Intermountain zinc rot and serial numbers

[ATSF_Ron]

I know the zinc rot issue has been covered, particularly F units. Is there a way to tell if a loco is in a batch prone to this problem by looking at the product number? I can’t seem to find info on that.  The one I’m looking at is #69724-05. F7 B unit. Thanks!

[Bill H]

Ron:
Cannot speak to that specific number, but I have 14 IM F7s with no zinc rot and there are innumerable threads on IM F7s with nary a mention of the problem - most of the threads deal with lowering the ride height or DCC. I suspect that zinc rot issue was seriously overblown or perhaps the environment in which the loco was stored.

Kind regards,
Bill

[Englewood]

I have over 40 IM locos and checked them all earlier this year.  No zinc rot. This includes F units, SD40T-2s, and Cab Forwards. I really seem to think it's an issue of where they're stored.

[kiwi_al]

It's not an issue of where the models are stored, there have been documented cases where models in humidity / climate controlled locations have been subject to Zinc Pest This is well documented across the internet. As far as serial numbers of affected runs are concerned I don't think anyone has that metric. However, I have seen 2005 and 2012 manufacturing dates mentioned. Also a widish range of models have been affected including F3's, F7's FT's, Tunnel Motors and Cab Forwards.

The degradation of the frames is caused by the manufacturing process in that usually lead has been introduced into the zamac.
This is just my personal opinion for what it's worth.

[ATSF_Ron]

Thanks for the replies, guys.  I have one A/B F3 set (so far fine) and a few F7As.  So far all are fine.  F3s were 2006 ish?  F7s were 2016, I believe.  The F7B I've been watching is cheap, so I may go for it.  No way for me to know the year of manufacture, but I believe it's from a newer run.

[nstars]

I have 3 F7 units with no zinc rot and 3 F3 unit’s with zinc rot in all three units. The zinc rot was limited to the right frame half.

Marc

[u18b]

From another forum...  (forgive if not allowed)

The top photo is pretty amazing in how bad it can be.
(not sure if you have to be logged in to see photos)

https://www.trainboard.com/highball/index.php?threads/intermountain-frame-rot.151894/page-3

[brokemoto]

I sold most of my IMs several years past.  I still have some B&O F-7s, Old and Weary FTs and an Old and Weary F-3.  I check them regullarly.  None have shown any zirmac rot Y-E-T.