Advice putting Harmonic Balancer back on after it fell off
 

I have a 1984 300D 185,000 really nice car The previous owner said the car was driving just fine until the crankshaft bolt wiggled out and the harmonic balancer and pulleys fell off. I have read and read and read all the posts I can find about this issue and from what I have learned the best thing for me to do is get a used HB new crankshaft bolt, new hex bolts, and new pins. The problem I read about the dowels or pins is that the new ones from the dealer were at one point a little long (4mm) and if you didn't trim them down it would put too much pressure on the pins after cranking down the 27mm bolt and they would shear off. I am a little concerned with the end of my crankshaft and I will add pictures below. I read a post that said to put HB on crank and drill out each keyway with a 10 mm 3 lipped twist drill bit put a little temp loctite on OVERSIZED dowels and put them in and then the bolt with a little temp loctite on that as well. Where can I get the oversized dowels or pins and the drill bit to drill it out? Also read people using JB Weld or Loctite 660 on the worn out pins and filling the void with that. Or am I being a worry wart and all I need to do is get new pins and put her back together?? Hopefully the pictures are worth a thousand words. Looking for thoughts and ideas. Thanks in advance.

I personally have never had this issue. Much will depend if there is any nose damage or taper damage. I personally would do a dry run without pins to make sure the taper is still capable of locking first. But that is just me.

how does the HB fit when you put it on the crank? On mine the balancer took a lot of abuse and was way oversize. The new balancer (PNP part) fit pretty snug so I redrilled the crank for two new pins 90 degrees away from the first two. My original holes were really far gone, not sure how bad yours are from the pics. Its all up to you and your capabilities. Another question is how long did the PO drive without a water pump? I thought my HB failed a second time and in my anger I drove it 4-5 miles to get off the highway to a good tow spot with no water pump, I was sure it had failed again and I knew I couldnt redrill it. Turns out the pulley bolts came out the HB was fine, but after driving so far with no water pump the engine does not sound right. SO I am now in the process of putting in a $300 donor engine with less than half the miles and good history

Thanks Barry and LutzTD, I will dry fit the parts as soon as I get a new to me HB. I have 2 donor cars same engine. Would it be ok to get the HB off one of them and slap it on? Otherwise scrap yard? I saw online I could get a used one for 58 plus shipping. Anyone know where to get the pins too? LutzTD What drill bits did you use? I read online to not use 2 lipped drill bits because they make a round end and the three lipped one doesn't???? Not sure there either. Then did you just drill all the way through the HB and into the Crank? As far as the water pump issue goes I don't think they drove it too far. The crank bolt, fan, pulleys are all good and must have been parked when it came off to have all the parts picked up. I started it before I bought it and it sounded good I didn't let it run long though. 300 bucks for the newer engine? Thats great. Are you putting the engine in yourself? I have another car I was thinking about swapping engines in but would be having someone else do it. What are the labor costs or hours to do a job like that? Thanks again guys.

Wow - that's some damage. I would definitely go down the road of repositioning the holes - but how to do that with the engine in place? I wouldn't be that confident of a good outcome with a hand drill. Could you rig up a pillar drill like contraption that could help you drill the holes in straight?

I'm thinking something like this:-

http://cgi.ebay.co.uk/Dremel-Drill-Press-Stand-Workstation-Rotary-Tools-220-/400014076895?pt=UK_Home_Garden_PowerTools_SM

If you get the dowels from the dealer definitely cut them down if they are too long. If they happen to be the correct length could you post that in this thread please?

http://www.peachparts.com/shopforum/diesel-discussion/295471-warning-om617-dowel-pins-now-supplied-incorrect-length.html

Oh and welcome to the forum!

I bolted on a homemade drill jig. I drilled .032 undersize and reeemed it to size, you should never make a dowel hole with a drill. Since both parts are soft I went .032 undersize with the drill, usually you can only go .064 undersize or the reemer cant handle the material. I drilled and reemed through the fixture so it was a one time use fixture. There is a thread on here somewhere showing how I did it, if I find it I will attach it later. Also, I did it in the car.

the fixture is easy to make. It can be any thick piece of soft metal thats big enough for the 3 holes. Make the center hole tight on the flywheel bolt, then the two outer holes centered at the diameter of the crank/HB hole sized to .032 under the dowel, attach with the holes approx 90 degrees away from the current ones. make your drill length for the appropriate depth with a marker or tape. drill the crank and HB assembly, then reem them, remove fixture and tap in the dowels, then bolt it all together without removing the HB. Also, I had to buy a longer HB/crank bolt and grind the head down to clear the two dowels holes. Make sure you use a drill press to drill the holes in the fixture, they need to be perpendicular to the part. you cant get this right with a hand drill. once you have the fixture straigth, then you can hand drill the crank and HB.

