Thud/Hum when coasting-- ice??

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Newscutter
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Joined: Wed May 31, 2006 7:22 pm
Location: Pittsburgh, PA

Thud/Hum when coasting-- ice??

Post by Newscutter »

:(


So it has been cold. And very snowy. Because of my job I have to slug it to/from work regardless of weather (which is why I'm on my second Subaru) and at sometimes unpleasant hours of the day.

Admittedly, after one of these sticky snowy commutes I was so late getting to work (not because of MY driving issues but because I kept getting stuck behind numbskulls who were spinning their wheels, throttle floored, trying to get up hills and they wouldn't move out of the way!) I just ran in. I did not knock any of the snow off the wheelwell areas.

Fast forward 36 hours -- I've now made several commutes with attached ice here and there and we've had enough freezing rain that the Baja is now a good 1/2" larger in all dimensions -- it looks laminated. I drove in to work uneventfully but on the drive home I notice a fairly loud THUD/HUM that kind of sounds like a gear skipping/grinding. -- This is an automatic transmission, btw. --

The sound appears to be coming from the front passenger wheel but I can't be sure, but I can feel it in the seat. This doesn't affect driveability in any way that I can tell and it ONLY appears when I am coasting. Even the slightest application of throttle silences the noise. On one of the larger hills I shift into neutral and the noise stops. Shifting back into drive it reappears -- downshifting to 3rd had no significant effect either way.

Arriving home I commence to pound and scrape all the snow out of the wheel wells that I can (LOTS of ice and buildup snow in there -- very hard -- and especially at the rear it seems to be in near constant tire contact). Nothing looks awry but there does appear to be more snow/ice hardened to the underbody out of my immediate reach (I don't have gorilla-long arms).

This morning my wife drives it to work and says the sound is still there.

I'll be taking it to work this afternoon/night and will recheck -- it hasn't been above freezing in a long time and our commutes are 5-10 miles so there isn't a lot of extra melting happening -- and it is a silver Baja so no hope of "sun heat" either). Perhaps I can find a spot in the garage at work to park it for a while so it can thaw, but unlikely.

Does anyone have any ideas? It just seems too coincidental that this condition would suddenly appear in the midst of this snowy/icy weather -- and do so only after being parked for 9 hours or so while I was at work. The fact that it only occurs in coasting and in a drive gear makes me think there is something frozen onto something somewhere that is the cause-- especially since any throttle at all immediately ceases it.

Any thoughts? Please?

Thanks!

MCS
2003 40K or so

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brujah
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Post by brujah »

I feel your pain. Tuesday night we got snow, more snow Wednesday morning, and then sleet and freezing temps. There is only a foot and a half of snow on the ground, but it has a two inch thick ice coat on the top. I actually saw someone today using a pick-axe to break up the snow into movable chunks!! :shock: Needless to say, I've got the exact same problem you have (extensions on the bumpers and everything). I went to the carwash and used the high-pressure wand (not the automatic one). The soap/wash setting is pretty hot, and after about $6, I had most of it out of the wheelwells. It made a definate improvement.
2005 turbo - WRX intercooler, Samco hoses, GFB bov, 3" Helix catless downpipe, 2.5" SS CatBackEx, front and rear skidplates(for rocks and logs), Westin safari bar, lots of Hella 500's

mbaksic
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Post by mbaksic »

HI Newscutter, I had a similar problem last year, we had a very wet snow out here in Cheeseland, then it froze harder than heck. I had a weird noise/vibration that I noticed, on right turns, or slightly moving the steering wheel to the right when moving. I also knocked all the snow/ice off of the wheels and wheelwells but it was still there. Since I work at a Dodge stealership, I put it up on my hoist for a look see. The driveshaft was encased in ice!!!!! The snow had packed up underneath when driving, packed around the driveshaft above the heat shield for the exhaust. The exhaust must have heated it up enough to turn it to ice. So when you drove and turned slightly, all kinds of vibrations and weird noises. I had to flush all the ice out with water in my stall at work. Noise gone. However, since then, there is a vibration type noise that I have never located at 1700 rpm's. I think it is in the exhaust somewhere.
So thats my story on this, you may have the same type of problem. Let us know what happens, and good luck. If you are lucky, maybe it will warm up a bit and thaw it out. Mike
Even though I work on Dodges, I don't own one.

n3now
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Re:

Post by n3now »

mbaksic wrote:HI Newscutter, I had a similar problem last year, we had a very wet snow out here in Cheeseland, then it froze harder than heck. I had a weird noise/vibration that I noticed, on right turns, or slightly moving the steering wheel to the right when moving. I also knocked all the snow/ice off of the wheels and wheelwells but it was still there. Since I work at a Dodge stealership, I put it up on my hoist for a look see. The driveshaft was encased in ice!!!!! The snow had packed up underneath when driving, packed around the driveshaft above the heat shield for the exhaust. The exhaust must have heated it up enough to turn it to ice. So when you drove and turned slightly, all kinds of vibrations and weird noises. I had to flush all the ice out with water in my stall at work. Noise gone. However, since then, there is a vibration type noise that I have never located at 1700 rpm's. I think it is in the exhaust somewhere.
So thats my story on this, you may have the same type of problem. Let us know what happens, and good luck. If you are lucky, maybe it will warm up a bit and thaw it out. Mike
Well it may be dated, but it's still valid. I went from "oh crap, what's suddenly wrong" to chipping ice from around my driveshaft. Annoying, but far better than taking it to the garage.

Thanks for the post.

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