# IS THERE A CHECK VALVE IN OIL SYSTEM



## dagosrods (Dec 7, 2008)

OK guys. I have a 1994 Nissan hardbody 4cyl 5speed. This truck has right at 90,000 miles on it. The timing chain was replaced right before I bought it. Runs good drives good. My problem is that when it sits for a few hours or so. The oil drains back into oil pan and when I start it the chain rattles or valves just for a few seconds and it goes away. It is not the oil pump because I just put a new one on it. With the same results. Is there a check valve that keeps oil up in the block so this doesn't happen? Not sure if it was making the noise before the timing chain change. Thanks ****.


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## smj999smj (Jan 1, 2006)

There's likely an oil pressure relief valve pressed in at the oil filter adapter. Sometimes the brand of oil filter makes a difference; you may want to try a genuine Nissan filter. If there's sludge in the oil channel to the chain tensioner, you could also experience this symptom. I recommend that this channel be cleaned out during a timing chain replacement.


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## TheRepairMan (Jun 30, 2009)

dagosrods said:


> OK guys. I have a 1994 Nissan hardbody 4cyl 5speed. This truck has right at 90,000 miles on it. The timing chain was replaced right before I bought it. Runs good drives good. My problem is that when it sits for a few hours or so. The oil drains back into oil pan and when I start it the chain rattles or valves just for a few seconds and it goes away. It is not the oil pump because I just put a new one on it. With the same results. Is there a check valve that keeps oil up in the block so this doesn't happen? Not sure if it was making the noise before the timing chain change. Thanks ****.





smj999smj said:


> There's likely an oil pressure relief valve pressed in at the oil filter adapter. Sometimes the brand of oil filter makes a difference; you may want to try a genuine Nissan filter. If there's sludge in the oil channel to the chain tensioner, you could also experience this symptom. I recommend that this channel be cleaned out during a timing chain replacement.


I agree with you smj999smj, about the sludge build up being one a possible cause, but there is a big difference between a check valve (anti-drain back valve) and a pressure relief valve. They serve two completely different jobs. A pressure relief valve does just that, regulates oil pressures to a max setting to protect the oil pump, filter, bearings and seals from experiencing failures in which extremely high pressures can lead to, especially when the oil is very cold and thick.

Nearly ALL modern oil filters have an anti-drain back mechanism (check valve of sorts) built into them. That's the flexable seal or flap you can see directly under the small outer holes in the oil filter base. Since all filters are different some of those seals just don't work as well as others. 

As a general rule, most over head cam cylinder heads with hydraulic lifters also have a check valve somehwere in the oil galley to prevent a dry start up. If they become clogged or stuck open that will cause a very noisy top end especially after sitting any length of time.

You might try some Seafoam or other brand of Valve Lifter and Top End Cleaner in your oil for a bit to see if that helps. And, as was suggested, a different brand of oil filter next time also. Be sure to carefully follow the directions on the cleaner so not to over-use any product which could cause other engine problems.

-R


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## zanegrey (Dec 5, 2005)

PROBABLY THEY DID NOT ADJUST THE TIMING CHAIN GUDES CORRECTLY...


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