Audi Workshop Service and Repair Manuals > A4 Mk1 > Power unit | 4-Cylinder engine (5-valve), Mechanics | Engine cylinder head, valve gear

4-Cylinder engine (5-valve), Mechanics

Servicing valve gear

Notes:

◆ Cylinder heads which have cracks between the valve seats or between valve seat inserts and the spark plug thread can be used further without reducing service life, provided the cracks do not exceed a maximum of 0.3 mm in width, or when no more than the first 4 turns of the spark plug threads are cracked.
◆ After installing new tappets wait for approx. 30 minutes before starting engine. Hydraulic valve compensation elements have to settle (otherwise valves will strike pistons).
◆ After working on the valve gear, turn the engine carefully at least 2 rotations to ensure that none of the valves make contact when the starter is operated.
◆ Renew all gaskets and seals.



65 Nm ◆ Use counter-hold 3036 to loosen and tighten Camshaft sprocket ◆ For exhaust camshaft ◆ Note installation position: smaller webs facing forward and TDC marking for cylinder 1 visible from the front=>Page15-49 Oil seal ◆ For exhaust camshaft ◆ Renewing



Cylinder head ◆ See note => Page 15-33 ◆ Checking valve guides, grinding-in valve seats => Page 15-73 ◆ Dowel sleeves for bearing caps must be located in cylinder head ◆ Sealing points => Fig. 15-9 ◆ Reworking valve seats => Page 15-77 Valve guide ◆ Checking => Page 15-73 ◆ Renewing=> Page 15-74



Valve stem seal ◆ Renewing=> Page 15-69 Valve springs ◆ Removing and installing => Page 15-69 Valve spring plate Valve cotters Hydraulic bucket tappet ◆ Checking => Page 15-66 ◆ Removing and installing => Page 15-69 ◆ Do not interchange ◆ Store with cam contact surface downwards ◆ Before installing check camshaft axial clearance => Page 15-44 ◆ Oil contact surface



Inlet camshaft ◆ Check radial clearance with plastigage (bucket tappets not installed) Wear limit: 0.1 mm ◆ Run-out: max. 0.01 mm ◆ Checking axial clearance => Page 15-44 ◆ Removing and installing camshafts => Page 15-54 Bearing cap for inlet camshaft ◆ Must be located on dowel sleeves ◆ Dowel sleeves must be located in cylinder head ◆ Note installation position ◆ Installation sequence => Page15-59



Double bearing cap ◆ Must be located on dowel sleeves ◆ Dowel sleeves must be located in cylinder head ◆ Apply a small amount of "D 454 300 A2" to sealing surface before installation ◆ Seal sides of jointbetween double bearing cap and cylinder head => Fig. 15-9 Exhaust camshaft ◆ Check radial clearance with plastigage (bucket tappet not installed) Wear limit: 0.1 mm ◆ Run-out: max. 0.01 mm ◆ Checking axial clearance => Page 15-44 ◆ Removing and installing camshafts => Page 15-54



Bearing cap for exhaust camshaft ◆ Must be located on dowel sleeves ◆ Dowel sleeves must be located in cylinder head ◆ Note installation position ◆ Installation sequence => Page15-59 10 Nm 10 Nm Drive chain ◆ Check for wear ◆ Mark position of chain before removing ◆ Removing and installing: =>"Removing and installing camshaft," Page 15-54

◆ Vehicles ä 07.97
◆ Secure with retainer for chain tensioner V.A.G 3366 before removing
◆ Removing and installing
=> Page 15-54
◆ Seal connections between hydraulic chain tensioner and cylinder head => Fig. 15-9



Metal/rubber gasket ◆ Renew Gasket ◆ Renew Exhaust valve ◆ With sodium filling ◆ Note instructions on scrapping valves with a sodium filling => Page 15-43 ◆ Do not rework, only grinding-in is permitted ◆ Valve dimensions => Fig. 1 ◆ Checking valve guides, grinding in valve seats => Page 15-73 Inlet valve ◆ Do not rework, only grinding-in is permitted ◆ Valve dimensions => Fig. 1 ◆ Checking valve guides, grinding in valve seats => Page 15-73



Oil seal ◆ For inlet camshaft ◆ Renewing=> Page 15-45 Hall sender rotor ◆ Note installation position: locate lug in notch on camshaft Washer ◆ Convex ◆ Note installation position 25 Nm Housing for Hall sender -G40 10 Nm

→ Fig. 1 Valve dimensions

Note:

Inlet and exhaust valves must not be reworked. Only grinding-in is permitted.


Dimension		Inlet valve	Exhaust valve
øa	mm	26.80 ... 27.00	29.80 ... 30.00
øb	mm	5.95 ... 5.97	5.94 ... 5.95
c	mm	104.84 ... 105.34	103.64 ... 104.14
font=symbol charset=fontspecific code=181 descr='[prop]'	<°	45	45

Caution

◆ Worn exhaust valves with sodium filling must not be disposed of until they have been treated as follows:
◆ The valves must be sawn into two sections with a metal saw at a point between the centre of the shaft and the valve head. They must not come into contact with water when this is done. Then throw the valves into a bucket of water (not more than ten at time). Then step back because a chemical reaction occurs when the sodium filling burns.
◆ After this treatment the valves can be disposed of in the normal way.

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