Cylinder head oil pressure
 

Hey guys I was wondering if oil will come out from the head when I crank the engine just want to make sure before I put the valve cover on thanks

Oil is not going to come gushing out of the head if you have the valve cover off while you crank the engine.

If you actually start and run the engine then there will be some oil flying around, however this will mostly be oil flung from the camshafts as they rotate.

Thanks Joe for the reply cause I was just wondering how does the head get oil

https://www.miataturbo.net/attachmen...ine=1434516261

In the image above, the thick vertical passage with an "oil control plug" in the middle of it feeds oil under pressure from the block up into the head. There it splits out to a number of different passages which carry oil to the lower half of each camshaft bearing as well as to the side of each lifter bore.

With the engine running, you'd see oil seeping out from all of these places; out of each camshaft journal as well as up from each lifter.

This image is from a 1.6 engine, however the flow of oil is identical in all '90-'05 engines. The only differences are that the '99 and later engines have solid lifters rather than hydraulic lash adjusters, and the '01 and later engines have a variable intake cam drive which is powered by oil pressure, although the oil to drive this system is delivered to the head via an external pipe not shown in the above image, rather than being drawn from the main oil supply.

Thats soo interesting I never have seen it that way ohh and Joe there's seem to be oil leaking between the back head and the block I got the block decked and the head mill and torqued the headbolts to the right spec would I have to
head gasket again?

And you basically can't hook that external pipe up with the valve cover off, so if you try to start it like this then oil WILL come gushing everywhere. :)

--Ian

I'm told that if it's a 90-97, then that's probably a leaking cam angle sensor o-ring.

--Ian

Hard to say.

Depending on the year of the car, it could be coming from the cam angle sensor ('90-'97 only), although the gasket is a possibility.

I had a very elusive external oil leak on my '92 years ago- oil was winding up in the strangest places, such as on the top of the valve cover around the spark plug holes. I replaced the cam sensor seal, the valve cover gasket seal, the rear main seal... In the end, it did turn out to be the head gasket. No idea how, and I didn't have either the block or the head resurfaced, I merely installed a new OEM gasket and the leak finally went away.

Cool Ian ill replace my cas seal and Joe I got a cometic HG ill probably get a FM one or oem

VVT head will give a different experience :D (for reference)

Well, yeah. Oil will come gushing out of the external pipe which normally delivers it to the VVT solenoid which lives on top of the valve cover.

Since the OP noted he was going to change his CAS O-ring, I assumed he doesn't have a VVT head. :D

After getting my 1999 BP4W head rebuilt with new valves, guides, seals and springs, it idled great for about 10 minutes then there was a clunk and the engine stopped!

Turns out the intake cam sheared the dowel pin and there was a gouge in the front cam journal.https://www.miataturbo.net/attachmen...ine=1462466319


It appeared not to get oil and seized the cam. So I polished the cam journal faces and blew air through the oil passage and air came out various places along the intake cam side so I though that I was good. So I started it up and idled for about 30 seconds. When I inspected the front cam journal there was no oil, and there was no oiil anywhere along the intake cam. The exhaust cam had oil.

According to the diagram that shows the oil galley, oil comes into the head on the intake side then goes around the head. I do not want to take the head off again. Has anyone seen something like this before?

I haven't experienced starvation on a head, but it would be an easy thing to have happen if the machine shop doesn't adequately clean out the passages.

In your picture, it looks like you do have oil present (red circle):
https://www.miataturbo.net/attachmen...1&d=1462468844

Clearly, you ran the front cam journal dry. I'll bet there's a blockage in that port. BTW, you should always do first starts with everything lathered in assembly lube. With a blocked passage, you would still have the same result -- but even with everything perfect, it takes a bit of time for the oil to circulate through a dry head due to the volume of the passages and the oil restrictor in the block. The assembly lube gives protection during this time period.

I personally think the machine shop owes you a head.

First, thank you for the feedback.

The discoloration you have circled is permanent, it was dry to the touch as were all the journals and cam lobes on the intake. There was visible oil on the exhaust lobes. After discussing with a local shop that does lots of Miatas, it was the head gasket blocking the passage. They knew what had happened right away. I am too old and tired to take the head off again so I am having them do it and use a Miata head gasket.

I did not check every single hole to make sure the head gasket was on correctly. I tried a few ways and the way that fit, so I went with it. I cannot believe they would design something like that you could put on wrong!. For instance, every connector in the engine is unique so you can't plug the wrong one in. The coil packs are the same, one way it runs and the other it doesn't.

Anyway, of to MSR Cresson this weekend and I will have all 4 cylinders, I only had 70 PSI compression on #1 before the head work.


Turns out I used aftermarket head gasket set Fel-Pro HS9717PT-3 Cylinder Header Gasket Set that blocked the oil galley!

Do not use Fel-Pro HS9717PT-3 Cylinder Header Gasket Set. I was told to buy Mazda parts but went the cheap way. It cost me 3 days of track time at Texas World Speedway and another $500 for a shop to install the Mazda Gasket.

Fel pro is ok, but you can definitely put it on upside-down. This blocks oil and killz stuff.

Ebay has 1.8 MLS head gaskets for around $26 shipped. They are identical to OEM Mazda head gaskets but a third of the price. I have used them on well over a dozen cars now and never had an issue with them.

Is there a feature that prevents the OEM gasket from being installed incorrectly?

No.

https://www.miataturbo.net/attachmen...ine=1463446453

This is an OEM head gasket, and you can see how it's possible to flip it over and block the oil port (bottom of picture, next to the center stud)

--Ian

That's what I thought. From his post he made it sound like the Fel-Pro design was unique in that it allowed this.

And he probably believes that to be true, based on the not entirely unreasonable assumption that a major automaker wouldn't design the OEM head gasket in such a way as to allow it to be easily installed improperly, thus destroying the engine. This assumption is incorrect, of course, but understandable.

This isn't the first time someone has made this mistake, and it won't be the last.