Engine noise

[Mike66]

Hi,

 

I have 150bhp diesel manual, which has developed an engine rumble noise, when under load thru approx 1800 to 2000 revs. Before and above this the engine is its usual quiet self. If nor under load the engine again is fine. A bit annoying, as the revs match to approx 70 mph.

 

Has anyone had similar issue or know what it might be?
 

Thanks,

 

Mike

[Mike66]

Has no one else had this issue?
 

Mike

[Ootohere]

@Mike66

How many miles has your car covered before developing this engine rumble noise?

[Mike66]

Currently on 48k after just over 4 years. Probably started 2k ago.

[Txmax]

Where do you hear this noise? Maybe through the center vents? I have a noise I hear through the center vents but only under load on the gas pedal. It is a bit annoying. Other than that, car is great!

My car is a 2.0TDI manual with 78.000 km (48.500 Miles)...

[Mike66]

I thought it was engine related and only happens between 1800 and 2100 approx, lower or higher revs are fine. Also when not under load all is fine. Difficult to tell exact source.

[SpAwNtoHell]

Hi i have something similar on my one, only between 1000-1200rpm and again between 2000-2200rpm. I think i pinpointed to the heat shield on the bulkhead resonating as has a loose corner also no sign that used to be a fitting there...

 

My one is 150hp manual reg jan 2017 and currently with 113k miles.

 

As soon as i can get something to hold it that can withstand high temperature....

[Txmax]

5 minutes ago, SpAwNtoHell said:

Hi i have something similar on my one, only between 1000-1200rpm and again between 2000-2200rpm. I think i pinpointed to the heat shield on the bulkhead resonating as has a loose corner also no sign that used to be a fitting there...

 

My one is 150hp manual reg jan 2017 and currently with 113k miles.

 

As soon as i can get something to hold it that can withstand high temperature....

Can you please point that with a picture or a photo? I think it might be the source of my problem. It will help me massively... Thanks!

[SpAwNtoHell]

I will when i get a chance on daylight. And last night i noticed it started doing it at 1800 and stopped or diminished above 2100rpm but din not done it in the low revs above 1000...

 

I read around the forum is a common issue with the ac pipes but i could not find anywhere more than that comment. Not sure if is the same with what i think it is but following the ac pipes from left front to where are going in to the dash i have seen the heatshield and puting my hand on with cold engine and moving it to simulate vibration of the engine the sound was similar just louder and not that much buffed like from inside the car... Determining this is pretty hard as it happens under load and i cannot reproduce it in neutral with the car parked.

[Txmax]

On 12/02/2020 at 08:50, SpAwNtoHell said:

I will when i get a chance on daylight. And last night i noticed it started doing it at 1800 and stopped or diminished above 2100rpm but din not done it in the low revs above 1000...

 

I read around the forum is a common issue with the ac pipes but i could not find anywhere more than that comment. Not sure if is the same with what i think it is but following the ac pipes from left front to where are going in to the dash i have seen the heatshield and puting my hand on with cold engine and moving it to simulate vibration of the engine the sound was similar just louder and not that much buffed like from inside the car... Determining this is pretty hard as it happens under load and i cannot reproduce it in neutral with the car parked.

 

Hi, I thinks this might be the cause of my rattle. It’s more something happening on the engine bay that is amplified through the dash and the center vents than the dash itself. 

 

Sorry to ask again, but a photo would be massively helpful.

[J.R.]

I had a tinkly rattle at similar revs, it was quite audible when idling next to a wall or shop front on the RHS with the window down, could not identify it at the time but seemed to be coming from the aux belt/aircon pump/alternator area.

 

Not long after the aircon failed, it was a new Chinese pump and the centre splines stripped, I would say the central nut was not properly tightened as my old pulley and shearplate worked fine when fitted but it was used as a spare as I had already bought a new one, the new one was tight and has held together for 9 months.

 

As you mentioned it being when the aircon is on I would check carefully the pulley in regard of the shearplate and central nut and the splines behind which you wont be able to see.

[SpAwNtoHell]

1 hour ago, J.R. said:

I had a tinkly rattle at similar revs, it was quite audible when idling next to a wall or shop front on the RHS with the window down, could not identify it at the time but seemed to be coming from the aux belt/aircon pump/alternator area.

 

Not long after the aircon failed, it was a new Chinese pump and the centre splines stripped, I would say the central nut was not properly tightened as my old pulley and shearplate worked fine when fitted but it was used as a spare as I had already bought a new one, the new one was tight and has held together for 9 months.

 

As you mentioned it being when the aircon is on I would check carefully the pulley in regard of the shearplate and central nut and the splines behind which you wont be able to see.

