Overdrive440

I've been chasing an oil canning noise on my new-to-me '85 crew cab. It only happens when I am turning left or right or moving over large bumps.

Its either the front of the bed bumping on the back of the cab (its a bit bowed), or the roof panel. I'm going to try to pull the panel back away from the cab to see if it helps.

I also noticed when cleaning the snow off the roof this weekend that the roof boings in pretty easy with the weight of the snow brush. Is this normal? Has anybody done anything to stiffen the roof panel a bit? I was considering spraying some urethan expanding foam in a few locations to add a bit more support, but not seal off the whole area. I don't want my roof rusting off.

I've checked my cab mounts, and other than sagging a bit, they're fine.

Anybody have this issue? Anybody get rid of the issue?

Trebor

If I were to guess I'd be looking at the frame brackets and the rubber isolators between the brackets & the cab. I'd say there is a 90% probability that the rubber in the isolators is no longer located in the bracket holes and the cab is shifting around. The noise can be caused by the mounting bolts rubbing into the inside of the frame bracket mounting holes. This usually ends up egging out the center holes. You can usually expect to see 3 of the 4 having severely egged out holes. Usually the back ones go first.

Bencie

I would check where Trebor said, if the cab was swapped out in the build maybe it was bolted down solid and not utilizing the rubber isolators and then flexing and causing the "durnkle durnkle" sound

NoFrills

I had the same oil can sound in my crew cab the roof had gotten walked on a few time before I owned it the dents where poped out but the only way I got the noise to stop was to put spots of spay foam in between the inner and outer roofs

thrashingcows

My crewcab roof is pretty weak as well. On the highway it vibrates and rattles. I've been trying to come up with a way to stiffen it up, without having to resort to spray foam. I feel the foam will hold moisture and eventually rust the roof from the inside out.

Trooperthorn

I foamed the inside of my crew so much the ceiling bowed down as the foam grew in a few spots. I did it close to 15 years ago and the truck has lived outside ever since. I did it right after I patched the rust on the front edge of the roof. It still looks good still. I am planning to foam my new cab. This time I will probably try to keep the foam away from the edges where condensation may collect. On the other hand, if the space is full of foam, maybe there will not be a condensation problem.

I have also thought of slipping plastic bags in the gap and spraying the foam in the bag. I may even try it with ziplocs to seal out the moisture.

Overdrive440

This truck is still original, but has had a hole drilled in the center for an antenna. It isn't dented or stretched looking, so I think it's probably just weak, being a huge, slightly curved sheet of metal. Unless they caved it in drilling that hole and fixed it. The later ford crew cabs have nice stiffening ribs in them, but I'm not about to cut up my rust free cab.

I'm about to change my cab mount rubbers, so I'll check the brackets at that time. I'll probably need new bolts?

I wonder what foam stuff they use on hoods to seperate the ribs from the skin. Something like that might work to prop up the roof. I wouldn't fill the whole ceiling cavity with foam, but a few spots between the edge and the center.