Author Topic: Injector knock (Read 5947 times)

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

dillenger1 · « **Reply #1 on:** September 08, 2008, 03:21:25 am »

take a screw driver (or a stethiscope)And listen to each one.

Smokey Eddy · « **Reply #2 on:** September 08, 2008, 11:46:20 am »

i dunno about a stethoscope (ears may bleed?)

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:

jtanguay · « **Reply #3 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.

Smokey Eddy · « **Reply #4 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....

theman53 · « **Reply #5 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.

jtanguay · « **Reply #6 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.

Smokey Eddy · « **Reply #7 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?

Smokey Eddy · « **Reply #8 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?

fatmobile · « **Reply #9 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.

Smokey Eddy · « **Reply #10 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?

gigaz2 · « **Reply #11 on:** September 10, 2008, 02:13:44 am »

overbore= new pistons

jimfoo · « **Reply #12 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.

Smokey Eddy · « **Reply #13 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?

gigaz2 · « **Reply #14 on:** September 10, 2008, 11:03:29 am »

with any... new pistons

rings can't take that much slack