Engine Knock on start-up? Why?

[Brent Spomer]

1997 Rav4 2.0L recent overhaul.

If the car has set for 24-48 hours, it will knock/rattle for a few seconds after start. During this rattle the idiot light is on. When the rattle stops the light goes off. And after that and particularly when the engine is fully warm, it sounds great. The overhaul included new most everything including new bearings, OEM pump and an OEM filter is always used. Oil level is not an issue. The pressure was checked with a quality gauge and runs well in excess of 60psi at say 3000 rpm and 30-40 at idle.

I know from Eric’s Youtube on oil pressure that pressure is created by bearing clearances. And a lack of pressure can cause knock or rattle. Since the pressure on this engine seems fine I’d contend the clearances are fine. So why the seemingly ‘dry start up’? Is there some sort of oil leak down that has to be replaced when the engine starts?

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[Lou Merrell]

I know that on my 2003 Chevy tracker (2.0 Suzuki interference engine) that a rattle on start-up may indicate a failing timing chain hydraulic tensioner. Not sure if this is the engine in your Rav 4 though.

[Lou Merrell]

Try to start it to trip the light and connect a scanner to read the code.

[Lou Merrell]

No, your RAV4 is not an interference engine.
But I would trip the light and read the code.

[Author]

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