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Hi guys, new to the forum, first miata (95, 1.8L, bought it for the ladyfriend so she can learn manual and enjoy a sportscar). We've had it for a little over a year and it has been great for her (and a blast for me as well).

Disclaimer: I grew up my entire life working with cars, so this is nothing new to me, just asking for new opinions.

I'm completely lost over the current situation with it though. About a week ago I'm 1100 miles away for work and I get a call from her that it's over hearing about an hour away from home. I had her crank the heat and pull over ASAP (downtown ATL traffic you can't just stop four lanes away from the curb). She gets it stopped after a minute or two of over heating and gets it towed home. I fly in the next day and crank it just to move it into my detached garage to fix whatever has gone wrong.

It runs great, but is billowing smoke. It's kinda hard to tell if its blue or white smoke but it certainly reeks of burnt oil. First thought: Head gasket, as I've heard these head gaskets go easily. Do a compression check, 160 psi across all cylinders. Cylinder 4 has oil (i think) on the plug.

Okay so that's seems odd, figured that would be an easy sanity check to diagnose the thing. I run a leakdown test and get 20% loss in all 4 cylinders. Still really odd as that is saying it's not the head gasket.

I did find a pinhole leak in the small hose on the back right side (passenger/intake) side of the motor (devil hose I think?) Which explains the loss of coolant. That's okay, but while the hell is it burning oil a lot more than it used to?

It used to burn a little oil here and there because I assumed it's a 23 year old 140k mile engine, and because the valve cover leaked like a SOB.

My next move is to just go ahead and pull the head but I feel wrong doing that because it runs so well and the compression and leakdown looked okay.

No signs of coolant in the oil yet, I haven't drained it, but the filler cap looks clean and the dipstick oil looks alright.

Sorry for the longwinded post, and I'm sure I missed some info, but was just really hoping someone could give a better idea of what's going on with anything that I might have missed.

Thanks for the help!
 

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I wouldn't diagnose a head gasket as ok only because the leakdown and compression tests are ok. Have you pulled the spark plugs yet to see if the engine is burning oil?
 

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Sounds like the valve stem seals. If the compression test was ok the valve seats are sealing well but a poor leak down test would point to poor sealing stem seals.
Look for smoke on deceleration to confirm seals are the culprit.
An easier job than a headgasket replacement.
If it pumps out clouds of grey-ish dark smoke on acceleration it is your piston rings losing their seal. No need to point out the increase in difficulty to rectify that issue.
If it produced good compression almost immediately after one or two compression strokes the rings should be ok.
Perhaps a good time to give it a good service and replace timing belts, seals, cam cover gaskets and the like if in a position to do so. Good luck with getting it sorted out mate.
 
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