Servicing valve gear — AUDI

AEC AHK
Engine code ABH => Page
15-68

Engine code AEC up to engine number

-004 708 with manual gearbox

-004 841 with automatic gearbox => Page
15-68

Engine code AEC from engine number

-004 709 with manual gearbox

-004 842 with automatic gearbox => Page
15-72

Engine code AHK=> Page
15-76

Engine code numbers ABH and AEC up to engine number

-004 708 with manual gearbox

-004 841 with automatic gearbox

Notes:

Cylinder heads with cracks between the valve seats or between a valve seat ring and the spark plug thread can still be used without any reduction in service life, provided that these are only incipient cracks not more than 0.3 mm in width or provided that only the first four turns of the spark plug thread are cracked.
After installing new bucket tappets engine is not to be started for roughly 30 minutes (otherwise valves will strike pistons), then crank crankshaft twice.
Check valve guides for wear => Page
15-93
.

15 Nm
Bearing cap
Installation position =>Page
15-85
.
Installation sequence => Installing camshaft, Page
15-83

Drive chain
15 Nm
Bearing cap in front of chain
Inlet camshaft
Checking axial play => Page
15-85
Removing and installing => Page
15-83
.
Check radial play with Plastigage: Wear limit 0.1 mm
Runout 0.01 mm

15 Nm

Exhaust camshaft
Check as for inlet camshaft

Hydraulic bucket tappets
Inspecting => Page
15-86
.
Lubricate bearing surface before installing
Set down with cam bearing surface facing downwards.

Valve guide
Inspecting for wear => Page
15-93
.

10 Nm
Flange
Cylinder head
Reworking valve seats => Page
15-96
.

Valves
Exhaust valves filled with sodium: Observe notes=>Page
15-92

Warning!
Worn sodium-filled exhaust valves cannot simply be scrapped. They must be cut in two with an iron saw between centre of stem and valve disc. 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 a time). Then step back because a chemical reaction occurs when the sodium filling burns. Following such treatment, the parts can then be handled as normal scrap.
Engine code AEC from engine number

-004 709 with manual gearbox

-004 842 with automatic gearbox

Notes:

Cylinder heads with cracks between the valve seats or between a valve seat ring and the spark plug thread can still be used without any reduction in service life, provided that these are only incipient cracks not more than 0.3 mm in width or provided that only the first four turns of the spark plug thread are cracked.
After installing new bucket tappets engine is not to be started for roughly 30 minutes (otherwise valves will strike pistons), then crank crankshaft twice.
Check valve guides for wear => Page
15-93
.

15 Nm
Bearing cap
Installation position =>Page
15-85
Installation sequence => Installing camshaft, Page
15-83

Drive chain
15 Nm
Inlet camshaft
Checking axial play => Page
15-85
Removing and installing => Page
15-83
Check radial play with Plastigage: Wear limit 0.1 mm
Runout 0.01 mm

15 Nm

Exhaust camshaft
check as for inlet camshaft

Hydraulic bucket tappets
Insepcting => Page
15-86
Lubricate bearing surface before installing
Set down with cam bearing surface facing downwards.

Valve guide
Inspecting for wear =>Page
15-93
.

10 Nm
Flange
Cylinder head
Reworking valve seats
=>Page
15-96
.

Valves
Inspecting=>Page
15-92
Exhaust valve is sodium-filled and cannot simply be scrapped.

Warning!
Worn sodium-filled exhaust valves cannot simply be scrapped. They must be cut in two with an iron saw between centre of stem and valve disc. 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 a time). Then step back because a chemical reaction occurs when the sodium filling burns. Following such treatment, the parts can then be handled as normal scrap.
Servicing valve gear, engine code AHK

Notes:

Cylinder heads with cracks between the valve seats or between a valve seat ring and the spark plug thread can still be used without any reduction in service life, provided that these are only incipient cracks not more than 0.3 mm in width or provided that only the first four turns of the spark plug thread are cracked.
After installing new bucket tappets engine is not to be started for roughly 30 minutes (otherwise valves will strike pistons), then crank crankshaft twice.
Check valve guides for wear => Page
15-93
.

15 Nm
Bearing cap
Installation position =>Page
15-85
Installation sequence => Installing camshaft, Page
15-83

Drive chain
15 Nm
Bearing cap in front of chain
Tappet
Compensating element
Cotters
Upper valve spring retainer

Valve springs
Valve stem seal
Replacing => Page
15-88

Inlet camshaft
Checking axial play => Page
15-85
Removing and installing => Page
15-83
Check radial play with Plastigage: Wear limit 0.1 mm
Runout 0.01 mm

15 Nm
Exhaust camshaft
Check as for inlet camshaft

Hydraulic bucket tappets
Inspecting => Page
15-86
.
Lubricate bearing surface before installing
Set down with cam bearing surface facing downwards.

Lower valve spring retainer
Exhaust end only

10 Nm
Flange
Cylinder head
Reworking valve seats
=>Page
15-96
.

Valves
Adjusting, inlet side only => Page
15-81
.
Inspecting=>Page
15-92
Exhaust valve is sodium-filled and cannot simply be scrapped.

Warning!
Worn sodium-filled exhaust valves cannot simply be scrapped. They must be cut in two with an iron saw between centre of stem and valve disc. 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 a time). Then step back because a chemical reaction occurs when the sodium filling burns. Following such treatment, the parts can then be handled as normal scrap.
Adjusting valve clearance

Note:

Valve clearance only has to be checked/adjusted following valve gear repairs and can only be adjusted at the inlet camshaft.

Turn crankshaft until cam pair of inlet camshaft of cylinder to be adjusted is facing upwards.
Check valve clearance between camshaft and tappet.

Setting dimension 0.10... 0.20 mm

Note down test values of valves which are outside setting dimension tolerance.
Removing camshafts => Page
15-83
.
Remove tappet.

Remove compensating element from valve stem and measure using commercially available micrometer caliper with offset measuring faces (max. ø). 6 mm.
Replace compensating element by one to match the difference measured.

Example:
Measured setting dimension · 0.30 mm
Prescribed setting dimension · - 0.15 mm
Difference · 0.15 mm

0.15 mm thicker compensating element must be fitted.