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Rb25/30 Top End Knock

Wetherhead622

By Wetherhead622,
in General Maintenance

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Wetherhead622 Rookie

Wetherhead622

Posted
Posted

Hello all . I have built a rb25/30 the car runs well enough and revs fine and smooth . The only problem is there is a top end noise . We think it's the lifter . Also have put lifter cleaner in , We changed the lifters taken them out and fully cleaned them. It got better, but was still there and slowly got worse. Now there is a consistent knock. No distinct area of the noise . We don't know if it had a restrictor or not . The head has the vct mod and all . Would any one know what the problem is or even what we could do . I'll also try up load a video on YouTube

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https://www.sau.com.au/forums/topic/450206-rb2530-top-end-knock/
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Ben C34 Grand Master

Ben C34

Posted
Posted (edited)

The vct oil supply supplies oil to the front cam bearing on non neo heads. So with no vct oil feed you have no oil to the front journal.

That's bad.

Deleting vct is bad as it loses response. People pay heaps to get vct onto RB26s.

Deleting the oil feed is worse as it removes the oil feed to the front bearing.

Why an rb20 cam? What happened there?

Edited by Ben C34
Ben C34 Grand Master

Ben C34

Posted
Posted (edited)

Oh just remembered, on th pre neo head you can drill out a brass plug in the front of the head near the inlet cam gear. That might be what the guy did before you?

Edited by Ben C34
AMR33 Mentor

AMR33

Posted
Posted

I had a similar problem in my BMW e36. Knocking noise from the top near the rocker cover. Used a screw driver to my ear to try and pin point it but couldn't. Some people thought lifters. Turned out it was the water pump. Check yours, that may be it

Wetherhead622 Rookie

Wetherhead622

Posted
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Posted

Well I pulled apart the lifters and cleaned them all. But I never bleed them . So they would have been soft when I put them back in . Therefor making the slapping noise because they are bottoming out and slapping on the cam draft it self ?

Dale FZ1 Veteran

Dale FZ1

Posted
Posted

Deleting VCT on a non-Neo head will not cause oil starvation to the cam bearings.

VCT on a road-only engine is probably a good thing to achieve broadest torque spread. On other applications, it is open to debate.

If you disassemble lifters, yes they have to be bled before installation. It is as simple as collapsing them so that they will pump full of oil without any air pockets.

Try using a piece of hose as a stethoscope to identify which one(s) are noisy.

Could be a weekend spent lifting the cams and lifters to give them some attention.

SkudR33 Proficient

SkudR33

Posted
Posted

I'm reasonable sure the front cam bearing is fed via the vct oil supply, so blocking off the vct oil supply causes it to run dry I could be wrong of course!

I'm about to complete a rb3025 build and I blocked off the VCT oil feed as I'm not running VCT. Can somebody please confirm that blocking this feed off will starve the front cam bearing...

Cheers

Ps: sorry bout the thread hijack! Lol

Ben C34 Grand Master

Ben C34

Posted
Posted

I'm about to complete a rb3025 build and I blocked off the VCT oil feed as I'm not running VCT. Can somebody please confirm that blocking this feed off will starve the front cam bearing...

Cheers

Ps: sorry bout the thread hijack! Lol

Check it yorself by blowing compressed air into the cam oil feed and seeing where it comes out, assuming that you have the head off. That way you will k ow for sure.
SkudR33 Proficient

SkudR33

Posted
Posted

Check it yorself by blowing compressed air into the cam oil feed and seeing where it comes out, assuming that you have the head off. That way you will k ow for sure.

Problem is, I've already grub screwed the f**ker closed and assembled majority of the motor. Lol

Now you got me shitting my pants Ben...

Ben C34 Grand Master

Ben C34

Posted
Posted

Are the cams in? You could blow air through the oil galleries by blowing it into the cam journals.

I haven't used a pre neo head. The info came from my machinist who had seen the damage on a head from lack of oil.

Ben C34 Grand Master

Ben C34

Posted
Posted

Problem is, I've already grub screwed the f**ker closed and assembled majority of the motor. Lol

Now you got me shitting my pants Ben...

Check this out.

http://webbersrbguide.com/index.php?option=com_content&view=article&id=89:rb30dettt-internal-a-external-oil-feed-mod&catid=50:rb30dettt&Itemid=29

Pay attention to second last paragraph.

SkudR33 Proficient

SkudR33

Posted
Posted

Wow - I better investigate... I've pretty much out it all together without the manifolds. I'm spewing! I might speak to my machinist and see his opinion on the matter otherwise I gotta rip the head off...

Thanks for the heads up dude!

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