What does pull start cable on 240D does
 

I have a 77 240D is fitted with 76 or older engine. That has the cable push to stop and pull to start.
The starter switch had been moved to a toggle switch.
When going uphill pulling the cable gave a bit more power.
So what does it do exactly, increase more diesel inj or advanced the timing?
TIA.

Sounds like the pull knob was rigged to the IP. Have you traced the cable to the engine bay to see what it is linked to?

HA! All I could initially picture was a lawn mower type pull start line attached to the motor. I'm trying to learn about MB's on here, but that's would be crazy. Sorry..can't help answer your question, just wanted to share my laugh.
John

The pull-start knob has a cable which is attached to a manual shut-off lever on the injector pump on this model, the same as my '74 240D was if I am not mistaken.

If pulling it makes the car go faster then the cable might not be adjusted properly to have the shutoff lever be fully opened when the pull-start knob is fully extended. There's a bracket at the end of the cable under the hood with a metal clamp that holds the cable, that is how it is adjusted. You loosen the bracket and slide the cable's jacket and tighten it so that the lever on the injector pump deflects properly when the pull-start knob is pulled out. Try that adjustment.

NhDoc
Yes is almost the same as your 74. I don't think I can adjust it any ways, reason the engine barely shuts when I push her all the way in.
I found her start easier this morning when I pull the same time as I hold the starter down.

This is called the Bowden cable as I read from some 240D manual.

Newer ones don't have them.

Is attached tot he injector pump.

Another wild idea is putting a small turbo in it too.
If I don't run too much boost is not going to kill her!
reg Turbos run about 6 PSI. Or fabricate a intercooler or water injection to cool the air.

Being 240 she has lots more room.
Talked to an experienced MB Mechanic, he says the Turbos are identical, except there is oil squirting underneath the pistons. To cool off the excessive heat.
Or put in a cooler thermostat or toss it out.
Need to tap oil line from the cooled side of oil cooler to run thru Turbo and drain it into the valve cover or sump.

Pulling the cable will provide extra fuel. In the stock setup, you pull the knob out to the first position (where it rests) that is the 'run' position. Pulling it out a bit farther turns on the glow plugs. Pulling all the way starts.
The connection of the cable to the lever on the IP should have a slot in it. In the preglow and run positions, the pin will be within that slot. When you pull to start, it is suppoed to pull that lever a bit farther to give a little extra fuel for starting.
Pushing it in shuts off fuel flow. On my 220D, if you unscrew a small bracket that holds the end of the cable sheath, you can rotate the bracket around the cable and move it up and down to adjust the cable to properly shut off the engine. When I first got my car this was misadjusted and it wouldn't hardly shut off!
Does pulling it make more power at WOT? If pulling the cable provides more power (does it make black smoke out the tailpipe?) then you might try looking into adjusting the throttle linkage or the smoke limit screw to provide more fuel via the pedal, since the knob is only intended for starting and stopping the engine. I would think that if everything is in proper tune, that MB would have designed the IP to provide as much fuel as the engine needs at WOT, and that pulling the knob would only provide unnessacary excess fuel - making black smoke but no more power.

I dunno about running a turbo, even a small one. As you found these engines to not have oil squirters for the pistons to cool them like the turbos do. You would also have to do alot of work recalibrating the IP for the extra air.
Whatever you do, do NOT remove the thermostat entirely. Not a good idea because it decreases coolant pressure inside the block. Even dirt track racers don't really run no stat, just a restrictor plate where the stat was. Might try that, but not such a good idea for a street car.

Hi Blue eyes
Thanks for your reply being very informative, is only a wild idea in my head of Turbo her.

bad idea
 

Put turbo on your engine = junk engine.

also forget
 

running wo the stat. a restrictor in place of it is also a bad idea. the stat in a benz is a directing stat. it directs the water to the radiator when the engine is hot enough to need cooling. when cold i directs the water back to the block, bypassing the radiator until the car warms up. if you run the car wo the stat, in cool weather it will never warm up. in hot weather it will overheat cause the water will still mostly be going direclty back to the block. path of least resistance, you know.

tom w

Compression ratio for turbo and natural are different also.

Newbie here, why would adding a turbo trash your engine? Would that be with any engine or just a diesel engine? :confused: Asking in ignorance.

On our MB Turbo diesels the crank has been hardened for the extra severe service, there were oil squirters added to cool the underside of the pistons, and likely other upgrades to handle the higher horspower and heat generation. The ADA was changed to an ALDA on the turbos, so that the IP can increase the fuel admitted with increased boost. None of the items mentioned are present on an NA 4 or 5 cylinder MB diesel engine, so just hanging on a turbo is likely to cause durability problems. This is especially true if the ALDA featured IP is used to increase the fuel charge as boost pressure increases.

So if one was to put a turbo on say a 79 240D, before long it would tear up the motor? Kinda like running nitro?

I am looking at buying a 240D for mostly highway driving but not sure about poor acceleration and low end power. Have searched and found some great info here about those issues but still wondering if there isn't something that might be done to give it a little boost. Thanks.

nothing that won't cause it to grenade prematurely

Get a 4-speed car. Automatic trannies waste power.
Also, my gut feeling says to buy the oldest model year you can find. Probably lighter. My '71 is only about 3000#, so its 60hp 220D moves it around plenty fine. It's not a dragracer, but I'm comfortable driving it.

I'm kinda surprised that Mercedes would build the engines so much on the edge in terms of power. I mean, the 4-speeds are reputed to be able to take alot more power than they are burdened with in stock form, how come the engines are said to give up so fast? Even most domestic engines can take a fair amount of additional power in stock form without becoming a grenade if everything is tuned correctly. Or is it just the non-turbo diesels that are this way?

Answer
 

It is generally speaking, the non-turbo diesels that are this way.

The big failure of MB was the 350 rod bender/head buster = junk.
Very few people will touch them, they are great while they last; but it is a time bomb waiting to devastate your bank account...

well nobody
 

actually said they would grenade. but the turbo engines are built for the extra combustion pressure. heavier internal parts including double topped pistons in which the oil squirters can squirt oil up into the hollow top to cool it. the pans are heavily ribbed to add rigidity. the crank has a longer nose to take a bigger hb. mb built the turbos to deliver years of reliable service and they do. putting a turbo on a non turbo motor would just result in a much shortened life.

if you want a turbo motor just find one, they arent that rare.

btw the compression ratio (mechanically) is generally the same for turbo or non. 21.5 to 1.

tom w