I have a 2001 e450 (23' RV) with a 'howl' when lightly accelerating at highway speeds. Not sure what it is. If I coast it's quiet. If I accelerate harder, it's quiet.

History: My dana60 full-floater was obviously going bad (scraping sounds and glitter in the gear lube!) But I also had, what I figured was, an intermittent hanger-bearing howl. So I had the dana60 rebuilt. No more scraping sound! The howl is, I think, worse (or it's a new 'howl'). So I replaced the hanger bearing, and while I was at it, the front U-joint. No change. I'm thinking my next step is probably to replace the rear-driveshaft u-joints -- because I cannot think of what else it might be --unless the data60 rebuild was sloppy, or something. (First thing I did was check to make sure they put gear-lube in! They did.) Then I thought: maybe this is some common problem that everyone, except, me, knows about!

Ideas?

Thanks,
Joe

 

Where did you have the rear end rebuilt? If the noise you describe, is more of a combination of a whine and/or howl becoming more pronounced under acceleration or deceleration, the the most likely source would be the pinion bearing(s). Did the symptom occur before or after the rebuild, or remain the same throughout? Did it worsen? What exactly was done in the rebuild? All new bearings, or new crown and pinion as well as new bearings? Either way, a job like this is a very tricky job that requires a lot of skill and attention to detail, requiring the pinion depth, pinion bearing preload, ring gear backlash and proper gear tooth contact pattern on the drive and coast sides to be set correctly. Anyone of which failing to be set correctly, can cause the exact symptom you describe.

Years ago, when I was less experienced, I recall a vehicle that I had replaced all the bearings in, had suddenly developed a very loud hum during deceleration after I had it all assembled, and took it for a post-repair road test. Of course, I couldn't release it to the customer in that condition. When I took it all apart to assess, I had discovered that I put a burr in the housing where the inner pinion bearing race was supposed to seat when I was hammering the old race out. This meant the new race wasn't seated fully bottomed out as it was supposed to. Long story short, I had to take a die grinder to the bearing race surface to ensure it was flat, before reinstalling a new bearing race, and reassembled the rest of the inside parts. Once done, the problem was fixed. The point of this? It is very easy to let a minor mistake go unnoticed during this particular type of repair where there are a lot of very tedious steps involved. Catching those mistakes is half the battle. Doing what is needed to correct the mistake to achieve a satisfactory outcome for the customer is the other half.

 

m-hcan68, thanks for the reply. What you are saying makes total sense! Ya... I cannot get that thought out of my head. I've never re-built a dana rear-end, I'm a ford-9 guy;-) The place that did the re-man does a lot of these, I *think* it's pretty much all they do. Supposedly all bearings (pinion, carrier and wheel) and gears (pinion, ring and spider) were replaced.

I've got a couple things to try before taking the rear-end back out. The sound (or a similar sound) was intermittent BEFORE the re-build. But I'm not sure it's the same sound. Even if it is, it's much worse now. I'm going to try a few things first to eliminate all other possibilities.... (swap tires, for example, to make sure it's not just tire-noise, I don't want to be too quick to take the rear-end back! ) Thanks-Joe