audifield1

98 a6 2.8 qttro
replaced a cylinder head and have replaced the entire timing belt assembly with all new parts. I have spun off the cam gears (gear puller) and centered the tension however the timing belt keeps moving forward off the cam gears about 1/4 inch when hand turned for testing. I see burn marks in the timing covers so I know this will tear up the belt so no sense putting it all back together.

( I drove it a short time after i put in all new parts due to a bad thermo. I had a bad misfire and thought i was off on the timing only to trace it to a bent valve in the #6 cylinder.)

now i'm putting it all back together - again! ...what gives?
thanks for any help,
stumped in denver.

Airbag

usually if it rides one way or the other everything is not square .. what parts did you replace exactly .. where you very carefull and methodical around the hydraulic tensioner ? i imagine it is moving forward off both cam gears so i would suspect an issue with the idler rollers or tensioner.


BTW did it do this BEFORE the repair too ? you said there were marks on the covers.

audifield1

yea i did replace everything the first time around. I had overheating probs and figured it was the thermo so i replaced the TB, tensioner, rollers, hydraulic piston, Wpump, fan clutch and then put it all back togehter. I had a bad misfire so I pulled it all apart again to check the timing to find it was dead on so I started going through the obvious. ( could not get any codes to come up on any scanner - I kept getting "communication error" ) so I replaced the MAF, plugs, wires, cleaned the throttle body, replaced coil packs etc.
after doing some more reading I was suspecting a bad or stuck valve in #6 due to low compression so I pulled the head and found a slightly bent exhaust vavle. Now I've got it all back together and am on the last leg of the journey. I pulled it all off again yesterday and looked at everything and it just seems completely fine except for the stupid rolling off the cams - yes u are right it's both cams and torwards the front.
I'm sure it's the damn tensioner or piston because I remember the first time i did it it rolled to the inside.
but I can't figure out why.

jschick

if it's rolling off, you need to remove your rollers and tensioners and make sure they are good and mounted properly! the only other possibility is you damaged a cam Gear/pulley (bent it) while doing the heads!
have someone crank the engine and watch if the cam gears wobble, if not it has to be the rollers/tensioner. remember the one on the passanger side has a pin that must fit in a divit, if it isn't on correctly that pin will force it to mount offset!

audifield1

well pulled it all apart again and found that the cylinder head front was slightly bent. the black metal front which mounts to the aluminum top of the engine was out of whack a smidge. got bent somehow during the re-assembly. it was pushing the belt off it's axis when rotating around the top roller. tapped it in a hair with a rubber mallet and now the belt runs true........