300SD won't turnover - PeachParts Mercedes-Benz Forum

Boinftw · #1 01-31-2007, 01:23 PM

Long story short, '85 300SD, father-in-law's car, driven by his son. Son is driving the other day, says the car sputtered then quit and won't turnover. Not that it won't start, but it won't turnover. One guy gets out his 27mm socket and says the engine is froze. After reading alot on here, I highly doubt that's the case. Granted, it does have somewhere north of 400k (odometer broke several years ago.) I take of the valve cover and get my 27mm socket out and see what happens. I can move the crank, but only counterclockwise (toward the passenger side) a few degrees. Timing chain isn't moving, on the cam, but the tensioner is adjusting for the slack. Being such high compression, should I be able to really move the crank alot? Another question I'm embarassed to ask -- shouldn't I get some movement in either direction, and which direction is the correct rotation? I'm still trying to procure a good manual for this car, but I gather that the fuel pump/rail/distribution is driven off the timing chain as well? Would it be possible for the fuel system to lock up and not allow the crank to turn in that direction, since the chain wouldn't have any slack between the pump & the crank?

Lots of questions and there's alot I don't know about this car. I'm somewhat used to my 87 190E, but this is for sure a different ballgame. Thanks in advance for any thoughts & suggestions.

TheDon · #2 01-31-2007, 01:29 PM

turn the engine over.. Clockwise only

pawoSD · #3 01-31-2007, 02:20 PM

1. ONLY TURN CLOCKWISE, you may have already messed it up (the timing chain) by turning it CCW
2. does the engine have any oil in it?
3. the engine should not be that hard to rotate with a ratchet on the crankbolt
4. with 400k there's a variety of things that could have happened
5. if the starter can't turn the engine over then it is likely seized

winmutt · #4 01-31-2007, 04:09 PM

Cut the AC belt

pawoSD · #5 01-31-2007, 04:56 PM

Quote:

Originally Posted by winmutt

Cut the AC belt

Thats a very good idea, but if the compressor would have seized it could probably still turn over, and the driver would have smelled the clutch burning away.

Our '83 had the alternator seize, and the starter could STILL start the engine despite both belts dragging over the alternator pulley.

(Made a lot of smoke)

Boinftw · #6 01-31-2007, 05:00 PM

I hope I didn't do any damage myself: it just barely moved and not enough to get any slack in the chain.

I was more suprised that it moved in one direction, but not the other. That's why I got to thinking about the fuel & such. I'll have to put a little more

in it tonight. Clockwise of course.

The other guy already cut it. I was shocked to hear that it could have caused it to shut down. I would have expected a burned or broken belt first.

Engine does have oil -- can't tell much about the age, but it does have some. It's just a little low.

Boinftw · #7 02-08-2007, 09:08 PM

I drained the oil, pulled the sump, and found this at the bottom. I assume the two nuts are off a rod; the metal pieces were similar to tinfoil, but much heavier. Bearing material perhaps?? Can the rest of the oil pan be removed with the motor in the car?

bgkast · #8 02-09-2007, 03:25 PM

Quote:

Originally Posted by Boinftw

I drained the oil, pulled the sump, and found this at the bottom. I assume the two nuts are off a rod; the metal pieces were similar to tinfoil, but much heavier. Bearing material perhaps?? Can the rest of the oil pan be removed with the motor in the car?

Wow

I think the cross member is in the way so you must pull the engine go have a gander at the whole bottom end.

pawoSD · #9 02-09-2007, 05:45 PM

I bet what happened is that your engine with over 400k on it simply died of old age....probably a number of parts in there at that point that are all just about ready to let go...especially if maintenance during the engine's life was not spotless....

Sbean · #10 02-09-2007, 06:11 PM

If you remove the injectors or the glow plugs then there will be no compression to resist turning the engine over. Steve

rrgrassi · #11 02-09-2007, 07:35 PM

Those are connecting rod nuts in the pan. It is possible the connecting rod in the bad cylinder is wedged against the wall and the ecentric rod journal preventing turning, except for CC. It would be easier and less costly for you to swap engines. I did see an OM617.952 on e-bay for $500.

Boinftw · #12 02-10-2007, 11:44 AM

That's what I was afraid of. I'll get it out & opened up a little more just for curiousity's sake. I appreciate all the input.

Boinftw · #13 02-14-2007, 10:16 PM

Indie has a rebuilt short block for sale. I haven't seen it yet, but what are some of the main things to look for regarding a rebuild? I know cranks can't (or shouldn't) be re-ground, but what about the cylinder walls? Can they be polished & new rings added to exisiting pistons & rods with positive results? I'll have to use my current head -- it'll need a magniflux check & new valve seals at a minimum I'd think. Any thoughts or advice on how to approach the replacement block is appreciated.

Not sure if I should post a new thread, or can change the name to reflect the current state . . .. Thanks.

pawoSD · #14 02-14-2007, 11:52 PM

These engines have iron cylinder sleeves, they are removed and new ones pressed in during a rebuild, so you end up with brand new cylinder walls. Not sure on the pistons, I think it depends on their condition, at 400+k that could be hit or miss. Even so, a brand new set is only like 1.5k, not bad when you factor how long they last. A full proper rebuild should cost around 3,500-4,000 for a 617 diesel I believe....metric motors does them best.

bgkast · #15 02-15-2007, 02:43 PM

I would go for a used engine my self.