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Engine Specific Info and Questions => IDI Engine => Topic started by: Smokey Eddy on September 08, 2008, 01:55:37 am

Title: Injector knock
Post by: Smokey Eddy on September 08, 2008, 01:55:37 am
I can hear a pretty harsh knock on my 1.6 td and it's always sorta been there and i've done a fair bit of ... *hopefuly* maintenance ; mercedes nozzles, lapping, head gaskets, head cleaning and so on. Just cleaning stuff and the nozzles really. The knock has changed sound a little bit after i lapped the injectors and replaced the nozzles but i can still hear it! It only sounds like 1 is doing it but is there a way to tell which one it is? if you feel each cylinder will it feel differently that the other three?

Sorry i should have put this in trouble shooting
Title: Injector knock
Post by: dillenger1 on September 08, 2008, 03:21:25 am
take a screw driver (or a stethiscope)And listen to each one. :)
Title: Injector knock
Post by: Smokey Eddy on September 08, 2008, 11:46:20 am
i dunno about a stethoscope (ears may bleed?) :P
so with the screw driver will it feel like a physical knocking?

I had a dream last night that i lapped all my injectors and it ran like a sleeping baby afterwards.... Do i need to spend my time on something else for a while? :roll:
Title: Injector knock
Post by: jtanguay on September 08, 2008, 11:59:46 am
sometimes you can get a sticky injector... one product that has had quite a bit of praise is lubro moly diesel purge.  you run this stuff straight from the can (both in-out lines go into the can so keep an eye on the fuel level in there!!!  :wink:)

it took me about 20 mins to run through the can (or so)  ill advised to drive it like that, but i did rev it quite a bit..  works for some, and others aren't so lucky.  but for the price-$10 or so, it's cheap compared to replacement parts.
Title: Injector knock
Post by: Smokey Eddy on September 08, 2008, 12:04:12 pm
lubro moly diesel purge eh... So it replaces the fuel filter?
could i pick this up at my local Crappy Tire? (Canadian Tire)

the injectors were apart not long ago....
Title: Injector knock
Post by: theman53 on September 08, 2008, 03:34:16 pm
put the handle end of the screw driver to your ear and the other on each individual injector. The one that is loudest you'll know.
Title: Injector knock
Post by: jtanguay on September 08, 2008, 03:44:54 pm
Quote from: "Smokey Eddy"
lubro moly diesel purge eh... So it replaces the fuel filter?
could i pick this up at my local Crappy Tire? (Canadian Tire)

the injectors were apart not long ago....


AFAIK cdn tire doesn't sell it.  :(  it doesn't necessarily replace the fuel filter, but it does bypass it  :wink:.  they say to use a fuel filter.

http://forums.tdiclub.com/showthread.php?t=87948&highlight=diesel+purge

that is a really good DIY guide.  i just stuck both lines (filter on the IN line) into the can.  i left a little bit in the can as my car started to chug, then i just shut it right off.
Title: Injector knock
Post by: Smokey Eddy on September 08, 2008, 10:46:38 pm
Ok so i found the loud one, do i need to lap it or ... ? what is a knocking injector exactly? I don't know where to get the purge stuff... :( would something else do the job? a bit of Paraffin?
Title: Injector knock
Post by: Smokey Eddy on September 09, 2008, 09:00:53 pm
There are two that sound like a smacking sound with i have the screwdriver right to my ear the other two are smooth as a whistle.

But i don't know how to fix it!!!
How do you fix knocking injectors?
I had them pop tested and they were all within spec. Could pump timing cause knocking injectors?
Title: Injector knock
Post by: fatmobile on September 09, 2008, 09:37:09 pm
Timing being too advanced can make it clackity.
 The knocking injector I had to mess with was pissing.
 I cleaned a small piece of paint out of the nozzle and it was fine.
 I've heard those mercedes inserts piss for a short burst before they spray.
 Might be the cause of prechambers pushing out.
Title: Injector knock
Post by: Smokey Eddy on September 09, 2008, 10:53:49 pm
it tried to run away today after a lot of load (pedal almost to the floor) and i don't have the fuel screw turned in at all....
i know the head has cracks between the valves (or warping bad enough to cause...) bad enough that there is a bit of coolant in the oil and my exp tank hisses. I'm still trying to figure out what i need to get for an aaz conversion but the site im using (a prothe site) sells an aaz head for 8mm valves but aaz valves that are 7mm??? why would he do that....

Also, anyone recomend having the block 1mm over bored at the same time. I'd need new pistons of course or should i just get it honed and keep the ones i've got?
I really neeed to replace the head but im retarded with this stuff. Any suggestions?
Title: Injector knock
Post by: gigaz2 on September 10, 2008, 02:13:44 am
overbore= new pistons
Title: Injector knock
Post by: jimfoo on September 10, 2008, 06:26:37 am
I found 8mm valves are really hard to find, but you can get 7mm guides put in the head and then run 7mm valves.
Title: Injector knock
Post by: Smokey Eddy on September 10, 2008, 10:55:23 am
Thanks Jim, i'll do the 7mm valve guides and 7mm valves. So i have 1 Yes for over bore?
should i go 1 mm or 0.5?

So check the timing of the IP to fix the knock?
Title: Injector knock
Post by: gigaz2 on September 10, 2008, 11:03:29 am
with any... new pistons

rings can't take that much slack
Title: Injector knock
Post by: Smokey Eddy on September 10, 2008, 11:23:15 am
I wasn't suggesting i get an over bore and keep stock pistons & rings...
Im asking if anyone reccomends over boring over just honing and if YES for over bore how much? (1mm or 0.5)
I need to mention that im very much broke in regards to the car. School is a massive drain on funds :roll:  so, is it worth the 250$ plus new pistons for an over bore?
Title: Injector knock
Post by: myke_w on September 10, 2008, 11:42:22 am
bore only as much as you need to, so the next step up from where you are.
Title: Injector knock
Post by: gigaz2 on September 10, 2008, 11:51:21 am
or better still, measure everything to know if you really need an overbore, if not, just hone :D

I am rebuilding an engine with about the same funds as you but I'm lucky, after 140K km I can still see the factory honing marks :D
Title: Injector knock
Post by: myke_w on September 10, 2008, 12:14:01 pm
Ditto,
measuring is always recommended, otherwise you have no idea and are only guessing.

In general, the bores in these motors wear in a taper with the top ring land being the widest margin of wear. If the bore is at all worn conically and you put new rings in, you can almost bank on tearing it down in the next 20-30k miles to address the issue of compression, oil usage, or runaway again. The constant spring action of the rings compressing and decompressing in the conical bore will wear them out in a hurry.
Title: Injector knock
Post by: Smokey Eddy on September 10, 2008, 01:33:50 pm
Hmmm okay
So i don't have digital calipers.... I could use a compass?
(gah i don't want to take the head off AGAIN...  twas off less than 2 weeks ago)

Quote
address the issue of compression, oil usage, or runaway again.


You [myke_w] mentioned the run away. I'm just wondering what caused my run aways...
when it happens i take my foot completely off the pedal, it starts pulling HARD and there is just an astronomical amount of white smoke. I shut it off and i can smell something funky... afterwards while idling it smoked white/blue and reaks but runs very smoothly
I thought it was an IP problem.
Title: Injector knock
Post by: fatmobile on September 15, 2008, 09:03:38 pm
On the only time I've had a runaway,...
the great cloud of smoke was black
Title: Injector knock
Post by: Smokey Eddy on September 15, 2008, 09:34:46 pm
how do i fix sticking injectors?
Holy! i just noticed how many views this thread has