Just got a 1976 240d with an automatic.
Its a temporary replacement while im fixing my 300sd turbo.... and my fixing, I mean upgrading turbos (little bit of fab work)

so the new car seems to run good... but on the freeway when i take my foot off the gas, and count to 3 seconds... a HUGE cloud of oil smoke pours out the back! then as soon asI accelerate again it goes away....

are my rings totally shot? or is there something else going on that I dont know about?

another problem.... when i fire up the car.. it idles just fine.. but then the idle will creep up to about 2000 rpm. Put it in gear... and its fine.. put it back in nertral, or park, and it slowly creeps back up...??!!?

is there some weird vacuum thing going on? or is my IP just bad?

I only paid $400 for the car... so i dont really care... it runs and drives.. just want to make sure the smoke problem isnt too severe....

thanks in advance for any advice / thoughts!

-Dan

 

hmmm bad oil rings eh.....

how about the increasing idle? it starts at a normal RPM then creeps up for no reason when in neutral or park...?

thanks!
-Dan

 

how do i know if its a 115 or 123? its a 1967 240d non turbo 4 cyl w 3sp auto tranny

when the idle starts to creep up, if i push in on the engine control ****.. it will always slow the motor down... it dosent seem to smoke unless I am at full decel at over 50 mph.. I have had diesels in my shop runaway because of oil seals in turbos gone bad.. I keep a CO2 fire extinguisher handy at all times for that.. those works wonders at stopping runaways!

why do these diesels have throttle plates on them? all the diesels I have worked on dont have them.. except these older ones..?

thanks!
-Dan

 

OK, so i adjusted the valves... BTW.. this is by far the EASIEST car i have EVER adjusted valves on!

and went for a little road test on the freeway.... when i was on heavy decel.. id put my foot down on the pedal just enough to open the throttle plate a crack... and POOF!! no more vacuum, no more smoke! so were onto something here.....

is there anything else in the system that can feed oil into the intake under high vacuum conditions? like the vacuum pump.. or somehow the crankcase vent oil seperator system?

the valves wernt really that far out of adjustment... all the exhaust ones were fine. except for one.. that needed just a tiny adjustment. the ODO dosent work.... mileage unknown..

and the last clue to the puzzle... when the car is in park or neutral... the idle picks up to like 1500 rpm.. AND there is a lot of oil smoke coming out the pipe.... so im assuming someone was right about that as well.. its getting oil from somewhere, and burning it as fuel.

this engine appears to be in good shape..... BUT i dont know... being clean on the outside dosent really have anything to do with it, and it also dosent leak any oil.... and inside the valve cover seemed neat and tidy... no sludge or anything...

so whayaddya think? bad motor? rings? SUPER bad valve seals? or my hope... something else in the system thats leaking oil into the intake..?

I know this next comment may trigger a speech or 2.... but canI just drill the throttle plate full of holes... or rip it off? :^)

thanks again for any advice.. comments
-Dan

 

and one last note.... today i was driving down about a 9% hill.. and I decided to engine brake... get the usual blue cloud of smoke.. but after a few seconds of that.. the cloud turns gray-white.. and the car tries to backfire! what does that mean? ive never heard a diesel doing that before!??

anyways... if the motor is bad.. I'll stop bugging everyone with questions ;^)

I'll have to do a compression check... it always fires right up, cold, or hot, and idles right away.

thanks again!
-Dan

 

Yes its a 115... the vacuum pump seems to be ok.. I'll check the CCV system.

thanks!

 

I checked the CCV system... no major oil leaks there... yesterday I poured in a can of seal expander... and today on the freeway on normal decel... no smoke! engine braking still produces the cloud... but normal driving dosent! so thats good news!

This motor dosent seem to have ANY blowby... there isnt anything coming out of the oil fill cap, or the breather tube on top...

I took the intake hose off, and saw somthing weird... there was a little copper pipe flattened, and jammed into the hole where the vacuum line attaches (the one that goes to the ip)

see pic...

whats up with that??

I still have the creeping idling problem... but if i push in the engine control **** halfway.. the idle returns to a normal level... and stays that way, till i pull it back out. is there an adjustment spec for the cable that connects to the pump? how do I know where it needs to be set at?

thanks again all :^)

-Dan

 

fixed it!!! there was a problem with the vacuum line that goes to the IP... now it idles like it should... (mostly) good enough for me! thanks!

-Dan

 

Well now im not so sure.... I took out the copper tube, and the idle shot way up to like 2000 rpm. I put the tube thing back in there, and it went back down.... but its still not like it should be... I was thinking that the governor worked off of vacuum... but maybe not?

I check the tube for dirt, and everything looks fine...

I am convinced this is the problem with my creeping idle. but i dont know how to fix it!

as far as the smoke on decel... sometimes after driving on the freeway for a while it will do it, and sometimes not.. but DEFIANTLY dosent do it as much with that copper tube removed...(less vacuum!)

HELP!! no venturi!! make my car idle!!

one other thing... on the top of the IP pump there is a red screw on plastic cap... and under it is just a giant threaded hole into the IP... is that normal? or is something else supposed to be there? there's german writing on the cap...

the only reason im screwing with this car, is the motor runs really well, and seems to have a lot more power than it should... and there is ZERO blowby.. the valves wernt really even out of adjustment... seems like it dosent have "too many miles" on it

thanks!

 

thanks for the IP oil info.. never knew!

as for the venturi on the ip gov.. when i apply a vacuum to the tube.. the car idles down just fine... do i need to replace the throttle body or something? its not getting a good venturi / vacuum effect going to the IP.. i checked the yellow hose... no cracks or anything there..

thoughts?

thanks!
-Dan