Cold Start Rattle

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
Hi all. I have a rhythmic rattling coming from the engine area when the engine is started cold. The rattle sounds rhythmic and oscillating, coming from the engine bay. It occurs when the engine is started cold and is gone after a trip down the road, seemingly once operating temperature is reached. It does not occur during the subsequent starts while the engine is warm. It is more prominent when the car has sat for a few days, but still disappears after driving. This rattling has been around for a while. If I had to guess, maybe since 60k miles… maybe longer. The symptoms have not changed since first noticing it.
A video of the rattle:

Some background to hopefully narrow things down:

2015 Golf S TDI with DSG
86k miles
Malone Stage 2 and Rawtek exhaust done at 70k miles

The car was purchased in 2017, new, after returning from the DieselGate fix. The original owner was close family, so I’ve been fairly familiar with this car since it was new. I also drove it quite often. They were on point with the basic servicing – oil, tire rotation, fuel filter, and air filter have been changed regularly at the correct intervals. Since owning it, I average 600 (mostly highway) miles/week, so I’ve become zealous about learning/performing preventative maintenance. I was horrified to find out the DSG had never been serviced. So, I did the first at almost 80k miles… however the fluid/filter looked surprisingly good. It may be worth mentioning there were no changes in drivability/feel after this servicing, nor did it affect the rattle.

I’m self-taught and learning as I go, (praise YouTube, and all y’all in the forums) but I’m detail attentive enough to notice the smallest new noise/vibration/etc. To me, the car runs and feels fine. There has been no noticeable difference in feel or performance while the car is warming up and the rattling is occurring. However, I’m no mechanic and my knowledge and experience is limited. I’m hoping y’all can get me pointed in the right direction.
 

Mike_04GolfTDI

Top Post Dawg
Joined
Nov 19, 2003
Location
Richmond, BC, Canada
TDI
Mine: 2019 Golf R DSG, Wife's: 2015 Golf Comfortline TDI
Maybe it’s hydraulic lifters? The pressure bleeds down when the engine is stopped for a while, and then they firm up again when you drive. Their purpose is to maintain clearance between the cam lobe and valve stem.

That engine can run the oil pressure at a reduced level depending on operating conditions, so that may play a role.

I could be wrong. It’s just a thought.

Do you have to actually drive to make the rattling go away? If you just hold the RPM at maybe 2500 for a few seconds would that make the rattling stop?
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
Sounds about right to me. Can you post a video with the engine warmed up?
Here's a video at operating temperature:
Maybe it’s hydraulic lifters? The pressure bleeds down when the engine is stopped for a while, and then they firm up again when you drive. Their purpose is to maintain clearance between the cam lobe and valve stem.

That engine can run the oil pressure at a reduced level depending on operating conditions, so that may play a role.

I could be wrong. It’s just a thought.

Do you have to actually drive to make the rattling go away? If you just hold the RPM at maybe 2500 for a few seconds would that make the rattling stop?
Driving does not affect the rattle. Reconfirmed with getting this video -- drove around a bit through the neighborhood but the engine was still below operating temp, and still rattling. I let it idle until it hit operating temp and the rattle is gone, or at least inaudible to me. Before warming it up I also tried revving the engine as you mentioned and nothing changed. The sound is more prominent on the passenger side and sounds like it's coming from the middle-ish (top to bottom) of the engine bay.
 

Mike_04GolfTDI

Top Post Dawg
Joined
Nov 19, 2003
Location
Richmond, BC, Canada
TDI
Mine: 2019 Golf R DSG, Wife's: 2015 Golf Comfortline TDI
So probably not hydraulic lifters. They should stop rattling in a few seconds unless something is wrong with them (not likely).

My wife’s 2015 TDI has always made the same noise, as far as I can remember. So it’s probably somewhat normal, or not serious.

I’ll have a listen to hers sometime and see if I can figure out what part is making the sound.
 

ticaf

Veteran Member
Joined
Nov 15, 2018
Location
US Mid-Atlantic
TDI
Stock 2015 Golf SW S Manual TDI
I assume you are referring to the oil pump noise. I have a similar noise, since new. I'll pay more attention to see if there is less noise with fresh oil.
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
I’m not sure, it’s difficult to describe. It sounds like it’s in the “background” behind the engine noise. And rolling? As in it gets louder-quieter. It very well could have been since new, and I didn’t notice it until later. I wasn’t the primary driver so its definitely possible. I have not noticed a change with fresh oil, I’ll be more attentive next change.
 

Victor Huge

Veteran Member
Joined
Apr 18, 2009
Location
Alberta
TDI
Mk7 Golf TDI
Heya, I have the same noise, changed timing belt and all components thinking it was the water pump (slight leak) and the noise remains. It's an odd rhythmic thrumming noise like in the first video. The second video the cover is on which muffles it considerably.

Don't have a solution for you, but it's not in the timing belt area best I can tell.
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
Heya, I have the same noise, changed timing belt and all components thinking it was the water pump (slight leak) and the noise remains. It's an odd rhythmic thrumming noise like in the first video. The second video the cover is on which muffles it considerably.

