check engine AUDI A4 1998 B5 / 1.G AFC Engine Lock Carrier Removing For Service Workshop Manual

15-18

Compression pressure, checking


Engine warm-oil temperature at least 30 C
(86 F)

Throttle valve fully open during cranking

- Disconnect harness connectors from ignition coil
power output stage and from all six fuel
injectors.

- Use compression pressure recorder VAG 1381
together with adapter 1381/5 or equivalent to
measure compression.

Note:
Refer to operating instructions for use of the
recorder.

- Operate starter until tester shows no additional
increase in pressure.

Compression pressures
New: 9-14 bar (131-203 psi)
Wear limit: 7.5 bar (109 psi)
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15-22

Hydraulic valve lifters, checking


Note:

Irregular valve noise during cranking is
normal.
Do not interchange hydraulic lifters. If
necessary mark them when they are being
removed.
Place lifters that have been removed on a clean
surface with the contact surface (camshaft end)
facing downward.
Hydraulic lifters cannot be repaired or adjusted.
Faulty lifters must be replaced.

- Start and run engine until warm-until radiator
coolant fan has come on at least once.

- Increase engine speed to approx. 2500 RPM for
2 minutes
If the irregular valve noise stops and then re-
occurs again each time vehicle is used in stop
and go traffic:

-
Replace the oil check valves Repair Group
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15-23

- Use a wooden or plastic wedge to press valve
lifter down.

CAUTION!
Note:
The illustration is used to show an example of pressing down on the lifter
checking the clearance with a feeler gauge-it does not specifically show
the 2.8 liter V6 engine. - If a 0.20 mm (0.008 in.) feeler gauge can be inserted between
camshaft and lifter, replace lifter.
After installing new or re-installing old lifters, and after installing
the camshaft(s), the engine must not be started for at least 30
minutes. Otherwise the valves could strike the pistons. After working on the valve train and lifters, crank the engine
carefully by hand, at least two full revolutions, to make sure that
the valves do not strike the pistons.
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15-29

Valve guides, checking and replacing


Checking
When repairing engines with low compression
due to leaking valves, it is not sufficient to reface
or replace the valve seats and valves. It is also
necessary to check the valve guides for wear.
This is particularly important when checking
engines with high mileage.

- Insert new valve into guide until end of valve
stem is flush with end of guide.

CAUTION!

Due to the difference in valve stem diameters,
make sure that only an intake valve is used to
check intake valve guides, and that only an
exhaust valve is used to check the exhaust
valve guides.

Wear limit - Determine valve rock-amount that valve can move side-to-side.
Intake valve guide 1.0 mm (0.039 in.)Exhaust valve guide 1.3 mm (0.051 in.)
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