Oil leak or residual oil trapped

I've been hunting down an oil leak with not too much success so far.

First the rear head cover gasket leaked oil in the near of the TB, down on the rear 97+ header. That has been fixed successfully more than a year ago. Now, it takes some months to build a drop of oil on the gearbox side, the stiffener between the gearbox and the engine. It also drops on the front header end letting it smoke when hot.

It's not the VTEC solenoid. I thought about the head gasket.

Is it possible for the lower 97+ header shield to store some oil in some pockets and release it while driving?

Found it. But it must be related to a heavy leak on the left side, not the right side of the engine.

Attachment 14192

The upper cover is ok to remove but the lower one is a PITA with the engine in place. Not sure if I'm going to mount it again, maybe later when the source of the oil leak has been sorted out.

Another question: what are the round screws in the middle for. Are they prone to leak oil?

Attachment 14193
in the front cylinder head, the ones with the greenish color.
Attachment 14194

I assume this is one of the sealing bolts for the oil passage of VTEC.
Sometimes they start leaking oil from there.

I had the same problem some years before.

I doesnt found new bolts into the parts catalogue, so I removed these bolts, cleaned them to new condition, triy the thread hole at the block with some zewa wipe overnight.

Than put a small amount of Hondabond on the bolt and torqued the bolt to the right spec.
This will work with all kind of these bolts.

Attachment 14195

Thenks.
The upper one in the rear head leaks on the "yellow" coolant line and then down onto the end of the front header.
I'll fix it with Teflon tape and good cleaning.

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What about the area at the front especially behind the front Eng/Gbox mount?

As you seemed to have checked thoroughly, could be not the case on your NSX but on many NSX engines,
noticed the wet oil markings at the rearwards of the engine that were originated from the front side.

The leaked oil from the valve cover gasket, the corner edge above #1 cam holder, black disc cam seal under #4 cam holder,
the sealing plugs in your photo above, etc will land on the narrow horizontal surface just above the oil pan/sump fixing bolt/stud area.

With the air flow while driving and the engine being slightly tilted towards the rear, it can travel fair amount of distance towards the rear along the narrow horizontal surface.
If you remove the thin half-moon like metal cover behind the flywheel, you may see wet marking there as well.


For now, I'll leave the possibility of oil seepage from the crank end seal at the triangle-like cover.




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The structure of oil pan and the way it's attached to the eng bottom end would transfer the seeped oil quite some distance.

There is U-shaped narrow metal rail/bar at the oil pan where the fixing bolts and nuts sit.
This design is to spread the force while squashing the rubber gasket.

Because of the position and the way this rail/bar attached to the oil pan, it can attract lots of seeped oil between the tiny gap.

Also, there are many through holes used for the fixing bolt thread at the eng bottom end.
This can pull some seeped oil to the bolt head side over many years.

Some people think that their oil pan gasket is leaking when it's not.


All these seeped oil could travel towards the rearward and end up at that stiffener bracket between the Eng/Gbox.

Kaz

Thanks for your detailled reply, Kaz. Always very helpful.

After MOT in June 2020 the car has not been driven unfortunately. So I pretty sure the oil is coming from the rear. I've taken a photo a few years ago of the two plugs in the front and they were oily too. So I have to sort them out too. Right now, I can only do the rear ones. I might have to take the headers off and hope I can reuse the gasket.