Engine Rattle When Cold
09-03-2003, 02:23 PM
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Engine Rattle When Cold
Upon start-up after the car has sat for a few hours, I get a rattle similar to tappet clatter or light pinging under light accelleration.
It only takes ~ 1/4" of throttle travel and cuts in about 2800 RPM. It does not do it in neutral and I can prevent it by staying in low gears and using almost no throttle.
In 3 to 4 minutes the sound dissapears and the engine runs fine.
I have swapped the stock chip in and out with no change. I have always used Mobil 1 in 10W-30, 5W-30 and 10W-40. I usually use Audi filters. It makes little difference. After a recent oil change it quit for awhile, then started again.
When I brought it up to the dealer (while still under warrantee-- now expired) the tech said 1.8s often make tappet noise when cold -- not to worry. It has become a little more persistent since.
Has anyone experienced this or have any idea what is causing it?
Haynes suggests that a leaky oil retention valve could be letting oil out of the hydraulic lifters, increasing clearance until it builds up again. That does not (in any obvious way) explain the fact that the sound is torque related.
Worn main bearings can cause a deep knocking under torque and piston slap can get better when the engine warms up.
Could the knock sensor be faulty?
John
99.5 1.8Tqms
GIAC V1.5 chip
It only takes ~ 1/4" of throttle travel and cuts in about 2800 RPM. It does not do it in neutral and I can prevent it by staying in low gears and using almost no throttle.
In 3 to 4 minutes the sound dissapears and the engine runs fine.
I have swapped the stock chip in and out with no change. I have always used Mobil 1 in 10W-30, 5W-30 and 10W-40. I usually use Audi filters. It makes little difference. After a recent oil change it quit for awhile, then started again.
When I brought it up to the dealer (while still under warrantee-- now expired) the tech said 1.8s often make tappet noise when cold -- not to worry. It has become a little more persistent since.
Has anyone experienced this or have any idea what is causing it?
Haynes suggests that a leaky oil retention valve could be letting oil out of the hydraulic lifters, increasing clearance until it builds up again. That does not (in any obvious way) explain the fact that the sound is torque related.
Worn main bearings can cause a deep knocking under torque and piston slap can get better when the engine warms up.
Could the knock sensor be faulty?
John
99.5 1.8Tqms
GIAC V1.5 chip
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