mark on the camshaft housing and do the 2mm method on the intake cam right?

Essentially - you can align the crank and the exhaust marks and guess the inlet. You need to make an educated guess though. Read through the FSM carefully to make sure you make the correct guess! I have no experience with your engine but based on how a four stroke engine works - it should be about 180 degrees "away" from the exhaust one.

If you can remove the rocker arms then you're golden as you can arse about with the camshaft timing to your heart's content safe in the knowledge that the pistons will not be hitting the non opening valves. Check in the FSM on how you are meant to remove the rocker arms - there might be a different torque value for the camshaft bearing clamps without the rocker arms fitted (There is for a M102/M103 engine)

"The catch is that the intake cam sprocket went missing so I got a new one from MB. The only problem is that it doesn't have the timing mark :confused:"

If you have not yet discovered it, the timing mark on the sprocket is aligned with the center of the keyway. Use of a temporary mark in that location wil allow you to assemble the top end to the block, and with only the rockers for #1 cylinder installed, check the valve timing more closely.

^Classic!

I love the way that block is built,plenty of cylinder walls if you want to supercharge.

I already checked if the keyway is aligned with the timing mark, but even in the original exhaust sprocket it isn't :( . I spent sunday afternoon trying to time the engine and got it assembled in a way that the valves won't hit the pistons when rotating it.
I centered the exhaust sprocket mark with the camshaft housing, put cilinder 1 in TDC and messed with the intake cam until the cam lobe would sit right against the valve rocker. The slightest turn on the crankshaft at this point will start opening the intake #1 valve.

http://i982.photobucket.com/albums/a...217_184435.jpg

http://i982.photobucket.com/albums/a...217_184447.jpg

This is how the crankshaft looks after two complete turns and aligning the cam mark again.

http://i982.photobucket.com/albums/a...217_184618.jpg

I still have to check the "valve begins to open" measurement and the 2mm lift but I'm waiting on some tools to get here. Am I missing something?

is it the original timing chain? you didn't mention a replacement on your first post.

Lastly, would a used cam gear help?

-CTH

The timing chain along with all the guides, rails and tensioner are brand new from MB.
Yes! A used cam gear would help a lot to check the relación between keyway and timing mark.

Thanks a lot!

Hi again guys, there are some good news over here. The timing issue has been resolved and the engine is back in the car.
The only problem right now is all the vacuum connections this car has :D .
It seems there are a lot disconnected and didn't looked up on them until now.
Already have the vacuum diagrams from repair manuals but the car seems to have more than the ones listed.
Is there a way to simplify the vacuum routings or does anyone has pics of a 1980 280E that I could use as a guide?
Here are some pics.


http://i982.photobucket.com/albums/a...331_124144.jpg

http://i982.photobucket.com/albums/a...331_124200.jpg

http://i982.photobucket.com/albums/a...331_124208.jpg

http://i982.photobucket.com/albums/a...DOHC/image.jpg

http://i982.photobucket.com/albums/a...OHC/image1.jpg

The ideas I have so far are:
- EGR valve to one end of the thermoswitch on cylinder head. Intake manifold source to the other end of the thermoswitch.
- WUR big vacuum hose to direct intake manifold source. The other connection on the WUR (¿?)
- Intake manifold source direct to distributor (I think it is a clear/red line), the other connection on the distributor seems to go to a 4 way connection and ultimately to the intake manifold (clear/yellow line).
- All the lines going to the cabin share a vacuum source at the back end connection at the intake manifold (¿?)

Thanks!

This might help

toxonix: M110 Vacuum diagram

And another

http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1438755-need-engine-vacuum-diagram-280te-m110.html

And one more

http://www.scribd.com/doc/38396928/MB-M110-Engine-Vacuum-Connects