Oil Leaking From Between Head And Block

[iruvyouskyrine]

It is with great disappointment i have to ask this question.

RB25 Neo head on RB30 block. Head was welded for VCT and decked flat. Block was scraped with a razor blade to get everything off and then cleaned using WD40 and brake cleaner to ensure a clean surface. I did not check block straightness at all with a steel rule etc. Using an RB25 Cometic Multi layer metal head gasket and RB25 ARP head studs torqued to ARP specs (80 ft/lb)

Oil is weeping from between the head and the block on the passenger side at the very front of the engine. Compression test on cylinder 1 shows 170psi and oil pressure at cold idle is 70psi, using a 10W-40 oil. The oil leaks very slowly but enough to be noticeable as a mark on the ground. Even once then engine has been shut down it will continue to leak for maybe 15 minutes, which i guess it only stops when all the oil has drained from the head.

I'm guessing that the block just isn't straight enough to get a good seal with the metal head gasket? I guess my options are take the head off and replace with a standard nissan fibrous gasket, or spray some hylomar (not sure exactly which one to use, the blue spray or the copper?) on the gasket and put it back on?

Video attatched below of issue.

[XKLABA]

Oh that sucks

Are you sure its coming from the HG and not the cam seal and running around the HG

Even hylomar can only do so much and if the block isn't straight then that needs to be fixed to guarantee a good seal which would unfortunately mean having the block decked

[iruvyouskyrine]

Yeah I'm pretty positive that's where it's coming from. Block was removed from a running car with no oil leak issues so thought I would just be able to use Nissan gasket.

[XKLABA]

A good cleaning which it sounds like you did and a Nissan gasket with hylomar should have been fine but I think the metal gaskets need perfect surfaces, but I could be incorrect

[jiffo]

I would have expected a head gasket oil leak to come from the right side so I'm also leaning to a leaky cam seal.

Here's a photo of my 32's exhaust cam which made quite a mess. Previous owner had decided to replace cam seals and had done a poor effort.

Oil travelled a long way and it was hard to track where it originated, belt etc stayed clean as the oil leaks between the rear cam belt cover and the block.

[iruvyouskyrine]

I replaced the cam seals with brand new Nissan items before I put the engine in. It is very hard to track where the leak is with the cam backing plate on but I am very confident it's not from the cam seal (unfortunately)

[jiffo]

Since all the cam components still have to come off whether it's a head gasket or not, take care when dismantling and see how things pan out.

Fingers crossed for you.

[Ben C34]

I agree it's very unlikely to be head gasket leaking oil from that side.

Fingers crossed.

[White GTS-T]

It might be a long shot, but since It's been heat cycled, I would re-torque the head before pulling it down. Did you use the supplied ARP lube while torquing the head in sequence, or engine or similar? Maybe try another torque wrench?

Sucks to hear man, hope it works out for you.

[iruvyouskyrine]

Yeah I had the cam gears off only 3 days ago and there did not look to be any evidence of oil leaking from the seals. Will inspect before taking the head off though.

I agree it's unlikely that it's leaking oil from there, but as I said there is no oil above there or any oil from behind the cam backing plate (that I can see), have cleaned it multiple times and it only seems to be coming from where you can see in the video

Yep used arp moly lube in all studs and nuts torqued in correct sequence to ARP specs (80 ft/lb). Used my torque wrench which has hardly been used (done flywheel bolts 3 times and 2 sets of head studs)

Only thing with that is my 13mm deep socket just touches the cams when torquing them up. Some of the pressure I am applying would be applied to the cams not the nuts but I don't think it would be too much, it barely touches them.

[steve200b]

Why the plated vct drain?

[Ben C34]

Why the plated vct drain?

It's a neo head.

[iruvyouskyrine]

Alright. I tried putting liquid gasket in where it was leaking to see if it would run down the front if it so I could see if it was coming from the cam seal or not. None run down the front but it did come out of between the head and the block just further down the engine where I didn't put liquid gasket. So I'm now almost positive it's not the cam seal. still the cam gears and backing plate coming off tomorrow night for inspection.

Am I able/should I also give a standard Nissan headgasket a spray with hylomar? Just for that extra sealing?

I'm about ready to set this thing alight if it leaks again.

[GTSBoy]

2 things.

1) Check your torque wrench. Put it on a nut (like a wheelnut) so it sits horizontal and hang a known load from it. You can work out the torque from a known mass easily enough. All you need is mass, 9.807 and the length of the lever arm between pivot centre and the load point,

2) Having done that, use it to torque the head bolts up again.

[Kinks]

my car leaked from there and it came from the cam seals. don't rule out coincidence!

I pulled the rocker cover gaskets off twice and replaced the VCT drain once and finally realised it was the cam seals.

[iruvyouskyrine]

Torque wrench is calibrated fine.

Replaced both cam seals. Now leaks substantially less, but still leaks a noticeable amount of oil

[KiwiRS4T]

Did you use sealant on the cam seals? (Yes even new ones!).

[jiffo]

Unsure how the cam seals were initially installed, but both front cam bearings are important.

Their front sections need a wipe of 3-bond to stop oil weeping between the cam cap and the head.

This is easiest to do by first installing the cam with all caps, then removing the front cap to apply the sealant, and then finally torquing down all the caps.

It has to be done carefully so the seal oil drain back hole isn't blocked.

I also give the outers of the seals a very light wipe of 3-bond as they're only a light push fit.

As the head was re-built I presume the actual seal surfaces were tidied up.

[iruvyouskyrine]

I used grease on the cam seals (as recommended by my mechanic mate) and was considering using liquid gasket on the cam caps but didn't.

There is 3 points at which oil drains into behind the cam seal, one in the head itself and 2 little holes either side of the cam cap. So you are saying I should liquid gasket everywhere around the cap but not where those drain holes are?

[Ben C34]

As per the manual you use three bond or the actual nissan sealant as previously mentioned , sounds like that's your problem.