crank hub question.... (was balancer rotating on hub)

[JoeyTheB]

I'm thinking my crank hub woodruff key is toast -
can I use a parts house kit to remove and inpect ?

Symptoms:
I went to check the timing on my car and balancer
was showing 60 deg advanced !!!

I think the problem was due to an incorrectly installed A/C compressor -
the a/c bracket was rubbing against the balancer.

Finally removed the balancer last night - no signs of failure,
but numerous bolts were loose (including the crank hub nut !)

Checked for chain stretch/TDC/cam timing -
Hand cranked using a wood dowel in spark plug hole
to "reckon" TDC - Top of pistion travel is at Cam Timing Mark,
so I don't think there is chain stretch /slippage.
(Chain is almost brand new).

At this point, I think the woodruff key on the crank has been sheared,
and the "hub" has rotated. (the flange looking piece of metal the balancer attaches to).

any input appreciated....

joe
72 280SE

[300SDog]

If it was me, I'd approach this as if I was replacing the front crankshaft seal. With sheared woodruff key you might have to torch it to remove the broken piece imbedded in the groove. Do they come in offset sizes or just standard size? Probably best to get the exact woodruff key you want from dealership parts counter armed with engine numbers, etc.

Am also thinking that pulling the hub, ballancer and pulley from a suitable parts car can teach you alot about what to expect. And is the hub ballanced to the crankshaft?

[psfred]

This a six or an eight?

If it's a six, you have the wrong pointer/balancer set. There are two pointer and three balancers, one with two scales on it, one on the front edge, the other on the back.

The scales are 40 degrees off.

Peter

[JoeyTheB]

Thx for the pointer about the pointer.
Saw that in a previous thread

I only have one set on my balancer.

thx though...

[psfred]

Either pointer and all three hubs will fit any engine! I don't know what is available for replacements these days.

The story is that when the 2.8L was stuck into the 300SE, the pointer had to be moved to accomodate the air pump for the suspension (so it was visible, the air pump covered it). At some point, it was decided to standarize on the "new" pointer, but with the "old" one in common use, a hub with both scales was produced, you just had to know which one to use.

Eventually, only the "new" scale was put on the hub.

Here's the scoop:

Old pointer is 9mm wide, straight sided with a corner nipped off on the left (driver's side). Short, uses the rear scale on the hub.

New pointer is triangular, 6mm wide, and extends out past the rear scale.

Front scale reads 0 TDC at 40 degrees BTDC on rear scale.

another clue: the old pointer is directly under the bolt that hold it on, the new one is about an inch to the right (passenger side) of the bolt.

I'm guessing you have the wrong pointer for the hub installed, and all you have to do is adjust the "correct" timing by 40 degrees. You can't be too far off, as the engine won't run 40 degrees off!

Peter

[JoeyTheB]

Ok - got the hub off.
Looks like the crank hub bolt was loose and the hub worked itself off the woodruff key. Lucky for me I caught it - I've never touched the crank hub !

Question(s)
How do I get the crank seal out on the front ?
How do you get the hub back on the key correctly - that thing is like 2" back and hard to see.

[psfred]

You will have to remove the old key and check if for damage, also check the slot in the hub for scoring or dents. If the key is damaged, replace it, it's a standard metric size. If the hub is damaged, you can take a fine file and clean up the slot at the end so the key will slip into it easily.

To reinstall, just slide the hub back on aimed as close to the key as you can get. Id should slide easily enough for you to fell when you touch the key and get it into the slot.

Make sure the three conical washers have the high side out, replace if you don't have them.

Peter