My 98 imprezia outback sport has a developed a knock in the engine when it is cold. Only lasts for 5 or 10 seconds. Usually is barely noticable but sometimes is pretty loud. The car has 78k miles and I have always run synthetic oil with changes every 5k miles. Does anyone know if this is something to worry about or not ?

 

try searching the topic. its been covered a few times recently. pretty common. hydraulic lifter tick (its stuck) would be my guess. its a 2.2 right?

-PJ