Ahu engine strange noises

NrgzLeonardo

New member
Joined
Jan 8, 2019
Location
Italy
TDI
Ahu engine
Hey guys, I'm experiencing some strange noises with my Ahu engine with 220.000 km on it. The first noise is a sort of creaking, it occurs when the engine is cold and it shakes, for example when i shut it off, when i start from a nearly complete stop in second gear without accelerating, when it's a bit low in rpm and i'm turning in a roundabout. Maybe it's the famous harmonic balancer, but there is no noise when the engine is idling, only when it shakes; when it reaches operating temp i can't hear any noise. The second strange noise occurs with the engine in temperature, usually after a long trip (highway driving for example). It's a sort of chirping, with a high pitch, like some metal touching something else. It occurs when i mantain a constant speed (for example 70-80 or 120 km/h). It goes away if i accelerate or if i brake slightly. I'm facing these issues from two years, but one year ago they were less noticeable. It's significant that the noises appear usually in september/october, when temperatures start to decrease, in summer i didn't notice anything. I will try to make a video in the next days. Any suggestion? Thanks in advance.
 

Tdi Junkie

Active member
Joined
Apr 18, 2018
Location
Springfield, MO
TDI
1998 VW Jetta TDI
Chirping sounds like a water pump issue. Especially since it didnt start until winter

Sent from my SAMSUNG-SM-G891A using Tapatalk
 

iluvmydiesels

Veteran Member
Joined
Nov 21, 2015
Location
phila area
TDI
AHU
the first -shaking noise, may be motor mounts, bad or loose.

just because 'you dont hear noise, or a problem' doesnt mean there isnt a problem.

the 2nd noise, there are hundreds of moving and rotating parts on the car, any of these could be rubbing. you would have to pull both upper and lower timing cover, and/or pull some stuff, like the big crank balance ribbed pulley. the cam timing gear is famous for rubbing, inner on the timing tin, other timing gears/pulleys can rub. injection pump(?), esp the intermediate pulley, this iirc has a lip for axial play, if this lip gets separated the shaft will move out and in with out control. can be a pita to replace. if in doubt pull the seal carrier to look at inner portion of shaft, lip may be in here.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Probably the harmonic balance but could also be a water pump, idler pulley, ect... dont waste money ordering parts without figuring it out first.

One way to do this is to pull off all the covers on the timing belt and run the car, useing a mechanics stethoscope, probe around and see whats making the noise. Replace parts that sound BAD
 

NrgzLeonardo

New member
Joined
Jan 8, 2019
Location
Italy
TDI
Ahu engine
Thank you all for your answers! I think i've found the "second noise" cause: brakes. in this video on youtube (https://www.youtube.com/watch?v=KTKPW3FBbZo) that car has the same noise i sometimes hear on mine, and it makes sense because the noise goes away pressing slightly the brake pedal, so i will check pads (they were changed one year ago however). For the first noise i will check engine mountings first and then harmonic balancer/pulleys and so on... Tomorrow i will run the car and try to make a video...
 

iluvmydiesels

Veteran Member
Joined
Nov 21, 2015
Location
phila area
TDI
AHU
jacking up one side and removing the wheel. you can see the outer brake pad, the inner you can look on top and see that part of pad, the caliper should be open in the middle, again you can get a look at that part of pad, if you look from under you may get a look at that side of pad. look for pad to be even. you say you changed pads, there are other brake parts. caliper, master cylinder, fluid. it could be a sticky/sticking caliper.
axles can make noise, as well as wheel bearings, and other suspension parts. or any of these parts may started rubbing somewhere and may need to be checked.
 

iluvmydiesels

Veteran Member
Joined
Nov 21, 2015
Location
phila area
TDI
AHU
For the first noise i will check engine mountings first and then harmonic balancer/pulleys and so on...
the accessory 'balance pulley' (as i call it) (crank pulley)you can loose the belt and take that off, and check it and the timing cover beneath. loosen water pump p/s belt and check water pump by turning by hand, again take a look at pulley and cover for rubbing.
the upper timing (plastic) cover comes off, shouldnt be much problem. you can check somethings. cam gear and inj pump gear for interference/rubbing.
the intermediate shaft id recommend not, unless you know how to service a timing belt and time this motor. i think you can get a look at im shaft with out removing belt, but if you have a problem, or get stuck, you could lose your motor, i dont think its the best idea.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
The chirping sounds like symptom of the harmonic balancer failing.

028105243T is the part number for that item:



Steve
 

iluvmydiesels

Veteran Member
Joined
Nov 21, 2015
Location
phila area
TDI
AHU
nice pic steve!, yep thats the updated part#.
if its even available from VW its a $400+ part. aftermarket you can find.
the part/pulley on the car youd have to check. if i recall this updated pulley does not separate, the older pulleys do/tend to.
yep a possible culprit.
 
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