161k Do I need to change my Timing Chain?, damaged Injection Pump Timing device
 

I have 161k on my 300d (603 diesel engine). It runs great. It sat for about 2 or 3 years before I bought it. I got it running again with no problems. Anyways, I've already invested a good amount of cash and time into this puppy. Glad I have it's a great car. Very nice acceleration.

Anyways, before I go on my way with this car, I want to make sure it's not going to blow up on me. It's got the 14 head. Oh well, not going to spend that kind of cash and time at this point. But a new Timing Chain is around $110.

Do I need to do the chain job? Also, I've read when I've searched that it's good to also change the tensioner. ANYTHING ELSE???

it's doubtfull you need a chain, but be sure and check the vacuum pump. if it is the open bearing type, it could fail and destroy your motor.

This is one thing that's always kindof surprised me about 603 owners... the 617 drivers have only the open bearing type available and don't really worry about it.

I will of course change it. But when I drove a 617 engine people always seemed to say, 'change it when you hear it knocking'. Isn't there some type of similar warning with the 603's old style vac pump?

Have you inspected your chain and checked stretch? That will tell you if you need a new chain.

nope, no warning, just popped bearings and a destroyed oil pump, or worse.
the 617's have no openings to dump parts into the chain. plus it's a different style vp altogether.

You can measure it yourself.
 

I did mine a month or so ago. You will need a dial gauge and a fairly good base for it. Have fun and FWIW, I did mine and thought 15 DEGREES!!! Oh, I see, not from zero... I did it three more times just to be sure, I have ONE MORE DEGREE to go, whoo hooo!

Can you just measure stretch from the Crank and Cam timing marks? At least approximately?

I would think if the chain had stretched some (and of course no woodruf keys are in place), the cam tower marks would be off when the crank is at Top Dead Center.

So far this is what I will change (chain related):
Chain (of course)
Tensioner
Vac Pump

Anything else adviseable?

You think? Check out what the vacuum pump did to my 617:

http://www.peachparts.com/shopforum/diesel-discussion/151324-stuck-ne-vacuum-pump-failed.html

Refer to post #24 for ugly photo, the whole mess ended up costing about $2500.

oh yeah, I remember your post! but a 617 this problem is WAAAAAY more rare than on a 603. a 603 has that set of bearings just sitting out there and just a little wear and they go all over the motor destroying stuff left and right!

A friend of mine that is on this list found ball bearings in his "early" 616 oil pump screen, :eek: indicating a past catastrophe caused by his diaphragm type VP.

I agree that it is much more likely on a 603, and the consequences are likely to be much worse. I just didn't want to give the 61x owners the impression that it's OK to ignore a failing vacuum pump.

There are many reasons not to just change the timing chain without checking it. The most important is what if the previous owner changed it say 10k ago? Then just a waste of money.
More important is to inspect the chain guide in my opinion. If the chain checks good. There is no really sensible option to getting a proper chain stretch reading. To be accurate you have to make sure that an offset key has not already been installed on the cam. They tell me harbour freight has a dial gauge and magnetic base for about twenty five dollars on sale. Useful for other things as well over the years.

Partially.
 

You can check the cam timing that way, but that only really tells you that you have or have not skipped a tooth. The ZIP file is the FSM specified method and much more precise than eyeballing since it goes on valve lift to 'X'mm. For the 603 you're looking for the cam mark "7" (there is a table for that.) When you rotate to the point of 2mm of valve lift, a NEW chain would indicate 12 degrees AFTER TDC on the damper. The allowable wear on a 60X is "...if a difference of more than 4 degrees of crank rotation angle exists, replace the timing chain." There is no woodruff key for the 603.

Check the stretch. But on a 160k mile 603 their is probably very little. Put another 100k miles on it then start thinking about changin the chain.

I'd worry more about the vacuum pump, is it the old style?