Yes I am swapping the engine myself, While its out I have changed the oil filter housing gasket, the turbo drain seals, the air cleaner drain orings and the dipstick orings.

heres the old thread

http://www.peachparts.com/shopforum/diesel-discussion/262162-bummed-engine-running-but-accessories-not-turning-1982-300cd-turbo.html?highlight=harmonic

PS. make sure you locktite the pulley bolts

As long as either of your other balancers have never loosened up they should be as good as new. No sense buying another if you have two spare ones.

Until they spin in relationship to the crankshaft they remain exactly as they were made. I have not had a balancer loosen up myself on a mercedes but have observed the issue by many others.

I am going to think about this all too often reocurring issue on site a little over time. I doubt there is a way around it but there may be. The issue is the method would have to be usable by the majority.

I have a suspicion that the manufacturing tolerance in production of the two tapers might have been too great. A really good taper lock fit is very difficult to separate. The impulse loads from the engine are large in my opinion as well though.

I almost discount the accessory loading in comparison. In otherwords even without the accesories the balancer could eventually loosen up if the taper is out of tollerance..

Also a friend of mine keeps raving about a certain type of glue he uses at work. He has told me it is unbelievable in strength and was designed to bond clean metals. I will get and try a sample of this out on something.

That also reminds me that the balancer and crank snout taper should be cleaned well with laquer thinners before fitting. The effort may or may not be worth anything but it cannot hurt in my opinion. It might even promote a little oxidation in there. That increases grab I suspect.

the MB snout and HB bore are not tapered, this is part of the issue. It has to be pressed for the full length of engagement and if you use the bolt it tends to turn a little bit.

as long as the bolt stays tight and its not removed for some other service and reinstalled incorrectly, I would bet this is a very reliable joint. The issue is the round pins and the difficulty to get them aligned when reinstalling. There is a special tool for putting the HB back on, or so Ive heard, Ive never seen one, using the bolt to put it on has a lot of challenges for the dowel alignment. I think there is also a tendency to loosen the bolt by using the HB bolt to adjust valves. If this was a non adjustable valve engine likely there would be fewer issues.

Chapter 03-340 doesn't mention a special tool for putting the balancer back on - but that doesn't necessarily mean someone hasn't made one.

So long as people turn the engine in a clockwise direction I can not see any harm in turning the engine over with a 27mm socket... now if they were to back it off in an anti-clockwise direction then that could contribute to a loosening effect...

In my attached thread I was lectured that there was a special tool and that I am negligent for not using it. I am not suggesting there is one, but I was told there was one.

just missed it by a little bit, it wont hurt to turn it backward a little will it........ :rolleyes:

May be tangofox007 can enlighten us then?

I've done a quick search on google and I can't find anything for an OM617... but I did find a nice video of a home made tool:-

http://www.youtube.com/watch?v=eZxxqCNN5Uw

Doesn't help with this problem though.

Well if there is no taper then the pins should fit tight. Any slop is going to cause problems. The impulse loads from the engine are short and powerful.

speaking of mine only. even after its pressed on without the dowels I was able to turn the HB with a prybar and a 2x4, they do keep it in place somewhat, but that high torque bolt is doing the lions share

Consider it so.

http://www.youtube.com/watch?v=Ex_yJ_V5UH8

Thanks for that - I understand what you mean now.

I would argue, however, that in the case of the OM616 / OM617 something as heavy duty as that wouldn't be necessary. Now I've only worked on one engine - my engine - but I have found that you can quite easily put the harmonic balancer in place with (very) careful tapping of a rubber hammer before you install the dowels.

I got the impression that the dowels provide the real tight fit between the balancer and crankshaft.

I know this because I've had the thing on and off / with and without dowels several times - partly due to a front crankshaft seal fix that didn't (due to a misaligned upper oil pan) and then later an unexpected engine rebuild...