You need diesel-rated motor oil in the engine because it has to deal with the soot produced in the combustion process. In the injection pump there is no soot, only the camshaft of the IP needs to be lubricated. So you can use more or less any engine oil. Because the oil needs to be changed every time you change the engine oil, it is most practical to use the same oil as you put into the engine.

A little amount of diesel seeps past the pressure cylinders of the IP. This is to lubricate. That diesel collects in the oil sump of the IP. That is the main reason why you should change the oil in the IP. So if open up the bolt, diesel will come out, certainly if you haven't changed the oil in a while.

Excellent!
30wt dinosaur oil is really cheap, even from a top brand so that's what I'll use. I have a few quarts anyway so that'll last me a long time.

Phil Forrest

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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Last night the 220D was running well. I fixed a bunch of electrical issues and got everything but the blower working. It was all corroded contacts.
This morning I adjusted my valves on a dead cold engine and afterwards the engine idles way too high. Its probably double what it was doing last night.

I have the intake off and the engine will *almost* die if I plug the vacuum line to the IP. It will shut off normally if I use the starter to shut down the IP.

So now I'm wondering if one of the linkage rods got out of adjustment when I removed the valve cover? The high idle cable is slack so that's not the issue.

Any help is appreciated.

Thanks all!

Phil Forrest

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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Sounds like you've knocked off the vacuum line that runs from the venturi to the back of the IP governor's "bladder"

(PS with your photographic skills you really ought to some MB pictures)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

That's what I thought at first but it is there and it is intact. I can plug the llittle vacuum line port at the plenum and just about kill the car. Is there another vacuum line back there?
I pulled off the IP oil filler cap and stuck my thumb over the hole. No engine rpm change or different colored smoke.
This thing is confounding me and I want to make sure I don't wind up with a runaway on the freeway or worse, in town on a crowded street.

I'll be posting more Benz photos, surely. I just need to get this maintenance done first.

Thanks,
Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

The accelerator pedal controls the butterfly valve in the intake manifold. From there one rod runs over the valve cover. It connects via a lever to the rod to the auxiliary mechanical governor at the back of the governor housing. If you knock those rods out of whack it will not idle high, but rather low. You could have done something to the control rods from the accelerator pedal to the butterfly valve, but if you remove the valve cover, it is unlikely. The rod runs across along the firewall to the passenger side of the car.

It could also be that the idle was adjusted on the wrong valve clearance, now that the valve clearance is ok again, the idle can be higher. A double idle is however unlikely.

Maybe you removed the spring from the butterfly valve assembly. The spring is there to return the butterfly valve to the idle position.

You could have damaged the vacuum line to the IP, an air leak will cause a high idle.

I can't find any damage in the vacuum line to the IP.
Butterfly valve still closes properly. The valve behind it just flaps freely as I believe it is supposed to, moved only by air volume.

Linkage rods look ok. All are connected and lubed up at the ball joints.

Adjusting the idle screw on the throttle body can't lower the rpm any more. Only shortening the mechanical governor linkage or restricting the vacuum to the IP will lower rpm.

Thanks for the help, keep it coming!
Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

There is only one big vacuum line from the intake manifold to the governor of the IP. Putting your thumb over the oil filling opening doesn't affect the running of the engine, because there is still ambient pressure on that side of the diaphragm.

First adjust the linkage to specs, especially the mechanical auxiliary governor. Do you have access to the FSM?

Is the spring of the butterfly still there?

Have you read these threads on how the pneumatic governor works?
IP running full open on 74 240d
and this one, with a test to test the air tightness of the governor house:
74 240d Grey smoke questions

Yes but reading about IP diaphragm leaks, putting one's thumb over the filler hole is one way to diagnose a leaking diaphragm. Unless I'm reading a thread wrong.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Not really. Better method is the one described in the threads (which is a copy of the test in the FSM).

I just put the MightyVac against the vacuum connection on the IP and it won't hold anything. Diaphragm leak, yes?
I'm pretty sure I got a good seal against the fitting.
(This is the part where I use profanity off-forum.)

But I tried to get vacuum against my thumb which was covering the oil filler hole and felt nothing there either. I have a known good MightyVac as I just used it last nitght and tested it right before I stuck it on the IP housing. Could the fitting be leaking perhaps? Is there another port of air entry into the IP?

Thanks all,
Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Did troubleshooting on the IP and idle speed all I could today.
After not getting the governor to hold a vacuum, I'm of the opinion that the diaphragm might be leaking but I couldn't get eh vacuum to pull on my thumb blocking off the oil filler cap so perhaps the leak is at one of the shaft seals?

This thing is a bit confounding but I think I've dealt with worse before.

Thanks for the help and advice. I can always use more.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

If the governor house doesn't hold a vacuum, it can be because of a torn diaphragm or a leaky axle bearings of the poppet cam or both. The axle bearings almost always leak when they never have been replaced.

You can take off the governor and inspect the diaphragm.

Read also the FSM
07.1 Diesel Injection System - OM616

section 07-125, 07-130, 07-215

When I take the governor off, will there be any small pieces trying to fly away? I have a deep aluminum tray (for cooking) that I'll stick underneath to catch anything that may fall but it looks like only the spring is a lose part on that side of the diaphragm.

Also, will the diaphragm possibly be wanting to come away with the governor housing when I take it off or is is positively attached to the IP side?

Thankfully this area on my car is very clean so I'll be able to see better what I'm doing and just maybe the screws won't be all seized up.

As for the leak, I know the poppet cam axle feels a little loose so it's my first suspect. I'll start the motor and dribble a little oil on the shafts of the cam and start/stop switch to see if I can locate the leak.

I stress out these little (or big)maintenance problems at first but the Mercedes have proven to be so simple and reliable that fixing them is not hard at all.

Thanks to the forum members for all your help!

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson