Author Topic: Fresh 1.6 TD Knocking on Startup.... (Read 6659 times)

jimbote · « **on:** October 17, 2008, 02:42:03 am »

Started my newly rebuilt 1.6TD MF code engine yesterday....heard a slight tapping upon first firing but that went away almost immediately....but when I revved it the tapping came back with a vengeance!!! :cry: ....Sounding like something right on top of a piston!!!!....Yikes!!!.....Checked around and the only thing I found was too long of a bolt rubbing the inside of the IP sprocket (totally unrelated) ....fixed that ....fired it back up and it knocked (not a lifter or Rod) for a few seconds and went away....cranked the engine several more times revved it, idled it the whole bit...purred like a kitten....the sound was def. like something on top of the piston....anyone ever seen a sticky valve on these engines?....cuz thats the only thing I can think of....and Ohhh yeah whenever it would tap/knock the engine would run rough and puff black diesel....this has to be a sticky valve right?.....when I rebuilt the engine I pretty much did not touch the head as it had been rebuilt recently....anyone ever seen this?....please chime in :?

blkboostedtruck · « **Reply #1 on:** October 17, 2008, 07:18:47 am »

stickey /dirty injector possibly?
Duane

jtanguay · « **Reply #2 on:** October 17, 2008, 10:00:17 am »

i've had sticky valve a few times... but i mainly believe it to be lifter related. an italian tune-up while driving quickly fixed it though. if you don't use a good synthetic oil, then you can get sludge/etc buildup that will cause the parts to stick/malfunction. mine is very temporary probably due to low oil pressure at startup, and because i use a very good oil.

like stated above, it could also be an injector though. if they sit long enough they can temporarily 'seize' into place, unless stored with something like ATF in them.

Quantum TD · « **Reply #3 on:** October 17, 2008, 10:27:36 am »

Quote from: "blkboostedtruck"

stickey /dirty injector possibly?
Duane

X2. Sounds like an injector. If it were piston/valve contact, you'd hear it at all RPMs.

jimbote · « **Reply #4 on:** October 17, 2008, 01:59:34 pm »

started again today showing it off to a buddy....was totally quiet at idle and revs....I will pull the valve cover off manana to check for suspect lifters....but like the consensus it was probably a sticky injector....

jimbote · « **Reply #5 on:** October 17, 2008, 07:43:19 pm »

So from what I gather "piston slap" can be caused by a leaky or stuck open injector correct?......I guess the sound could be likened to "pre detonation"....

Smokey Eddy · « **Reply #6 on:** October 18, 2008, 12:50:52 pm »

buy heat shields, take the injectors out (mind the little excess fuel tips), take them apart with a vice and clean the poo out of them with brake cleaner - laquer thinner - compressed air and throw em back in!!!

Your timing could possibly be too advanced as well?
jtanguay, what is an italian tune up ?

blkboostedtruck · « **Reply #7 on:** October 18, 2008, 01:01:24 pm »

even if you take them apart and clean it! you won't know what it's doing with out putting it on a pop tester and get some readings !
since your doing 1 you might as well do them all so you know all thier performing right! i have had to take new one's back apart to reclean just to get to work properly! so without testing them after cleaning your just playing Russian roulette!
Duane

Smokey Eddy · « **Reply #8 on:** October 18, 2008, 01:31:41 pm »

Who doesn't like russian roulette?

I took mine to an injection place and they pop tested them for free but they couldn't tell me any numbers :?
they just said "yeah they're working properly"
and i said "155bar?"
and all i got was "yeah in the right range"
and i said "how many bar?"
I was puzzled to be responded to with "here you go sir!"
they work as far as i can tell :roll:

blkboostedtruck · « **Reply #9 on:** October 18, 2008, 01:42:09 pm »

Quote from: "Smokey Eddy"

Who doesn't like russian roulette?

I took mine to an injection place and they pop tested them for free but they couldn't tell me any numbers :?
they just said "yeah they're working properly"
and i said "155bar?"
and all i got was "yeah in the right range"
and i said "how many bar?"
I was puzzled to be responded to with "here you go sir!"
they work as far as i can tell :roll:

i guess you got what you paid for :|
Duane

jimbote · « **Reply #10 on:** October 18, 2008, 11:25:18 pm »

I'm thinking new nozzles while im in there....I have an extra set of injectors from an 85' NA that I can use....any recomendation on nozzles (not looking to spend a crowd) ?

jimbote · « **Reply #11 on:** October 18, 2008, 11:31:38 pm »

Quote from: "Smokey Eddy"

buy heat shields, take the injectors out (mind the little excess fuel tips), take them apart with a vice and clean the poo out of them with brake cleaner - laquer thinner - compressed air and throw em back in!!!

Your timing could possibly be too advanced as well?
jtanguay, what is an italian tune up ?

I did set the timing to .042" (my gauge only reads inches) before firing the engine and the sound was only coming from one piston as far as I could tell.....I do believe it needs new nozzles as it does shudder a little just off idle....

Smokey Eddy · « **Reply #12 on:** October 18, 2008, 11:49:11 pm »

If you stick a big screw driver right onto the injector and put the round butt end in your ear you can really hear if its definately one injector or several or advanced timing.
so you're probably right but i'd try that if you haven't taken it apart yet. it's interesting to hear the differences.

I bought nozzles from this bloke
http://www.veg-injection-service.com/store/index.php?main_page=product_info&cPath=6_8&products_id=29

I dont know if thats over paying or what. I bought those before i knew about the forum. there are really good vendors on the forum.

CoolAirVw · « **Reply #13 on:** October 21, 2008, 07:19:28 pm »

Knock caused by a leaking injector will go away if you loosen the fuel line to the injector in question. (but some rod knocks might quiet down as well)

Mine sounded like a sledgehammer coming through the side of the block. I could tell it was coming from the #1 cylinder and it was seemed from the top of head area, combustion chamber. described in the following post.

http://www.vwdieselparts.com/forum/viewtopic.php?t=8346&highlight=

And when I tested with a pop tester it was leaking so bad I couldn't make it pop, even though the knock went away shortly after it started. Point being.... Just cuz the knock goes away dont mean your injector isn't still leaking.

jimbote · « **Reply #14 on:** October 23, 2008, 01:16:13 am »

Quote from: "CoolAirVw"

Knock caused by a leaking injector will go away if you loosen the fuel line to the injector in question. (but some rod knocks might quiet down as well)

Mine sounded like a sledgehammer coming through the side of the block. I could tell it was coming from the #1 cylinder and it was seemed from the top of head area, combustion chamber. described in the following post.

http://www.vwdieselparts.com/forum/viewtopic.php?t=8346&highlight=

And when I tested with a pop tester it was leaking so bad I couldn't make it pop, even though the knock went away shortly after it started. Point being.... Just cuz the knock goes away dont mean your injector isn't still leaking.

Just read the thread link.....sounds exactly like what I experienced!!!.....thanks!!!