przez Długi » 10 gru 2003, 15:34
Wracając do tematu service tips w poszukiwaniu klekotania
Model: Probe 2.5l 24V
Markets: Germany, Great Britain, Switzerland, Sweden, Netherlands, Spain, France and Austria
Subject: Knocking, clattering, ticking or tapping noise from top of engine – service tips
Summary
Should a customer express concern over knocking, clattering, ticking or tapping noises from the top of the engine, it is important to consider when the noise occurs as well as the type of noise during diagnosis. A knocking noise heard when starting from cold and disappearing as the engine warms up could result from carbon build up in the combustion chamber and on the piston crowns. Alternatively, a tapping noise from the rear of the right-hand cyclinder bank exhaust camshaft area, which starts during the warm up phase and increases as the engine reaches normal operating temperature, may be the result of a loss of tension in the camshaft gear friction spring. Hydraulic lash adjuster noise can be caused by either internal failure of the hydraulic lash adjusters, air trapped in the lubrication system or low oil pressure. Verify the concern using the procedure detailed in this bulletin before undertaking further remedial work.
This bulletin supersedes pages 1 2 of TSB 136/1997 dated 03.07.1997 and features the inclusion of '97 MY vehicles under `Model'. Please destroy the corresponding pages of the previous edition of this bulletin.
Parts Required
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ł Description ł Finis Code ł
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ł Carburettor Tune-up Cleaner ł 3 612 427 ł
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Diagnosis tips
Carbon Knock
Carbon knock is caused by carbon accumulating in the combustion chamber and on the piston crowns. This reduces the clearance between the piston and the cylinder head resulting in contact.
To distinguish carbon knock from hydraulic tappet noise, slowly increase the engine speed. Carbon knock should disappear by the time the engine speed reaches approximately 2500 rev/min.
NOTE:
The engine number is stamped on the right-hand side of the cylinder block, adjacent to the timing belt cover.
µ Cylinder heads fitted since 08.03.93 (engine number KL326295 onwards) have a revised combustion chamber with increased clearance.
If carbon knock is diagnosed, carry out `Procedure A'.
Camshaft gear friction spring
Typically a heavy tapping noise which may be heard from the right-hand (rear) cylinder head in the area of the exhaust camshaft directly behind the timing gear cover.
The tapping starts during engine warm-up and the noise level may increase as the engine reaches normal working temperature. In some cases the noise may begin to oscillate in three to five second cycles.
µ Using a suitable stethoscope listen to the engine just behind the timing belt area on the valve cover.
Engines built since 28.08.94 (engine number KL520946 onwards) have a revised camshaft friction gear spring.
If camshaft gear friction spring noise is diagnosed, carry out `Procedure B'.
Hydraulic tappet noise
When a cold engine is first started, some hydraulic tappet noise is normal. The duration of the noise will depend on the time lapse since the engine was last run.
Hydraulic tappet noise is a ticking or clattering noise from the top of the engine at various engine temperatures. The noise level will also vary depending on the number of noisy hydraulic tappets.
Hydraulic tappet noise is most usually caused by:–
l Low or poor oil pressure.
l Internal failure of the hydraulic tappet.
If hydraulic tappet noise is diagnosed, carry out `Procedure C'.
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ł Type of noise ł When the noise ł Repair ł
ł ł occurs ł ł
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ł Knocking or clattering in ł Immediately after ł Refer to ł
ł upper engine lasting 3 – ł cold soak start ł Procedure ł
ł 5 minutes ł ł A ł
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ł Heavy tapping noise from ł During engine warm ł Refer to ł
ł rear cylinder head ł up ł Procedure ł
ł ł ł B ł
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ł Ticking or light ł Immediately after ł Refer to ł
ł clattering in upper part ł cold soak start ł Procedure ł
ł of engine lasting ten ł ł C ł
ł minutes or more ł ł ł
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ł Ticking or light ł During engine warm ł Refer to ł
ł clattering in upper part ł up ł Procedure ł
ł of engine ł ł C ł
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Procedure A
1. Bring the engine to normal operating temperature then switch the engine off.
CAUTION:
A separate 610 mm (24 in) length of 3 mm (0.125 in) inside diameter vacuum hose must be used for feeding the cleaner into the engine. Do not use any of the vacuum hoses fitted to the engine as this may result in the deterioration of these hoses.
