1980 RX-7 12a White Smoke at high RPMs
 

Hello Everyone,

So, I realize there's a lot of threads about these sorts of things and I've been googling for the past few hours, but I decided I'll ask and see if anyone has some suggestions.

I got an RX-7 FB pretty cheap last weekend.

I've been searching it for problems and this is the most concerning thing I've found. Let me tell you what happens:


1. I start the engine cold, and get no white smoke. It just sits there and idles like I'd expect.

2. If I start driving before it's warmed up much I'll get some trailing white smoke. It's not at Honda level yet, but it's definitely noticeable and probably irritating to drivers behind me.

3. If I rev up to 7k, I won't get smoke immediately unless I do one of two things. Either I start decelerating and I start getting a decent amount of smoke or I switch gears and keep flooring it at which point I get a little puff then it starts fading out again.

4. When it starts smoking, it tends to continue for a few seconds and then eventually fade out when I stop or decelerate enough.

5. On two different occasions, the car was idling and I pressed the gas (out of gear) and a huge cloud shot out the back. Like Honda huge.


From some research, the things I see are that it could be oil control getting worn and letting oil in at high RPMs when a strong vacuum is created.
Potentially it could be coolant, but it smells like straight fuel and I haven't noticed the coolant dropping.

Is there any surefire symptoms I can be looking for given what I've said?

If your not noticing the coolant dropping i doubt you have a bad coolant seal, especially if it sounds like raw fuel

You said you got the car cheap, the biggest question is why? Does it look like the carb has ever been rebuilt? Have you looked at the plugs to see what they tell you? Are you premixing or is the OMP still hooked up?

Hello Iduley!

Good questions. I'm gonna be honest with you, I'm not a car guy. I'm gonna be taking the car to my friends garage who is a car guy and change oil cooler fittings and clamps in the hopes of stemming a leak. If that doesn't work, I'll be buying new oil cooler lines :(

Well I'm there we'll check out the carbs and plugs as you suggest.

This OMP thing is concerning. I haven't removed it and I'm not premixing; but someone else looked in my engine before and said they didn't see the OMP and it's pretty common to remove.
I'll look for it specifically today. If it is removed, I take it I'll have to premix as per suggested here.

So, I'll look for the OMP, check the plugs and look for signs of wear/rebuild on the carbs. Anything else I should check at that time?

Again, I apologize as I'm not a car guy. I want to bring this RX-7 back to it's former glory and I'm willing and eager to learn what I need to know.

As a precaution, if you do not have the OMP start pre-mixing.

Fortunately I've only drove it

Apparently I can't edit, so:
Fortunately I've only drove it less than 30 miles as I didn't want to worsen any existing problems. I'll check if the OMP is in and if not I'll start premixing.

Could that cause white smoke if the OMP is not in and I'm not premixing?
If so, what would be smoking?

EDIT:
Ah, shoot. The problem is the unsupported "Less than" character. Sorry for the double post. If an admin could delete my first post, that'd be great.

If the OMP is not hooked up, than HOPEFULLY it has been prmixed

Have you put any gas in it yet? Or still the old owners gas? Its possible, depending on how much oil he used, or what kind, that is your high end smoking

I *have* added a significant amount of oil, what with trying to fix the oil leak with the cooler lines and a slow drip from the oil pan gasket.
The oil I've been running is 5w-30. I read somewhere that I might wanna look into a thicker oil if it's the control rings.

The previous owner was damn near empty on gas when I bought it. So the first thing I did was hit a gas station and fill up on regular (I had heard about premixing with my RX-8, but it never applied to me so I never thought about it.) I have not gassed up since then and I'm at about half a tank.

I'll have a solid answer on all of these questions by the end of the day.

20-50 is recommend by mazda with summer temps coming up, and 5-30 is thin for a rotary

Oops, I meant 10w-30.
I'll switch to 10w-40 or 10w-50 when I get my oil changed this weekend (waiting to replace oil pan gasket before changing oil).


Anyhow, updates.

I (mostly my friend though...) was able to fix the oil cooler line leak. My buddy took off the fitting and did a little machining and fit an O ring on and it appears to be sealed pretty well now.
I looked with diligence for the OMP and I did not find one. Where I expected to find one was a plate bolted on. If I was correct in where I looked, then it appears it was removed.
If this is the case, then I hope I didn't wreck my engine driving it around thus far.



Also, if this provides any clues:
Before driving to my friends house, I let the engine warm up to operating temperature (idle for like 10 minutes) and saw no smoke during this time. On my way there, I kept the RPM's below 4k and saw absolutely no smoke at all.

The OMP is on the front passenger side of the engine, right on the front cover, will jave hoses coming out've it and a rod going to the carb....its pretty hard to miss

Since it is MIA, goto walmart and get some TCW3, and something to mix it with (i use a opti-2 bottle myself) and get it in your tank, mix it rich this time, and top the tank off to mix it

Also, you didn't make mention about spark plugs

Where you say the OMP is matches up with where I was looking. I checked again this morning and I am definitely not seeing it.
I've been reading about premixing and I'll give that a go after work.


I didn't have a chance to check the spark plugs or the carbs for rebuild signs yesterday, but I'll be able to give that a go after work today.

Seeing if the carb has been rebuilt is easy, if its clean, its been rebuilt, if its filthy and looks like it has 30 year old grime on it, it hasn't been touched

When you goto look at the plugs, rent a compression tester and check your compression too, from what your telling us it sounds like its fine, but its good to know the health of your engine since its new to you

Okay, so I'm blind. I'm pretty sure OMP is there. I went and looked again.

https://cimg5.ibsrv.net/gimg/www.rx7...8a7f3101de.jpg

Sure looks it, is there a rod going up to your carb?

Yeah, there is a rod going to the carbs

On another note, I filled up on 10w-40 yesterday. I didn't drive it very hard (I think I got to 6k at one point) but never saw any smoke.

So, these appear to be the symptoms right now:
The car won't smoke at ALL (not on startup, not on idle, not when cold, not when warm) unless I rev it up to redline at which point it begins letting out smoke, which increases if I decelerate.
I've heard opposing stories. I've heard that more smoke on deceleration is a classic sign of engine failure for rotaries. I've also heard that if the control rings are going out, you should get smoke on startup and regular cruising (until the engine is hot), not just on red line.
I currently have 10w-40 in.
Really what I'm looking for at this point is dead giveaways that my engine is reaching the end of its life.


I was thinking about getting an oil change and filling up on 20w-50 along with some lucas stabilizer. If the smoking decreases significantly from that, it would seem to be a strong indicator that control rings are going (right?)
Is there anything simple that I can check or try to verify engine health?
I'll be checking compression as soon as I can get a meter that will work for this.

any compression tester will give you a good idea on engine health, but it won't tell you if your oil control rings are bad. But either way its a good idea so you KNOW YOUR ENGINE.

Being as its only smoking at high RPMs, i honestly wouldn't let it worry me. Just pay attention to the coolant and oil (as you always should on anything with an engine) and enjoy the car, it could get worse, it could get better, but spring/summer is just beginning, enjoy it, then worry about the smoking if it gets worse