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Rb30 25 neo cometic head gasket problem

lcxu105

By lcxu105,
in Engines & Forced Induction

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lcxu105 Proficient

lcxu105

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Posted
Rb30 25 neo cometic head gasket problem

Ok everyone. 

Problem is a brand new engine 30 25 neo so all surfaces are machined flat fitted cometic rb30 head gasket and have a oil leak between the head and block rear passenger side. 

The gasket can only fit one way so thats not the problem.

Engine has 1mm oil restrictors fitted and vct mod. 

Just pulled the covers off and checked the torque settings at 110nm i know that it's 108.49nm for arp studs.

Just bumped it up to 118nm figured it couldn't hurt much.

Can anyone give me any insight as to why it might leak.

Thanks in advance.

 

Weaselman Collaborator

Weaselman

Posted
Posted

Usually on the first steps of tightening the head you need to back the studs off and re do them. When using cometic gaskets I don't back them off because you've flattered the metal plates already and unloading them can cause them to leak. Now I'm not a qualified mechanic but it's how I do it and I've never had them leak.

89CAL Grand Master

89CAL

Posted
Posted

So are you saying you have loosened it all off and re-torqued it?

If it's already leaked and you've taken all the pressure off the gasket and torqued it back down, I would be putting the order in for a new head gasket now. Once oil gets inbetween the surfaces, its not likely to seal properly, And I agree with above, after the first time the gasket is crushed, I wouldn't use it again.

rx-line Enthusiast

rx-line

Posted
Posted (edited)

Threads need to be lubbed in order to keep the steel alloy of the stud from galling the aluminum, this will give an accurate torque, rather than a false torque if galling has occurred. A false torque could cause a leak for sure.

Also you might want to try torquing from the inside working your way from side to side to the outside of the head, we have had good luck with this.

As for a reason things change a fair bit when you clamp a head to a block, it's surprising how things move. If the above fails I would look at the head and block to see how well they have been surfaced.

Here's a thought as well, you might be experiencing above average crank case pressures due to you rings not being seated in with the new build. Make sure not to use synthetic oil when breaking it in, it delays the process by a lot. This may be exaggerating the leak.

Hopefully this may help you.

Edited by rx-line
lcxu105 Proficient

lcxu105

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  • Author
Posted (edited)

Lube was used on threads to tension block was decked square  to tunnel and head was machined with reco and port work  i use hpr5 penrite. engine was run in on a dyno. 

I do think i have over filled the oil tho too.

 

Edited by lcxu105
KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted
1 hour ago, lcxu105 said:

 i use hpr5 penrite. engine was run in on a dyno. 

Including initial fill? As RX-Line said mineral oil is better for running in - but probably too late to change now. Did you use Hylomar or similar to stick the gasket down? How much oil actually leaked? I wouldn't have expected overfiling to result in a leak from there.

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