Author Topic: Strange Intake Knocking (Read 4448 times)

only8v · « **on:** January 13, 2009, 07:50:08 am »

Hey, I recently purchased a 1989 jetta 1.6td. It has 328xxx km on it.
I love the car and it has been working great. Im new to diesel so please excuse my lack of knowledge.

On occasion, usually when the car has warmed up, the car will make a very loud knocking sound coming from the intake. It will continue to knock for a few seconds, then it dissapates. It seems to occure at random intervals.

I had a lot of air bubbles passing through the clear fuel line on the inlet side which i fixed last night. I changed the fuel lines, removed the water seperator, and changed to a standard fuel filter (sans fuel heater). all the return lines on the injectors have been replaced as well.

I thought the noise had something to do with all of the air that was passing through the fuel line. Now that the air has been fixed, and the noise is still there, it seems that its something more serious.

Now im thinking it may be:
injector pump cavatation,
Injectors,
valves,
lifters

I have a spare junkyard pump that i could put on, but thats a last resort.

Please shoot me some info on how to troubleshoot this.

Cheers,

jason

rallydiesel · « **Reply #1 on:** January 13, 2009, 09:37:31 am »

Good chance it could be a bad lifter. Pull the valve cover and check. Could also be a dirty injector.

Lifter can be checked by warming up the engine to operating temp, pulling the VC, and pushing down on each lifter with a soft dowel like wood or plastic. If the lifter can be pushed down, it is bad and needs to be replaced.

Check injector by running the engine and listening for the knock with a screwdriver to your ear with the end on each injector line.

only8v · « **Reply #2 on:** January 13, 2009, 10:45:53 am »

Im guessing it is a bad lifter. the sound is much louder than i would expect from a bad injector.

however, can you clarify what is ment by a bad injector? i would assume the sound it would make would be similar to loud injector nailing? The sound I can hear is directly from the intake track.

thanks for the quick response.

jason

jtanguay · « **Reply #3 on:** January 13, 2009, 12:41:58 pm »

the bad lifter noise i had on my 1.6 went away at about 2k rpm. only showd up at idle. car ran alright though...

Smokey Eddy · « **Reply #4 on:** January 13, 2009, 01:12:21 pm »

Quote from: "libbybapa"

If an injector needle is not seating properly (e.g. a piece of crud is between needle and seat) then it can sound like a bit of nailing or downright horrendous, like you'd expect a rod to come exploding through the side of the block any second.

Andrew

Hear hear!

Did you do the screw driver test on the injectors?
If you take the hose off the intake and it gets notably louder then i'd say lifter too. Because it comes and goes intermitantly also tells me that it would be a lifter.

You can take the cam off and pull the lifters our with a magnet very easily and either find the sticky one, or what i did was i sat mine in solvent for a few days (you probably don't need to let them sit, i just had the time so i left them in there) flushing them with solvent. then sat them in oil for a little while while i actuated them to flush them with out and just kept flushing it until clean oil came out. Then they all worked wonderfully. But for all that time and fiddling, for you, it might be worth just getting new one(s).

danwithagolf · « **Reply #5 on:** January 13, 2009, 11:33:25 pm »

my 1.6 n/a kina makes the same noise its almost a pop thunking sound it comes and go ive had the car for a year and runs fine i always wanted to figure out whats wrong to.

only8v · « **Reply #6 on:** January 14, 2009, 08:49:27 am »

Thanks for all the replies. I replaced the lifters last night and problem solved!!!

car runs much better.

Thanks for the quick help guys.

Cheers,

Jason

jtanguay · « **Reply #7 on:** January 14, 2009, 10:19:22 am »

Quote from: "only8v"

Thanks for all the replies. I replaced the lifters last night and problem solved!!!

car runs much better.

Thanks for the quick help guys.

Cheers,

Jason

thats great! how much did you pay per lifter? i've wondered about the quality of the prothe lifters... $7 each isn't bad at all... for my mTDI i paid about $20 each :shock:

only8v · « **Reply #8 on:** January 14, 2009, 10:55:22 am »

whenever I need parts, i usually go to Concept-1 in calgary. Never had a parts quality problem with them. I paid $9 per lifter. not bad at all.

http://www.autopartsonlinecanada.com seems to have good quality product and really good prices as well.

http://parts.autopartsonlinecanada.com/parts/apocanada/wizard.jsp?year=1989&make=VW&model=JET-D-001&category=A&part=Cam+Follower

$10 bucks per lifter. not bad

they even sell Bently manuals for 67 bucks!!!

jason