Smoking 90 Miata

Oct 23, 2003 2 Replies

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David Smith 22 years ago

I found a 90 Miata with 118K miles. It runs great and is very tight. I spoke with the 2nd (last) owner. She took really good care of the car. She bought it with 32K miles on it in

95 and she has had lots of prev maintenance (timing belt, oil, clutch, etc) and there are records to back it up.

She did tell me it used oil and smoked when it was cold outside (winter in Kentucky). She said a new set of rings would fix it. She also told me that she liked to "drive" it so I assume she meant she liked to run it hard. This year has a true oil gauge so is it ok for the pressure to drop just a bit above zero when idling? The dash seemed to be loose in several areas and the plastic to the right of the gear shift was broken, is that expensive or hard to replace? The hazard light button seems to sink in when pressed also?

My main concern is the oil consumption and smoking. Im no gearhead so can I get some good responses about my above questions?

Pluses are that the car has a new soft top, hard top (faded) and it has the

3 piece boot cover.

The guy wants $3000 US for everyting. What do you guys and gals think?

Thanks

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Lanny Chambers 22 years ago

Perhaps it was the previous owner, but someone let it overheat, run too low on oil, and/or was using an inadequate air filter. 118k miles is probably 50-75k too early for a well-maintained Miata to be using oil.

Oil pressure at idle should be 15-25 psi when the engine is warm. Pressure at 5000 rpm should be 50-60 psi.

This car *might* be worth $2000 if it smokes. How much oil is it allegedly using?

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Hal 22 years ago

If needed, the good news is that a set of piston rings is probably less than $50. The bad news is that it could cost about $900-1500 to install them. Cheaper to buy a used engine and install it.

The smoking could be water vapor out of the exhaust on cold mornings (normal). It could also be oil coming from either rings (very expensive) or valve guides (less expensive). How much oil does it burn (or leak)? I would find 1 quart/1000 miles tolerable. Others will say that's too high.

NOT OK to drop near 0 psi when idling. However, the 91 miata has an oil pressure sensor read by an electrical circuit that is sensitive to dirty electrical contacts. Sometimes abnormally low oil pressure is a dirty connector. My miata did that to me so I cleaned the connector. In most cases, if wiggling it changes the oil pressure, then you know that was the cause. On the other hand, it really could be a mechanical problem with a real 0 psi. Then you don't want that car.

Since you're not a gearhead, hire one to inspect it.

David Smith wrote:

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