I know a 123 that was destroyed by a vac pump that disintegrated, they aren't immune from that problem but it was a run of the vac pumps on the 603's that were cost reduced or something and are responsible for a lot of dead engines :grim:
Don't wait until you hear knocking unless you like to tempt fate. They can fail before any noises start. Timing chain? If the engine runs strong you probably don't need one. I replaced mine at something like 260K just because the engine was being rebuilt. If your radiator isn't fairly new I would consider changing that as a plugged radiator can lead to a warped head. flushing one out is another alternative but they sometimes crack and leak.

Speaking of vacuum pumps, my "new" 617 vacuum pump just started making noise again (about 60K miles, 1.5 years). I thought it sounded like a loose valve, but it's the silly pump again. My indy is replacing it today. :rolleyes:

Man, your hard on vacuum pumps:D Better take a good look at the little "roller coaster" track on the timing device.

LOL, you are way ahead of me. I just got back from the shop and it turns out the vacuum pump is fine but the timing (IP advance) device is hosed, it has way too much axial movement (which is what I could hear clanking) and the cam is pretty scored up. With any luck my indy can get his hands on a new one (and a new thrust bushing) by tomorrow. If it get put back together, I need to drive it to chicago on sunday.

I think thats the first I have heard of a timing device going south. Wonder why. I had too pull one once and remember having a bugger of a time getting the timing chain off it and then back on. Your engine isn't ready for a chain yet is it.:) Good luck.

403,000+ miles!:D

It happened to me too. So it is not that uncommon.

Tom W

I agree with this. Never change anything you don't know is bad, mercedes parts are just way too expensive.

Tom W

Not sure, but he thinks it may be the thrust bushing behind it that got beat up when the first vacuum pump failed, when I saw it yesterday afternoon they were still trying to get all the down pins out the release the chain tensioner so they can slide it out. Now it has too much play front to back. The chain only has about 70K miles on it, so it's OK.

Ah, didn't notice that, I still hadn't heard of one going bad, now with Tom's story, thats two:)

I don't remember but I think the intermediate gears must be removed also, be interesting too see what those look like. That would be good if its only the thrust washer.

By "intermediate gears" are you talking about the chain sprocket (which does have to come out) or the drive gears for the IP (which come out the back, I think)? Anyway, since they are in this deep I'm having them replace the timing unit (including the sprocket) and the thrust bushing. They are not removing the IP, they just locked everything in place to (hopefully) not mess up the timing.

The "intermediate gears" (2) drive the oil pump and IP .there is allot going on behind that timing device and its all gota come out in the right order, I remember witting too this forum to figure it out :) I put the shaft that drives the oil pump in upside down.

eyeball it for now
 

I would check for stretch the eyeball method first and dig in deeper if not happy with those results. I followed the often mentioned procedure of lining up the camshaft and crank marks on mine at 220k, original chain and they lined up to Zero eyeball stretch, if I had more than 2 deg I would have gone into it per the FSM.

Just make sure to do it multiple times and average your readings, I did mine 5 times over each time showing zero so I'm not concerned. Eyeballing it should get you to within 2 degrees of precision. Since the tolerance limit is 4 degrees I'd recommend checking it with a dial indicator if eyeballing it gives you 2 degrees or more of stretch.

OK, I'm not messing with the IP drive now, the IP isn't even coming out, just the bushing on that shaft (from the front). On the 617 turbo, the oil pump drive is a chain, not a gear drive like the 616.

Edit: on the 617 turbo, it looks like this:

Oh, I was thinking of my 616s, what does gear 104 drive I wonder? Maybe nothing if its a turbo:confused: I know if I was doing that job, I'd wind up retiming everything:)

Apparently that gear doesn't do anything on the turbo engine, but they use the same part.

Mine is now back in one piece with everything replaced. The engine sound is gone and it is once again a happy car, just in time to drive about 2000 miles next week. Now I have to install the cruise control amp and actuator that just arrived from GDL.

BTW, the tech ended up having to retime it too, the IP moved when he pulled it apart. He ended up putting almost two days into it.

:confused: What is this vac. pump everyone is talking about. My 1987 300DT has 151,400 miles on it.

