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2,7l Crankshaft Damper inner diameter

969 views 14 replies 5 participants last post by  Ronbo 
#1 ·
hello,

I have another biiiiig problem.

While driving at -4°C my crankshaft damper has loosened itself!
It stayed on the crankshaft. It became hot and abrasive steel powder. The crankshaft has turned blue.
Now I have to find out whether the crankshaft is irreparably damaged or whether the material "only" was abraded by Damper.

So please, can you measure the inner diameter of the crankshaft damper?
 

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#2 ·
Hope this can be some good news, it depends how the crankshaft is.

Where I work for opposed airplane engines, the discoloration is normal on some engines that overheat. Sometimes the journals will turn into what appears to be a flash coat, (yellow, orange, red, blue and/or purple)
We usually can polish it out, if it stayed hot too long and has a stained appearance it is most likely rejected,
If you can get yourself microfiber or fine scotch brite and polish the "blue" areas, see how bad it is. Don't use sand paper at all unless you have a lathe should you take that sucker all apart.
Clean look: healthy
Stained: possibly bad

Measure the inside diameter of the damper and outside diameter where it rides on the crank.
I don't know what the measurements should be or weather these run by pinch or just being torqued down and have clearance.
 
#3 ·
I'd worry more about the diameter of the crankshaft snout!

It's hard to tell but in that first picture it looks like the crankshaft diameter is "Uneven" across the length front to back.

Do you have a picture of the crankshaft from above?
 
#4 ·
I'm thinking the important question might be how tightly does the pulley fit into the crankshaft now and after polishing as BG00 suggested.

Is it a loose fit? Unless it is a loose fit (with noticeable play), even if it is a close slip fit, I'd be tempted to put some medium strength Loctite on it and put it back together putting full specified torque on the bolt - also put some blue Loctite on the bolt threads because the direction the crankshaft turns will put a loosening torque on the bolt if things start slipping due to accessory drive load. (There's a stud and bearing version of Loctite, but I don't know how tough that is to break loose if you ever had to take it apart. I guess you could take a torch to it, but that could damage the rubber in the pulley and the front crankshaft seal seal - however both could be replaced.)

For that to happen, I wonder if the bolt wasn't torqued and if an accessory locked up. The normal fit of that pulley is pretty tight on the crankshaft. Strange that it would have spun on the crankshaft, again, unless the bolt wasn't tight plus some non-typical accessory belt loading.
 
#6 ·
Wow!! That's 1.5mm (0.060"). How did it even work like that?

Did someone substitute a different part? I have trouble imagining how it could have been running like that long enough to wear that much metal off without it being noisy and vibrating and/or not throwing a belt off!! The wobble and vibration would have been tremendous. Like I said, once the bolt loosened, the rotational direction of the crankshaft with the pulley slipping would have continued to loosen the bolt.
 
#7 · (Edited)
That'll need to be polished down to get that smooth again, I would do that on lathe or send it somewhere,
Even then you need a damper that will then have the correct dimension for what was taken off the crankshaft, plus it already has 0.060
Crank has most likely reached the end of its life now.

Could also replace the crankshaft, they run for about $200 - $300
Chrysler 2.7L Crankshaft Kit, Chrysler 2.7 Crankshaft Kits
This kit is $270

Max allowed is 0.030 aka M030 (this is different from the 0.060 measurement above, rods and main journals, not end piece)

Edit: If you can get the end piece correctly smoothed out I can talk to my boss about welding the inside diameter of the damper and CNC'ing it to the correct dimension for what the crank now is, then cryogenic treat the damper to bond the metals
 
#9 ·
This may be one of those "I know there is no such thing as a dumb question, but if there were such a thing, this would be one of them", but could the engine be used as it's own lathe to turn the nose of the crank before the ID of the pulley was built up and sized to fit the nose? Maybe use Loctite sleeve and bearing retainer and sleeve either the crankshaft nose or the pulley (or get a new pulley and sleeve the crankshaft to fit it).
 
#10 ·
I was thinking that earlier actually peva, as long as no detrimental parts are in the way, the engine can spin on its own and he can use sand paper to smooth it out and then scotch-brite to clean it up.

Take a thin strip while the engine is turning, and move back and forth until its smooth, its important to do this evenly so it remains straight.

Go in this fashion, as if the crankshaft was sitting long ways
Wrap 80 grit sand paper 1/4 to 1/2 of the width that is sticking out of the block,
Apply good amount of force and move back and forth evenly.
Note: 80 grit is very rough it will take it down fast. Keep an eye on the part, you want to remove the least amount of metal as possible.

After it is smooth and no longer bumpy and gouged change to 240 and repeat this process once

Take a piece of scotch-brite and cut it to about the same width of what is sticking out, then rest it against the end piece and polish,

Measure the new outside diameter and use that as the reference to make the new inside diameter of the damper.

WEAR SAFETY GLASSES
 

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#12 ·
What did you do to get a good fit on the new harmonic balancer over the crankshaft?
 
#15 ·
Yes it's normally a press fit but did you read his original post about the measurements and clearances? It was unclear whether the crankshaft had excessive wear or if it was just the damper that had worn.
 
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