Volvo: about valve adjustment, hydraulic lifters, low oil pressure

Question
So, how it can be fix?

Thanks again
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The text above is a follow-up to ...

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but why the valves are so noise when the engine in idle moment. the sounds like "tick tick tick......"
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The text above is a follow-up to ...

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I have a 98 S70 T5, just want to ask those valve can be adjusted or not because it's so noise.
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Tom,
You have hydraulic lifters in your car no adjustments needed.
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Thomas,
You could have a bad set of lifters or low oil pressure, leaking oil pump pick up seals, so the supply of oil is low. If the engine oil has not been changed often, the engine could be slugged up and internally clogged.

Answer
Thomas,
Check the oil pressure, see if there are air bubbles in the oil while running. Remove the oil cap while running hot and see if there are bubbles. While watching have someone turn off the engine and continue to see if there are bubbles. If yes pull the oil pan and replace all the oil sump pick up seals. If the bubbles go away and the lifters are not damaged they will quite down. If they are still noisy they are damaged and will need replacement. If the engine is all slugged up you may want to consider a replacement engine.