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9 hours ago, silencium said:

Lol what does that has to do about the question?

Well, putting the grey mush in my head to work, I cannot see how the 200ms that it would take to purge the air out of an oil gallery feeding the head when the oil pressure behind it starts to rise is going to make any difference at all to how much wear the head sees on start up.  I don't know if you've ever looked under a cam cover with the engine off.....but there's lots of oil sitting up there.

Check valves are a 0.0001% thing.

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Lately I was testing a camshaft for run out with a dial gauge. For that I put it on flipped front an rear bearing cap with some oil in between of course. Well after turning the cam approx 10 times by hand, the caps already had scorring marks despite the oil.

So without oil pressure that is all much more delicate than one might think.

Also the cam installed an all, there is a lot of load on it from the valve springs.

If oem there are check valves, I want to go with them again

Thats why I want to know

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P115_lube01.gif

The Japanese bit before 2.0 says Normal , as in original. That's not a check valve.

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There is a check valve in the oil filter. That would do all the check valving required to keep the oil up in the engine wouldn't it?

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The check valves behind the oil filter have another purpose. These are pressure controlled and open only if the oil pressure reaches a certain point, for example when the filter would be clogged.

I have found these pics before also, but these are not original nissan, but from a tuner... Even though it is a japanese tuner, that doesn't mean its all superbe.

I get it that you two do not think there are check valves... But I still want to know what originally the case is.

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Oil filters have there own pressure release valve , they also have an anti drain back valve (check valve) that holds oil in the filter. 

I've stripped and cleaned three RB's (20,25,26) over the years and i can certainly say there were no check valves in any feed to the head what so ever. Brake cleaner and air pass easily back through the orifices without a problem.

There is simply no need for them.

 

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The check valve on an RB25 is in the oil cooler not the block

I thought the standard restrictors had check valves but guess not. As I said previously, I never gave it a second thought. 5 years later and my head is still fine

As for the above about rotating the cams etc. And there being score marks - something else is going on there. I rotated mine several times while building my engine and no marks/scoring
Engines are not that fragile that they will die after 2 seconds without oil (at idle) on startup. Have you ever watched how long it takes for oil pressure to come up after doing a service?

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On 24/03/2018 at 6:47 PM, Ben C34 said:

P115_lube01.gif

The Japanese bit before 2.0 says Normal , as in original. That's not a check valve.

for anyone's future reference - the OEM oil restrictors on an RB25 are absolutely a 1-way valve. Floating-ball type, not spring loaded. Just under 1.5mm diameter.

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58 minutes ago, hardsteppa said:

 

for anyone's future reference - the OEM oil restrictors on an RB25 are absolutely a 1-way valve. Floating-ball type, not spring loaded. Just under 1.5mm diameter.

You got a picture?

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Have a brand new one sitting in my garage, but it won't show much unless i cut it open. Air will only flow thru it one way; direction of flow to the head.

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1 hour ago, hardsteppa said:

Have a brand new one sitting in my garage, but it won't show much unless i cut it open. Air will only flow thru it one way; direction of flow to the head.

What engine? Neo?

 

When are you cutting it open?

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nah just plain ol rb25 ..

wasn't going to cut it open but yeah ok I might do that, don't think I'll end up needing it anyway.

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