0.5 - 1mm run out on crankshaft V pulley ! ? Picture of car.

[Sharkbitemarky]

76 911

So first day driven out of the garage in 4.5 years (slow reno !)

About the only thing I have noticed is there appears to be a very slight run out on the crankshaft V pulley, the pulley is fitted well with no play and tight bolt. my questions:

a) How could this happen ?
b) After just putting the engine back in I don't want to drop the engine just to replace the pulley, can it be replaced without a drop?
b) What are they made of at £300 a pop ! ?

Cheers
Mark

[yelcab1]

Run out meaning it is moving side to side or front to back?

[boyt911sc]

Originally Posted by Sharkbitemarky

76 911

So first day driven out of the garage in 4.5 years (slow reno !)

About the only thing I have noticed is there appears to be a very slight run out on the crankshaft V pulley, the pulley is fitted well with no play and tight bolt. my questions:

a) How could this happen ?
b) After just putting the engine back in I don't want to drop the engine just to replace the pulley, can it be replaced without a drop?
b) What are they made of at £300 a pop ! ?

Cheers
Mark

Mark,

Please post a picture of the crankshaft and pulley where your are having a problem instead of the picture of your car. I think I am not alone having difficulty understanding your post. Thanks.

Tony

[Sharkbitemarky]

The pulley is warped /bent very slightly, so if I put a clock on the outer face of it it would deviate about the circumference by about 1mm.

Nothing is loose

It is not end play, it does not move front to back.

With regards to a picture, I presumed people would know what a crank pulley looked like. The problem will not be seen in a picture or video.

Cheers
Mark

[Sharkbitemarky]

It's the 131mm type. 911.102.017.04 item 14 from 1977 parts KATALOG "V-belt pulley"*

[boyt911sc]

Originally Posted by Sharkbitemarky

The pulley is warped /bent very slightly, so if I put a clock on the outer face of it it would deviate about the circumference by about 1mm.

Nothing is loose

It is not end play, it does not move front to back.

With regards to a picture, I presumed people would know what a crank pulley looked like. The problem will not be seen in a picture or video.

Cheers
Mark

Mark,

This is much better. Did you mean a dial indicator when you said “clock”? If the crankshaft pulley wobbles more than you like, simply replace it. What model is your car/engine? Do an engine partial drop to remove the front engine tin, engine console, and finally the crankshaft pulley. Make sure you test the replacement pulley before you install it.

Tony

[Sharkbitemarky]

Yep I meant Dial indicator = Clock ( Colloquialism )

[Walt Fricke]

These pulleys are pretty strong, so it should not be bent/warped. Nothing in normal operation produces an in or out force large enough to bend steel. Was the engine out of the car for part of those resto years?

Can I assume that you measured this because you could see a wobble? Given how close it is to the fan housing, 1mm might show up to the eye?

I'd be inclined to find a used one, with the deal being that if it, too, is warped you get your pounds (Euros?)back.

If you have access to a press, you might see about straightening yours. Straightening so small a bend isn't going to fatigue the pulley.

[Sharkbitemarky]

Walt, The engine was out of the car all of those resto years, in a heated & dehumidified garage, regularly hand turned over and oil missed internally, bores etc...... about every 3 months.

The engine runs very well and no smoke at any stage of operation.

Why ask ?

Your assumption is correct.

I intend to take the current one off check it off the engine and decide from there, just waiting tool to remove pulley without engine drop.

Cheers
Mark

[Walt Fricke]

I was wondering how something might have hit it. It is pretty well protected by the carrier, though, if that stayed on the while.

Does it climb smoothly up to the 1mm mark, then back down 1mm at 180 degrees? Like it isn't flush on the end of the crank?

Or is the raised (or lowered) part only over, say, 90 degrees? As from being dinged?

Same whether the gauge is on the outer rim, or the inner?

Looks like feeler gauges could be used against the fan housing as a secondary way of checking?

[Sharkbitemarky]

Thought I'd close this out:

1. I can confirm that with the minimum of a special home made tool (8mm Allen Key customized to lock the Pulley and 17mm offset ring spanner!), you can remove the crank Pulley quite easily without lowering the engine or removing the muffler.
2. I purchased a genuine Porsche crank pulley (# 91110201704 V-BELT PULLEY) and a new flange'd hex bolt (# 99909300502 HEX BOLT).
3. when I checked the new pulley by the same method it was so much better than the original less than 0.3mm wobble (Was at the limit of my measuring set-up).
4. When I installed the new Pulley on the crank with the new Hex bolt and run the engine I could not see/detect any wobble at all it was perfect/true (Unlike the original).

Still a mystery how the original got distorted in the first place. There was a suggestion that the pulley's have been known to distort overtime/45 years. !

Thanks again for the support.
Regards
Mark

[GH85Carrera]

Originally Posted by Sharkbitemarky

Thought I'd close this out:

1. I can confirm that with the minimum of a special home made tool (8mm Allen Key customized to lock the Pulley and 17mm offset ring spanner!), you can remove the crank Pulley quite easily without lowering the engine or removing the muffler.
2. I purchased a genuine Porsche crank pulley (# 91110201704 V-BELT PULLEY) and a new flange'd hex bolt (# 99909300502 HEX BOLT).
3. when I checked the new pulley by the same method it was so much better than the original less than 0.3mm wobble (Was at the limit of my measuring set-up).
4. When I installed the new Pulley on the crank with the new Hex bolt and run the engine I could not see/detect any wobble at all it was perfect/true (Unlike the original).

Still a mystery how the original got distorted in the first place. There was a suggestion that the pulley's have been known to distort overtime/45 years. !

Thanks again for the support.
Regards
Mark

I am amazed it is possible to remove the pulley without removing that engine mount that surrounds the pulley. I just replace my seal behind the pulley, and that required removing the muffler and a lot of other items, and dropping the engine a couple of inches. Glad it worked out for you.

All I can guess is at some point when the engine was moved while out of the car, something somehow bent that pulley, or maybe during the rebuild it was bent. Steel does not spontaneously warp like a piece of wood can.