engine knock -- Help

[Midas_187]

I have a B5 01 passat , tip-tronic AUG engine, with 60.5k on it. I have replaced my timing belt and other belts yet i still have an engine noise. When I start the car it will rev to 1200 rpm and hold for a minute or so then drop down, and after being driven a while there is a knocking sound from the back of the engine. Anything thing below 1000 rpm and the sound comes back, it sounds like something that rotates is knocking. Rarely does my CEL come on and then if i let it sit for a while it goes off (engine is off while it sits. I got a VAG from autozone and it said cam shaft timing off (which i thought replaciing the timing belt would resolve). So anyone have any ideas? I don't want the stealership to robb me blind in Diag charges.

[soundfxinc]

Sounds to me like your cam chain tensioner is noisey.You may want to do a search and see if anyone else has posts on it.




manny

98 1.8T
Windsor Blue

[danteshors]

or you might be a tooth or 2 off top dead center when you put the belt back on. Good luck.

[Elias]

I don’t know what a AUG engine is but my 1.8 never had a high idle @ startup but my 2.8 did. Is it a 2.8? Based on your description, sounds like a rod or main bearing may be damaged thus reducing oil pressure @ idle. You indicate the knock was present prior to the belt change. Therefore, it appears the belt was properly installed. I suggest you try to pinpoint the knock by canceling it out during idle.

If it’s at the rear of the motor as you indicate then… allow the motor to idle and warm up until the knock is present. With the motor idling warm, remove only one coil pack, starting at the rear. (I doubt the motor will stall but it will run rough. The CEL will come on though. You indicate you have a reset tool, so you can reset the CEL after the procedure). If it still knocks, reinstall the coil pack you removed and remove an alternate, again from the rear. Repeat the process with each coil pack. Doing this will eliminate combustion in each cylinder thus reducing the load on the crank. If a crank bearing is damaged, the knock will go away when the coil pack on the damaged cylinder is removed.

I hope I’m wrong, but if the knock is coming from the lower end then the motor needs a crank, bearings and effected rod. Considering the amount of parts and labor involved, it’s cost effective to replace the motor.

Good luck and be careful should you choose to follow the above.

[Scuba2001]

A knock can also be due to a spark plug that is not properly gapped. If you havent had a tune up recently, replacing all of the plugs, I would do that. Check the plugs for any abnormal wear.

Wish you luck,
Steve

[Elias]

A knock can also be due to a spark plug that is not properly gapped. If you havent had a tune up recently, replacing all of the plugs, I would do that. Check the plugs for any abnormal wear.

Wish you luck,
Steve

Wouldn't that be considered detonation or pinging? Arent these motors equiped with variable valve timing and knock sensors to avoid pinging? If a plug(s) was damaged he would of complained of noise under load. He indicated a knock @idle though.

[Scuba2001]

I've heard this knock/pinging at idle. Thats why Ive suggested it. BTW, It was happening on a '98 AEB 1.8T.

[Elias]

I've heard this knock/pinging at idle. Thats why Ive suggested it. BTW, It was happening on a '98 AEB 1.8T.

I've yet to see a motor pinging @ idle... there's no load, how can it ping? But then again... :roll:

I hope it turns out he's got a faulty injector or something simple and not a crank bearing... let's see what he says... :???:

[Midas_187]

I am leaning toward it being a crank issue or tensioner chain becuase of the two things. One previous posts i have been reading. Second when driving on roads and such, over dumps and pot holes (gotta love New England) i can hear a rough grind similar to the knocking as it hits a hole or goes over a bump. The engine usually starts to get loud around that point too. I have an appointment Tuesday with my VW/Audi dealership, but in the mean time i think I'll test the coil packs.............
cross your fingers!

[Midas_187]

it is also worth noting
I bought it used at 45 and I really believe it has the orginal plugs. I had the coil packs replaced under the re-call. So hopefully it is a plug issue......

[Elias]

I am leaning toward it being a crank issue or tensioner chain becuase of the two things. One previous posts i have been reading. Second when driving on roads and such, over dumps and pot holes (gotta love New England) i can hear a rough grind similar to the knocking as it hits a hole or goes over a bump. The engine usually starts to get loud around that point too. I have an appointment Tuesday with my VW/Audi dealership, but in the mean time i think I'll test the coil packs.............
cross your fingers!

Wait… :???: Now the motor knocks when going over bumps?

Forget what I said above?

Just take the car to a mechanic and have him take a look at it.

[Midas_187]

So you don't think i should check the coils / plugs?
The over the bump thing is like a rough grind on a rotation,maybe because i'm not accelerating and at that point the rotations have dropped below 1k, i don't know ??? :???:

[Midas_187]

And the verdict..............
cam shaft adjuster. and of course there is no 'certified pre-owned extended warranty......... :thumbdow: ya da ya da ya da.
$1200.00

OUCH