1995 Mazda Miata Oil Smoke and Bog

1995 MAZDA MIATA
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SKIPPYSMAZDA
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Hi, I have a 95 mazda miata with 334,000km's that seems to be having several problems starting with the oil consumption. It seems that the first start of the day it blows a heavy fog from the exaust. I did a wet and dry compression test and every thing seems fine about 5 psi lower than man. spec. but yet I am burning about a ltr. of oil a week, in 200km.....another issue that I think is part of it is when I excellerate in any gear it bogs out like it wants to stall, it doesn't stall but will bog, bog, then all of a sudden take off like a rocket! I have tried as follows. 1)change fule filter and have a flush. 2)oil change, spark plugs, wires, o2 sens. and catylitic.
it still smokes and still bogs but not as much when it's topped with oil. Does anyone think that I could have a broken piston? or rings? or a leaky head gasket? Please help! fresh out of ideas.
Oct 2, 2006 at 8:35 AM
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COSMO
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Seems like two problems here.

1. Oil consuption.....more than likely a valve guide or seal problem, or just plan worn out motor. Best be is to yank it and have it checked over by an machine shop that knows Mazda engines.

2. Sounds like you might want to check out the MAF sensor....these things are notorious for causing the problems you describe....but check out fine.

Cosmo

Mazda TEch
Oct 3, 2006 at 11:52 AM
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BUBBA_KOSKI
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ok number one its just plain stupid to yank an engine when your syptoms are just that, are you trying to make him bankrupt???? the mass air flow sensor will not have anything to do with that at all, if your engine light comes on then i'll think that, but anyways somethiing simple look at your crankcase cap, is it tight or defective, or something complicated like resurfacing the heads

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Oct 4, 2006 at 9:58 PM
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COSMO
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Hey Bubba gump.....

Notice the name....Cosmo, Mazda Tech. I have worked for Mazda for over 15 years I have seen lots of things go wrong on Mazda's and have had a VERY large gambit of problems with mazda's to solve over the years.

Ok here goes. The 1.6L and 1.8L motos are KNOWN for either wearing out valve seals or wearing out valve seats. The block itself is buillit proof but in some cases of high milage, I have seen cylingders that are egg shaped (on the mic).

THe PCV system on the Miata is faily simple and foolproof. AS long as the PCV is working properly (oh and the car won't run if its stuck open).

Now they problem that he is describing is "smoking when first started". This sounds to me like a great candidate for either worn out or dried up valve seals/guides.

I wouldn't however sudgest just doing a 'head' job at this point with that milage. I would personally have the complete motor looked at.

P.S. If a motor job bankrupts you....Maybe you should buy a bus pass and not a car buddy....

Cosmo

Mazda Tech
Oct 4, 2006 at 11:22 PM
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CATCH_15
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I agree. If it's only smoking during start up, it sounds like valve stem seals. Also, the mass air flow sensor could be your problem but it's hard to say without seeing it in person.
Oct 24, 2006 at 5:27 AM
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Suggested Repair

Startup oil smoke and high oil use most likely point to worn valve stem seals or guides, and at this mileage the engine should be inspected for worn seats or out-of-round cylinders rather than only a head job. Also test the MAF sensor for the acceleration bog, and confirm the PCV and oil filler cap are working.

Conversation Summary

A 1995 Mazda Miata with very high mileage burns about a liter of oil per 200 km and blows heavy exhaust smoke on the first start of the day, then bogs under acceleration before suddenly taking off. Compression is only slightly below spec, and fuel filter, oil, plugs, wires, oxygen sensor, and catalytic converter work did not fix it. A Mazda technician attributes the smoke to worn valve seals, guides, or a worn engine and recommends a full machine-shop inspection, while also suggesting the MAF for the bog. Another reply disagrees with pulling the engine immediately and mentions the filler cap or head work; a third agrees startup smoke fits valve stem seals and that the MAF is possible but not certain.

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