72 - 350sl won't start - PeachParts Mercedes-Benz Forum

afmcorp · #1 06-15-2003, 11:15 PM

well i think i found the problem. my 72 has sat for 2 years now and i started the detailing etc: that it needed. garage kept. it got started every couple of months and ran fine until 3-4 weeks ago. i had gotten one side done so i wanted to turn it around any way...tried several attempt at starting including using starter fluid down the throat. nothing not even on starting fluid. well everything seemed to check out ok (you name it the po had just replaced it)but the ignition was poor at best if at all...just by accident i threw my vom at the rotor and found i couldn't get a thru connection. now i'm on to something. nothing i did to the rotor or it's mechanism seemed to give a connection to the front striker.

now my real question is can anybody explain to me what the spring mechanism does. there seems to be a ground that touches the inner shaft of the dist. then there is a spring loaded piece that can go back and touch that gounded piece. but the gap between them is too great for an electro magnet effect and centrifugal force is out. so what does it do. now the center piece of the rotor gets it from the coil thru the dist cap fine. but the connection between the striker and the center piece is buried in a black mixture. but there is no connection. movement of the center mechanism does nothing.

does anybody know how this rotor works.

any help is appreciated.
tks
craig

erubin · #2 06-16-2003, 11:25 PM

I have a 72 350Sl (more correctly called a 450SL). I take a stab at this.

I understand there are two style rotors for our year car. The rotor you showed in the photo is for engines 005019-030108. Are you sure you have the correct rotor for your car? The other rotor which is the one in my car (see photo) is dead simple, no springs or other gadgetry.

william rogers · #3 06-16-2003, 11:41 PM

why is it more correctly called a 450 ? Mercedes made a 350 sl from 71 to 80 I worked on friends Euro 73 350 SL 4 speed manual for a year ,very fast car tight car. Im not sure if all the 350's were Euro models or not..........
William Rogers.........

hill · #4 06-17-2003, 01:05 AM

Quote:

why is it more correctly called a 450 ?

Because it probably has the 4.5 lt engine and the automatic three speed. I have gone through the European and the US spring specs and the European models have tauter springs. The 3.5 in the euro models has higher compression and I think it weighs less. The reason I prefer the US 350 over the 450 is because most of the later 450's had power windows, climate control, ugly bumpers and a few other doodads to break.

erubin · #5 06-17-2003, 02:27 AM

The 107s MB imported into the US in early (all of?) 1972 were equipped with 4.5L engines but were badged 350SL! This has nothing to do with the more attractive, less oppresive (in my opinion) US style bumpers that came out in later years per US mandate. In 1972 the 107s sold in europe had engine options that maxed out at 3.5L.

Dealers in the US were made part of a recal campaign that allowed US "350 SL"s to get rebadged (correctly) 450SL.

The theory for this "mistake" was that MB did not want to allienate their undersized motored Europeans by offering only Americans a 450SL. I have a 1976 letter from MB that explains this.

The correct trunk lid badge depends on the original engine in the car. MB badged the trunk lids with 450SL if the car came equiped with engine numbers starting with 117982-12- and cars that came with engines starting with 116982-12- are correctly badged 350SL.

I have a friend who has an old 107 that was badged by MB Germany with 280SL on the trunk lid! It looks just like my car but the engine is 2.8L and it's a standard trans. He imported his car privately from Germany. He also wants to sell his car (perfect condition).

But what about that ignition rotor in afmcorp's car?

neileg · #6 06-17-2003, 04:11 AM

I'm not familiar with this engine, but there are a number of Bosch distributors that use a spring loaded rotor arm, and it is, indeed, a centrifugal rev limiter.

I have come across this causing a problem in a european Ford engine when the spring weakens. Perhaps this has happened to yours?

afmcorp · #7 06-17-2003, 11:03 AM

thank you all for responding.

this is what i found in my research. it is a mechanism to control rev's. at a certain rpm centrifugal force throws out that spring slide and grounds out on the tab.

the front striker is connected to the center pickup (the one that touches the dist cap in the center on the carbon pickup.) via a resistor.

my problem was i could get no connection from the center of the rotor to the striker. apparently there is a resistor embedded under that black fill. so i'm sure this was the problem.

once i get the new rotor i'm going to did out the black and see what it looks like in there.

FYI the factory calls for a 5k ohm resistance thru this center connection to the striker.

also, this set up was on the car when i got it and drove back to indiana. car ran extremely good, so i assume this is the right set up.

tks much
craig

psfred · #8 06-17-2003, 11:14 PM

The rotors are interchangeable. Usually see the rev limiter on manual trannies, helps keep over-enthusiastic drivers from over-reving the engine in lower gears. Automatic is more self-limiting.

No connection through the rotor will certainly prevent the car from starting!

Peter