240D dumped its coolant, belts slack
 

Noticed an odd sound and a cloud of liquid.....pulled over to find coolant everywhere. The whole big pulley assembly on the front of the engine was hanging loose with the belts all slack. I did notice power steering went out just as I pulled over. Thoughts? Temp worked its way to near 100 after I shut it off, but no overheating. I’m thinking the pulley sheered off due to old loose bolts - from what I understand, there are six that hold it in and most people find three missing screws and three sheered off screws, indicating three backed out over time and the other three failed due to inadequate load tolerance.

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Oh your lovely beautiful orange 240D! Sounds like the water pump seized causing the belt to seize and therefor stopping the power steering, especially with the loss of coolant.

Verify what pulley seized, probably the water pump. Replace the pump, belt and be on your way! Good job sir for not cooking the engine and pulling over ASAP.

Time to check the front hub assembly. There have been a few reports of them coming off from the bolts holding the vibration damper coming loose.

Here’s a photo - that pulley circled in red (well below the fan) is the one that is seemingly not attached to the engine anymore and just hanging around slack with all the belts.

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Agree, likely the pulley bolts. When reassembling check the torque on the center crankshaft bolt and use correct grade hardware. I was able to get the bolts (hex head), at a local hardware store. Use thread locking compound.

Might need pulleys and new hub, hopefully not though.

Good luck!!!

Good luck and please let us know how it turns out....BEAUTIFUL color too. We have one just like it around here and I wanted to buy it just because of the color, but the owner never wanted to sell......

Link to good discussion on fixing same problem with an 82 300SD. http://www.peachparts.com/shopforum/diesel-discussion/128488-crankshaft-pully-fell-off-help-i-may-call-quits-1982-300sd.html


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Well, got the diagnosis from our local Benz indy shop and sure enough, looks like a busted crank pulley. Pumps and other pulleys appear working, but a full belt change required to be safe. Thermostat and coolant change as well. As it’s going to involve getting those dead screw carcasses out, and screwing that up could result in more problems, I’m just having them do it. It’s going to be far more expensive than I imagine most of you would consider paying, but it’s that or let it sit and waste away until I have free time (which won’t be anytime soon).


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That happened to my 240d a number of years ago. AC compressor failed causing it.

My Indy fixed it, very straightforward. It did bend some fins on the radiator but no damage.

Hope your coolant dump/temperature didn't damage anything else.

Good luck!

Good luck. In the spectrum of engine problems, that is pretty minor, but any time you pay a shop it is painful. On the plus side, you will get new belts which you might have needed anyway, and the mechanic should spin each accessory to insure no bearings are close to failing. Should also inspect the water pump weep hole to insure the seal isn't starting to leak, since now is the time to install a new water pump.

Is this a known documented issue with 240D's? It seems odd that Mercedes would design the crankshaft pulley components to be not strong enough to withstand a seized AC compressor. The 6 bolts that fasten the pulley certainly look strong enough to smoke the AC belt instead of shearing the bolts.

240D dumped its coolant, belts slack
 

Funola, good to see you here! Apparently it is not a rare occurrence, and the 4 cylinder has a history of backing out the six allens over time (due to the potential for additional vibration as I understand it) whereby when the AC/PS/WP seizes, you’re likely not playing with a full deck but maybe only 3-4 (or less) screws and it sheers off as a result. What sucks here is that from some of my old videos you can see that even after a three day cold start, I had zero engine shake/vibration, so I’m betting that rust probably played a greater role in the degradation of my six allens than vibration/backing out.

As to the AC specifically, I actually asked him whether it made sense to just remove the AC belt but not replace it because my AC doesn’t work and it would decrease liability if the AC compressor were to seize - he said that certainly makes sense.

They refilled it with coolant (I bet mostly water) to check for leaks after letting it run briefly but found none. I’ll ask about the water pump bearing/weep hole check too, but expect it back this week. We have our local concours event this weekend and my guy’s shop is entering an insane restoration of a 1952 Porsche 356 so I know they are cranking this week.

His car, not mine:
https://uploads.tapatalk-cdn.com/201...ec979d51c7.jpg


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Very interesting!, so this affects 240D only and not 300D? I thought the only difference between the 2 is the 240D has 1 alternator belt groove and the 300D has 2 grooves on the pulley, everything else is the same behind the pulley. I still don't buy that a seized AC compressor will shear all 6 crankshaft pulley bolts on the 240D. Something else is going on.

As I think somebody else mentioned earlier, the 716 in the 300 had a recall issued for crank pulley sheering off in like 1979, but aside from that, I believe it’s normally the four cylinder in the 240 that created the problem for itself. That said, every instance I found there were multiple screws already backed out or significant enough corrosion that something else liked a seized pulley could inflict more damage than it otherwise would.


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Not being argumentative, but what exactly else would you say it is?

I mean, it's a salt and rust free 240D that had about 71k at the time. Uses zeronoil. Runs great on the highway. Maybe a bit rough at idle but I'm doing valves and mounts currently. It's not like this is an old, poor condition car.

Look at how clean the block is:

https://i.imgur.com/HHBKzHHl.jpg

https://i.imgur.com/0DJk9b5l.jpg

When I took the fan bolts out the other day, they were like new.

I'm just not seeing the plausibility of corroded bolts or other means of failure. My new compressor is a bit crooked, but it only manifested itself this year as a noisy belt.