'91 Honda civic burning oil smell (down hill driving)

I own an old Civic and I noticed in the past several months that I get a burned oil odor in the passenger compartment, but only when I drive downhill. I more recently notice that if I accellerate while driving down the hill, a cloud of smoke trails out behind me then clears when I let off the gas. This car has 294,000 miles on the odo. (I know) and I DO have to add a quart of oil every 2 weeks or so. It runs great though. Is my motor about ready to blow or what . . . ?

I think your piston rings are worn. Since you are keeping an eye on the oil, your engine may go a while longer. At 294,000 miles, it probably doesn’t make sense to rebuild or replace the engine. You might start looking for another vehicle.

Wow. That was quick. Thanks for replying so fast Triedaq. I was afraid it might be something like that. I’m hoping to break my personal record and get 300,000 from a vehicle. After that, I’ll start looking for something else to drive. I should mention that I drive 20 miles to work every day. Starts out running nice, and smooth, but by the time I get to work, she runs a little rough.

I agree with Triedaq. You might consider going to a heavier weight oil at the next oil change as that could slow the consumption down some.

The rough running could be due to spark plugs trying to oil foul. If you remove the plugs and they appear to have a black substance caked on them that could be the oil that the engine is burning.
If this is the case, you might install some new spark plugs and widen the gap on the plugs a little bit as that could make them less prone to oil fouling. (Add .005 or something like that.) Hope that helps.

I’m going to take a slightly different guess. Since it’s happpening only when you’re going downhill, I’d suspect the valve stem seals. When you’re using the engine to keep the speed down, the vacuum in the cylinders is very high. It’ll draw oil past worn valve stem seals. I suspect that when you then step on the gas that oil burns, making a cloud.

Whether it’s the rings or the seals, it’s normal engine wear. At 294,000 miles I’d suspect that both are pretty tired.

I pulled the plug wires to take out the plugs to check. One of the plug 'wells" was full of oil. I changed the plug wires, valve cover gasket and plug well seals about 6 months ago. After I reinstalled the plugs (this time) the car smoked really bad for agout 4 miles then cleared up. I figure this was mainly due to the oil in the plug well area falling into the combustion chamber when I took out the plug.

By the way I take it that it is expensive to fix the seal/ring thing?

The “seal/ring thing”, as you put it, can be, yes.

The rings are on the pistons, which requires a stripdown of the motor. The valve guide seal are in the head, which - depending on tools, know-how, and the build of the motor - might be able to be accomplished without even removing the head. I"m not a Honda guy, so I can’t say if it’s possible with this motor or not.

Ditto to what Chaissos said.

That oil in your wells, by the way, is unlikely to be getting drawn past your spark plug seats and threads and into the combustion chambers. That oil will be coming from leaky rings at the base of the spark plug tubes. These should be inexpensive to repair, but are unrelated to the smoke clouds. Your spark plug seats have to seal the pressures from the explosions during combustion. They’ll not pass oil.

Anybody here done valve stem rings on this vehicle?