First I am a auto tech but not on Mb's. Only my own. I have a 91 300D 2.5 Turbo with the 602 engine.
Today I desided to do some maintaince and adjustments. I removed the injectors and checked the spray pattern and pop pressure. All were within 50 psi of pop pressure and all had a good spray pattern. Good, things are going great. While the injectors are out I desided to check the IP timing. Not having the correct equipment to time a MB diesel, i improvise.I found a procedure by Richard Easley which didn't require any special tools. Basicly, you remove the #1 injector line and soak out any fuel you can see where it was unhooked from the IP. You then turn the engine over (glad I left the injectors out for this procedure) until you see fuel just beginning to come up in the #1 IP port. After 5 trys, I averaged the readings and came up with 10 deg BTDC, which is very late. According to Alldate, this engine should just start at 19 deg BTDC. Well my other plan was to remove the timing plug from the IP and turn the engine to 15 deg ATDC and make sure the pointer was lined up with the hole. This is not the perfect way to set static timing but I figured it would be close enough. Well, the pointer in the IP hole was exactly in line with the center of the hole. Now I am confused, so I pull the valve cover and check the cam timing and it was within 1 deg of TDC. So, now I say to myself, What should I do? Well I desided to change the IP timing to as close to 19 deg BTDC as I can get it. When I started, the slots in the IP were all the way to retarded as they would go. I got the timing using Richards method as close to 19 deg BTDC as I could get it. Now the IP adjustment slots are just about centered. I then set the crank to 15 deg ATDC and the pointer was nowhere in site.
Now just some facts.
Engine 602.
Mileage 297,000 miles
Engine now has a little more diesel chatter (expected)
Engine now runs much better (a good thing)

Now my questions.
What am I doing wrong?
What is the best way to set the IP timing on the 602 engine? Remember, the drip method won't work on the 602 because it has no manual pump to pump fuel through the IP.
Should I put it back the way it was?
Should I leave it as is?
Why is there such a difference between the static method and the start of fuel flow method?

Thanks very much for any help or suggestions or hints or advice or comments (all welcome)

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84 500 SEL (307,xxx miles)

The ONLY way to set IP timing is with the A-B light. Maybe your professional contacts can put you in touch with someone who has such a device. Short of that, I don't know which manual method works best. I've used the IP timing lug vs crank pulley at 15 ATDC with acceptable results.

I've seen inductive Diesel timing devices for sale. Not cheap. An inductive pick-up hooks to the #1 fuel line and triggers a timing light. I don't know how these thing work on MBs.

A shot in the dark - maybe the centrifugal IP timing sprocket is sticking.

Sixto
95 S420
87 300SDL

Thanks Sixto for the reply.

What is, and where is this "centrifugal IP timing sprocket" thing. That sounds like something that could cause this problem. I was told by the PO that the IP had been replaced when the vacuum pump broke and distroyed the timing chain and IP. The head was also rebuilt and new IP, vacuum pump, timing chain and guides. This was about a year ago, but it was not used much after the repairs. When I got the car it had a lot of problems, most of which have been fixed.
Thanks again for any help in this matter.

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84 500 SEL (307,xxx miles)

I don't know how a timing chain failure destroys the IP but I suppose anything is possible. Anyway, the sprocket that drives the IP has an advance mechanism. You can get to the sprocket by removing the vaccum pump. I don't know how to inspect the sprocket but to remove it you remove the chain tensioner, turn the crank and cam ever so carefully so the slack is all in the area of the IP sprocket, then 'unfeed' the sprocket from the chain. The bolt that holds the sprocket to the IP has a left hand thread. Such will be indicated by an arrow on the head of the bolt. Hmm... come to think of it, release the IP sprocket bolt before releasing tension on the chain. The sprocket has a splined fit onto the IP main shaft.

Sixto
95 S420
87 300SDL

First, you cannot improvise a timing method for that engine, nor any other MB diesel. You can use a drip tube to set the timing just like for any older MB, or you can use the IP locking tool.

What you need to know is that correct injection timing varies by the tool you use. I would NOT use any method that relies on the you to notice fuel rising in anything, it just won't work well. The drip tube goes in place of #1 injector line with the pressure valve removed from the holder, with timing determined by the point at which fuel stops running freely as the plunger in the sleeve inside the pump covers the fill bore. This is a PITA on the 602 as there is no hand pump, you have to rig up a fuel tank held high enough to generate sufficient pressure to cause the fuel to flow fast enough through the IP to see it stop.

The semi-official method is to use the locking tool to engage the tab on the governor (screw port on the rear of the pump with a plug in it) -- you MUST very carefully rotate the engine in very small increments until the locking tool seats properly, engaging the tab, then read the crank pointer. This will read 15 ATDC (yes, AFTER TOP DEAD CENTER) due to the location of the tab. the pump will NOT be at start of injection, and it won't show fuel rise, etc.

To do it really right, Bosch sells an inductibe pick-up tool in two versions to set the timing. Both screw into the locking port, but are a Hall effect pickup. One just turns on a lamp when the pickup isn't aligned with the tool and anther that is, the other (expensive) one drives a strobe like a standard timing light and can be used to set timing with the engine running.

If you get the timing significantly off, you will have running problems. If you were indeed 9 degrees late, you would have some serious smoke problems, hard starts cold, and lousy fuel milage.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks Sixto and Psfred,
The car actually runs much better (more power) and smoother. I know that any adjustment done by eye is not as good as an adjustment made with the correct tools. I guess it is time to look for help. I don't like to borrow tools, and can't justify buying them just for one car, and I like to "do it myself", then I know it was done right and if its not, its my problem not someone elses.
Thanks again and I will let you know what I end up doing and what I learned from the experience.

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84 500 SEL (307,xxx miles)

The correct way to do this method is set the crank at 15 deg ATDC minus 1/2 chain stretch. Then rotate the injection pump until the tool locks in. So if you determine you have 2 deg stretch you set the crank to 14 ATDC and time the IP. This is a very accurate way to set the timing.

If you rotate the crank with the tool in the pump you can ruin it easily.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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