The Copper Washers for the innards of the IPs are generally thinner and they are made of a harder alloy.

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84 300D, 82 Volvo 244Gl Diesel

A Phototachometer uses a piece of reflectorized Tap. When I did this on the Volvo I put the Tape on the Crank Damper.

While the Engine is running You point Phototach in the direction about where you put the Tape and press a button and a beam of light hits the Tape and reflects back and the rpm shows on digital screen.

I am not sure if Harbor Freight sells them or not. I got Mine on eBay for about $16 total cost. They may even cost less now.

The other types of Tachometers are Contact type ones and you need to make contact with the center of what ever it is that is rotating and you press it against it and the Plunger turns with what You are checking.

The work OK on shaft ends that were center drilled during the Machining process. If You stick the Contact Tachometer into the center Drilled Hole you have the perfect spot as long as you do not get caught in any moving Parts.
There is also Wheel attachments for them to run off the outer diameter of something if it smooth enough for that. Again the Wheel on the Tach must make contact with the part.

An expensive and spooky one to use is a Strobe Tachometer. My experience with it is You draw a chalk line on the rotating part. You turn the Strobe Tach on and the light Flashes (not unlike a Timing Light).
You adjust how fast the Light Flashes until the Chalk Line appears to stop moving.
It works good but what I did not like using it as I was looking at the rotating Generator Field and at the same time the bright Strobe Light was flashing; making it a rather disorienting Hypnotic experience for Me. I did not feel safe using it around large moving Parts.

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84 300D, 82 Volvo 244Gl Diesel

Just checked and it was there, along with useful and cool information such as injection pump timing, valve lash hot and cold, build date, engine series and even horsepower. I never payed attention to that sticker or even knew that kind of information was on there. Thank you for the useful tip.

I didn't use copper washers on the injection pump itself but on the fuel filter banjo bolts. Can copper washer be used there, or should I replace them? Sorry for the bad pictures, its dark out.

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I did a quick google search and found them at harborfreight. Its a one time use so I am not worried about quality. They have both the photo one and the contact one. Any experience as to which one works better and yield a more accurate result. From what you described I think the photo one will be better as there is little room to position the contact one on a rotating surface such as the crank. Opinions?

Unless you can get the contact tachometer near the crank, I would advice an optical one:

Non Contact Tachometer: Electrical & Test Equipment | eBay

I would get the photo one. It should be much easier to use than the contact one.

I'm baffled by your problem too. I can only think the timing is off...

Those are the ones that gave me the most trouble. Not sayin that that won't work. Saying that All my problems went away when I replaced all the washers with original equipment.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

I did this dance with the seal on top of my fuel filter housing. I eventually put the original washer back in with a rubber gasket of the appropriate size and that stopped the leak.

Retained pretty static air bubble in the pre filter is totally normal. If you have a little time available as what I suggest is a partial tune up on an older diesel. If it is a 616 four cylinder this part especially applies. Make sure you have 15-19 pounds fuel pressure in the base of the injection pump. There are cheap but adequate 0-30 pound liquid filled Chinese pressure gauges on the market for this. Usually about 10.00 at harbor freight.

I have decided that if when using the primer pump it gets substantially harder to push prior to hearing the squeal of the relief valve opening. This indicates to me that at least the relief valve is probably in decent condition. If when priming there is no or very little noticeable resistance increase either the relief valve on the injection pump is soft or fuel is going back by the check valves in the lift pump.

One other test that does not have great meaning or is particularily conclusive. If the return line from the injection pump is closed off. If everything is in good condition you should notice a change of some sort. More power, smoother idle etc. If no change you usually will find some deficiency in the fuel supply system. This closing off the line will not hurt anything as the lift pump does not care if the output from the injection pumps return is closed off for a temporary test.

Personally I like the 616 engines. Keeping the fuel supply system in good condition may avoid a fairly common type engine failure on them. I cannot be totally certain but have a strong suspicion that low fuel pressure may just contribute to the number one rod bearing failures we see on the 616. This requires low fuel pressure over a long time frame though as well.

Running with old partially obstructed fuel filters combined with a weaker output from the lift pump by manufactures design can contribute in my opinion.

