Hi
I have a 1957 180D with the OM636 diesel engine. The compression numbers are (cylinder 1,2,3,4)-- 330, 380,350, 320 (psi). The oil pressure is about 90 pounds at start up but then as it warms goes down to about 30- 40 pounds. Runs pretty good, no severe smoke. Just doesn't seem to go too fast. I have a 190D with the OM621 engine which runs very well as a comparison. So its not like I don't have diesel experience! This is my first time with the OM636.
Any thoughts?
Thanks Angus

Well, it is a pretty small engine, so there's already a certain amount of lack of power built in.

I looked up some photos of this setup, and I see that there are two adjusting screws mounted to one end of the throttle shaft. One of those screws controls idle speed, and the other max throttle. One thing you could try is turning out the screw that controls maximum throttle position. Allowing the throttle to open more reduces the vacuum signal to the governor thus producing more fuel at max position.

I'd go easy with this, though. You don't want the engine to deliver too much fuel. I'd go by how much black smoke you might see on acceleration. If you make an adjustment and notice a whole lot more smoke I'd back it off some.

Later cars with the OM621, OM615, and OM616 engines have top speed marks for each gear on the speedometer dial. These can be used as reference points when dialing in the governor, as in the car should not go faster (or slower) in 2nd and 3rd gears than those marks on the speedo with the accelerator pedal floored. Maybe your car has these top speed marks on its speedo, too.

I just thought about something: Before touching the injection system, it would be a good idea to check for fuel starvation. Have you replaced the fuel filter(s)? Are you sure the lift pump is working correctly?

Hope this helps!

__________________
- Greg -
1973 220D, The Prodigal Benz
1974 240D

I’ve driven a couple of 180D’s and your experiences are pretty normal.

As I recall its 40hp maybe?

Top speed on level ground and not into a headwind is about 65-70 mph and it takes the entire state of Kansas to reach those velocities.

It was a very different time period.

The OM621 was a significant upgrade.

if it has the pneumatic throttle controlled IP, the spring may be tired. may not be getting full travel.

__________________

1977 240D auto w/OM616.916 engine
2005 Matrix 5spd
2006 Prius

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Thanks guys,
I'll look at the injection pump setting screws as suggested. I think the comments about it not being a hot rod are probably valid!

Any comments on the oil pressure fluctuation or the compression numbers?
The oil pressure on my OM621 never changes through idle to full speed so I'm not used to the OM636 dropping down at idle like it does.
The compression numbers according to the Mercedes manual say anything below 270 PSI requires attention. My numbers were all above 320. Is that ok? What would new rebuilt compression numbers be?
thanks again Angus