1993 W124 300D Timing Chain Issues

[i-osprey]

Ok, I have heard the horror stories but haven't had a chance to check mine yet.

I bought the car about a month ago and have been meaning to check the timing chain for stretch. But in the mean time I had to replace all four rotors and pads so the timing chain check got put on the back burner.

My main question is what kinds of symptoms should I experience if I have a slack timing chain?

This engine has NO blowby, NO oil usage whatsoever and I am routinely getting 28.7 MPG in mixed driving.

I am hearing two sounds out of the engine that make me nervous though.

When I shut off the engine, I swear I hear a metallic "clinking" under the hood as the engine stops. When I use the engine shutoff lever with the hood up, I don't hear this.

Also, I ran out of fuel the other day and now have algae contamination throughout my fuel system(Startron enzyme treatment and Startron tank cleaning treatment will be here tomorrow and the next day).

As a result of this I am getting some rough running on a cold startup and even an occasional miss. When I do get the miss, I swear I hear the timing chain bouncing around in there.

Could I have no oil usage, no blowby and normal MPG and still have a slack timing chain?

I will check this weekend for myself but I really need to drive a LOT this week for work and won't have the time to check it before hand.

The engine has 207K on it.

[compress ignite]

The only issue you mention affected by Timing Chain Wear (It Don't "Stretch")
[AND Sprocket Wear] would be Fuel economy, MAYBE!
'Slack Chain puts Injection Pump "Out of Timing"
('Lead Foot? You're a wee bit low on Fuel Economy)
(Injectors original?)
(HINT: Replacing a worn chain WITHOUT replacing the worn SPROCKETS
is counterproductive)

If you're hearing Timing Chain Slap,STOP do not run the engine...
(UNTIL you verify you're not about to BUY a New Engine,Involuntarily)

Those of us who are DIY Afflicted have preliminarily,conditionally,almost
agreed that 100K Miles is a GREAT time to check the Timing Chain System.

If you do not know your engine's complete service history (Provenance) or
if it's been run on Regular Oil (DINO as opposed to Synthetic),207K is past
time to check the Timing Chain and Sprockets.

[i-osprey]

Well, I live in the VERY windy and at times hilly Texas Panhandle so I don't know what my real world MPG might be anywhere else. It has been anywhere from 20-40 mph most days lately, until today when it was so calm the wind turbines weren't even moving.

I am driving anywhere from 72-77 MPH in these conditions.

As far as I know it has always been on synthetic oil.

It is now according to the previous owner and I have yet to change it myself.

I really am worried that I might have some issues to deal with.

I am almost positive that I am hearing something when I turn off the car and occasionally on a misfire.

Any suggestions on checking/changing everything you mentioned?

[rummur]

take the valve cover off and line up the mark on the washer behind the cam sprocket with the line on the cam bearing tower. Then look down on your crank pulley, if its past 2* then you have a possible problem.

I think mb would prefer you do the 2mm #1 intake valve drop technique though, which is easy but you need a dial indicator to tell you when the 1st cylinders intake valve has droped 2mm .08". when you get the valve to 2mm, again look at the crank pulley and you should be near 12*.

I do remember someone saying that on the 603 engines, the washer to cam bearing tower measurement was a good representation of cam to crank timing. Which is good because its easier.

[rummur]

One more thing, on the 2mm valve drop measurment I said you should be near 12*, thats not completely true. I dont know where a 603 should be timed... 617 950 is 12* Should definitely find that out first.

[compress ignite]

rummur's correct (620/603 are the same procedure)

Check procedure:
http://www.w124performance.com/docs/mb/OM60X/OM60x_Timing_Chain_TSB.pdf

Courtesy gsxr.

R+R procedure:
http://www.w124performance.com/docs/mb/OM60X/OM60x_Timing_Chain.pdf

Also courtesy gsxr.

[i-osprey]

Can you turn over the engine using the power steering pump pulley bolt instead of the crank shaft bolt?

[compress ignite]

You'll probably incur "UNTOLD" expense in the Tensioner/Pulley section of the
Belt drive system!

BeLieve Me, I know how much fun it is to get the Ratchet on the Driveshaft Bolt...
BUT, It's the Only Way!
(Ask the Fool,How long it took to r+r everything except the Radiator to get that damn Ratchet on it!
Then to figure out how much easier it was from below!)

You almost HAVE to employ a Helper to watch the Camshaft sprocket whilst You're Below.

[i-osprey]

So, doing it from beneath is the way to go?

Do you have to remove the fan if you do it this way?

I wonder if I can find a creative use of a mirror to pull this off without a helper?

[compress ignite]

Everything's still off the "Deceased" OM602 and not yet on the Replacement
(AND I have early "Mad Cow" so I 'can't remember the fan's clearances)
(Since I was gonna remove everything anyhow...I did not, BUT it may be
possible to get a really long handled ratchet on the bolt from above,without
fan removal.)

Heck, someone over on the UK forum,took the plug out of the side of his
Injection Pump and used a "Mirror On a Stick" to look at and time his I.P's
shaft "Notch",while he turned the crank by hand...After seeing that I'm
almost convinced Anything is possible on these cars with enough Guile.

[JonL]

On a W201 OM602, there is just a tiny bit of room to swing a ratchet on the crank pulley from above. Much easier from below, but then you do need a helper to watch the marks.

[i-osprey]

OK, how do I replace the timing chain sprocket/gear?

And what is the other sprocket/gear? How do I replace that? Where can I find that part?

I ask because my regular parts supplier doesn't seem to have it nor have I yet to see any direction on replacing it.

[compress ignite]

http://www.mercedesmanuals.com/Mercedes_Benz_W_124_Manual_p/w124.htm

(EDIT: Let's drop back for a second.A bad or worn Tensioner would allow
Timing Chain slack.)

First , Inspect the drive sprockets as detailed in the link in reply #6(Above),for Wear/Breakage.

There are three drive sprockets.
(I'm listing in sync with the Cyrillic Pictograms below)
#29 in the first depiction is the Injection Pump/Timer/Vacuum Pump Sprocket.
#23 in the second depiction is the Camshaft Drive Sprocket.
#23 in the third depiction is the Crankshaft Sprocket which does "Double Duty"as it also drives the Oil Pump Chain system underneath.
In order of ascending difficulty:Camshaft,Injection Pump,Crankshaft
The Camshaft sprocket is a breeze compared to the other two.
The IP sprocket entails removing the Vacuum Pump and Finessing the Chain
away from the Sprocket.
The Crankshaft Sprocket would require removal of the Timing Cover,Oil Pan
AND everything in the Belt drive system bolted to the Timing Cover.
It may not be necessary to replace any of the sprockets,BUT a proper
inspection of all the components will tell you what you need to know.

[compress ignite]

MB Club of Russia's Illustrated Electronic Parts Catalog:
http://www.detali.ru/cat/oem_mb1.asp?TP=1&F=124128_15S&M=602.962&GA=722.418&GM=717.437&

GSXR's "WEBSITE" (AKA W124 Bible):
http://www.w124performance.com/images/

Link to free registration of MBNA's EPC for one year:
https://epc.startekinfo.com/epc/subscribe.jsp

(I find the RU EPC to be more user friendly)

[JonL]

Removing the timing cover is a lot of work. The oil pan does not need to be removed however. Let me re-emphasize this. Removing the timing cover is a lot of work.

It may well be time to do it though. You cannot replace the tensioner rail without removing the cover (because of a poor design by MB... it could EASILY have been made differently). You cannot replace the crank sprocket or oil pump chain and tensioner without removing the front cover. The IP sprocket will be easier to do with the cover off. But it is a lot of work. If you are inexperienced, better budget a couple of weeks of part time work. I'd estimate doing the chain, sprockets, rails, front cover etc... will take an inexperienced mechanic 40 hours. I wonder what the book time is.