FR Tdi 150 weird noise accelerating from low revs

[danthemanwhocan]

Start the car, pull away and it's fine. Then once on the road and the car is a bit warmer, pulling away and accelerating from about 20mph in 2nd or say 30mph in 3rd, along with the normal diesel sound is this other noise, like a very light, rapid tapping sound, coming from the engine I *think*. It merges with the noise of the turbo, but its audible inside the car. Its not loud, but is distinguishable.

I've stuck my head out the window and slowed to about 10mph then accelerated, not hard just normally and its clearly there, although letting off the revs and its not - only when the engine is under load. At highter speeds its doesnt appear to do it.

Any ideas what could be up?

Thanks chaps.

 

[volvic]

taking a wild guess, i'd think something is hitting/touching one of the belts. whip the cover off and start the car. you might want someone in the car so they can rev the engine slightly and hopefully you'll be able to home in on the sound...

good luck and keep us updated!

 

[ChrisUK]

It's not flywheel judder is it (if booting it from low revs ?)

 

[danthemanwhocan]

gawd, i hope not...

I don't have to boot it to produce this noise. Would I be able to feel something through the pedal if it was flywheel related?

Got me worried now

 

[Viking]

It merges with the noise of the turbo, but its audible inside the car. Its not loud, but is distinguishable.

Do you mean it comes in when the turbo spools up and isn't connected to engine speed? If so, it's the turbo as nothing else follows that.

 

[danthemanwhocan]

It only occurs at low revs. I can accelerate hard at higher revs and the noise doesn't occur. If it was turbo related wouldn't the sound be audible whenever the turbo spools?

At the low revs it does make the sound concurrently with the turbo however. Reading about DMF judder, perhaps it might be that

 

[glynnd]

I have this sound on mine, it only occurs when the engine is warm and on light throttle. Mine goes away if you get above 3k or at full boost. Its been doing it on mine for 35k and I have replaced the cam, followers, cam bearings injector harness and just about all the sensors and maf and its still there.
I now believe its the injectors, but my car goes well returns 55+ easily on a run, so not bothered any more. If anything it smokes a bit more on spool up than it used to! but then its mapped now so assume its normal.
Now covered 133.6k
Glynn

 

[danthemanwhocan]

Cool, thats reassuring. Its exactly as you describe, only occuring when warm and on light acceleration from low revs. Got it booked in next friday to be looked at anyway just in case its really serious...

Thanks for the suggestions/advice chaps, always appreciated.

 

[glynnd]

let us know if its rectified Dan. If it does not cost too much to do, then I will get mine sorted. Just for comparison with yours, mine is sometimes worse than others and I will be suprised if it can be diagnosed unless its on a rolling road.
I have had vagcom on mine and looked at the injector values which are all well within their range.
It was very frustrating when I first noticed it, just learned to live with it really although I know something is not quite right as my car should not be making this noise!
Glynn

 

[glynnd]

When you take it to the dealer, ask if its diesel knock?
Glynn

 

[danthemanwhocan]

Will do Glynn. It's only been doing it for a couple of weeks now, but I hate to think it could leading to something far worse if I don't at least get it looked at. Hopefully diagnostics might shed some light on the problem.

I'm not taking it to a dealer, but to a garage we've used for years. Either way i'll ask him about diesel knock...

 

[glynnd]

Have you been adding millers to the diesel at all Dan?
Glynn

 

[glynnd]

Suggest to your garage that they take the rocker cover off to look at the camshaft. That was my starting point and my cam and tappets looked a bit worn but not severly. Some owners of the 150pd have had holes in their tappets from the incorrect oil being used. Its unlikely that this is your problem as the noise would be there all the time. But all the same get the rocker cover off to have a look at the cam etc.
Glynn

 

[danthemanwhocan]

Yeah is used Millers, have done pretty much since i've owned the car. I'll certainly get him to have a look at what you've mentioned, thats for the heads up fella...

 

[devonutopia]

Sounds more like compressor stall due to overboosting. Basically the turbo pushes Z, but at low revs the engine can only munch Y - The extra boost just stalls basically. Better to keep WOT for well above 2000rpm.

Does it sound a little like "wch-ch-ch-ch-ch-ch-ch" ?? (damn, I don't know how to type the sound lol)

 

[BenO]

My PD150 also has the dreaded tappity noise, (or a version of it), but unlike yours it is constant. I've read about all these different causes from incorrect oil usage to hair line cracks in the tappets and chocolate cams and i now have mechanical hypochondria. Im real interested in what you find, good luck.

Ben

 

[glynnd]

Sounds more like compressor stall due to overboosting. Basically the turbo pushes Z, but at low revs the engine can only munch Y - The extra boost just stalls basically. Better to keep WOT for well above 2000rpm.

Does it sound a little like "wch-ch-ch-ch-ch-ch-ch" ?? (damn, I don't know how to type the sound lol)

No devon its not due to that at all.
This noise you could almost guarantee is tappet failure, but as I have replaced all the stuff in the head and not cured it then its not a tappet/cam problem. I am almost sure its diesel knock.
Glynn

 

[frenchy]

I have this noise on mine, only occurs with light throttle. I would almost discribe it as 'pinking' like pre-ignition knock on petrols.

Under moderate/ heavy throttle it goes. Had one of our techs take it up the road and he said its normal and didn't really notice it.

My previous Ibiza Fr tdi and current one I have have did it. Both from brand new.

 

[glynnd]

From new?
Mine only started at about 97k
Glynn

 

[danthemanwhocan]

Well, I took it to a local garage last week and he thought possibly a gear box bearing, but wasn't that sure.

However, I also too it to my local SEAT dealership, Holders of Congresbury and went for a drive with the workshop manager and after about a minute he said, "thats the flywheel making that noise"

So well done to those who identified it as a juddering flywheel

He said I need to get it sorted asap as it can apparently begin to rub on the gearbox housing which could result in a damaged gearbox. He also told me that an Ahlambra caught fire with a similar problem!

However, he recommends getting the clutch done (again!) and its a gearbox out job which with the horrendous labour charges is in total gonna cost me about £1000...

Seems like these remaps do hammer the engine more then you think. How much cheaper should I be able to get that at an independant garage, now I know what the trouble is? Also, would be cost effective to get a Sachs clutch kit. I really don't wanna spent a grand!!!

I don't have that much money to throw at my car these days now I have a dirty repayment mortgage, so I need it sorting cheaply tbh.

Arse.