Hy, not the case in my case at least as a prevention i already changed all puleys tensioner and belt ( i considered that 110k miles was enough for that belt, and knew that alternator freeruning pulley can create problems so changed the lot except torsional dampener).

[J.R.]

If you changed the aircon pulley then there is every chance that the spline drive could have play, the pulley itself runs on a large outer bearing and drives the aircon pump shaft through a shear plate and the splines, it can make a hell of a rattle or in my case tinkle with no visible movement, the splines can strip completely or the shear plate fail and the pulley will continue to turn noiselessly but no refrigeration.

[SpAwNtoHell]

10 hours ago, J.R. said:

If you changed the aircon pulley then there is every chance that the spline drive could have play, the pulley itself runs on a large outer bearing and drives the aircon pump shaft through a shear plate and the splines, it can make a hell of a rattle or in my case tinkle with no visible movement, the splines can strip completely or the shear plate fail and the pulley will continue to turn noiselessly but no refrigeration.

Is not in my case the sound was before at those certain revs and is now.

 

As for the heat shield picture attached. As stated i can not do a picture on day light. Done it last night. The sound this morning was cut in more then half but... Is something else also but big improvement from before( is not that obvious now as a sound that something is buzzing). I can only assume is something else also so i am a bit dissatisfied that is still something but now is so small i really have to pay attention and close cab ventilation and radio to hear.

 

When i get the chance i will get undertray off and check lower down but for now will do.

[Txmax]

13 hours ago, SpAwNtoHell said:

Is not in my case the sound was before at those certain revs and is now.

 

As for the heat shield picture attached. As stated i can not do a picture on day light. Done it last night. The sound this morning was cut in more then half but... Is something else also but big improvement from before( is not that obvious now as a sound that something is buzzing). I can only assume is something else also so i am a bit dissatisfied that is still something but now is so small i really have to pay attention and close cab ventilation and radio to hear.

 

When i get the chance i will get undertray off and check lower down but for now will do.

Many thanks, with this photo I will have a look tomorrow. By your description it looks exactly like my problem. Depending on the day it sounds more or it sounds less. Now I’m switching on the AC the sound seems to disappear. Does it also happen to you (no sound with AC on)?

[SpAwNtoHell]

2 hours ago, Txmax said:

Many thanks, with this photo I will have a look tomorrow. By your description it looks exactly like my problem. Depending on the day it sounds more or it sounds less. Now I’m switching on the AC the sound seems to disappear. Does it also happen to you (no sound with AC on)?

My AC is normally on and on auto set to 21 Celsius with sync on. Was not AC dependent in my case just on those revs of the engine.

[digifish]

On 12/02/2020 at 00:52, Mike66 said:

Currently on 48k after just over 4 years. Probably started 2k ago.

 

Could be a failing serpentine belt tensioner. Or any other pulley on the belt-driven accessory system adding vibrations that were not there before. 

Edited 15 February, 2020 by digifish

[pcspinheiro]

I have a metallic rattle under load at low rpm that is definitely ac related, as it goes away when I turn the AC ON! It's only getting worse and car has only done 35K km! I'm really annoyed by this, took the car once to the dealer within the 2 year factory warranty to be told it's the injection. However, it can't be as it's worse on a hot engine and completely goes away with the AC on, two situations in which, if anything, the injection works slightly harder. Even though I have an extended warranty I'm pretty sure that now they'll find the fault and it's not going to be covered under the extended warranty 😡😡😡

[pcspinheiro]

Update to those that may be in the same boat: the chief mechanic did notice the problem this time (especially after I pointed out how it disappeared when the AC was on) and after checking the car for a whole day Skoda say it's a faulty AC compressor that need to be changed. Actually, they say it explains the metallic rattle, belt side cricketing and excessive engine vibration. Surprisingly, they'll repair under warranty without fuss (factory warranty is over and in the shop they were not even aware I had an extended warranty) but have to wait for the compressor to come from Germany. With the current crisis it cod be a while. Hope this helps others.

Stay safe!

 

[Petros]

On 14/02/2020 at 07:03, SpAwNtoHell said:

Is not in my case the sound was before at those certain revs and is now.

 

As for the heat shield picture attached. As stated i can not do a picture on day light. Done it last night. The sound this morning was cut in more then half but... Is something else also but big improvement from before( is not that obvious now as a sound that something is buzzing). I can only assume is something else also so i am a bit dissatisfied that is still something but now is so small i really have to pay attention and close cab ventilation and radio to hear.

 

When i get the chance i will get undertray off and check lower down but for now will do.

 

Hi what did you actually do to the heat shield to stop or reduce the noise?