911vet

I would ask this on the Miata forums, but they aren't half as useful as Rennlist. All the people I trust are here

I bought a 96 Miata, haven't got it on the track yet. It's smoking badly from the tailpipe. The theory is bad valve guides. 130K on the engine. Haven't done a leak down but the PVC pressure is good and the mechanic thinks the rings are ok. Smoke is primarily on acceleration.

It's smoking so much I'm guessing I'd be black flagged.

Mechanics are telling me to go after a used engine. But it seems I'd be risking getting another that needs a rebuild. Doesn't it make more sense to rebuild? Obviously, I don't know what all the engine will need... so exact cost isn't known. But it's definitely cheaper to get a used Miata engine than do a rebuild.

Thoughts?

Thanks.

rusnak

I don't know squat about Miatas. But sounds more like rings to me. The problem is you don't know the condition of the bottom end. Maybe a really sharp retired racer or tech could take the oilpan off and let you know how the bottom end bearings look? Can the valve covers be pulled to check valve guide wear/ valve play? Just wondering about this myself, not saying what you should do...

Ed Hughes

Smoking on acceleration is one of the classic symptoms of rings. I'd think the odds of getting a good engine would be pretty high if you can get one from a lower mile car that had been taken care of and then wrecked. I always thought these things had durable engines? A smoker has to be a rarity.

I've no clue what a used engine costs or what it costs to rebuild these. Has to be WAY cheaper than a 911.

race911

Many a Spec Miata uses a junkyard engine. And run (nearly) up front. Pick one up for what a set of intake valves cost on a 911 engine............ (On the flip side, the previous owner of my SM probably spent what a good 911 rebuild cost. But he was running, and won, a pro championship.)

KILRWAIL

You can replace the rings and con rod bearings, plus all gaskets and a valve or two in that engine for a couple of hundred bucks, while the engine is in the car. I'd do an oil pressure test first to see about the main bearings. Or you could buy an unknown quantity for $300-400. I did that to my MX-3 engine 3 years ago and it's strong as ever with 200,000 kms.

whalebird

probably rings. race911 pretty much has it figured out. I messed with a spec Miata for a brief period and they are easy to work on. If you decide to rebuild, pull the motor and make sure everything is in good shape. You know the WYIT list...clutch, seals, etc. You should be able to have a ton of fun in a Miata for low $$$. You can probably get a reman motor from any of the major engine builders with a warrenty for resonable money as well.
Keep us posted. Nothing beats Rennlist, but I would have assumed the Miata community would have a few brains that could help.