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Engine Specific Info and Questions => TDI Engine -General Info => Topic started by: JKnowledge on September 12, 2005, 08:23:48 am

Title: TDI Knock??
Post by: JKnowledge on September 12, 2005, 08:23:48 am

What would cause the #1 Cylinder in an ALH engine to knock? Will lean fueling ni a diesel cause a knock situation? I am trying to help a friend get his TDI running after an engine rebuild, and everything seems fine, but after idling for a few minutes, the engine begins to knock. I have the timing slightly advanced, and there is sufficient oil pressure. The rebuild was done by a reputable machinist in Northern VA, so I don't suspect problems there. Anyone have thoughts on what could be causing this?

Title: TDI Knock??
Post by: Maarten on September 12, 2005, 09:39:10 am

Advancing the timing will cause the eninge to produce more noise (diesel knock/rattle)

I suggest you adjust it back to spec and listen again :)

Title: TDI Knock??
Post by: JKnowledge on September 12, 2005, 09:48:02 am

It is only very slightly above the center line in the TDI Timing Graph, well within spec. Even with the timing retarded about halfway between perfect timing, and the edge of spec on the retarded side, it was making lots of noise. Not just a diesel rattle, a discernable knock. I am sure that the timing is right, and the machine work is good. Thanks for the bump, though.

Title: TDI Knock??
Post by: Maarten on September 12, 2005, 11:00:01 am

Did the rebuilder check the injectors?

Title: TDI Knock??
Post by: JKnowledge on September 12, 2005, 11:14:26 am

Yes, he put in a complete set of new injectors, and had the same result. We are wondering whether the injction pump may be starting to fail. But I can't get anyone to verify that we would get this result from a faulty injection pump.

Title: TDI Knock??
Post by: lord_verminaard on September 12, 2005, 12:15:06 pm

Pull the valve cover real quick and check the lifters.  I've seen more of those fail than anything else engine related (ie. no electronics) on a TDI.  :P

Brendan
84 Scirocco 8v
00 Camaro L36 M49

Title: TDI Knock??
Post by: JKnowledge on September 12, 2005, 01:04:24 pm

Thanks. I hadn't thought of that. I'll take a look!

Title: injector seals
Post by: Vhunter on October 04, 2005, 12:39:08 pm

If that don't get your knock sorted out, you might check what size injector seals were used.  IF they are to big OD, they will not fit  down into the pocket
inside the injector hole.  

This causes the tip of the nozzle to sit to high, and part of the spray pattern will hit the head, causing a pinging/rattleing noise.  

I had this happen to mine when installing injectors.  Get the OEM ones, as there have been several people who early on bought injector install kits
that got the wrong ones.  I think it has since been sorted out, but it is good to check on it.

There is a thread on TDIclub.com that actually shows the nozzle in a head that was removed from the engine,  and it is sitting to high in the head.
They show the difference with a correct washer too..

Made my car sound a lot smoother, and a lot less smokey with the same
ECU parameters.  Now I can tweek the IQ setting up a bit more for just a
touch of smoke on WOT! :)    or run this way and get better MPGs!

Drive ON!              
Arnie