'76 300d stalled and won't restart - PeachParts Mercedes-Benz Forum

binder123 · #1 11-25-2009, 08:32 AM

I'm going to look at a '76 300d this weekend. The car is supposed to be all original, 2-owner car with only 90K actual miles, no rust (and not much paint left). Here's the problem, as described by the owner- He was driving it about a month ago, it was running fine, then just started "missing" and losing power, then eventually stalled. He had it towed home, now the engine won't even crank. He's charged the battery and tried to jump it, but it still won't crank with the starter.

The owner thinks it just needs an alternator (?) but I can't understand how that could cause it to stall. Isn't the fuel shut-off vacuum controlled like the W123s? The car's about 2hours from here and I won't be able to get to it till this weekend, but I'm wondering if maybe the engine is seized up. Any ideas what else to look for?
Thanks!

::matthew · #2 11-25-2009, 08:40 AM

alternator wouldn't cause it to lose power or stall.

binder123 · #3 11-25-2009, 10:09 AM

I sure didn't think it would- isn't the shut-off valve vacuum operated?

pimpernell · #4 11-25-2009, 10:15 AM

Quote:

Originally Posted by binder123

I'm going to look at a '76 300d this weekend. The car is supposed to be all original, 2-owner car with only 90K actual miles, no rust (and not much paint left). Here's the problem, as described by the owner- He was driving it about a month ago, it was running fine, then just started "missing" and losing power, then eventually stalled. He had it towed home, now the engine won't even crank. He's charged the battery and tried to jump it, but it still won't crank with the starter.

The owner thinks it just needs an alternator (?) but I can't understand how that could cause it to stall. Isn't the fuel shut-off vacuum controlled like the W123s? The car's about 2hours from here and I won't be able to get to it till this weekend, but I'm wondering if maybe the engine is seized up. Any ideas what else to look for?
Thanks!

I would say that your "engine is seized up" remark is the prime suspect of all the possibilities. You could bring a a wrench along, and try and turn the engine over by hand. If the alternator is bad, that would not stop the engine from cranking with a jump or good battery. If the starter is bad, then a jump or a good battery would not help in cranking it over. You make no mention of price, so I would assume that the owner has lowered it to reflect the non running condition. If I were the owner, and if it were "only" the alternator or starter, I would throw one in, get it back to running condition, and ask a higher price. Its like buying a car with ac that is non functional, and the seller says "It only needs a recharge to work ". If it were only that simple, why didn't he do it himself???? Good luck......

pselaphid · #5 11-25-2009, 10:38 AM

Perhaps something very simple was overlooked by the seller. A bad battery terminal or starter connection would allow the battery to charge, but still not crank.

#6 11-25-2009, 10:40 AM

I agree, it the engine will turn by hand it should be something fixable.

JEBalles · #7 11-25-2009, 11:40 AM

Sounds like a seized engine. The only other case I can think of would maybe be the tank screen causing the stall and then a starter problem at the same time. Shut off valve would still let it turn. Try turning it by hand, make sure to use the crank bolt-only some engines turn by the P/S pump.

tbomachines · #8 11-25-2009, 01:06 PM

The car would run just fine without an alternator. You wouldn't have lights or anything but since these aren't gas engines and dont require an ignition source, the alternator going out has nothing to do with an engine seizing up. If it turns over by hand it is a fuel problem, hopefully it is not seized.

79Mercy · #9 11-25-2009, 02:26 PM

Take a 24mm socket with a good size beaker bar and turn to turn the motor over by hand, clockwise.

diametricalbenz · #10 11-25-2009, 05:15 PM

I wonder if the owner mentioned that it had any oil in the crankcase at the time it started missing.

tbomachines · #11 11-25-2009, 07:56 PM

Quote:

Originally Posted by 79Mercy

Take a 24mm socket with a good size beaker bar and turn to turn the motor over by hand, clockwise.

27mm?

79Mercy · #12 11-25-2009, 08:00 PM

yes, 27mm, i was thinking about a different bolt. Sorry

binder123 · #13 11-25-2009, 10:59 PM

Quote:

Originally Posted by diametricalbenz

I wonder if the owner mentioned that it had any oil in the crankcase at the time it started missing.

Yes, he says it wasn't run low on oil, and in fact still shows full on the dipstick. I'm interested to get there myself and check it out. I'll post what I find out. I just wanted to ask for ideas, in case I was missing something totally.
Thanks!

diametricalbenz · #14 11-25-2009, 11:30 PM

Quote:

Originally Posted by binder123

Yes, he says it wasn't run low on oil, and in fact still shows full on the dipstick. I'm interested to get there myself and check it out. I'll post what I find out. I just wanted to ask for ideas, in case I was missing something totally.
Thanks!

Unfortunately low oil can be fudged by refilling it minutes later. Trying to crank it by hand will quickly eliminate that possibility. In the event it is not seized those IP's are a real pain to prime for some reason so beware of that to economize on the battery power when you go inspect it.