The lift pump is more suspect on the 616s simply because it does not operate at as high an output pressure as on the 5 cylinder turbo engines. It is actually another part number but can be upgraded with a tubos lift pump pressure spring installed or substituted with a whole turbo lift pump. Easy junk yard item.

When you have restored proper fuel pressure if not present and problem remains. Study the milli volt thread in the archives if you have a digital meter or can spring five dollars for one.

You could previouisly loosen one injector at a time line nut. Looking for any imbalance from any one given cylinder. Another item is to quickly check that the rebuilt injection pump was installed correctly using the drip method. I really try to keep troubleshooting as cheap as possible but still effective.

The ideal of shot gunning and guessing as a troubleshooting method is both costly and still too easy to miss a problem. I guess this qualifies me as a cheap Mercedes benz owner. Actually I am not really cheap by nature but do not like to waste money particularily.

A working knowledge of the milli volt method can really help locate or clear many types of problems. It is not rocket science but instead gives you a reading of the cylinders individual burn temperature in comparison to the others. The better this is the better the life of the engine and more efficient it may be. You also need or should want all the power that the engine can potentially deliver. The 616 can idle pretty smooth for what it is if everything is in good shape. It also is a possibility that your idle speed is a little low of course but these engines after all these years should undergo the tests mentioned unless running perfectly. You can usually get a little improvement over what is felt to be good. These systems are old and so logically they partially deteriorate with time and milage.

I was also wondering if you had the same symptoms before installing the rancor fuel filter before the lift pump. At low rpm I was just thinking if suction pressure by the lift pump might be marginal. Just a thought by the way.

On the other hand since you had overflow from the return line at idle I suspect it is not an issue. Keep us informed as I suspect there is something to be learn by people like myself as you run this down.

As to several forum members suggestions to replace the copper washers with original mercedes sealing rings, I went ahead and pulled the ones off my parts car. They seem to be in good shape as the ones I replaced with the copper washers were severely crushed. It also looks like the photo tachometer is the better choice. Harborfreight lists them on their website for $40, I will stop by later today and purchase one. Once I adjust the idle I will report back my findings.

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When I purchased the car it was not running. Once I got the engine apart and took the head off I found out that the timing was off and the chain skipped a gear or two. Also the injection pump was installed incorrectly by the previous mechanics. I reassembled the head and set the timing and the injection pump. I followed several threads on the forum so I hope I did it correctly. This was done over a year ago so I don"t remember exactly what I set the timing to. Is there a way I can check just to make sure?

Personally....I would just idle it up, till its running as smooth as I can make it.....then I would drive the snot out of the car....

There are so many factors that can cause the rough idle, it could be one or a combination of three of them.....the IP has been rebuilt by who knows who, you've had the head off...the timing chain skipped a tooth....the car is what 34 years old....your going to drive your self mad attempting to find the issue.....have you even took the car on a long freeway trip at highway speeds? As to burn the gunk out of the engine....

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I am going to mess around with the idle to get it running as smooth as possible.

I actually found who rebuild the pump. Oregon Fuel Injection Inc. in Eugene. Their website is Oregon Fuel Injection, Rebuilt diesel injection pump, turbo, injectors, diesel performance products and repair parts for diesel pick-ups.. Whether or not they are a good shop I don't know, maybe someone has some info or experience. I know I am going to drive myself crazy trying to find the issue. For me this is my hobby and problem solving is part of the fun.

Thing is several months ago the car was running fine and idle fine. What happened in between then and now beats me. I have had the car up to 70MPH for a long period of time. But, since the new injector nozzles, which are supposed to have a 500 mile break in period, I have not had the car up to highway speed.

Thats probably where your problem came from, since you have actually been driving the car, like a car and not a go go scooter....you have successful burnt all the carbon and gunk out of the engine....and now you see the after effects. My car was the same, it sat for 10 years before I got it...with the IP removed....after I got the entire fuel system rebuilt, it idled very very nice....after lots of freeway driving my idle become rough...idled it up enough to smooth it out and now I just drive it....the only cure is to have the whole engine overhauled....did you have the head rebuilt after you pulled it?

How about posting a video of the idle? This way we can see how high is your idea of high? It maybe normal to the rest of us.

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