Currently when i pull away and the drive is taken up, or apply a dose of heavy throttle from a low speed I get a popping, come knocking noise from what sounds like the front center of van. I can feel it slightly knocking through the floor in sync with the noise.

I dont think its CV joints as there is no noise when turning. Im thinking maybe a central UJ joint in the longer drive shaft? or isnt there a mount/carrier bolted to the chassis that supports the longer driveshaft also?

thoughts appreciated!

Engine mounts OK?

the lower rear mount is new, it actually sounds like the noise is coming from this area. But ive had a look at it and it still looks fine. Replaced about 2000 miles ago.

Have my suspicions that the gearbox mount under the battery may be shot, but ive not had a look at it yet.

upper one, by the coolant tank, seems fine.

Normally (if anything can be normal on a Dob ) when a shaft bearings gone, it's gone across the rev range and you're well aware of it?

Is it a single "pop" or a series of "pops"?

can be as many as 3 when pulling away.

Also it will pop/knock, usually once, when letting off the power as well!

SAABstu said:

can be as many as 3 when pulling away.

Also it will pop/knock, usually once, when letting off the power as well!

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i would have thought - that if you jacked it up and hand span the wheel backwards and forwards, you'd be able to sense a drive shaft giving up?

Are you 100% sure it's not something like a suspension bush or a strut top mount? (Not trying to teach granny etc... just chucking thoughts in)

Failing that, maybe differential? or clutch pressure plate springs....?

Why I bring clutch into it, is since I chipped the old wagon, if I get power down wrong from start or slow (20 - 30mph) , the clutch will slip. But when I'm already doing say 60 and hit the loud pedal, I get like a series of what I think are small slips and grabs which feels a bit like a wheel has gone 50P shaped. Which obviously long term, aint great... hence why I drive like granny

ill test out that method of jacking it up and spinning the wheel by hand over the weekend.

today over my lunch break, my dad and i attempted to replicate the noise by bringing the clutch up to the biting point with the handbrake on to make the engine rock about on its mounts. no noise.

there is a bit of bearing noise at all speeds though, you know that sort of "womwomwom" noise.

you can also feel the knock through the gearstick to coincide wit the 'pop' noise.

Right, so ive had the front of the van in the air. The wheels rotate smoothly, and there is no movement in the hub.

I can however recreate the metal on metal noise by grabbing the driveshaft and moving it laterally (ie. pulling it in and out of the gearbox/cv joint.) The O/S has a few mm of movement and doesnt really make a noise when moved by hand, the N/S has a few more mm and makes a distinctive metallic clunk at the CV end of the shaft. There is no tell tale sign of the CV being bad when the van is turned in a tight circle.

SAABstu said:

Right, so ive had the front of the van in the air. The wheels rotate smoothly, and there is no movement in the hub.

I can however recreate the metal on metal noise by grabbing the driveshaft and moving it laterally (ie. pulling it in and out of the gearbox/cv joint.) The O/S has a few mm of movement and doesnt really make a noise when moved by hand, the N/S has a few more mm and makes a distinctive metallic clunk at the CV end of the shaft. There is no tell tale sign of the CV being bad when the van is turned in a tight circle.

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It's all pointing to it being ker-nackered, innit... just plain worn out.

so, best way forward. just buy a complete shaft with joints included?

Not worth messing around with is it? New one is around a oner, a second hand (if it checks out OK) about 40 notes.

That said it could sit there like that for a while and be no problem. It's one of those ones I start sticking £20 a month behind the clock for. Then it does go in a few months you'll be well on the way. If you can live with the noise

Is it by any chance a diesel engine with a DMF? They can make strange knocking/rumbling noises when worn. Hope not, because they can cost several hundred pounds to fix.

it is. But id have the noise constantly if it was DMF related wouldnt i? Ive had a listen to various youtube clips of cars with failed DMF's and they certainly dont sound like what im experiencing.

SAABstu said:

it is. But id have the noise constantly if it was DMF related wouldnt i? Ive had a listen to various youtube clips of cars with failed DMF's and they certainly dont sound like what im experiencing.

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Always thought when a DMF went it shook the thing to bits...?

anything come of this, was it the drive shaft?

i have now a popping noise from the front of my doblo jtd, when i pull off there will be a popping noise itll be gone until i ease off or brake.

its like something popping out of place when i pull off and popping back in when i stop, its not a constant noise or a metal on metal noise either. not always there but something is on way out, i also have my suspicions about the gearbox mount under battery. or could it be drop links or arb bushes?

Heat shield bolt sheared off. Needs a quick weld.

alienscolln said:

Heat shield bolt sheared off. Needs a quick weld.

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that'd do that while stationary though

creon said:

anything come of this, was it the drive shaft?

i have now a popping noise from the front of my doblo jtd, when i pull off there will be a popping noise itll be gone until i ease off or brake.

its like something popping out of place when i pull off and popping back in when i stop, its not a constant noise or a metal on metal noise either. not always there but something is on way out, i also have my suspicions about the gearbox mount under battery. or could it be drop links or arb bushes?

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CV's should make more noise on FULL LOCK..,

varesecrazy said:

that'd do that while stationary though

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Didn't on mine. It moved under acceleration or decelleration, making a pronounced click. It may not be the same, but I wouldn't rule it out.