Don't have a solution for you, but it's not in the timing belt area best I can tell.
In the second video the engine has reached operating temp. In my case, once operating temp is reached the noise disapears (from what I can tell). Is this the case for y’all as well? And is the noise the only symptom also?
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
I checked, don't seem to have it when warm.... Odd
Odd indeed. I have yet to see any information on this sound. I’m new to the TDI world, but I used to drive diesel trucks. Pretty much all of the Cummins/Powerstroke engines. Never heard anything like this particular sound. It’s been around for so long though, maybe it’s just normal for these engines.
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2017 Alltrack SE; Totaled 2015 Passat SEL, BB 2010 Sedan Man; 2012 Passat SE w/ Nav,
In the second video the engine has reached operating temp. In my case, once operating temp is reached the noise disapears (from what I can tell). Is this the case for y’all as well? And is the noise the only symptom also?
How are you determining operating temp?

the cluster coolant gauge, or verifying the oil has reached >170F in the cluster?
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
How are you determining operating temp?

the cluster coolant gauge, or verifying the oil has reached >170F in the cluster?
Just using the coolant gauge. I have not verified through other means yet. I have the “Dynamic Idle” option from Malone, which they say kicks in until the coolant is about 158F. The rattling is still present when it returns to normal idle RPM, until the coolant gauge reaches the “12 o’clock position.”
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2002 Golf 6MT; 2015 Sportwagen 6MT; 2016 A3 e-tron 6DSG
Yeah - the coolant gauge is useless for determining actual coolant temp. It reads 90C/190F anywhere within a +/- 15°C range.
(Long mountain climbs, my OBD-based gauge will show up to 105°C while the cluster and infotainment display shows bang-on 90°C the whole time.)
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
I figured it was mostly a ballpark estimate. I’ll have to set aside some time to play with OBD11/VCDS and see exactly what temperature the sound dissipates at.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
I usually don't worry about rattles. They are an indication that the part hasn't fallen off yet...
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
It sounds like it’s not uncommom, and nothing has broken for this long. So I’m leaning toward your line of thinking.. lol.
 

FenexTDI

Member
Joined
Jan 2, 2023
Location
Florida
TDI
Mk7 Golf TDI
Reviving this thread because I have another example. I changed my oil the other day and let the car idle for a few minutes. I started to smell some oil burning, and also thought that the engine sounded just slightly different than usual. Popped the fill cap and discovered this blowby. Previously (usually check blowby when I change the oil) it barely had enough to move the cap, so this is a significant increase. Also, that rattling sounds pretty gnarly when the cap is off. Maybe I’m overthinking this but it seems strange. Also noteworthy:
— Engine oil was at the correct level after change.
— It’s consuming about a liter of oil every 5k miles.
—After discovering the blowby I checked the CCV and found a bit of fresh oil inside
—Sometimes theres a puff of smoke on start up, doesnt smoke otherwise.
— The car has been running as normal. Have not run it since finding this.
Heres the video. Any thoughts?
 

John Wesley Hardin

Veteran Member
Joined
Aug 28, 2022
Location
Rockport Texas
TDI
2003 VW Jetta 1.9 Diesel GLS , Five Speed Standard Shift
Hi all. I have a rhythmic rattling coming from the engine area when the engine is started cold. The rattle sounds rhythmic and oscillating, coming from the engine bay. It occurs when the engine is started cold and is gone after a trip down the road, seemingly once operating temperature is reached. It does not occur during the subsequent starts while the engine is warm. It is more prominent when the car has sat for a few days, but still disappears after driving. This rattling has been around for a while. If I had to guess, maybe since 60k miles… maybe longer. The symptoms have not changed since first noticing it.
A video of the rattle:

Some background to hopefully narrow things down:

2015 Golf S TDI with DSG
86k miles
Malone Stage 2 and Rawtek exhaust done at 70k miles

The car was purchased in 2017, new, after returning from the DieselGate fix. The original owner was close family, so I’ve been fairly familiar with this car since it was new. I also drove it quite often. They were on point with the basic servicing – oil, tire rotation, fuel filter, and air filter have been changed regularly at the correct intervals. Since owning it, I average 600 (mostly highway) miles/week, so I’ve become zealous about learning/performing preventative maintenance. I was horrified to find out the DSG had never been serviced. So, I did the first at almost 80k miles… however the fluid/filter looked surprisingly good. It may be worth mentioning there were no changes in drivability/feel after this servicing, nor did it affect the rattle.

I’m self-taught and learning as I go, (praise YouTube, and all y’all in the forums) but I’m detail attentive enough to notice the smallest new noise/vibration/etc. To me, the car runs and feels fine. There has been no noticeable difference in feel or performance while the car is warming up and the rattling is occurring. However, I’m no mechanic and my knowledge and experience is limited. I’m hoping y’all can get me pointed in the right direction.
I heard it on your video. just noticed it on my 2003 VW diesel Jetta. It was some time after I replaced my serpentine belt and the pulley. Seems there's a counter weight or something similar at the top of the pulley. This would be on the passenger side up towards the radiator close to the top of the hood. In my case I heard that same rattling . I pressed down on the top of the counter weight while the engine is running and it went away. It seems like that weight is filled with steel shot or something similar causing the rattle. Thats in my case anyways
 

Mike_04GolfTDI

Top Post Dawg
Joined
Nov 19, 2003
Location
Richmond, BC, Canada
TDI
Mine: 2019 Golf R DSG, Wife's: 2015 Golf Comfortline TDI
I wonder if the noise has something to do with the water pump shroud?

These cars have a shroud that will cover the water pump impeller when the engine is cold, so it will warm up more quickly because there’s little or no coolant flow.

When it gets warm enough, the shroud retracts to allow the impeller to work normally.

Maybe that’s what’s making the strange sound.

With VCDS I think you can engage or disengage the shroud to test it. Once the engine is warm, and the sound stops, try engaging the shroud to see if the sound returns. Sometime I might do it with my wife’s car if it makes the sound (I haven’t payed attention or noticed it lately.)
 
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