K Series

I just rebuilt a BP-Z3 and have what seems to be a high-pressure oil leak somewhere near the intake cam gear. I bought a gasket for the VVT "blind cover" (Mazda P/N ZL09-10-607), but looking at the car now, it looks like the leak is further back from that point.

Is there anything else that might leak on that cam gear? I'd like to get this knocked out in one go around so I can get back to getting the car running.

(Also hello. Been here over two years and apparently never bothered to post.)

18psi

iTrader: (76)

you sure its gear and not the cam seal? anything in that area will be one of those two

K Series

Not really sure of anything, to be honest. A shop in PA did the head rebuild; I'm the goober that thought taking the VVT stuff apart was a good idea (I ran out of ideas when I was trying to get the intake cam out.). The intake cam seal is a new OEM part, but as I didn't do the work myself, I can't be certain it was actually done correctly.

I'm going to flip if it turns out to be the cam seal. Is there a way to check it?

18psi

iTrader: (76)

it should be relatively evident what's leaking once you pull the front timing cover and valve cover off

K Series

Timing cover is already off- I left it open above the water pump.

But I'll go scope it out. Thanks.

18psi

iTrader: (76)

behind cam gear - seal
front of cam gear - that other seal

K Series

So I went and scoped it out. Took the VVT actuator apart, put it back together, everything looked good so I fired up the car and immediately found the issue.

The hole at the front of the oil galley which I assume feeds the intake can journals is plugged by a steel ball... Only now it isn't plugged anymore. Oil pours out of this hole steadily at idle.

Any ideas on how to seal up this hole? Its the one about center in the photo with the three arcs around it.

Dustin1824

iTrader: (2)

Hey there, don't mean to wake the dead, but that steel ball is part number 996113000. Hope this helps someone, maybe in the future?

-Dustin

K Series

Good info, Dustin.

What it turned out to be was in fact the cam seal. I was looking for an improperly installed seal, but the shop (AP Tuning) didn't install the seal at all. They mostly do VW/Audi work, so maybe they're not used to cam seals or something, but it seems hard to miss considering I supplied them with a new seal along with the cylinder head, and they did not return the seal. They also did a pretty terrible job with valve seals, and now the engine leaks oil into the cylinders, so much that it will not run.

Anyway, I did two things before figuring this out:

First, I tried drilling out that ball with the idea that I could thread something in to reseal. Don't bother with this. The ball itself was extremely tough (and impossible to steady a drill bit on anyway), and attempting to cut away the aluminum around the ball never got the ball free. On the plus side, none of that seems to have damaged the head. I was indicating up to about 70psi of oil pressure on startup, and even after cutting the ball did not leak. So, if you're reading this in the future, the ball is not the source of any leak you have.

Second, I took apart the VVT actuator to check for any obvious problems. It's actually pretty simple internally, with an inner rotor and outer shell, both of which have "wipers" at their contact surfaces, supported by springs, not unlike a rotary's apex seal. There are eight wipers total. If your VVT for some reason doesn't work properly and you trace it to the actuator, this is what I would check for wear before buying a new one.