I just got my 300SEL 3.5 M116.981 overhauled, all original parts, I´ve driven 2k miles. The engine runs good, I had to disconnect the air temp sensor because it was making it run very rough. Every 2 or 3 days it will smoke like crazy for a few seconds(we are talking big cloud of white smoke) and then it will run ok again......any suggestions?

Does it do this at op temp? idle? when first started?

Perhaps you need a new air temp sensor?

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82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
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93 300E 195k

It does it @ operating temp, never when it starts, you are just driving along, suddenly you look on the rear view mirror and there it is, a thick cloud of white smoke..... takes 20 seconds and it's gone. You drive another 250 miles and nothing. I ruled out valve seals, since it always has clean starts, piston rings woud smoke almost all the time..... I'm thinking it could be a fuel inyection problem?? I have a brand new ECU, wiring harness, trigger points, pressure valves....they only thing I didn't get new were the inyectors. For some odd reasonn the air temp sensor (also brand new) messed up the engine so I disconected it. Could a bad inyector be casusing this?