deafening engine 'drone' at certain revs

[Doris]

hi all! I was going to hold off posting this until I had a video,but I thought I'd get the ball rolling.

ok,stock 1600 sp.stock exhaust,carb etc.

may I just add that I've had several aircooled VW's so I know they're not as quiet as a brand new Audi,but I know this ain't right!!!

right,so the problem is when you start getting toward 50mph the engine noise turns into an extremely loud drone,reaching the loudest at about 55mph.when I say loud....I mean head ache stuff....you cannot hold conversation! as you get toward 60-65 it goes away,i.e.the usual/expected noise of the engine working hard.

It only happens under load,so if I ease off the gas at say,55 mph, the drone disappears.

there is nothing in the fan or shroud & everything else seems in good shape.even have the og tar boards in place.

my thoughts.....
a) is it exhaust related due to the drone only under load?

b)it is a harmonic sound,such as when you drive a car on the motorway with the back windows done,you get that loud rapid 'thudding' sound.

c) could it be related to my slightly wobbly pulley wheel mentioned in other current thread?

d) only happens in a certain rev range which suggests something out of balance?


holidays planned for July and I think this noise would make for an unpleasant journey for the family for any length of time.

any thoughts or experience of this?

thanks in advance :-?

 

[crede999]

i get this now and again depends which way wind is blowing and how fast im going etc i try and find a speed and drone im happy with although it doesnt sound as deafing as yours , mines quite barible to be honest ? are you soundproofed inside ? and in engine bay ?


chris

 

[67panel]

God ain't you changed that pully yet(slap around kisser smiley)it will cause vibration and could wreck your bearings ,DO IT NOW

 

[bubba dubba]

mine does this too, not deafening but just the same as crede999's above, i put it down to wind noise or tyre noise and adjust my speed to whats comfortable, i will be watching this thread with interest now in case its something i should be worried about, (like i need something else to worry about :lol: )

...........................kev

 

[meowdmucker]

Does sound like resonance to me, most likely the pulley out of balance, just like a wheel that has'nt been balanced properly will resonate worse at a certain speed. As above, change the pulley ASAP.

 

[uber cool]

could it be tyres, wheel balancing, wheel bearings, gearbox, or diff noise?

Try in 3rd or 4th gear to see if its speed or rpm related noise. If it only does it at certain speeds and not revs I would not have thought it would be the pulley. However you still should change the pulley before you go on holiday. If you can drive though the niose I would more likely suspect some sort of transmission problem, as above.

 

[Doris]

thanks so far guys! ok,so you think I should change the pulley then!? :grin:

wish it were az easy to do as say! working long night railway shifts,voluntary work commitments,a young family,not 100% health & a wife who would sell the bus tomorrow for scrap value.so finding time is difficult you see :roll:

 

[Doris]

by the way....please tell me I can change the pulley wheel without taking the valance off!???? can I just take the tin off? ( I know, I know but a long story)

 

[crede999]

If your doing 55 and it's droning push the clutch in does the noise go away ?

Oh and change that pulley :shock: anyone would think you'd just done a full resto :lol:

Chris

 

[Doris]

If your doing 55 and it's droning push the clutch in does the noise go away ?

no Chris....still there as long as I hold the revs....defo engine rev related.

someone suggested loose cylinder head bolts flipping hope not!!

 

[ZedBed]

Maybe you "just" have a hole in your exhaust system...

 

[Doris]

Maybe you "just" have a hole in your exhaust system...

do ya know that zed,that would fit the symptoms actually.Its only done a few hundred mile and it looked ok when I fitted it but I think its worth another check.it is like that sound....like one of those big exhaust back boxes you see jubilee clipped to the back end of a 1.0 saxo :grin:

 

[crede999]

Sounds a good call by Zed , get the bugger in the air as spotting holes or leaks in the exhaust system can be a bugger I had one on my exhaust I could feel it blowing but couldn't see it took the exhaust off ... Stonking big hole ! :shock: only been on 18 months from brand new !

Good luck fella ... Teething probs don't you love em ...er no !


Chris

 

[Doris]

checked for exhaust leaks by blocking the tail pipe......all seems well.can't hear any escaping exhaust :-?

someone suggested it could be the big panels 'booming'.gonna try a big magnet on them to stop any vibration.

waiting for vwed to get back to me about a bottom pulley,see what happens once that's done.if it were a ford focus or a Toyota corollary it'd be gone now....good job I love her :grin:

 

[le catweasel]

Sorry to dredge up an old post but did you find the cause of this? Very similar to how our bus is at the moment, seems to get loud at around 55 but can be driven through it just the same

Thanks

 

[guyers73]

HI all have you checked the fan.what normally happens is a bit of rag or other foreign object get sucked into the fan.this then puts it majorly out of balance and makes a deafening noise.it only takes a few mins.and costs nothing.it only takes a small bit of crap to cause this problem.

 

[monkeyvanwestybike]

HI all have you checked the fan.what normally happens is a bit of rag or other foreign object get sucked into the fan.this then puts it majorly out of balance and makes a deafening noise.it only takes a few mins.and costs nothing.it only takes a small bit of crap to cause this problem.

your not wrong there
its amazing how much noise a foxs glasier mint wrapper makes in the fan !

 

[sparkywig]

HI all have you checked the fan.what normally happens is a bit of rag or other foreign object get sucked into the fan.this then puts it majorly out of balance and makes a deafening noise.it only takes a few mins.and costs nothing.it only takes a small bit of crap to cause this problem.

your not wrong there
its amazing how much noise a foxs glasier mint wrapper makes in the fan !

Or a crisp bag shoved in the back of a wheel.

 

[matt-me]

Apart from the 'thudding' sound the OP mentions, i had exactly the same noise appear last year when i got to 50mph just on the M25. It came totally out of the blue. I couldn't work out why it only happened at this type of speed and only in 4th gear, my thinking was the gearbox or clutch bearing, but as it wasn't in other gears couldn't work it out.

Long story short, it was a rear wheel bearing. Jacked up the bus, rocked one wheel, normal play, rocked the other, 10-15mm play across the wheel. Apparently the bearing came undone by hand when changed by my man...felt very lucky it didn't give up on the motorway fully laden with wife and kids...

Check the wheel bearing, read the manual to confirm 'play' tolerances (think a couple of mm but double check).

Good luck

Al