HI yall! I have a 1991 miata with a 1994 Motor, Megasquirt Forged rods and pistons 9.0. Acl Race Bearings. BE Oil pump. Head has stiffer valve springs. Everything is brand new. Gt2560 turbo. Im having issues with water and oil mixing. The first time I though it was the head so I had another head redone and put on. Now its doing the same thing. I will be out driving and I noticed that my oil pressure was lower that usually. So I stopped and checked the oil. I added some oil and heading on to the house. About a mile before I made it the temp started creaping up on me. I finally pulled in the drive way and as so as I stopped it died. I turned the key and it would hardly turn over. I am completly lost and i just dont know what to do anymore.

 

Head gasket on upside-down?

 

Missing one of the Allen plugs in the head, from the rebuild?

 

Head gasket is right triple checked it and I was wondering about the last one. I need to pull the valve cover and check it.

 

pictures when you find it

 

Is there any other places for coolant and oil to mix

 

Cracked head
Warped head
Improperly torqued head
Failed head gasket (rare from 1994 onwards)
Cracked turbocharger center section
Cracked block (extremely rare in all years)
Cracked oil cooler (OEM from 1994 onwards)



You haven't mentioned (in this thread) finding oil in the coolant or milky froth in the oil, only that you've got smoke coming out of the tailpipe and seem to be overheating. I'm not clear on whether you added oil because it was low on the dipstick or just for the hell of it.


More details, man!

 

And my oil pressure was dropping. And I'm finding a mixture of both coolant and water and water in coolant. I couldn't tell if it was low on he dip stick I added a little just for safety. But now the motor isn't wanting to crank and I can't get it to start. I'm gonna train the oil and coolant tonight and replace with new. Gonna try bypassing the oil cooler and remove water lines from the turbo.

 

so you can waste another batch of oil and coolant and the time doing it?

I'm gonna be shocked if it's either of those. The last time we saw a cracked chra was....never....and the last time we saw a cracked oil cooler was, I'm gonna say never too.

I'm still thinking it's head or head gasket related, or even possibly those plugs ryan mentioned in the head, and don't keep cranking the engine because you're likely gonna seize it or spin a bearing or 2

 

After it done it the first time I swapped over to another head fresh out of the machine shop. New gasket and arp studs torqued to 60lb in 3 steps. The head was given the clear and we matched the head gasket up perfect. I'm running a felpro gasket. I will check the plugs first and go from there.

 

And the little tidbits just keep coming.

You're going to ruin that engine for sure if you don't settle down and think.

 

I realize you think the 2nd head can't be bad, but I've seen my friend install/remove a head 3 times, each time having it inspected and gone over by machine shop only to find on the 4th time a small crack around one of the valves which would open up when hot and dump coolant into cyl3

Just sayin. Machine shops make mistakes too

 

Have your machine shop magneflux/dye the head

 

The shop told me the head was good. But I'm not sure if they did all that to it. I just need to narrow this down till I can figure out what is wrong.

 

Mine was good too, then while I was polishing the valve area, I found a Crack just like 18 said. After it got warm from polishing, it opened up. Let it cool, couldn't find it. Check for those plugs though. Not sure how many there are.

 

That does make sense cause it was running great till it got warmed up. About 15 miles in is where I got my problems. But I have had the same result with 2 different heads. The first time I though I put the gasket on wrong. But it looked right.

 

should be two

 

Ok are they known to leak? If there there do they need any sort of sealant on them?

 

Will running lean blow ur head gasket?

 

They are not known to leak. But if removed or loosened, they will mix your fluids with teh quickness. And I doubt that's your problem, cause it would take seconds for that to happen.

Running lean can blow a whole lot of things, including the gasket.