1980 300D. No turbo. 280K+

I’m driving down the road today. All’s well. Then all of the sudden, I loose power steering. Then about a quarter of a mile down the road I notice the temp gauge screaming for the red-line, and the battery light comes on. Engine at idle, I coast into a parking lot and shut it down. Water boiling out of the overflow. Open the hood, thinking I’m going to see some missing belts, but no. All the belts are fine, but the main pulley is no longer connected to the crankshaft. The harmonic balancer is fine, and still attached to the crank but the main pulley assembly will slide right out the front of it. I can see the bolt holes in the back of the pulley assembly. They look fine. I can’t get the assembly out, do to the A/C hose in the way, and will have to tow the car home to pull the fan, etc to get it out through the top. I haven’t reached into the harmonic balancer to see if the (6 ??) bolts have sheared off, or just backed out.

Has anyone else experienced this? Is there a trick to pulling the balancer off if I need to? Special puller?
What are the odds of those (6 ??) bolts coming out? I’ve never touched them in 26 years. I don’t mind a failure with a 26 year old car now and then, but this one seems rather odd.

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1980 300D - Veggie Burner !

These crank pulleys sometimes want to take a walk for unknown reasons. From what I've read it because the pulley bolts shear. Kind of has me worried myself. Doesn't seem to be any way to prevent it. Hasn't happened to me yet, but it has to a lot of others. Fun part about it is getting the balancer/pulley assembly aligned properly when you put it back together. There are round metal dowels on either side of the crank, make sure you still have yours. They're easily damaged when the whole thing is reassembled. Hopefully the crank nose is not damaged.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

Thanks for the reply.

Further investigation with a flash-light and a mirror, reveals 6 bolts sheared off in the harmonic balancer.
The balancer, the big bolt and the crank (which I’m assuming is covered/protected by the balancer and the bolt.) seem to be fine. If the pins you speak of are between the balancer and the crankshaft, they are probably still good for now.

So, I guess the balancer will need to be pulled. Any tricks to getting it off? What’s a good way to hold the crankshaft while I loosen that big bolt holding the balancer on?
I hate broken bolt extractions!! Especially when they’re recessed down inside something. Should I just replace the balancer at this point and age/mileage?

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1980 300D - Veggie Burner !

I put a socket and bar on the crank bolt and bump it over. It works every time and has done so for years. Just make sure the bar is solit against the frame or floor just a little bump of the starter should do it.

It is a difficult job to get those six broken studs out of there. But there are any number of small shops that can do it with the HB on the crank. I wouldn't take that off unless there is no other way. Getting it off is difficult, getting it back on right I understand is near impossible for a novice mechanic. So find a mechanic who will come out, or one that has a shop, pull the radiator and do it. From reading past threads, I think that over tightening of the belts can really do a number on those six small studs. Don't make those belts too tight!

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

The only trick to getting the balancer off is loosening the big bolt. The balancer should have a couple of cutouts. One option (per FSM) is to jam the balancer with a chisel or 1/2" extension bar through one of the cutouts. Use a wrench with a long handle, 24" at least. Once the bolt is out, just pull the balancer off with a generic balancer puller. Autozone will lend you one for free.

The trick is getting the balancer back on. Getting it lined up properly is just about impossible. So don't take it off if you don't have to. It's entirely possible that the bolt ends will come out easily since they are under no torque. If you do remove the balancer, match mark it to the crankshaft so you don't put it back on upside down.

WVOtoGO, did you experience any load vibrations/noise at a particular rpm band leading up to this? I ask because I'm having really annoying vibrations between 2800-3300 rpm and its a devil to track down. Thanks.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

Seth;
Funny you should ask.

Not really any odd/new vibrations, but a couple of days ago, I had it idling cold in the hangar. Man, was it making a weird knocking noise from the front of the motor! Too metallic to be a rod but seemed to be inside the front of the motor. One of those funky detonation dirty injector type of knocks. I had just (within 20 miles) run a can of Purge through the injectors, I figured maybe it was an injector thing. I took my stethoscope to it but couldn’t find it. Soon as I touched the throttle it stopped. After warming up it seemed to go away. Yesterday, it didn’t do it at all when cold. But had a weird knock after sitting at idle for 5 minutes or so. Stopped when I touched the throttle. This morning it did it, but not for long. Numerous stops and starts today before the failure. I’m actually hoping this was the cause of the knock.

