Just replaced nozzles with Sprint 520 - Nailing persists!

I just replaced all 4 of my nozzles with new Sprint 520s. With 210k on the odometer, I suspected they were original. Upon removal, I am quite certain. I had expected that changing the nozzles would quiet it down because it has a pretty consistent tapping/nailing sound. The old nozzles were super dirty, but I can tell no difference in sound with the new nozzles installed. Lifters perhaps?
The car is not yet on synthetic so that may help. Another thing to note is that the fuel temperature sensor is bad according to Vagcom. I have the part, I just need to get a stripped bolt out. I have no idea what the IQ is set at either.
Any thoughts? The car is also on jack stands in the process of getting wheel bearings replaced so I cannot drive it yet. What else can be causing a loud tap tap tap, which is throttle dependent? It increases as pedal is pressed.

jonbobshinigin said:

I just replaced all 4 of my nozzles with new Sprint 520s. With 210k on the odometer, I suspected they were original. Upon removal, I am quite certain. I had expected that changing the nozzles would quiet it down because it has a pretty consistent tapping/nailing sound. The old nozzles were super dirty, but I can tell no difference in sound with the new nozzles installed. Lifters perhaps?
The car is not yet on synthetic so that may help. Another thing to note is that the fuel temperature gauge is bad according to Vagcom. I have the part, I just need to get a stripped bolt out. I have no idea what the IQ is set at either.
Any thoughts? The car is also on jack stands in the process of getting wheel bearings replaced so I cannot drive it yet. What else can be causing a loud tap tap tap, which is throttle dependent? It increases as pedal is pressed.

Click to expand...

Rod knock?

Check the cam and lifters as well.

jonbobshinigin said:

I just replaced all 4 of my nozzles with new Sprint 520s. With 210k on the odometer, I suspected they were original. Upon removal, I am quite certain. I had expected that changing the nozzles would quiet it down because it has a pretty consistent tapping/nailing sound. The old nozzles were super dirty, but I can tell no difference in sound with the new nozzles installed. Lifters perhaps?
The car is not yet on synthetic so that may help. Another thing to note is that the fuel temperature gauge is bad according to Vagcom. I have the part, I just need to get a stripped bolt out. I have no idea what the IQ is set at either.
Any thoughts? The car is also on jack stands in the process of getting wheel bearings replaced so I cannot drive it yet. What else can be causing a loud tap tap tap, which is throttle dependent? It increases as pedal is pressed.

Click to expand...

You might want to PM Growler. He had a similar problem (albeit with an ALH engine, instead of an AHU).

mine was a piston knocking on a wrist pin, caused by wrist pin retainer failure.
I also had a ticking in my cylinder head that did not go away when we swapped in a new set of injectors and nozzles. the knocking was mostly only felt when taking off in 1st gear. the ticking was there all the time.. never did nail down the cause of the ticking.

I only found the wrist pin retainer failure and subsequent cylinder scoring when we removed the head to swap on a different one. piston protrusion was checked and #1 was low by .010" (ten thousanths)

I wound up replacing my entire engine with a new (to me) 120k mile takeoff from a wreck.

take a good hard look at your cam & lifters, then go from there.

Would a compression test reveal an issue here? I did not see anything right off when I have the Valve Cover off a while back, although I was not particularly looking.

I'm in the same boat with the addition of not getting enough fuel as well. Mines noise is most noticable at idle and i like you thought having new nozzles would solve it, no such luck for me either. I'm wondering if mine is a bad pump causing poor fuel delivery and performance and the knock is a side effect of it.

Yeh, I am thinking that I may need to adjust my IQ, but I barely have any time behind a VagCom so I will have to learn that and see.

my compression was good in all 4 cylinders. FWIW

Is the noise clearly mechanical? Timing is dependent on fuel temp. If temp sensor is sending erroneous data, perhaps the timing is too advanced.

Also, I thought synthetic oils were required on these cars...

twentyeight said:

Is the noise clearly mechanical? Timing is dependent on fuel temp. If temp sensor is sending erroneous data, perhaps the timing is too advanced.

Also, I thought synthetic oils were required on these cars...

Click to expand...

Synthetic was an afterthought on the MK3 tdi. Originally they were filled with regular 15w40 diesel rated oil based on what I have read. Still the best idea for a long engine life is synthetic of course.

Ok...I have a Vag-Com for a couple days so what can I check? I got into the IQ area and it was at 4.2ish. I got it up to 5 but couldnt get it to stay below that really.

The knock is really annoying.

Also pulled codes, cleared, then pulled them again.
First set:

8 Faults Found:
00539 - Fuel Temperature Sensor (G81) (Replaced)
30-00 - Open or Short to Plus
00750 - Warning Lamp
31-10 - Open or Short to Ground - Intermittent
01050 - Glow Plug Monitoring
35-00 - -
00765 - Modulating Piston Movement Sensor (G149)
35-00 - -
01268 - Quantity Adjuster (N146)
18-00 - Upper Limit
01268 - Quantity Adjuster (N146)
19-00 - Lower Limit
00542 - Needle lift Sensor (G80)
30-00 - Open or Short to Plus
01269 - Commencement of Injection Valve (N108)
31-00 - Open or Short to Ground

Then I cleared it and ran it again:
00750 - Warning Lamp
31-10 - Open or Short to Ground - Intermittent
01268 - Quantity Adjuster (N146)
18-00 - Upper Limit

Any thoughts? I am researching them now. The glow plug harness is all messed up but appears to be functional, although glow plug light blinks. Also, there is a wire with spade connector loose in the engine bay near injector pump...where might that connect?

jonbobshinigin said:

Then I cleared it and ran it again:
00750 - Warning Lamp
31-10 - Open or Short to Ground - Intermittent
01268 - Quantity Adjuster (N146)
18-00 - Upper Limit

Click to expand...

