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Noise when upto temp

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by Andy-R, Nov 8, 2013.

  1. Andy-R
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    Andy-R Member

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    Just wondering if anyone has any idea as to what this noise I get could be? Best way to describe it is its like a ghost going oooooo like a Scooby doo cartoon it kind of sounds like washer motor when your washers are empty aswell, I only get it when the cars up to temp and only when accelerating between 1500 and just over 2000 rpm doesnt appear to be down on boost and drives and idles fine it only started on Monday I've had the car a month tomorrow, any clues would be appreciated
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  2. sidibear
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    sidibear Looking for Zombies !! Staff Member Moderator

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    What engine?
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  3. Andy-R
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    Andy-R Member

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    Sorry its 2.0tdi 170 brd engine.
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  4. lynallbel
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    lynallbel Member

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    Turbo hose split?
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  5. Andy-R
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    Andy-R Member

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    Does sound like something like that but boost pressure seems fine.
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  6. Andy-R
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    Andy-R Member

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    Would a split turbo pipe only produce the noise when the car is driven? it doesn't do it when revived stationary or when just rolling only when I'm on the power, thanks.
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  7. lynallbel
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    lynallbel Member

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    Quick lesson in turbochargers, most people believe they produce boost all the time, BUT thats ******** they may shift air but nowheres near enough to produce meaningful boost, the engine has to be pulling ie driving, any squeals/rushing air means you have some sort of leak between the turbo and the inlet manifold, hoses are the favourite.
    Even a small leak can make a lot of noise, but the turbo is still making enough boost so as you say its still drive okay, but and theres always a but, the turbo is now having to work even harder to make the boost so the leak needs finding before anything else goes wrong.
    You can get a cheapo gauge and a t piece to check the pressure.
    But if its making a noise it should be obvious, the hard bit is finding the split hose.
    On the land rovers the one nearest the turbo always failed first as it was subjected to the most heat, ie pre intercooler
    Wait till motor is cold and feel up each hose giving it a good squeeze! to feel for any splits, or bits that obviously feel wrong i have had a couple delaminate on the inside but looked fine outside


    Lynall
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  8. Andy-R
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    Andy-R Member

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    Ok thanks will have to get it looked at I wouldn't have a clue, would a smoke test show any splits up?I'll just have to drive it a bit more conservatively until its sorted cheers.
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  9. lynallbel
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    lynallbel Member

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    Ive never used a smoke machine but have heard good things about them, i bet if you google your engine type and add the words hose failure you will get some useful hits and have a rough idea where to start looking.
    Just reread your post if you mean exhaust smoke test the answer is no, if you mean where they put the smoke into the hoses then yes.
    Just looked on ebay theres an awful lot of listings for an S shaped turbo hose, so maybe worth a squint in the engine bay?
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  10. Andy-R
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    Andy-R Member

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    Thanks, yes I meant smoke into the hoses to try and expose a leak, just a thought would it only make the noise when up to temp if its a split hose? it doesn't do it until the cars fully warmed up cheers.
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  11. sewell10
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    sewell10 Member

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    Possible water pump
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  12. ChrisShepB7
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    ChrisShepB7 Member

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    Easy way to find/eliminate a split hose, go to halfords and pick up a tin of easy start. Get the red straw off a tin of WD40 (so you can direct the easy start to a particular area) and spray all the hoses with the engine running, a change in idle/engine note will tell you that particular hose is split.
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  13. Andy-R
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    Andy-R Member

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    interesting I'm also losing coolant, the water pump was done when the cam belt was changed in Jan tho could it go faulty that quick?
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  14. Andy-R
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    Andy-R Member

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    I've seen this done on you tube, going to take the big intercooler pipe off tomorrow to have a good look at it first then if that's ok may go down this route cheers
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  15. lynallbel
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    lynallbel Member

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    Guys you lot are just ****ing hilarious!
    Spraying anything onto the hoses wont achieve squat as the turbo to manifold hoses are under pressure, so they wont be sucking any of your spray in.
    What you are suggesting is an old trick for leak on old carbed engines, which works on the inlet manifold to head joint and is under vacuum not pressure.
    But now you have bought another factor into play ie the coolant leak changes all bets.
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  16. Andy-R
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    Andy-R Member

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    So any idea what to look for? Didn't think it was related as the noise sounds like an air leak type noise, not 100% it is losing coolant I'm monitoring the level to see what happens but am pretty sure it is, I really need this sorting as soon as possible any clues to pass on to the garage would be appreciated thanks.
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  17. Andy-R
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    Andy-R Member

