stuey Posted August 27, 2006 Share Posted August 27, 2006 do these filters have a non return valve in them so the oil dosent drain down from the top of the engine when turned off......... .. the reason i ask is beacuse wen i start my car from stone cold it sounds like the cam rattles for about a half a second then its as sweet as a nut ie when the hydralic valves refill wiv oil........ is this normal?? i do know that my supra had this valve in the filter but the pattern part filters didnt...... any ideas.....!! Quote Link to comment Share on other sites More sharing options...
lomoto Posted August 27, 2006 Share Posted August 27, 2006 no valve in filters, only if it gets totally blocked with crap., it will allow flow through with no filtration effect Have you changed your oil recently?? sounds like its ready + a filter for good measure Quote Link to comment Share on other sites More sharing options...
amsoil Posted August 28, 2006 Share Posted August 28, 2006 Oil filters are a black art in their own right. They can have one or two valves or none at all. It is very rare for people to know or even ask about this. Most filters have a 'blow-off' valve which opens when there is a pressure differential from one side of the filter to the other; this will open and save your engine if the filter gets blocked to any degree. Better to have unfiltererd oil than no oil! However on start up it will open and allow unfiltered oil through for a very short time until the pressures are balanced. This is why on an engine with a filter you will still find small particles embedded in the bearings. The pressure differential required to open the valve can vary considerably. Some filters have a 'drain-back' valves; this isn't to stop the oil draining from the top of the engine but to stop the oil comming out of the filter if the car is left for some time. As is easily imagined on start up it takes a small amount of time for oil to feed the bearings, if the filter needs to be filled first then this is not good. Some have no valving at all! Might appear strange but then some manufactures fit bypass and even over pressure valves in their cars oil filter blocks. This might be a clue that some of those who realise simply dont trust after market filter manufactures. Problems can arise if you move away from manufacturers supplied filters, yes the aftermarket filter is usually cheaper and fits but...... Problems also arise when things like oil coolers etc are added to the oil system They may cause the pressure differential to increase beyond the point that the filter opens and then you dont get the oil filtered anymore yet you still have a nice filter inplace! And when you use a thicker oil than you have to things are worse So keep to a Nissan filter unless you are sure the replacement is made for your car (not just the right tread to fit!) and use a 5w-30 fully synthetic oil (quality one) or if you are a cheapskate 10w-40 mineral and change it often (which makes this the most expensive option) Quote Link to comment Share on other sites More sharing options...
Liam's Z Posted August 28, 2006 Share Posted August 28, 2006 Thanks for the explanation amsoil Quote Link to comment Share on other sites More sharing options...
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