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84 300SD slightly rough idle with minor smoke from exhaust

Submitted by DougTx on 17 June 2008 - 9:53am.
Hey there. Quickly I have an 84 300SD. It is in VERY good condition, everything works (kinda scarry) AC,cruise,acutmatic climate control, I mean it is in really excelelnt shape all the way around. 139k miles and I bought it a few months back. I have done your diesel purge, paid a very reputable shop to do a vavle adjustment and they replaced a vacuum pot that was causing a little shifting gremlin. Anyway all is fine except that a new glitch has occured. I started the car the other day and the idle was a bit rough. Nothing earth ratteling but I also noticed that there is a little smoke coming form the exhaust and ther used to be quite literally none that you could see. I am thinking fuse for the glow plugs or maybe a glow plug bad? Air in fuel lines (I just got your new primer pump in mail and am about to install with my all new suspension from you)? Anyway, thoughts on anything I might be missing you sincerly be most appreciated. I am having tons of fun buying stuff from you guys and fixing up the last few little things to make it my perfect 300SD. Thanks a ton in advance. Doug in Dallas 300SD 1984 (126) 139k miles
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Clarification needed

17 June 2008 - 11:23am
admin

Hi Doug, does this roughness and smoke go away 30 to 60 seconds after startup? Does it only do it at a cold startup?

Did it do it right after they did the valve adjustment? Kent

Clarification

17 June 2008 - 3:23pm
DougTx
Doug 1984 300SD It does seem to get better after warm up, but sitting at a light sometimes it will shudder a little at idle, it is not consistent and I can see little bits of light smoke from the rear. Under acceleration it seems fien but that could be masking the issue. Yes it happend right after valve adjustment. Thanks Kent... Doug

Suspicions

17 June 2008 - 4:33pm
admin
Your symptoms are very typical of having one or more of the intake valves too tight on clearance adjustment. If it did not do it before then that is where I would start.

300SD Rough idle and light smoking after valve adjustment

20 June 2008 - 7:04am
DougTx
Doug 1984 300SD Thanks for the help. I called my shop and told them what you had mentioned and to my surprise they told me to just bring it in and they would check them all again no problem. I will be dropping it off Tuesday. Thanks again for all the great help and parts... Doug in Dallas