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    Just looking have you really got to remove the whole front of the car to get at the water pump?
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  18. Andy-R
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    Andy-R Member

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    Right guys 've had a good look over the car this morning and can't find any leaks, that doesn't mean its not there I just can't find it, basically what's happening with the coolant is it goes from Max to just under Min in less than a week but then doesn't appear to lose any more so I've marked the level and will keep an eye on it I'm hoping that's just the cars natural level and filling it up is causing it to burn it off somewhere although I'm probably not that lucky and it has a leak, I did notice what appears to be water in the bottom of the intake pipe the big one that goes from the MAF to the turbo(I Think) have seen something about tis online somewhere but can't for the life of me find it now to see what caused it, anyway don't know if the noise and coolant level are related but thought as much info as possible would help maybe diagnose the problem, cheers.
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  19. ChrisShepB7
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    ChrisShepB7 Member

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    Proves exactly what you know, on idle the engine makes a vacuum. Put any old boost gauge on the car and when idling the needle will be in the negative side of the gauge, indicating the engine is making a vacuum i.e SUCKING. The only time it's under pressure is when the engine is under load and the turbo is making boost.

    As the old saying goes don't teach your granny to suck egg's I was a diesel technician for over 8 years and we used the easy start many a time to much success.
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  20. lynallbel
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    lynallbel Member

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    Well obviously your 8 years beats my 25 hgv mech experience, as i said above ive never heard of any turbo diesel making vacuum in the pipework as the turbocharger is ALWAYS spinning regardless of engine rpm, surely your 8 years taught you that?
    Also as i mentioned above turbo engine shifts large amounts of air even when off boost, ie the turbocharger doesnt just stop spinning when the engine is at idle, but im sure you know that, if not check with granny:blow:
    Ps i run a boost gauge on my land rover tdi and have never ever seen it in the vac part of the gauge, i road test approx 5 to 10 hgvs every shift, on every one i run the built in dash boost gauge and only time when boost drops to zero is when using exhaust brake down a longish hill.
    But i will bear it in mind next time i get a squealer on road test and give it a try, could save me loads of time.


    Lynall
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  21. lynallbel
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    lynallbel Member

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    I forgot to say, there is a very very good reason the majority if not all small car/van turbo diesel engines have vacuum pumps for the brake servos, its because?
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  22. Andy-R
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    Andy-R Member

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    I appreciate both you guys experience and help, any ideas with the info I've given what to look at first? Its going to get looked at tomorrow it'd be good to have an idea where to start, cheers.
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  23. lynallbel
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    lynallbel Member

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    Andy just chuck it into the garage and let them do the looking, i would bet money they will have seen the two faults before, they wont be unique faults rarely are.
    Have you looked at the diagnostic map thingy on here? maybe someone local knowledgable who knows the common faults
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  24. Andy-R
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    Andy-R Member

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    No mate not looked, the guy it's going to apparently knows his stuff when it cones VAG so will see what he says just wanted an idea to see if I can offer any help or to see if what he
    says adds up with other suggestions on here cheers.
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  25. Andy-R
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    Andy-R Member

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    Ok update and I'm none the wiser, can't find an external leak with dye in the system it has only been in 2 days so may still show up but would of thought it would be obvious pretty soon so the guess is water pump but without spending money to take it all apart to check there's now way of knowing, the mechanic is convinced its not the head and since the egr cooler is only 5 months old he's happy its not that either so going to give it a week and see if the dye shows anything, he also thinks the noise is turbo related but nothing to worry about for now I'm still going to check the intercooler pipe tho for my own curiosity, so unless anyone has any ideas I'm stumped unless I start spending money to investigate which I can't really afford at the moment with Christmas just a few weeks off.
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  26. lynallbel
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    lynallbel Member

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    Some water leaks are so minor as the coolant runs down the hot block it evaporates and doesnt drip on the floor.
    Others dont leak at all until the engine switched off and left for a short time.
    K-seal is a very good product, its not like the old barls leak dog turd!, ive used it a few times and its always worked.
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  27. Andy-R
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    Andy-R Member

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    He did say try K seal just don't fancy it myself but if I can't find the leak I may try it wait till the leak stops then drain the system
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  28. Matt10160
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    Matt10160 Member

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    Just to throw it in the mix, check power steering fluid thst can make a weird ooooooing sort of noise​
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  29. Andy-R
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    Andy-R Member

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    I've checked that it's where it's supposed to be so I'd assume it's ok, or is it something to do with the fluid itself not the level? Cheers
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  30. Matt10160
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    Matt10160 Member

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    No just the level so if its ok it shouldnt wine
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