White smoke from 1988 RX7
11-01-02, 10:31 PM
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White smoke from 1988 RX7
Looking for your guidance on following problem for my 1988 RX7 SE non-turbo with 225K miles:
Problem : After initial acceleration with a cold engine, a white puff of smoke comes from exhaust for 2-3 seconds and then ends. Does white smoke indicate coolant and engine oil/gas mixing due to worn rotary engine - weak seals/walls?
Dealer Response : Although Mazda dealer said smoke indicates carbon deposits, I thought black smoke indicated carbon. Recent compression check indicated rotary engine ok.
Please advise.
Problem : After initial acceleration with a cold engine, a white puff of smoke comes from exhaust for 2-3 seconds and then ends. Does white smoke indicate coolant and engine oil/gas mixing due to worn rotary engine - weak seals/walls?
Dealer Response : Although Mazda dealer said smoke indicates carbon deposits, I thought black smoke indicated carbon. Recent compression check indicated rotary engine ok.
Please advise.
11-02-02, 01:03 AM
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No, white = water, which is a natural byproduct of combustion. If the car is used for numerous short trips, water can collect in the exhaust and puff out when everything gets hot again.
In any case, given the mileage of the car, I think it's probably oil smoke - oil's blue tinge is often hard to detect. Especially given that he's said that the car runs cool and doesn't drink coolant, I wouldn't worry. Rotaries consume oil, both via the MOP and the oil control rings, and it's NOT A BAD THING.
Brandon
In any case, given the mileage of the car, I think it's probably oil smoke - oil's blue tinge is often hard to detect. Especially given that he's said that the car runs cool and doesn't drink coolant, I wouldn't worry. Rotaries consume oil, both via the MOP and the oil control rings, and it's NOT A BAD THING.
Brandon
09-18-03, 06:05 PM
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Why does my engine smoke when I first start it?
When you shut off most piston engines, horizontally opposed designs being the main exception, oil drains away from the combustion chambers. This is not the case with the rotary, which leaves small pools of oil in certain locations that can leak from the these areas into the combustion chambers when you turn the engine off. On a new engine this doesn't happen, but as engine parts wear, certain of the seals become less effective. So, this behavior is actually quite normal.
On engines that have this minor and normal internal leak, the result is a puff of smoke when the engine first starts after being off more than a few minutes. The color of oil smoke is bluish-white, but many don't notice the blue cast and simply call it white. Also, a cold engine runs rich, so this startup smoke will be darker from fuel richness than pure oil smoke from a fully warmed oil burner. Within a minute or two this clears up. It is nothing to worry about, unless the nosy neighbors have the pollution police staking out your house when you usually leave for work or school.
When these seals, actually special high temperature tolerant o-rings, cause the startup smoke, they also cause extra oil to reach the apex, corner & side seals when the engine is running. This may accelerate deterioration of the catalytic converters, but it also maximizes compression sealing for best power.
Just be sure never to let the oil level get below the add line. A low oil level can result in an elevated oil temperature, which can in turn reduce the life of the oil seal o-rings in the engine. The only way to replace those o-rings is a complete overhaul.
When you shut off most piston engines, horizontally opposed designs being the main exception, oil drains away from the combustion chambers. This is not the case with the rotary, which leaves small pools of oil in certain locations that can leak from the these areas into the combustion chambers when you turn the engine off. On a new engine this doesn't happen, but as engine parts wear, certain of the seals become less effective. So, this behavior is actually quite normal.
On engines that have this minor and normal internal leak, the result is a puff of smoke when the engine first starts after being off more than a few minutes. The color of oil smoke is bluish-white, but many don't notice the blue cast and simply call it white. Also, a cold engine runs rich, so this startup smoke will be darker from fuel richness than pure oil smoke from a fully warmed oil burner. Within a minute or two this clears up. It is nothing to worry about, unless the nosy neighbors have the pollution police staking out your house when you usually leave for work or school.
When these seals, actually special high temperature tolerant o-rings, cause the startup smoke, they also cause extra oil to reach the apex, corner & side seals when the engine is running. This may accelerate deterioration of the catalytic converters, but it also maximizes compression sealing for best power.
Just be sure never to let the oil level get below the add line. A low oil level can result in an elevated oil temperature, which can in turn reduce the life of the oil seal o-rings in the engine. The only way to replace those o-rings is a complete overhaul.
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