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Hello all and Happy Easter( not sure if we can say that any more).
I have been irritated by a minor "rattle" in my 38 Twelve for the past nine years and used this holiday to trace it. I thought that I had found it a few years ago when I dropped the sump for an inspection and found No 7 wrist pin was slightly worn. I replaced the bush and the noise changed but a noise was still there. My thermostat failed a few weeks ago and a new one has arrived, many thanks to the Flackmaster "Mr unobtainium". Whilst prepping to change same I removed the belts to obviate water pump or generator "rattles". sure enough the rattle was still there but the absence of the belts yielded a new aspect to the noise. I noticed that the Crank wobbled. I shut off the engine and Viola!. The crank pulley is loose. It is a prick to get to and I would like to know the AF socket to use. Could someone with a V12 engine out of a car please check the socket size for "Motor Crankshaft fan pulley screw 221498" I suspect 1.875 ( inch and seven eights). April fools joke attached.

No new Covid positive cases in Australia today. good news Peter Toet

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I checked mine and it is 1 7/8".

Good luck

Thanks for confirming that. I suspect that the attachment bolt has bottomed as it will not tighten further and the pulley is still loose. I fear that I shall have to remove the bolt and check this. There is no washer listed and I may have to shorten the bolt or put a large washer on. Has anyone come across this issue before? I do not feel like pulling the front clip on the car just to get to the pulley bolt. Peter T

every harmonic balancer I've ever worked with has a big thick washer under the head of the bolt...sorry to say. But I've never done a 12..and I don't see a washer or lockwasher in the parts list either. Surprising...does show for 1703/jnrs in the 35-41 book.
DAF

LOVE the photo.
Had a loose dampener years ago that ate up the crank key way. The dampener was easy to source but the crank was metal sprayed & re cut for the new key.
Happy ending :)

If you look at a cutaway of the 12 in the parts book, page 98 in mine, there is obviously a washer under that bolt in the diagram.

Packard blueprint MISC1-847 (engine assembly details, Twelve) does not show a washer. It does show quite a bit of available threaded but unused blind space behind the bolt, such that it would be impossible for an OEM bolt to bottom out.

Just as an aside, these MISC-series blueprints of engine assembly notes for the 320, 385 and Twelve engine have a lot of information not easily found elsewhere.

Dave,

Is there a copy of that print on this site, if not where can I get one?

Thanks

Bill

Assuming they have it in their inventory, you could get the blueprint copy from the Packard Motor Car Foundation (Packard Proving Grounds). Bruce Blevins runs the project, just reference the print # I provided.

Hello all, Very appreciative of the input and I would like to provide a bit of detail in how I am convinced that I have resolved the loose crank pulley for others that may encounter the same problem.
Packard 12 engines are not cheap to do anything with...a $A40k potential problem.
Well, the pulley crankshaft bolt inch and seven eighth, seven eighth UNF 16tpi together with the crank thread were stripped as the bolt had topped out on the crank without the pulley being tensioned, possibly due to working of a developing clearance There was no way to make an original bolt work and a NOS bolt was doomed to fail. The original bolt has a 1.75 AF ( across flats) dimension and I defy anyone to get a socket behind the radiator shroud.
I was not prepared to do a front clip removal on the Twelve ( have done 120's and 25th Series) and decided to remove the lower approx 12 inches of the shroud and it is replaceable although the skin on my knuckles from the grinder will take a little longer. The original 1.875 bolt, .825 inch 16 TPI was 1.25 inches in length. I have manufactured a 13/16th AF 2.15 inch in length bolt of the same thread dimensions and a cup washer of 0400 inches, recessed .25 inch to allow it to press onto the pulley rather than bottom on the crank. there is 1.75 inches available in the crankshaft. I fitted this and also locktighted the arrangement. I have driven it approx 100 miles and it appears to have resolved a faint but "bound to get worse" noise. Twelves are quality products and are meant to be very quiet.
Peter T