450 SEL engine problem

1973-1980 : 280S, 280SE, 280SEL, 300SD, 350SE, 350SEL, 450SE, 450SEL, 450SEL 6.9
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Pete49
Adenauer
Posts: 329
Joined: Thu 09 Oct, 2014 4:42 pm
Model you own: w123
Location: Pt Augusta Sth Australia

450 SEL engine problem

Post by Pete49 » Mon 11 Jun, 2018 1:57 pm

Trying to start the engine and all I get is backfire through the air intake after a bit of cranking. With the crank at TDC and the cams seem to align with the marks but I'm not sure which marks as there seem to be 2 marks on the cam sprockets looks like a T and is small and another mark 90 degrees to the right when looking from the front which is easy to see.
The dizzy rotor lines up with the mark on number 1 cylinder. Any ideas on what to look for?
Pete
1978 W123 300D Maple Yellow
1981 W123 300TD Classic White (now sold)
1983 W123 280TE Champagne
1975 W116 450SEL Silver blue

CraigB
OZBENZ Admin
Posts: 4958
Joined: Thu 23 Jun, 2005 1:18 pm
Model you own: I own multiple different models
Location: Hawthorndene (Adelaide)

Re: 450 SEL engine problem

Post by CraigB » Sun 17 Jun, 2018 9:09 pm

Was it running before? I think i have experienced that sort of thing before but i can't remember. Do you suspect someone has played with valve timing? My gut feeling is that is not it. Does it behave different if you put a bit of fuel or startyabastard down the intake? Might help to narrow it down. Sure the leads are all going to the right ones - I have this gut feeling that is what happened when this happened to me - put the leads back wrong.
Craig Baulderstone
Lurch
280s's
280SE3.5
280SL
350SL
500SEC's
560SEL's

Pete49
Adenauer
Posts: 329
Joined: Thu 09 Oct, 2014 4:42 pm
Model you own: w123
Location: Pt Augusta Sth Australia

Re: 450 SEL engine problem

Post by Pete49 » Mon 18 Jun, 2018 3:57 pm

Hi Craig, since posting this I went back to basic mechanics 101. I found the cam timing marks (thanks to the 116 forum) and set up the crank at TDC then checked the cam mark on the RH bank (drivers seat view) and all was aligned correctly. Removed the dizzy cap and there it was ....180 degrees out, set it to number 1 and the beast fired up after a couple goes. Takes a bit of cranking but that's the dodgy points which will be replaced soon. Some people shouldn't be left within cooee of motors. :banghead: All I have left to do is the vacuum locking which doesn't work, adjust LH bank valve rattle and find the wire for the temp sender which is missing and the A/C . Well its now on club reg so no rush :laughing6:
1978 W123 300D Maple Yellow
1981 W123 300TD Classic White (now sold)
1983 W123 280TE Champagne
1975 W116 450SEL Silver blue

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