booming air box 300tdi???

this has been bugging me for months now! as revs climb there is an awful booming in cabin! very loud. first thought was blown exhaust.checked for leaks all good, replaced all zorst gaskets including manifold. started to think it might be related to my knackered head gasket. but thats all fixed now and still have the booming.
discovered when i move air intake pipes around the bassy engine note changes. so im fairly sure the booming is something to do with the air intake side.
have replaced all air box rubber mounts, new filter and removed all pipes up to turbo to check for splits, nothing!!
drove it today with wing to filter piping disconnected and its a little better. (goes much better like that! like getting a tune up)
anyone else experienced this? is it safe to test drive it with all piping right up to turbo off?
cheers

sounds like there may be a blockage in the intake section to the wing, or more likely that one of the plastic sections isnt mated to another properly. that'd cause decrease performance and possibly an odd noise as the air passes the bad join.

im running it without the wing to filter section and it feels much more responsive!! but the booming is still there! definitely not blocked or leaking there as when i took it off i filled it with water to check and it was fine!.
can anyone tell me if it is safe to test drive it with air box and pipe to turbo removed? that way i can eliminate that part next!

Check your valve clearances, I bet it's that.

clearances were done when i put head back on. And double checked!

I would check again as the noise could be exhaust gasses being expelled into the air intake. I had this issue and it actually turned out that my rocker shaft had broken throwing the clearances out completely.

Has it been doing this since the head was redone? And what was the head removed for? Did you skim the head before refit? did you lap the valves back in?

tetsu0san said:

I would check again as the noise could be exhaust gasses being expelled into the air intake. I had this issue and it actually turned out that my rocker shaft had broken throwing the clearances out completely.

Has it been doing this since the head was redone? And what was the head removed for? Did you skim the head before refit? did you lap the valves back in?

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head came off because i was losing a little water and it was smoking (white) from exhaust pipe at idle. engine hadn't overheated and ran fine. booming noise was present for a few month before head came off.
didnt have head skimmed tolerances were fine. i didn't remove valves so no lapping.

think i might just whip cover off and triple check them though!!

Did you remove the rockers when you remove the head or was it just a head off, new gasket and head back on job?

Again, the only thing I can think of is combustion escaping into the intake through bad valve clearances. Unless your engine is breathing heavily and the combustion is going into the sump and back up a breather into the intake. But if that were the case you would possibly end up running the engine on its own oil (which would be bad).

When you run the engine, remove the filler cap (and the dip stick) and see how much pressure there is there. If you see a lot of smoke coming out and if you can't seal the filler hole easily with your hand due to pressure then I you have a breathing engine which could be worn bores/rings, worn valves, worn valve stem oil seals etc.

tetsu0san said:

Did you remove the rockers when you remove the head or was it just a head off, new gasket and head back on job?

Again, the only thing I can think of is combustion escaping into the intake through bad valve clearances. Unless your engine is breathing heavily and the combustion is going into the sump and back up a breather into the intake. But if that were the case you would possibly end up running the engine on its own oil (which would be bad).

When you run the engine, remove the filler cap (and the dip stick) and see how much pressure there is there. If you see a lot of smoke coming out and if you can't seal the filler hole easily with your hand due to pressure then I you have a breathing engine which could be worn bores/rings, worn valves, worn valve stem oil seals etc.

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no pressure with cap off! i can sit the cap on and it bobbles up and down a little but it stays there! doesnt sound any louder with cap off too! cleaned all breather pipes and cyclone when it was in bits!
when you say"did you remove the rockers" i removed the rocker shaft as one unit and didnt take any of the shaft apart, just put a bolt in each end to keep the assembly together.

Yeah, that is what I meant. Can you take a video of the noise and put it up on youtube or something? If it's not exhaust gasses getting out the wrong way then the sound might be better diagnosed if it can be heard.

tetsu0san said:

Yeah, that is what I meant. Can you take a video of the noise and put it up on youtube or something? If it's not exhaust gasses getting out the wrong way then the sound might be better diagnosed if it can be heard.

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yuup will do, but might have to wait till tomorrow.

right, here is video
https://www.youtube.com/watch?v=C80XDn4U_hE

you can here a definite popping, always heard it since i bought it in Jan.
after lots of researching it seems this popping is NOT normal! im guessing this intake popping is what is turning into a loud boom when driving.
i will re set valves again tomorrow, and take it from there.
it will be 3rd time ive set valves and each time im pretty sure im getting it right. so if they are OK what next? do the rocker assembly wear out?

That sounds like my mates tdi the other day when we started it without the inlet pipe on,

What condition is the air filter in?

Try pull the pipe off the turbo inlet and go for a small drive see if its any diffrent

Two thoughts.

Inlet pipe collapsing as revs rise? Something on the engine/exhaust contacting the bodywork as it twists on its' mounts (under load)?

g-mack said:

right, here is video
https://www.youtube.com/watch?v=C80XDn4U_hE

you can here a definite popping, always heard it since i bought it in Jan.
after lots of researching it seems this popping is NOT normal! im guessing this intake popping is what is turning into a loud boom when driving.
i will re set valves again tomorrow, and take it from there.
it will be 3rd time ive set valves and each time im pretty sure im getting it right. so if they are OK what next? do the rocker assembly wear out?

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When you have done the valve clearances, have you had to adjust them at all?

I know it's probably a stupid question, but what values are you using to do them? Also, are the little brass caps still on the valve stems?

Oh yeah, and I watched on of your other videos. You look a little bit like Alan Carr!

tetsu0san said:

When you have done the valve clearances, have you had to adjust them at all?

I know it's probably a stupid question, but what values are you using to do them? Also, are the little brass caps still on the valve stems?

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im not sure if they were out or not as when i replaced HG i didnt check, knowing i would do them when it went back together.
bought 8 new collets so had to adjust a few when it went back together. cant remember which way though. also kept rods in order. used rule of 9 and set to .20.
gonna go outside shortly and whip lid off!

g-mack said:

im not sure if they were out or not as when i replaced HG i didnt check, knowing i would do them when it went back together.
bought 8 new collets so had to adjust a few when it went back together. cant remember which way though. also kept rods in order. used rule of 9 and set to .20.
gonna go outside shortly and whip lid off!

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Well is sounds like you have done it all right anyway, so at this point I am at a loss. I presume the engine runs fine anyway with plenty of power?

Update: Valve 8 had lost its collet! and the gap was .04 without it!! cant understand how that would be but anyhoo refitted collet and went through rule 9 no adjustments needed apart from v8 as stated. put it all back together and its less tapperty as you would expect, still has a bit of a popping sound from wing but im sure it isnt as bad. Unfortunately the booming is still present when driving!
here is a vid of the air intake sound. is this normal or not.
https://www.youtube.com/watch?v=4cC43p4S3zE&feature=youtu.be