I have a w123 that i have new glow plugs in and it starts so easily and it srays on even on cold weather without having to rev it up,now my w124 has old glow plugs and it is a slow starter,could glow plugs be the factor that causes these sluggish starts,id like my w124 to start fast,any help?

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W123 1985 300TD naturally aspirated

Sounds like you need to check those plugs, good luck.

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83 SD

84 CD

I was having this issue with my w123 even after I replaced my GPs. It would turn over pretty slow when cold (winter). I'm assuming from a 20 something year old starter. I switched to a thinner oil, and have not had that prob since.

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1989 300E 144K