Mechanics

TIMING OF DUAL CAMS

2002 Audi A4

Engine Mechanical problem
2002 Audi A4 4 cyl All Wheel Drive Automatic 105000 miles

Timing belt tensioner was bad, timing marks not aligned. I replaced Timing belt, tensioner, water pump, ect. Realigned timing using mark on crank pulley and mark on cam gear with valve cover case. No compression, engine won't start. I pulled the valve cover off to look at cam gears/chain. No marks on rear cam gear.

Where should the cams be positioned in relation to TDC of crankshaft?
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Apostle411
November 28, 2009.




Hello .. thanks for the donation .. much appreciated

Timing Belt Installation

CAUTION:To prevent pistons from hitting valves, make sure crankshaft is NOT at TDC for any piston before turning camshaft.

Place timing belt on crankshaft sprocket (if reusing belt, observe direction of rotation). Install lower part of timing belt cover. Install vibration dampener. The hole in the vibration damper must be located over the raised part on the crankshaft timing belt sprocket. Tighten vibration damper/pulley to specification. See TORQUE SPECIFICATIONS .
If necessary, align camshaft sprocket-to-cylinder head cover positioning marks and vibration damper-to-timing belt cover positioning marks. See Fig. 14


http://www.2carpros.com/forum/automotive_pictures/266999_audi_4.jpg


Install timing belt in this order: water pump, tensioning pulley, camshaft sprocket.
NOTE:If the timing belt tensioner has not been restrained and is at its travel limit, it must be pushed back in the installed position together with the pulley. This procedure can take up to 5 minutes. When compressing the tensioner, excessive force can damage the tensioning pulley. Push pulley on counterclockwise in direction of arrow with a socket head wrench using even (but not excessive) application of force until tensioner piston can be locked with Locking Plate (T10008). See Fig. 15 .


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Turn eccentric bolt counterclockwise in direction of arrow using special tool (3387). See Fig. 21 .


http://www.2carpros.com/forum/automotive_pictures/266999_21_1.jpg


Hold eccentric bolt in this position and remove locking plate. Turn eccentric bolt clockwise to right in direction of arrow until a gauge with dimension of 8 mm (e.g., drill bit) can be passed between tensioning lever and tensioner housing. See Fig. 22


http://www.2carpros.com/forum/automotive_pictures/266999_22_1.jpg


Hold eccentric bolt in this position and tighten pulley nut to specification. See TORQUE SPECIFICATIONS .

Turn crankshaft two complete turns by hand in direction of engine rotation until crankshaft is at TDC again. Mark on camshaft sprocket and mark on crankshaft must be at TDC cylinder 1. See Fig. 14 . Check dimension between tensioning lever and tensioner housing with a gauge. Dimension should be 6-10 mm. If dimension is not obtained, tension timing belt again. Go to step 3 .
Install center and upper timing belt cover and ribbed belt tensioner. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . When installing ribbed belt, make sure that direction of rotation is correct and that belt is installed correctly to pulleys. On vehicles with A/C, install ribbed belt to A/C compressor last.
To install lock carrier, reverse removal procedures outlined in REMOVAL (AVANT & SEDAN) . Torque all fasteners to specification. See TORQUE SPECIFICATIONS . Let support stop rest on rubber buffer for torque support with its own weight and tighten bolts to 21 ft. lbs. (28 N.m). See Fig. 23 .
NOTE:Before installing bumper, check for the presence of threaded pins at bumper rear edge as well as expanding clips and sleeves in the fenders. Always replace bumper retaining bolts.

Slide bumper onto impact absorber and re-connect hose (1) of headlight cleaning system and electrical harness connectors (2). See Fig. 7 . Move bumper into installation position. Make sure threaded pins in bumper side edges engage into holes at the fenders. Install bumper retaining bolts until bumper can stay in place without any assistance.
Do not tighten completely allowing for any necessary adjustments. Pull back wheelhousing liner (A). See Fig. 3 . Engage bumper rear edge into catch (B). Torque nuts. Repeat procedure on opposite side of the vehicle. Torque left and right retaining bolts to specification. See TORQUE SPECIFICATIONS . Install left and right air inlet grille on bumper. Remainder of installation is the reverse of removal.

hope this helps


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Dave H
Nov 28, 2009.
I familiar with all the procedures for replacing a timing belt. I just want to know before I put my vale cover back on, how to verify the precise position of the cams. Should both key slots on rear cams be at the 12 O'clock position to ensure both cams are in tune? Are there any hard to locate timing marks on rear cam gears?

