Author Topic: 300D injection timing question  (Read 5190 times)

merrill

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300D injection timing question
« on: October 05, 2014, 23:44:34 »
so, i am sure Joe or Dan will be able to answer this one.

I have 3 MB's,  66 230 sl,  78 300d and a 98 c230.

my question is why is the 300d injection pump adjustable while the 66 230 sl pump set via the timing chain?

it seems that timing using the 66 230 ls procedure is much more straightforward while the 300d is a pain.
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

ja17

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Re: 300D injection timing question
« Reply #1 on: October 06, 2014, 04:00:02 »
Diesel engines have no ignition system. The heat from compression alone,  in the engine (240 psi or more) will cause the fuel to explode. Injection timing must be precise as it is injected directly into the cylinder under high pressure (1400 psi or more).  This is" direct injection "  and must be precise with-in a degree or two or less.
With early gasoline injected engines, the fuel is squirted into the intake manifold and just hangs around (cloud of fuel vapor) until the intake valve opens and it is drawn in. Combustion occurs when the spark plug ignites the compressed mixture.

As technology improves, more and more gasoline engines are using direct injection for max fuel efficiency and power.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

merrill

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Re: 300D injection timing question
« Reply #2 on: October 08, 2014, 00:41:24 »
Joe,
hi,
Thanks for the response, makes sense to me.

do you have any advice on checking the timing?
I have read various tips on the procedure.  Seems like the 2 most common are
1. blowing thru the #1 orifice with the valve removed while rotating the motor to the proper btdc spec. Air should stop at that spec.
2. blowing thru the fuel input line while checking for the point that bubbles stop flowing thru the #1 orifice while the motor is rotated. ( using a line from the #1 with the valve removed into a can of water or diesel)

both seem more accurate than the bbb method
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230