Odd tapping sound on ALH - injector?

Smokepedal

Member
Joined
Jun 26, 2005
Location
Southern Oregon
TDI
2003 Golf
I have an '03 ALH with 90k miles and have noticed a subtle metallic-like tapping sound. It is easier to hear just off idle when taking off on a steep uphill incline, but can be heard at other engine speeds at light to moderate loads as well. However, typical engine sounds at high revs/loads make it impossible for me to detect. It might be there, but between normal diesel sounds and hearing loss, I can't be certain. Its speed is tied to engine speed and I believe it stops completely when coasting off-throttle, leading to me to believe it's injection-related.

Using a wooden rod as a stethoscope, I have noticed that #3 injector sounds louder and seems to almost make a snapping sound that is sharper than the other injectors. Is this normal for that injector since it has the needle lift sensor, or could this be the source of the noise?

Strangely enough, it is often easier to hear the tapping with hood closed. I guess it masks some of other typical diesel engine sounds. Open the hood and it seems to get lost in the clatter.

I have run several loads of Diesel Purge (It's an annual ritual for me) through the injectors without any effect. It has had CAT 2 micron filtration on it for the last 40k miles and I always run diesel fuel additives with every tank. MPG continues to average 51mpg, no CELs, no other strange behavior, no smoky or hard starts, no discernible oil usage, etc.

Valve cover, N75 valve, injection pump all sound smooth and comparatively quiet.

What could it be? Should I pop for a new #3 injector, or could it be something I've overlooked? I'm going on a cross-country trip next month and want this addressed before setting off.

Thanks for your help.
 

JBjunior

Veteran Member
Joined
Nov 27, 2007
Location
WA/NC
TDI
05 Passat Wagon/05 Passat Sedan/03 Jetta Wagon
Check for random things. I had an odd tapping noise yesterday and it ended up being a bolt on the power steering pump that was loose. Yours might not be that same issue, you could tell by rotating the steering wheel and seeing if the noise changes, but it come be something similar. When you are listening under the hood it is hard to pinpoint so many noises.
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Battle Ground, Wa
TDI
2002 jetta Wagon
are you sure this tapping sound is so odd? Or did you just notice it?

I hear mine and have read it is common for the pump to be audible...

If there are no other issues being created I am inclined to think that it is perfectly normal...
 

Smokepedal

Member
Joined
Jun 26, 2005
Location
Southern Oregon
TDI
2003 Golf
@ JBJunior: Thanks for the ideas; I'll keep looking for random causes.

@ eddieleephd: I agree, it could be normal. I just have a hard time accepting that nearly constant and annoying metallic "tink-tink-tink" sound as normal. On top of that, I also assume if I am hearing it, it is probably louder still to someone without hearing loss.

Thanks for your insight and ideas.
 

migbro

Veteran Member
Joined
May 19, 2010
Location
Lincoln, Mass.
TDI
2003 Golf GL
I had the exact same issue on my '03 Golf after getting the nozzles professionally replaced. Fairly loud tapping/ticking/tinking sound. Also coming from the #3 injector. 18,000 miles later the ticking has almost completely gone. No-one seems to know what this injector noise is.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
If it's the #3 lift sensor you'll here it every fourth rotation of the engine or something though because it only gets charged when it's due to fire.

How about on cold starts, do you get that little bit of lifter noise for a brief second or so? Can you tell if the noise is in time with that or if it's like twice the speed?

My engine has had a noise like that since I got it about 4 years ago and I'm still unsure exactly what it is, it has gotten louder with tuning too which suggests it made be a piston or small end. It's ok for me though as there's plenty of spares over here but I am still curious.
 

Smokepedal

Member
Joined
Jun 26, 2005
Location
Southern Oregon
TDI
2003 Golf
Today, I drove about 60miles (mostly freeway). Upon exiting the freeway, the tink-tink-tink that has followed me everywhere for weeks seems to be gone!?! Nothing has changed that I can think of -- even still on the same tank of fuel.

I'll have some time tomorrow to check things out more thoroughly. Not sure if it is my ears or my car that is playing tricks with me.

Maybe it is time to ditch the stock nozzles and do an upgrade... kind of a 'two birds with one stone' approach.
 
Top