Tiny
Apostle411
Nov 28, 2009.
Hold eccentric bolt in this position and tighten pulley nut to specification. See TORQUE SPECIFICATIONS .

Turn crankshaft two complete turns by hand in direction of engine rotation until crankshaft is at TDC again. Mark on camshaft sprocket and mark on crankshaft must be at TDC cylinder 1. See Fig. 14


http://www.2carpros.com/forum/automotive_pictures/266999_audi_8.jpg




http://www.2carpros.com/forum/automotive_pictures/266999_AAA2_516.png


Dave H
Nov 29, 2009.
My check engine light was on for " cam position sensor". I was informed it meant that cam was off by one tooth. I screwed up and move the cam with the belt off trying to find the sweet spot. Now my car won't start! Was asking if you could tell me by looking at the valve train (valve cover off) are there any distinguishing marks to verify the dual cams are in tune with crank at TDC. If the cams are not timed, would that be the cause of my low compression problem. Is there a procedure? Is the cam mark on outer wheel with valve cover my only way to verify correct timing?

Tiny
Apostle411
Nov 29, 2009.
The only way of verifying the cam and crank are timed correctly is using the marks on the pulley's .. you cannot tell by just looking at the valve train ..incorrectly set cam and crank will give low/no compression as the valves will be open at the incorrect time ! NOTE :- trying to start the car with incorrectly set timing of valves in relation to crankshaft can cause damage to the valve's !!

The check engine fault code for "cam position sensor" was telling you the SENSOR was bad not that the camshaft was out one tooth unless this code only came up after you had adjusted the cam/crank in which case it could be out more than one tooth !! ... the CMP picks up a signal from the camshaft's which tells the PCM/ECM (computer) when to fire the injector's/spark ..if the timing is out it picks up late/early signals ... when the CMP sensor gets worn/dirty/faulty it picks up late/early signals !!

You stated in your first post that the tensioner went bad causing the timing marks to be out !! did the belt slip/jump on the pulley's ?? ..

If the original cause of you commencing this repair was the fact that the timing marks were not aligned due to tensioner failure ? .. I would be suspecting there may be valve damage as this is an interference engine ?

Could you please tell me your original fault before you commenced work ? ie. was the car not starting/running rough etc. etc. .. the more details you supply the better we can diagnose ?

Hope this helps


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Dave H
Nov 30, 2009.
My car had just went over 100k miles. Was running a little rough. I bought a timing belt kit and replaced all. I noticed that the original belt tensioner was loose and excessively worn. After I replaced parts and put front end back together, car fired right up. I drove it for about 45 days, however the check engine light was on. Scanner said it was " cam position sensor". I bought and replaced sensor - no change! After a month of research several forums confirmed that the cam timing was off by one tooth. I tore everything down again to adjust timing and haven't been able to start car. Sounds like engine is just spinning with no compression. Timing marks perfectly aligned.

Tiny
Apostle411
Nov 30, 2009.
I need you to check that #1 piston is at TDC with timing marks on cam's lined up ... line up your timing marks ... take out #1 spark plug and using a thin screwdriver down the spark plug hole check #1 piston is at the top of the cylinder (TDC) ? if you rotate crankshaft back and forth using a wrench with screwdriver in #1 spark plug hole the screwdriver should go up and down with the piston at it's rocking point of TDC .. NOTE :- the piston/screwdriver will rock (up/down motion) no matter which position it is in ..you HAVE to make sure it is at the TOP when all marks are lined up

Do you have a compression tester .. if not autozone etc. usually loan these out .. we need to check compression next ?

Let me know


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Dave H
Dec 1, 2009.

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