Squeak when towing?

So I towed a camper on "hills" this weekend, nothing seriously heavy--~3600 lbs plus the crap in the bed. Kept it in tow/haul mode for the most part and drove a reasonable speed. Once I got off the highway there was an audible squeak coming from the engine compartment. Stopped for lunch and then when I cranked it again, the squeak was back. When I drove the truck after setting up camp the squeak was gone, came back when I was driving the camper back to the drop off, then stopped again. What the heck could be the cause? The truck sounded like the Chrysler Voyager my friend's mom drove back in the 90s...

 

Serpentine belt?

 

Possibly, but why would it suddenly stop when not under load?

 

If it was only heard under load like going up hills, and wasn’t super loud it could have been pinging. Maybe you had a tank of crappy gas. It also would be worse if it was hot out. You could try putting in some higher octane gas and see if it goes away.

 

Hill country Texas, so not mountainous at all. I suppose it would have been gas, it was at a Loves off 10. And I didn't hear it again when I filled the tank back up. I've only used 87. It really sounded like a squeaky belt, just odd that it only happened when towing

 

Shot in the dark - could the electrical draw of the trailer been causing the alternator to whine? I know the hot wire going to the 7way is on a 40 amp fuse…

 

In addition to possible bad gas, you could also try cleaning the MAF sensor with the CRC MAF sensor cleaner. If the MAF is dirty the fueling won’t be right and it can cause pinging.

 

It's sounded more mechanical than electrical.

Good to know on the MAF, thank you.

 

@LabRat - how long have you had the truck? Is this your first tow?

 

I bought it last April and yes, first tow. I don't think this truck hauled anything other than the previous driver or saw anything but paved roads.