Unlike a gasoline engine, diesels do not create vacuum in the intake manifold so they have a mechanical vacuum pump to support the power brakes and other components. It looks like this, and is bolted to front of your engine:

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ426P1BAXNL&year=1987&make=MB&model=300-DT-002&category=All&part=Diesel+Vacuum+Pump

The problem is, if they fail they can cause significant engine damage by getting small parts into the timing chain area. The design of the pump on your engine has be upgraded over the years, it's not a bad idea to make sure you have the latest version installed. If you search on vacuum pump here, you will find a few ugly stories.

Ah good, your back on the road. I think you're lucky to have a mechanic that dealt with this and got it done in two days. You'll have a much better trip without that noise for company;)

He's good, he heard the noise from about 10 feet away and told me exactly what it was. His tech really worked his butt of to get it finished by friday afternoon. I really didn't want to have to worry about it coming apart while I was driving, I probably would have taken another car if he couldn't get it done.

I read that Craig's mechanic had somehow moved the IP when the vac pump was removed. I think on my 603 the bolts that hold the Vac Pump also are Injection Pump fasteners that are loosened for timing??? Is that right???

If so, how do I avoid messing with my pump timing when I change the Vac Pump?

Mine went bad with 170k showing iirc, although I always wondered if the mileage on that car was correct. I bought it from a small used car dealer.

Tom W

that part 105 is the coupler that attaches to the ip right? I had one of those wear out on my 74 240d. It was really hard to figure out because the ip timing kept getting off. NObody had ever heard of one going bad before. The small indie garage in cincinnati figured it out finally and used one off a 60s 280e iirc.

Tom W

Your IP MAY have a place for a "locking pin" someone will chime in. Its good to learn how to do the timing, not really a big deal once you go through the learning curve and do it once, epically if you have the "pin"

Thats a good thing too keep in mind, maybe an oil passage got restricted and caused the problem.

Yes, 105 is that coupling to the IP.

Just to be clear, you can remove the vacuum pump without affecting the IP, he actually had to remove the IP timing device (behind the vacuum pump). That's the thing that drives both the IP and the vacuum pump and controls the IP timing advance based on engine speed.

Ok... I wonder why he removed that? I've changed a vac pump on a previous 123 300d and I never removed the IP timing device.

Also, on the 603 in my 124 300d I see that the Vac Pump is just bolted on with other bolts. Not the three bolts that are loosened to adjust IP timing. So shouldn't be too bad.

I really cut my arms up getting the fan off though. That 8mm allen bolt is a pain to loosen. NO CLEARANCE!!! Ouch!

I found a great way to break it free though. I taped an 18" piece of conduit as a breaker bar to my allen wrench, supported it well and had my wife click the motor over very quickly. I had to be VERY careful of course. But it worked great.

Actually that engine was the most worn one we have encountered by far. Everything that could wear out in one pretty much had to be redone, including all the oil pump parts.

The car itself was very very clean, a california car, and it showed 50 some thousand but who knows it was a 99k odo on the 115 body and it could have been turned over many times.

When I got it it had a holed piston iirc, with one cylinder that was down. A local indie who enjoys a good reputation but whom I have always fealt leery of had replaced the ip but of course that had not solved the rough running.

Tom W

It was the IP timing device that was the problem, it had too much axial free play so that it was getting pushed back and forth by the vacuum pump. I had a little clank sound (I thought it was a loose valve) when it hit the thrust bushing behind it.

Makes you wonder if the PO ever changed the oil.

Since I retired Iv'e bought several 240Ds with blown engines and in tearing them down, I gota say they all looked good inside, no "sludge" under the the valve cover or in the pan like you'd see in a gasser. I guess Ive never seen a warn out one:P

I figured either it had a million miles, they never changed the oil (like 240joe) or possibly never replentished the oil bath air filter and ran it unfiltered for an extended period.

When I got the car it had a big auxiliary tank in the trunk, so maybe it was used by a traveling salesman who did bags and bags of miles.

Tom W

I just helped a friend rebuild his three cylinder, Isuzu excavator, engine that had been run with a broken air cleaner bracket. We could actually wiggle the middle piston in the cylinder. This damage occurred in only a few hours of running in dusty conditions and the engine really didn't have that many hours on it. Really illustrated the need for clean air in an engine.