Well I've been towing for almost 150,000 miles with a 2012 6.7 Lariat 4 wheel drive. Things have been going pretty well with the truck. I noticed some sluggish and indecisive type shifts early on but now I'm worried. I depend on this truck for pulling a horse trailer all over the country and Canada. Just recently I've been getting a hard shift or a thump or a clunk when shifting up or down in to second gear. I'm at about 152,000 miles and did a hot flush with LV ATF at about 148,000 miles. Should I worry or keep running? I have a 97' PSD I'm thinking of giving a nice paint job and a flat bed but am reluctant to do so due to financial concerns and the fact that some folks may not want to see me pull up in an old truck no matter how nice it looks. My tranny temps have been stating under 200F and I really keep an eye on the temps when running up and down the hills while towing. The trailer is a 35' Gooseneck with a max GVRW or 14,000 pounds. Should I wait for the tranny to grenade and then drop in a built tranny and if so who's building these tranny's stronger than stock?
Thanks in advance.. long time no see but this site has always been my go to for all my Ford truck questions, upgrades, etc.

 

Sounds like you have a bad shift solenoid. All three of our newest ambulances have had solenoids go bad in them in the last year. It's not that big of a deal to change them, you just have to find the right one and drop the pan, change it, put pan back on, and refill. Of course you need a computer to tell you which one it is. Even at a dealer I don't think it would be that terribly expensive.

 

I agree with the shift solenoids. I had three replaced in mine to [mostly] fix a shift nightmare between 2nd and 3rd.

 

Thanks so much. I was thinking my tranny was about to grenade due to my constant towing and almost never being out of tow/haul mode. I'll give the service department a call tomorrow. I have a little down time to address the issue. Cheers!

 

Tale a peek at the tsb's for your truck ...

This is a great resource from Ford-trucks.com -->https://www.ford-trucks.com/tsbs/fulltext/

 

Thanks, I sent my TSB concerns to my service rep. Buzzing sound, shifting, etc.

Great resource!