Any thoughts on this....

[chris86uk]

Hi everyone.

My bus makes a horrendous rattle/vibration when accelerating (after about 25mph) in 3rd gear. At first I thought it was the gearbox failing for obvious reasons, but I've got a feeling something on the sliding door is vibrating.

Has anyone else experienced anything like this/is there something on the door that commonly starts to rattle? I've done thousands of miles and it hasn't got worse. With a noise like this, if it was the gearbox, I'm sure it'd have eaten itself by now! Oil level fine.

[Edit] I can instantaneously manipulate it with the throttle, the slightest movement will stop it. If I accelerate very slowly in 3rd, no rattle.
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1977 VW T2 - 1.6 Twin Port

[Danwvw]

Well have you checked that it didn't get something like a plastic bag sucked into the cooling fan?
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[EZ Gruv]

Have you taken the panel off the inside of the sliding door to see if something is loose?
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Eric
1977 Deluxe Westfalia - 2.0L FI Type IV, Completely Original
Photographer for HotVWs, VolksWorld, AirMighty, VW Camper & Commercial, Hayburner, and more.
My Photography Page.

[Wildthings]

Maybe you have a week ignition that will keep one or more of the cylinders from carrying its load at or near full throttle.

[cmonSTART]

Well that's certainly unusual. Are you able to document it on video at all?
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'78 Bus 2.0FI
de K1IGS

[dstimm]

I would just remove the sliding door, takes a couple minutes. https://www.youtube.com/watch?v=XUrQfarOcb8

Drive down the street with it off..
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1979 Sage Green California Westy.

[chris86uk]

Yep, I've had the panel off the sliding door, nothing seemed loose. If I push the bottom of the door in where the runner fits into the track, it makes a noise that could be related, but I'm not sure why it would resonate to this extent. The door shuts solidly.

I'll try to catch it on video as suggested. Thanks for all the replies.
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1977 VW T2 - 1.6 Twin Port

[chris86uk]

[scubasteve321]

What wild things said; opposing 4 cylinder engine plus mis-firing has caused horrendous vibration throughout my entire Bus at times in the past
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1971 Campmobile Tin-Top
1971 Campmobile Pop-Top
1974 VW Bus

[alaskadan]

you could rule out the sliding door by putting some thin foam or cloth in the top and bottom of the door jamb and close it.

[Reverand Hope]

ask a passenger to sit in the back and crawl around to see where it's actually coming from.
check obvious things like loose sliding door track cover panel, top and bottom roller bracket, loose tinware screws underneath etc.