Sounds like your IP is giving up the ghost based on the ticking and the QA code. Might want to consider a rebuild.

Stupid question: have you used a mechanic's stethoscope on the easy stuff yet?

I have not used a stethoscope. Although it sounds like the nailing comes from #1 cylinder. I do not know that I would be able to diagnose it myself based on sound anyhow. Is the pump something I could rebuild myself? I know there is a seal kit.

Once it stops raining I am going to check out some wiring and make sure everything is as it should be.

Boys
Any news on this problem yet. I have same sort of sound and was convinced it was injection knock. I replaced all injectors with new and she runs better but the noise is still there and I lack a small amount of torque below 1500rpm, above that she performs well.. Mine only has 120000km on the clock but i'm affraid I suspect the worst case from here. My next stop is compression test.

At our last TDI GTG a week ago, several people looked at it and decided that it may be the camshaft and lifters. Although I have been suspecting the IP, since it seems the sound is coming from there, odds are, it is not. There does not seem to be any FUEL problems with the car so I am leaning toward the Camshaft and Lifters now.

The car was recently changed over to Mobil 1 Synthetic Turbo Diesel Truck Synthetic with no change.

Jon
I have been chasing this problem for quite a while now. Sounds like a lifter and seems to come from the injection pump area. Is far worse when the engine is hot and I reckon I am short about 20% on torque, power not so much. The car used no oil and just a little smoke on cold start, seems to run OK but I get the feeling it wants to have a miss fire at idle or if things deteriorate much more it will.

Background on my car;

I have had it 18 months, it had 108,000km on it, the prev owner ran Mobil lube 15-40, lots of short runs and probably never really got warmed up, ever. I bought it from the original owner who is elderly. I now run Mobil 1 5W-50.

I have removed and cleaned the manifold and ports, it was a shocker.

New cam belt, tensioner, roller, idler. New harmonic damper, Aux belt, tensioner, roller, replaced bushes in Aux belt tensioner shaft.

Fixed numerous oil leaks etc.

Originally I thought it was a lifter and No 1 INLET was pitted so I fitted a new set. The problem persisted so I replaced the cam and lifters again together. Engine was a bit quieter but the nailing sound persisted..

I replaced the fuel temp sensor but that made no diference.

Pulled my injectors to find No: 1 a bit wet and No 4 a bit carboned up. So I fitted a new set. Engine is quiet apart from the persistant nailing sound. Whilst changing the injectors I pulled and tested my glow plugs. No 1 was damp and I think its fuel not oil.

I am leaning (hoping!!!) towards a sticking INLET valve in No 1 cylinder. Perhaps carbon has been dragged up the valve stem and is binding in the guide? Or the spring may be weak or broken. Hard to diagnose. My next step is compression test followed by a leak down if required, I just have to assemble the gear to do it. After that I'll borrow a borescope from work and stick it down the glowplug holes and check the bores visually as I have read about gugeon pin retainer failures. Anyway just thought I would buy in on your thread as our symptoms do seem similar.

Edit: INLET

Good info! We have just put up with it for a while. It it obnoxious but not unbearable. We also replaced the Temp sensor to no avail. I am glad to hear you replaced the camshaft and lifters...well, only so that we can avoid doing that and not fixing the problem. Please post back with anything you find!

I have retrieved the lost power with increased fuelling to 2.4mg/str. Still a bit of clatter for my liking so will work on that now.

jonbobshinigin
What sort of dring do you do? City Vs country. My car has done mainly city.

Edit: I am still waiting for my new compression tester to arrive, will report the findings.

I've not really experiences a loss of power. Although I do get more black smoke since the new injectors, which supposedly was not supposed to happen. Could that be a symptom of the valve stem issue you are suspecting?

I wouldn't think so. My theory is that soot in the intake from the egr gets draged into the valve seat each time the valve closes. Eventually causing the valve stem to bind just as the valve is closing. If I am right there should be some loss of compression. The nailing in my car seems inconsistant, happening for say three or 4 seconds and then nothing for a couple of seconds and varying all the time. Its hard to diagnose but if there is any loss of compression I will do a leakdown to locate it. If there is not, well i'm gonna forget I ever heard it and get on with life. I think short city running would be worse for carbon build-up and perhaps some good country running with good oild might just clear it out. Otherwise its a head rebuild.

Mine is constant and rpm based. I'll try to get a video up soon!

Mines at idle only, next on my list is the Harmonic damper which was from the old ABL engine when i converted to tdi power. Is there a difference between the ABL damper and the AHU one? I'm using all the belt driven ancilleries from the ABL engine on the tdi, maybe thats the cause of my problems?