injector nailing or is it a tappet?

[paolomarks]

So I finally got my AAZ back on the road after it threw a rod 6 months ago.  Rebuild included new pistons, one new rod, all new bearings, new head(I used the old guts including the hydraulic lifters)  I took the injectors apart and boiled and cleaned them.  Didn't do anything to the Injection pump since it was working great 6 months ago. It's been sitting for 6 months though with regular diesel fuel in it.
   I have the timing set at .035(.88mm)  I've got clear fuel lines and no bubbles in or out of IP.  Engine starts up pretty quick but runs a bit lumpy when cold (even with cold start cable out)  puts out whitish smoke.  I have an oil pressure gauge and pressure is good.   I've taken it out for a "break in" run and it makes a constant  loud ticking noise , frequency of ticking is related to RPM's.  Sounded like a tappet to me so I checked the lifters as Bentley recommends by seeing whether a .004 feeler gauge can be inserted between cam and lifter right after a warm up run.(rotating the engine over to gain access to all lifters of course)  and then pressing the lifters down with a wooden stick and checking again.  I wasn't able to slip the .004 between , so I think they're fine. 
   I'm not sure I know what injector nailing sounds like.  What causes it and how can you pin point the nailing injector?  I've loosened the lines from one injector at a time while engine idles and the rpm's drop about the same for each.  Should I just keep driving it a see if it goes away?   
   Thanks in advance, Paolo   
     

[wolf_walker]

Did the noise go away when you loosened any one injector?

The frequency of the noise will be slightly different if it's on a cam lobe or an injector, but it's hard to explain.

Did the lifters fit and rotate freely in the bore on the new head?

You can probably run some more initial timing, they usually start better with some more. 
I start around .90

[8v-of-fury]

I'd probably start with advancing the timing as well. I know it says 0.80mm for the AAZ.. I run mine at nearly 1.02mm and it runs fantastic.

The Bentley service manuals list the following "official"  settings:

Early Chassis:  (1977-1983)

1.5l non-turbo 1977-1980                                        0.88 +/- 0.05 mm

1.5l non-turbo 1980 with yellow dot                         1.15 +/- 0.05 mm

1.6l non-turbo  1981, 1982, and 1983 pickup            0.88 +/- 0.05 mm

1.6l non-turbo  1983 Rabbit and Jetta                        0.95 +/- 0.05 mm

1.6l non-turbo  1983 Vanagon                                  0.90 +/- 0.05 mm

1.6l tubo diesel (1982-1983)                                       1.00 +/- 0.05 mm

 

MK2 / A2 chassis:  (1985-1992):

Engine ME (1.6l non-turbo) 1985                             0.95 +/- 0.02 mm

Engine ME (1.6l non-turbo) 1986 and up                 0.90 +/- 0.02 mm

Engine MF (1.6l turbo)                                           1.00 +/- 0.02 mm

Engine 1V  (ECO diesel)                                         1.00 +/- 0.02 mm



MK3 / A3 chassis (1993-1997):

Engine AAZ  (1.9l turbo)                                        0.80  +/- 0.02 mm

[paolomarks]

 I think I've decided that it's a lifter after a simple test.  Tell me if you think this is conclusive.  Test was as follows.  As I coast in gear,  (say 35 mph in 3rd)  I can distinctly hear the tapping, then I turn the key off, effectively closing the fuel solenoid and preventing any fuel entering the injectors.  Result-  Tapping noise is unchanged.  Conclusive?
   I can't really hear the noise at idle, but as I rev it up it becomes more and more audible until it becomes masked by engine noise.   Paolo

[wolf_walker]

Sounds reasonable. Unless it's something else mechanical clacking.

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[wdkingery]

Yeah I like it. My nailing injector noise went away with the exact same test

[shwak23]

Not an exhaust leak is it?

Sent from Outer Space!