Only smokes after decelleration AND when it's hot outside.

This one has me scratching my head.

95 DX had nearly 300k on the odo, so I took the engine out, had it rebuilt by Perfect Engine here in LA, put it back in, broke it in, everything was cool. Two years ago, now.

Last summer it was hot as blazes here. Always is. (110+ in the Valley.) The engine started to really smoke under very specific circumstances:

If I run at a higher rpm, like around 4000 for a while then punch it, say, as if you're in 3rd on an onramp, you merge and steady your speed, then drop the accl, whoom, clouds of smoke.

But ONLY when it's hot. Only.

Right now it's like 60-70ish, nothing. Nada. No smoke. No consumption.

Even when it's hot, I can drive at a steady rpm whether it's slow or highway speeds, all rpm ranges, as long as it's steady- no smoke. AND even under heavy accelleration from a dead stop, no smoke.

But the second i back off the throttle, say if traffic slows down, then speeds back up and I accelerate, even if it's not a hard acceleration- smoke.

Head? Top-cylinder? I have another head ready to go on, but I'd like to hear some second opinions before I get all into it.

 

What color is the smoke?

Are you losing coolant or oil or running rich?

 

Oh right, definitely oil. No doubt about it.

I suspect the rings.

I really want it to be something else, but I'm definitely thinking rings.

 

Surely one of you guys has experience with engines, right?

 

What makes you confident that the smoke represents burning oil?

If the engine is indeed burning oil, then the source could be (1) bad piston rings, (2) a bad head gasket, or (3) bad valve seals.

The first two possibilities should be distinguished from the last possibility by doing a compression test of the cylinders and a leak down test. See Cylinder Compression link in my signature.

 

Basically experience, I guess. The smoke smells like oil, it's definitely bluish/gray, and I'm having to top off oil pretty frequently. It's definitely not coolant; that smell is very distinctive and thankfully not present, the coolant level is consistent and clean (also, oil shows no sign of contamination), and the cooling system maintains normal pressure. Fuel/air mixture is fine. ( no acrid odor, emissions are within normal levels, and the smoke is not at all black.)

I'll do the comp/leak-down today.

 

Ok yeah if its a blueish color then its oil. If the smoking only happens in hotter conditions then run a heavier oil in the summer. I would guess your rings are worn or stuck a bit. The rebuild on the motor may have poor, Hondas are built with tight specs on the piston to wall clearance. The smoke only coming upon deacceleration is the rings if it smokes while accelerating then its the valves.

 

From what I've read, when they're putting rings on during a rebuild, the gaps must be staggered away from each other, and no gap can be in line with the piston pin or at right angles to the pin. Provides the greatest sealing between the rings. You are making it harder for gasses to leak by the rings, creating a longer "leak pathway".