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Hi, I don't know if it would be considered a classic or not but I just bought a 1974 240D with 4 speed Standard shift transmission. I took the front 2 fuel lines off to adjust the valves. ( Made it easier to do the job) and now I must have air in the lines. I am hoping someone can tell me what the red cap on the top right of the injection pump is for.? I took it off and there doesn't appear to be fuel in the pump under it. Should the pump have fuel in it there ? I have dealt with air in the lines before as I have owned several 300 D's but this one is being a bugger to get going. I think a big part is that the primer pump is leaking and needs replaced or rebuilt. I have never seen this red cap on any other Benz Diesel before and am very curios what it's purpose is. Thanks in advance for any help.
I believe the rad cap is a fuel priming hand pump.
You unscrew like 90 degrees and pull it out and push it in to prime the injector pump
God it has been a long time since I worked on a 240D,
1982-84 working during summers at local indy MB mechanic in a New Orleans Suburb.
that German Josef taught me a lot about MB and cars in general
And yes, the 240D is a classic and a tank - Specially when a Stick.
should last longer than cockroaches if maintained.
PS next time try to keep fuel lines on... Make sure you install new valve cover seal as the old ones get hard and end up leaking. - Part of the job
good luck and post up more pics of car - you have a classic!
Thanks for the reply but looking at the picture the primer pump is above and to the left of the red cap.. I did the adjust the valves and put a new gasket on the valve cover but I meant to say I took the fuel lines off to put in new glow plugs. Makes it easier but wish I had left them on and went the hard route :-) My Primer pump is leaking pretty bad so I ordered a new one. I think that will do a better job of priming the injection pump and getting the air out of the lines. Thanks gain for the reply
Thanks for your response. That is a very good video on injection pumps but didn't hit on the red cap ? I will try peachparts forum. Thanks Again.
peachparts forum posts suggest the red cap marked "Oel" which means "Oil" in German, is used to fill oil in the pump. Does this ring true? How familiar are you with this engine?
I just recently bought the car and was doing some maintenance work on it. I got some air in the 2 lines I took off to get better access to the glow plugs. I've had this happen many time before on other cars and I can usually get the air out by using the primer pump. I discovered my primer pump was leaking badly so I have ordered a new one. Anyway that's when I discovered the red cap. I have never seen one on any of my other Mecedes so I have no idea what it is for. If it is for putting oil in the injection pump I don't know how much or what type? I suppose I will doing a lot more searching . Peach parts forum is my next stop. Thanks for your reply. I should have left those 2 lines on and did it the hard way. Live and Learn :-)
UPDATE. I did search on the Peach Parts Forum and found out the red cap is indeed for filling the injection pump with oil. There is a plug on the side of the pump that you remove and then flush all of the old oil out this drain with fresh 40wt. oil. When you are satisfied you have flushed it enough wait a few minutes and put the plug back in and you are good to go. There is also a small pipe on the other side of the pump that serves as an overflow in case you put to much oil in. It looks pretty tight access in that area so lots of patience might help :-)
God it has been a long time since I worked on a 240D, 1982-84 working during summers at local indy MB mechanic in a New Orleans Suburb. that German Josef taught me a lot about MB and cars in general.
I also worked for Josef way back in early 80's before I even could get license.
He was back in woods before he opened his new shop on highway 190 service road.
I Learned a lot from him and Billy (I think was his name had the 240Z)
Back in the 80's, a co-worker owned a 240D, of which he was extremely proud. One week, we were doing business with some visiting European clients. The first day when we broke for lunch, my colleague anxiously volunteered to drive us to lunch, wanting to impress our guests with his MB. On the way to the restaurant, one of ours guests asked, "Why do you drive a taxi"?
My 1959 220SE is a gas engine but has fuel injection and the injector pump is very similar to a diesel pump. The red cap is for the oil for the injection pump. You should see a dip stick near it.
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