ALH making harsh knocking at idle only

J

Jens590

Well-known member
Joined
Jul 30, 2009
Location
Comox BC Canada
TDI
01 TDI Jetta
I started the car a few mins before leaving work today walked away and came back 5 min later and the car was making this noise like a crankshaft knock or a broken motor mount but it goes away when you step on the loud pedal and start driving the car and everything seems normal again. when you slow down, push in the clutch and stop it does this weird transition where it feels like i have stock motor mounts for a sec then the knocking sound/feeling comes back. also there are no trouble lights and the no abnormal smoking and the boost gauge reads normal, loading/unloading of the turbo feels normal im competely baffled and my next move is taking the oil pan off to check the bottom end

the car is modified it has an 034 solid dogbone with VF upper mounts i dont think they are the problem i checked them out and nothing looks or moves like its broken
 
sisyphus

sisyphus

Veteran Member
Joined
Dec 8, 2008
Location
Appleton, Maine
TDI
99.5, '01 A4 Jetta sedans, 5 sp box, Hamman mod, Joey mod, Bilsteins, 2.00" lift
What's your IQ set at? Part of this could be related to "slowdown shudder" but IDK. How cold was it this morning? Does it do this even after the engine reaches operating temperature?
 
J

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 2005 BEW Beetle, 2005 Jetta Wagon
Jens590 said:
I started the car a few mins before leaving work today walked away and came back 5 min later and the car was making this noise like a crankshaft knock or a broken motor mount but it goes away when you step on the loud pedal and start driving the car and everything seems normal again. when you slow down, push in the clutch and stop it does this weird transition where it feels like i have stock motor mounts for a sec then the knocking sound/feeling comes back. also there are no trouble lights and the no abnormal smoking and the boost gauge reads normal, loading/unloading of the turbo feels normal im competely baffled and my next move is taking the oil pan off to check the bottom end

the car is modified it has an 034 solid dogbone with VF upper mounts i dont think they are the problem i checked them out and nothing looks or moves like its broken
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That does sound like a typical IQ issue. Once the car warms up a bit and the idle IQ drops below about 1.0 or so, the engine tends to thrash around like it is running on half of its cylinders.
 
N

Nevada_TDI

Top Post Dawg
Joined
Aug 17, 2008
Location
Reno, sort of...
TDI
2001 Jetta TDI
I was adjusting my IQ yesterday and bumper the pump too far; the IQ dropped below 2.0 and the engine was running terrible and bouncing around.
 
UhOh

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Sitting there at an idle it shouldn't run like crap even if the IQ is set really low (initially, and for a minute or two it'll run like crap, but then things should settle down).

With the clutch changing behavior it almost sounds like that's where the source of the problem lies.

How many miles? (mileage on clutch?)

Stethoscope time.
 
BobnOH

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Yea, 1st thing, with a stethoscope or even a hose-in-ear, try to isolate the source of the sound Likely it's the IP or the valves.
 
J

Jens590

Well-known member
Joined
Jul 30, 2009
Location
Comox BC Canada
TDI
01 TDI Jetta
the clutch is a southbend stage 2 with a single mass flywheel i doubt that it has anything to do with the clutch though but im gonna check it out anyway. i think the path to go is toward the IP, when i did the engine rebuild i got pressed for time and cash at the end so the IP is original and was untouched during the rebuild so im gonna play with it this weekend and do some investigating with the VAG-COM and pull some stuff apart.

Thanks for the tips guys i will let you guys know what i find out.
 
J

Jens590

Well-known member
Joined
Jul 30, 2009
Location
Comox BC Canada
TDI
01 TDI Jetta
the clutch kit(clutch, flywheel, press. plate) and engine rebuild has 43,344 KM (26,932 miles).
the injector pump (10mm) has 334,637 KM (207933 miles). it is original from the factory and has never been opened up or serviced in any way (aside from setting pump timing)
the injectors have just about 60,000 KM (37,282 miles) on them and came assembled and tested from Kerma with PP764 stage 2 nozzles
turbo is a vnt17/22 with 60,000 KM (37,282 miles)

The car also sat in my parking lot for most of 2016 due to deployments and other priorities
 
UhOh

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
So, is that fuel over a year old?

Might try running some Diesel Purge (which would also allow you to rule out fuel and fuel delivery from tank).

I'm mentioning fuel because of the suspicions of your issue being attributable to the IP. But, if it's the IP then a stethoscope would be able to identify that.
 
UhOh

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Oh! And what about the engine oil? Stuck lifter? (more a ticking sound)
 
I

Ill Named

Veteran Member
Joined
Apr 17, 2011
Location
Central BC
TDI
2001 Golf, 2003 Golf
I know you said that the motor mounts are good, but this is my 2 cents...

I, just yesterday, changed all the motor mounts in my 03 due to a symptom that sounds very similar to yours. It started out sounding and feeling like total sh!t when the clutch was engaging in reverse. Especially bad when reversing up hill. Then it got progressively worse to the point of sounding and feeling sh!tty when the car was just idling there. Really bad when changing gears. I thought it might be the clutch at first, by the way my wife was describing the symptom to me, but once I inspected, it was obviously the motor mounts. In my case, the passenger side pendulum mount had become very spongy. Cheap, easy fix...
 
P

Prairieview

Veteran Member
Joined
Jul 9, 2017
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Too close to Sturgis 'ithole
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Two 2000 Beetles, 2002 Jetta, 2002 gas avh Jetta, fleet of older 1.6 turbo and non's
Aaaaaauuuuuuggggggggghhhhhh…….no.
Jack up the car and put your phone right against the oil pan. THEN I will tell you if you have rod knock.
 
B

Brett San Diego

Veteran Member
Joined
Jun 25, 2013
Location
San Diego
TDI
02 Jetta wagon manual
antonio2001 said:
So it doesnt? What does that ticking/knocking sound like to you.?
Click to expand...
It sounds like you need to get into the engine compartment with a stethoscope and try to isolate the source of the sound yourself. Remove the serpentine belt and run the engine to check if it's from one of the belt accessories.

Brett
 
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