If I were you, I’d get a mirror and a flash-light and crawl under. Count the small bolt heads. Grab the main pulley assembly and hope it doesn’t wiggle. If it does, you may have found your problem.

BTW - Do you sail (or is that a Navy thing)? Texoma? Always looking for a good tach/trap-tician for the Laser-II regattas !!

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1980 300D - Veggie Burner !

Thanks for the help guys.

I got the car home tonight, and will dig into it tomorrow or it will have to be next week.

I figured I’d better go with OEM bolts and not something out of the NAPA bins. I talked with the parts guy at the dealer. He did say they were hardened. Duh, Like I didn’t figure that much out already. I have a guy that runs his own "MB Only" shop that I’ve dealt with for years. He’s got his OEM parts supplier delivering a set Tuesday. He’ll cut the dealers price in half for sure. $4.50 each is a bit much for that small of a bolt, regardless of its hardness.

So, I figure I’ll pull the fan out. Then the radiator out. Hopefully that will give me enough room to center punch and drill the studs. A soak of some penetrating oil, and if I’m lucky, they should unscrew with an easy-out. They are all broken off flush with the balancer, so no chance of grabbing them with small Vice-Grips.

If that doesn’t get it, I’ll look into pulling the balancer. I have a box full (tractor owner thing) of various size/length breaker bars to get after the bolt with. I have a few different pullers, but most would need to incorporate two of the bolt holes. (Unless there’s two other holes in it for pulling. Fat chance, huh?) So, I guess if I get one stud out, I’ll shoot for the one 180 out from it next. I’ll be sure to mark the alignment well before I pull.

Thanks again for all the help. Comforting for sure. Beats the heck out of diving in blind. I'll keep ya posted.

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1980 300D - Veggie Burner !

I just had my balancer off ('82 300D) for a front crankshaft seal replacement. The original bolts were grade 8.8. My local Ace hardware store has 12.9 grade for $1.00 each. Just make sure they are the correct length. If too long, they will damage the front seal.
And if you wind up having to pull the balancer, you might consider changing the front seal while the balancer is off.

Well - We’re up and running again. My thanks to the many of you who have helped along the way.

I must be the luckiest DIYer in town.
The old front crank seal popped right out with the removal tool. The spacer behind it slid smoothly off the crank. I cleaned all that up real good. Put the new seal in (quite slowly) with a soft mallet and a block of wood. I see what you mean by the spacer going on after the seal. It really didn’t look worn, but I flipped it over and put it back in through the seal. The HB took more time to clean then to install. I hit it dead on the first shot. I could push it on with my hands and then light tapping with a soft mallet about a third of the way. Looked like it was aligned, so I put the bolt in, and that pulled it right on. Pulled the bolt just to check everything was on and flush. Spent a fair bit of time cleaning the pulley assembly before installation. Enough dirt/grit/grease in there to throw everything off balance. Yuck. The face that mounts to the HB was a bit nicked up around the holes from the shear. So, I did a little draw filing across it turning 90 degrees every few draws, then 120. Didn’t really take anything off of it, just got it nice and flat/smooth and clean for mating. Getting the first bolt in was a chore but didn’t take more than about a minute. Thanks for the torque specs. I did go with a drop of Lock-Tite blue just for grins. Belts. Radiator. Trans lines. Fan. Coolant. Then, a nice smooth start up. Idled up to normal operating temp. Trans fluid check. Shut down. Checked belts. Checked coolant. No leaks. No worries.

Oh - I did go with 6ea MB OEM bolts. They were 2.00 each. (Ouch - for a bolt? Almost like aircraft parts!)
The new MB ones are T-45 head and not Allen head, for some reason. Oh-well - Was not a problem.

My thanks to all of you for the words of wisdom. This was my first venture into that area of the motor. I appreciate all your help.

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1980 300D - Veggie Burner !