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Rb25 Vct Oil Feed

megzz

By megzz,
in Engines & Forced Induction

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megzz Collaborator

megzz

Posted
Posted

I'm in the process of rebuilding my 25. Just looking at my VCT oil feed, I stuck a pick into it and it only went in a max of 2mm deep. Is this normal, does the oil feed straight up into the gallery from the bottom of the block or does it 45deg into it?

Hopefully this makes sense, I want to make its not blocked because VCT wasn't working when the motor was last running.

post-84181-0-92728400-1367539826_thumb.jpg

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89CAL Grand Master

89CAL

Posted
Posted

Think it works as a check valve so might just be bottoming out the check valve. Just blow some air through and see if you can feel it come out. If the engine is out that is. I think if you blow air into one of the ports where the filter goes and block the other 2 head feeds with your fingers then you should feel some air come out

  • 2 weeks later...
megzz Collaborator

megzz

Posted
  • Author
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So I drilled feed with the top of the block facing down (I used a bit smaller than the hole size so it didn't cut any metal) and some oil dried up like jelly came out. The feed seems free now and I can get a pick in there but compressed air still doesn't come out of the feed.

I've tried blow air through various spots including both oil filter ports and the oil pump port but i get nothing from the front VCT feed!

megzz Collaborator

megzz

Posted
  • Author
Posted

Hi Guys,

Does anyone know where in the oil system does the VCT feed, feed oil from? i.e where does the feed tap into the rest of the system? if possible could you highlight it on a photo for me? Its hard for to now that the engine is partially built.

89CAL Grand Master

89CAL

Posted
Posted

Yeah should be from the same feed as to the other head oil feeds.

oil pump --> Filter ---> main oil gallery ----> Head feeds

From memory anyway, I did sus it out when I had a bare block and some air and some cleaner spraying through it

megzz Collaborator

megzz

Posted
  • Author
Posted

can you track down a pic of the oil feed? if you can get a hold of a manual it will show it

I have the Nissan workshop manual but it doesn't detail the oil flow /path it just shows how to assemble oil pump etc.

Here's a photo of it

post-84181-0-96909000-1369099208_thumb.jpg

I got this from the oil control thread its for an RB26 though

post-84181-0-19310900-1369099313_thumb.jpg

How do you guys troubleshoot a blocked oil gallery - with drilling as a last resort as the block as it has already been cleaned and assembled...

  • 4 years later...
Ben C34 Grand Master

Ben C34

Posted
Posted
14 minutes ago, silencium said:

Sorry for digging up this old thread but I have kind of a similar problem.

Does anyone know if there is a check valve in the VCT oil feed or if it simply is a restrictor?

Thanks for the help

 

Why would there be a check valve?

How would that be useful?

Why do you think there is one?

why does it matter?

 

I vote my ass no check valve

silencium Apprentice

silencium

Posted
Posted (edited)

That is very simple: When the engine is stopped, oil could flow back due to gravity, leaving air in the oil gallery. Next time the car gets started the air has to go out through the journal bearing before the oil follows.

I do not know how much the oil actually flows back, but it is definitely a bit, because otherwise oil pressure would be instant on the first engine cranks during start up. But it usually takes about one second till the oil pressure switch goes off.

Using a check valves in the block would make sense imho.

If one has a RB block laying around it could be checked with a thin wire.

Edited by silencium
typo

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