CAUTION:
The Carburettor Tune-up Cleaner must only be fed into the engine at the point specified.
µ 2. Disconnect the purge control vacuum port vacuum hose and connect one end of the feed hose in its place. Place the other end of the feed tube into the can of Carburettor Tune-up Cleaner (see Parts Required).
3. Clamp the feed hose to prevent suction during start-up.
WARNING:
A large amount of exhaust smoke will be generated in the following procedure. An exhaust extractor must be used to vent the smoke.
4. Restart the engine.
CAUTION:
Do not allow the cleaner feed rate to exceed half a can in 10 seconds. A faster feed rate may result in liquid accumulating in the cylinders resulting in hydraulic lock-up and severe engine damage.
5. Allow the engine idle speed to stabilize then:–
While maintaining an engine speed of 1500 to 3000 rev/min, release the pipe clamp allowing the cleaner to be drawn into the engine. Regulate the flow as necessary until half the contents of the can has been used. Clamp off the hose again.
Allow the engine speed to drop to idle. The engine should stall. If not, switch the engine off.
NOTE:
If it is not possible to leave the vehicle in the workshop overnight, the vehicle must stand for not less than 6 hours.
6. Allow the vehicle to stand overnight, or for up to 24 hours, to allow the cleaner to saturate the carbon in the combustion chambers.
7. Repeat Steps 1 5. using the remaining Carburettor Tune-up Cleaner. DO NOT let the engine stall this time.
8. Remove the feed hose and reconnect the purge control vacuum hose.
NOTE:
After carrying out a carbon cleaning procedure the engine oil and filter must be renewed in order to remove any contaminates in the oil.
9. Road test the vehicle for a minimum of 5 to 6 Km (3 to 4 miles) using the full range of engine speeds to remove any remaining carbon.
10. Allow the vehicle to stand for a minimum of 12 hours. Start the engine and check for carbon knock. Absence of the noise on start up would confirm that the carbon has been dispersed.
Procedure B
µ 1. If a heavy tapping noise is heard, the friction washer which controls the backlash between the friction gear and the camshaft gear may have become weak and should be renewed using the latest level part (Refer to TSB 132/1997).
1 Friction washer.
2 Friction gear.
3 Camshaft driven gear.
Procedure C
1. Check the oil level.
If the oil level is correct and the oil clean and in good condition proceed to step 2.
Otherwise, top up to the correct level or renew the engine oil and filter as required.
2. Install the engine oil pressure gauge (T73L-660A) and Transmission Test Adaptor (D87C-77000-A) or equivalent.
3. Start engine and idle for 10 minutes.
Increase engine speed to 4000 rev/min for 10 minutes or until oil temperature reaches 100şC. Return engine to idle.
If hydraulic tappet noise is still present, proceed to step 4. Otherwise, proceed to step 6.
NOTE:
The additional oil must be drained from the engine before returning the vehicle to the customer.
4. Stop engine and add 2,25 L (4 pints) of engine oil.
5. Restart engine and run at 3000 rev/min for 5 minutes. Reappraise the noise level.
If the noise is still present proceed to step 9.
If not, suspect air in the lubrication system and proceed to step 8.
6. Allow engine to idle for a further 20 minutes and reappraise the noise level.
If the noise is still present proceed to step 7.
If not, no further action is required.
7. Increase engine speed to 3000 rev/min for 5 minutes and return to idle speed.
If the noise is still present proceed to step 9.
If not, air is trapped in the lubrication system – renew the oil pump. No further action is then required.
µ 8. Inspect the oil pump strainer, pick up tube, tube flange gasket and condition of mounting faces for possible sources where air could be drawn in. If no faults are found, renew the oil pump.
Reappraise the noise level.
If the noise is still present proceed to step 9.
If not, no further action is required.
9. Check engine oil pressure at normal operating temperatures.
Oil pressure should be:
l 2.0 Bar (28 lb psi) at 1000 rev/min.
l 3.4 to 4.9 Bar (50 to 70 lb psi) at 3000 rev/min.
If the oil pressure is within specification, check hydraulic tappets for wear, damage and tappet to bore clearances. Renew as necessary as directed in the procedure (refer to Probe Service Manual, Section 03-00).
If not, diagnose cause of low oil pressure (refer to Probe Service Manual, Section 03-01B).