Engine won't turn over - PeachParts Mercedes-Benz Forum

Jub · #1 10-08-2012, 07:01 AM

Hi everyone,

My 1971 Mercedes 250 slowly started to get harder and harder to turn over. I replaced the spark plugs, and the distributer and points seem fine, but still nothing (also not battery; jumped to my other car)

The only thing really that has changed is the weather (90 degrees to now in the 60s). I was thinking maybe it was the choke on the carbs (too tight; I have webers). Or maybe the coils (thinking of changing to pertronix electrical coils plus ignition system).

I guess my overall question is why now this problem (really happened over coarse of about month). Are ignition system issues like transmission issues in that it happens " gradually" get worse; or do they just stop "abruptly" like say a broken headlight bulb?

Thoughts/comments?

Thanks

meltedpanda · #2 10-09-2012, 01:11 PM

when you say "wont turn over" does that mean there is no cranking at all , or that there is cranking, but not starting?

when it runs, does it run well? burn any oil?

is the timing, valve lash and dwell all set to specs?

as others will tell you "could be a lot of things" the more details you provide, the better able we can help

Jub · #3 10-09-2012, 10:38 PM

The engine cranks. I just end up turning the key as it cranks but it wont turn over and start up. Of late, it now just will not start.

Replaced spark plugs, replaced spark plug wireset, and switched batteries.

If this doesn't work: Petronix electrical ignition and coils?

mercmad6.3 · #4 10-10-2012, 02:18 AM

It doesn't matter what sort of car you are working on because there is one basic set of rules;
1/ check compression.A leak down test is the only real way to make sure everything is OK.
2/ set the valves (and check timing chain wear on mercedes.
3/ overhaul all the ignition and get it perfect.
4/ Check fuel supply and make sure you are getting 100% fuel delivery.
5/ Check starter speed and overall condition of starter and battery.
6/ start the engine and double check the timing.
7/ check CO level.

meltedpanda · #5 10-10-2012, 10:04 PM

valves, yes valves;