After around 6 months of owning my seven, I am finally confident enough to drive it further than walking distance from my house. In the previous 6 months, I had put under 20 miles on the car because it ran like crap and died after a mile. I finally got the problem figured out and took it for several lengthy drives this past weekend. My smile was a mile wide.

My problem is that the car runs great at lower RPM's, but at around 4,500, smoke starts billowing out the exhaust. I am guessing it has something to do with the secondaries, but don't know why exactly they would be causing all of the smoke. The car runs great over that RPM point, nice amount of power and revs smoothly, but the smoke is really bad. Plus, with my exhaust leak (my next project on the seven) and slight rust through the floor, the inside of the car fills up with smoke pretty quickly.

What do I need to do to remedy this smoke-screen problem?

 

What color smoke is it? I assume it's black, but is it white?

 

if its blue smoke, you are looking at bad oil control seals on the rotors

 

It is kind of grayish smoke.

 

does it stumble whet its at 4500? if it were running too rich(causing the grey or brown smoke) it would most likely bog at that engine speed?

 

The RPMs raise smoothly. Once I hit about 4k, it feels like I have more power which I am guessing is from the secondaries opening. It is really smooth and power is nice. I didn't even realize something was wrong until the inside started filling with exhaust gasses. When I let off the throttle and the RPMs go back down, it quits smoking.

Under 4k, runs great and very little smoke (probably just from premixing)
Over 4k, billows smoke like an old freight train

 

hmmmm..perhaps its running a little rich or someone has really messed with the mixture screw on the carb...

 

But it runs fine below 4k. That is what boggles me.

 

How long has it been since you changed the oil? What weight oil did you put in? How long has the car been sitting since it was driven, prior to the most recent issue?
I'm guessing the oil control seals are not doing a good job. Sometimes they will start to seal better after having been driven a while.

 

I changed the oil less than a month ago. Can't remember what weight I put in, but I am thinking 5W-30? Plus MMO in the fuel (OMP linkage is disconnected). Previous to this weekend driving, I drove it about a month ago after I changed the oil, but I don't think I ever took it over the smokey threshold of 4,500. I put some SeaFoam in this last tank of gas as well to try to clean everything out.

 

MMO and 5w-30 and Seafoam! sounds like a smoke screen waiting to happen. 5w sounds a little thin for the rotary seals. The MMO is probably doing its job and cleaning up all that carbon. I would guess that it will clear up in a few days. Just wait a few weeks before you add anything else to the engine.

 

So you think it is just cleaning the junk out of the engine/exhaust? Hopefully, I will be able to go home this weekend and play around with it. Like I said, this is the first time I trust it enough to drive it anywhere more than 3 miles from home. If I go home next weekend, I will try to get the exhaust leak fixed so my eyes don't sting when the fumes come into the car haha. That way, I can run the engine at 4,500+ to see if it works itself out. Thanks everyone for your help.

 

5W-30 may be too thin. Prolly just runs past the oil seals. Drive it a while, and if the smoke seems to start going away, just use a little heavier oil next time. 10W-30 minimum, but during the hottest time of the year, 20W-50 is all I will use.

 

One more thing, when it gets down a quart, and it should do this rather quickly, add the same brand, except make it a quart of 20W-50. It'll mix, and will help thicken up the oil. If this makes a noticable difference in the amount of smoke, you know what to do.

 

try running that whole tank of gas out then see if that changes things

 

Mine does almost the same thing-

oil control rings!!!!

that's your problem

because they're old, at high rpm they loose their effectiveness, so they let a whole bunch of oil into the combustion chamber. Same thing happens when you start the car, but because they haven't fully expanded yet.

anyway- that's what I gathered from when I asked the question:
https://www.rx7club.com/1st-generation-specific-1979-1985-18/smokes-after-5000-rpm-484826/

hope that clears things up

~b.k.

 

So if my oil control rings are going out (which sounds like what is going on), will that cause my car to guzzle oil? I ask this because I took a 100 mile drive this weekend. About 40 miles into the drive. The "Add Engine Oil" light came on. So I stopped at the nearest gas station and bought some heavier oil. I added a quart and it brought it back up to operating specs. However, after about another 30-40 miles of driving, the light came on again. My car was giving me trouble so I just added another quart and went on my way. Would bad oil control rings cause that drinking of oil?

 

Try using some Lucas oil stabilizer in place of your oil until you can get it fixed. This should reduce the flow past the oil control rings. It completely solved the issues I was having, which sound a lot like what you are seeing. I use 2 quarts of Lucas with every oil change for now, until I can rebuild. But like I said, for now I am having zero issues, so I don't need to hurry and do the rebuild. Good luck with it.

 

If you are losing that much oil, it would smoke conciderably. Have you checked for leaks, your problem may be twofold. Also up your oil weight to 20/40 or 20/50 next oil change.