Bad hoody-doo with my 300D..... - PeachParts Mercedes-Benz Forum

AlexCole · #1 03-31-2015, 08:19 PM

My daily driver Gunther (1982 300D Turbo) may have suffered a fatal injury this morning. As I slowed to a stop not more than a quarter mile from work, I noticed that all of my 3 left-sided dash lights were lit up and my engine temp was starting to climb. I turned on the heater full blast and limped into work. When I got the chance to look in the engine compartment, it appeared that the engine was askew, the belts were loose, and the when I turned the fan it would clip the housing. I had it towed to my mechanic, and a couple of hours later I got the bad news: the fan is not Spinning with the rotation of the engine, which means (as I understand it) that either 1) the major connection between the fan and the crank shaft is broken, which is catastrophic for this engine, OR 2) the not-quite-so-major-as-the-major connection between the fan and the crank shaft is broken, which isn't catastrophic, but will still be quite expensive. I made every attempt to understand what was being said, but he was talking about territory that I haven't ever been in before, and got a bit lost. Has anyone ever experienced this, and /or can someone maybe explain it a bit more as to what is going on? I am at a loss.......this car is very important to me and although I've done quite a bit of work on cars in the past, I'm not sure how these parts fit together and what is broken. Any help would be appreciated. Alex

mannys9130 · #2 03-31-2015, 08:49 PM

The fan is bolted to the water pump pulley. The water pump pulley is driven by the belt to the crankshaft. The pulley is bolted to the water pump drive shaft which spins the impeller and moves coolant through th e engine.

The only connection to the crankshaft is the belt. Nothing about those parts failing is catastrophic internally. At worst, you blew the head gasket from overheating it. Assuming no HG damage, the worst scenario is replacing the water pump, water pump pulley, fan, and belts.

I'm hoping you misunderstood the mechanic. If you repeated him verbatim I'd run the other way.

Mölyapina · #3 03-31-2015, 08:53 PM

If you can post pics, that would help a lot.

sleepstar · #4 03-31-2015, 11:18 PM

take it to someone who knows what a w123 is...

Mölyapina · #5 03-31-2015, 11:34 PM

I'm curious what you mean by saying that "the engine is askew". Did you have some sort of major motor mount collapse or something?

Could it be that your WP bearing blew out, loosening the belts enough that neither the fan nor the water pump spun? That would sort of fit your description of the situation (I'm ignoring what you report your mechanic said, because it doesn't make much sense...). I remember once talking to a guy in the Market Basket parking lot who was stranded because his BMW did just that.

moon161 · #6 04-01-2015, 12:10 AM

The fan will not spin if anything blocks it, because there is a viscous clutch in it. It sounds like a motor mount collapsed and the fan is hitting the shroud. If all the belts are tight, that's an easy way to rule out a broken balancer or crankshaft. It doesn't sound worse than a blown head gasket.

Do make sure that none of the belts are near the oil cooler hoses, and check the hoses for wear. When they leak, lamentation follows.

AlexCole · #7 04-01-2015, 06:12 AM

Sorry, that was my interpretation of what my mechanic said, not a direct quote. I do have good faith in him, his family has been working on old and new mercedes for 3 generations now. With that said, as I have spent more time looking into it, it is the crank shaft pulley assembly that is not rotating with the rotation of the engine, and it is either the connection of the main bolt or the bolts associated with the dampener that have allowed it to come off--I THINK. With the engine running, the main pulley is not turning. It may also be that that is what is askew, making everything else look that way too. Alex.

mannys9130 · #8 04-01-2015, 01:44 PM

Oh damn... OK. I understand now.

Sounds like your harmonic balancer failed. It's catastrophic because when it fails and doesn't spin with the crank, it chews up the end of the crankshaft and you basically need to replace the entire crankshaft or replace the engine.

Look here at one of Whunter's extremely helpful link collections. Do you agree that this is what happened?

Diesel Harmonic Balancer threads

Stevo · #9 04-01-2015, 05:50 PM

I had the pulley come adrift from the harmonic balance on my 240D, actually my daughter was using the car. I had to pull the radiator to get at it and put new cap screws in to reattach the pulley. Hopefully your harmonic balancer didn't come lose from the crank, thats really bad news as proper reattachment is difficult.

AlexCole · #10 04-01-2015, 07:56 PM

In the hole where there is supposed to be an 18mm bolt, there is no bolt. So it either worked its way out (vibration?, improper torque?, no red lock-tite?, other?) or it is sheared off......... If it is sheared then the engine is going to have to come out and then crankshaft is going to have to be replaced. That's beyond me and my checkbook.
What if the bolt just came loose and backed out? Does that happen? Wouldn't I have had some signs that the bolt was coming loose, like pulley or belt noise or vibration?

BillGrissom · #11 04-01-2015, 10:49 PM

If the bolt just came out, you probably wouldn't feel anything until the crank damper moved out a lot. It is a fairly tight fit and has a Woodruff key, so would keep spinning w/ the crank until it moved forward enough to lose the key. Could be the crank is still fine, in which case an easy fix. I have had so much trouble removing the crank damper (both cars I recall), that it is hard to imagine one coming loose.

AlexCole · #12 04-02-2015, 08:08 PM

Got good news from my mechanic today- he went back and spent some extra time in the engine bay. Apparently it is a tight spot and difficult to get a god look at. But his son (also a mechanic at the shop) was able to get his phone in there and get some pics. Okay, so now I have pictures- welll basically 3 pictures of the same thing, but the 18mm bolt in question appears to be front and center and doing its job. So not a total loss and quite possibly something I can do myself (with the help of this forum of course). So now I'm going to have Gunther towed home and spend the next couple of months figuring out what needs to be done and taking care of it on my own time. Pretty excited that he's not a goner. I'll let you know how it goes! Alex.

moon161 · #13 04-02-2015, 08:50 PM

Piece of cake. Screws from the pulley broke. Pull the radiator, fan, shroud, belts and pulley. Extract and repair screws as required. What're you waiting for. They could probably do for 1/2 day labor in the shop.