m2cupcar

iTrader: (5)

I've picked up a new-to-me 90 to move my FE driveline over too. Until I have a garage built, I opted to just stick another 1.6 in it to replace the blown unit and give me a DD. So now that it's in and running, I'm getting horrendous smoke on startup. After it has been running at normal temp for awhile the smoke is gone.

The engine has sat for 4 yrs, so I expected the possibility of valve stem seals, but the fact the smoke goes away, makes me think this isn't seals. So I figured rings - sealing when they get up to temp.

I pulled the plugs and number 1 & 2 had trace oil on them after the engine had started and run for maybe 15 seconds. 3 & 4 were fine. Next I did a compression check and here's what I saw:
1 = 180psi
2 = 179psi
3 = 175psi
4 = 178psi

I thought that compression looked very good for a 92 1.6. The cylinder head is spotless, no oil staining and the piston stops don't have hardly any staining/carbon on them- you can see the metal.

I also pulled the pcv valve and that changed nothing.

Any suggestions on where to go from here? I considered checking the head torque - maybe I've got a gasket that leaks into the cylinder when it's cold and seals when hot. I had that with a coolant once. The only time I've had bad valve seals (another engine that sat forever) the engine made oil smoke all the time... or am I wrong and thinking it's NOT valve seals? Thoughts?

thx-rob

jayc72

iTrader: (14)

You'd still get good compression if your oil control rings were bad right? Once things warm up the rings could seal better and no more spyhunter smoke screen.

I'm not an expert, nor do I know very much

m2cupcar

iTrader: (5)

afaik - the oil control ring is about lubricating the skirt and cylinder wall vs. keeping the oil out of the combustion chamber.

Braineack

iTrader: (62)

isn't the #1 symptom of valve seals oil burning start-ups?

engine brake down a hill, then go WOT, I bet you seez smoke.

Prospero

Hell, if the motor has been sitting for a while... you just may need to drive it for a bit to let things "polish up" from sitting.

Cheers,
Prospero

jayc72

iTrader: (14)

Talking out of my *** after doing a 2 minute google, so be kind.

This sounds like your problem:

Smoking Tail Pipe - Mazda Scene Forums

Take that for what it is worth, but it makes sense to me.

Jay

m2cupcar

iTrader: (5)

Yes. I haven't taken it out yet for a drive, but will tomorrow. Just wanted to make sure there wasn't an easier answer. I did seals with the head on ten years ago with rope in the combustion chamber and it wasn't fun.

I was just told that oil is coming down from above the seals at shut off and pooling on the valve stems where it proceeds to leak into the cylinders as it sits.

Wasn't jumping on you Jay- and that's an interesting post. I'm hoping it's seals as the engine is visually pristine internally and the compression good.

I'll take it out for a drive tomorrow and see where the problem goes from there.

Oh yeah- the engine was sitting for four years, and by coincidence the same amount of time as the car.

jayc72

iTrader: (14)

Didn't think you were Rob.

Braineack

iTrader: (62)

This is why I had my mechanic helper mouse do mine last week. He used 100psi of compressed air, and used all the proper tools and he still didn't think it was that fun.

m2cupcar

iTrader: (5)

Somebody else just said to do the same thing. I hate doing the valves when the head is off the car. Oh- and I don't have a "head installed" valve compressor. I've got the typical type that seats on the valve face (and it's not mine, and it's somewhere in storage).

neogenesis2004

iTrader: (12)

I can send you mine rob, if you want to do the job.

m2cupcar

iTrader: (5)

Sweet - If I can't find one locally, I'll take you up on it.

I would much rather pay someone to do this, but otoh I've only got $500 in this car as it sits now and just can't justify spending any money on labor.

y8s

iTrader: (8)

compression numbers with oil in the cylinders are always great...

neogenesis2004

iTrader: (12)

ok corky!

m2cupcar

iTrader: (5)

I'll do another comp test after the smoking has stopped to see if they back up the first numbers.

m2cupcar

iTrader: (5)

Braineack

iTrader: (62)

Mr. Magnetic tool was utilized on my head.

m2cupcar

iTrader: (5)

That's the way I've always done it- magnetic stick, c clamp compressor and a SST made from a pvc pipe with an access port in it. Works fine for what it is. I dug around and found some good reviews on that valvemaster tool - and it'll work with the Miata head.

neogenesis2004

iTrader: (12)

I do this: Large socket, circular magnet inside, BFH, HIT!!!

Works everytime.

m2cupcar

iTrader: (5)

Took the car out today for the first drive. It put down a fairly heavy smoke screen during cold idle in the driveway, but once the heavy stuff cleared up I took off. As I drove around (easy on it) the smoke continued clearing up. So I headed on to the local four laner and cut loose. After just four runs to rev up to fourth gear the smoke was gone. And I couldn't get it come about under heavy vacuum (off throttle in 3rd at 6k) either. And the car felt so strong that I convinced myself to get the emissions done (instead of a hot [free of oil in the cylinder] compression check.) It passed easily (results below.)

I guess the real test will be what it does tomorrow from a cold start.