Greetings! My name is Spencer, and I live in Ann Arbor, Michigan. I was 10 years old (in 1980) when I tagged along with my mom to watch her autocross her wide body FB at various SCCA events across the midwest. The 7 and the rotary made an impression on me, and last summer I went searching for an FD, and found this one down in Austin-

Here are the modifications:

Race ported, 3mm apex seals, ported throttle
body upper and lower intake, Apexi front mount
intercooler, modified 62-1 non-bb turbo mounted
on a t88 Greddy turbo kit, Apexi boost controller and
PWR FC commander, MSD DIS2 and 6A + 2 MSD race coils,
10 mil spark plug wire, twin Mocal oil coolers,
ceramic coated upper & lower intake,elbow,turbo,down
pipe and headers, Koyo hi perf radiator, 2 primary
racing fuel pumps with SRAD regulator, two 550 cc and
two 1600 cc fuel injectors, J&S knock sensor, ACT
extreme pressure plate with ACT 6 puck clutch, light
weight pulleys, custom 4" RE Amemiya exhaust, JIC coil overs
w/ height adjustable pods, Cusco strutbar,
SSR GT3 18" wheels wrapped in Yokohama AVS 9.5s,
Brembo cross drilled and slotted rotors with EBC pads,
Greddy gauges include boost, fuel pressure and EGT,
A/F gauge and oil temp, Kaaz diff.
By far, the most important mod was the tuning done here (see testimonials and customer cars) http://mzmperformance.com/

At 21lbs with A/Fs as low or less than 10:1 and cold plugs (115s), it registered 442 @ 6900 rpm on a new DynaPak. The engine is built to handle over 28lbs... the rev limiter is set at 7500... and the tuning can handle A/Fs into the upper 11s with plugs two ranges hotter. The previous owner had a T88 with a bottle on it.

Since buying the car, I've learned quite a bit about rotaries, but have a long way to go in attaining the degree of knowledge many of you posess. I know what I don't know, and have managed therefore not to blow it or anyone else to pieces. I now have a problem that I can't figure out, and hope you guru's might be interested in helping me out. I will greatly appreciate your efforts!

There is a mystery smoke coming out of the tail pipe. A more experience person would probably be able to tell from the smell of the smoke whether or not it's oil or coolant. I'm having a hard time telling because just the race gas and Royal Purple mix smells so unique. I do think the smell is anti-freeze, but just not positive. I really can't tell if the color of the smoke is white or blue, it seems inbetween.

The car starts to lightly smoke just after the rpms come down from start/warm-up. WHen driving, I can't see the smoke at anytime, except for between shifts. Between shifts, I see a puff of smoke. If I stay in gear and am on or off the throttle, I don't notice the smoke.

If I shut the car off for just a couple minutes, and turn it back on, it starts to smoke just after the idle comes back down.

If I shut the car off for 15 minutes, and turn it back on, HUGE puff of smoke, intantly, then back down to light smoking.

My leading plugs usually have a tan colored coating. They now appear carbon coated.

My fear is that this is an internal coolant seal leak. Any opinions would be greatly appreciated. Happy to pay a rotary doctor who makes house calls. Thanks!

 

here are some pics of my car

 

"There is a mystery smoke coming out of the tail pipe. A more experience person would probably be able to tell from the smell of the smoke whether or not it's oil or coolant. I'm having a hard time telling because just the race gas and Royal Purple mix smells so unique. I do think the smell is anti-freeze, but just not positive."


If it's got a sickly-sweet kind of smell, it's antifreeze and you've got a coolant leak. You should be able to distinguish an anti-freeze smell from an oil or fuel rich smell. Neeless to say a coolant seal leak is not a good thing, though your engine many not die right away.
Read up on the stickies and consult a rotary engine specialist would be my suggestion.

 

I looked first in the archives and the stickies, but didn't find answers. This thread is my attempt to consult with rotary specialists. Do you have a phone number of someone specific in mind I could speak with?

 

The first thing I always suspect with a turbo rotary that smokes is the turbo itself. No matter whether new, nearly new, rebuilt, etc. I've seen all sorts of turbos smoke out the tailpipe. What you're describing sounds like a turbo that is letting a little bit if oil out into the turbine section. What you could do, if your turbo is fairly accessible (a t88 should be) is to remove it from the car and compare the turbine inlet and outlet areas...if they're the same color/coating, then the turbo is not to blame. If the inlet is lighter and the outlet is darker (or wet), then you know that the turbine oil seal is leaking some oil.

Other things that can cause smoke are overly rich mix (which you suffer from per your afr's and plug conditions), problem with the OMP or oil injectors, improperly vented oil crankcase (for those with removed emissions/purge valve), or porting done improperly to allow oil to build up in the intake ports and eventually get burned off.

 

My plugs were tan coated and I made no fuel system adjustments. WHen the smoke started, the plugs went to a carbon color. Would a turbo problem leaking into the exhaust manifold color the plugs?

 

How could it? Do you actually have knowledge about the workings of this car, or are you just looking for general ideas?

And how, with a 10-11 afr could you EVER have had tan plugs? This doesnt sound right to me...

 

Fair question... the leading are usually dark from the richness. The tan I speak of are the trailing (I misspoke earlier and stated the leading were tan; I meant to say "trailing" - I will go back and edit that). Also, I'm running 112 leaded, so that contributes to the tan coloration.


Damn! It won't let me edit my first post. I meant to say that the TRAILING used to appear tan, but now appear carboned up. Even though I'm running rich, it was the trailing side with leaded race gas that appeared tan, but is now dark. My leading plugs have never appeared tan.

 

hey, were you the guy that i talked to last summer at Yesterday's Collection on Jackson Rd.? I reconize your car, and if it was you, you and your wife had just rolled in from texas and were crusing Jackson. I was driving a red Ford Ranger

 

Yes, old friend! I had just that day brought the car to Michigan. Sup?

 

So it's fair to say that this isn't really a streetcar then

IF you're getting plug contamination that wasnt there before it's quite possible that there is some reason that you just started burning oil. THe engine internals can burn oil several ways, as described above; omp/injectors, unvented crankcase building up pressure, turbo compressor pushing oil through the intake, improper port work, and of course the oil rings/irons sealing surfaces themselves.

 

[QUOTE=RotaryResurrection]How could it? Do you actually have knowledge about the workings of this car, or are you just looking for general ideas?

And how, with a 10-11 afr could you EVER have had tan plugs? This doesnt sound right to me...[/QUOTE

Personally, I don't think it could do it. I meant to suggest in my opening post that I thought the problem was coolant. I also meant to suggest that the smoke is related to a change in the appeance of the plugs.

 

not a whole lot, just been cruising the forum, workin for the summer in ann arbor, think i'm going to be living a block from the stadium in the fall. i live out in Dexter. if you need help with stuff, let me know, i'd be glad to help. i know a little, but have never worked on a 7, so i'm just as much of a newb, but two brains are better than one.

 

On my way to holiday bbq (Base Line Lake in Dexter) .... be back later. THanks RR for helping me sort this out. Talk with you soon!

 

before I waste anyone else's time, I'm going to pull all 4 plugs and report back here with my observations. I had only recently pulled one trailing side, and I suppose it could reveal some more clues if I have a look at the other trailing plug. I typically look at the plugs every 600 miles, and when the smoking problem started I looked just at the one trailing and stopped there when I saw the change.

 

Hey Spencer! Sorry to hear you have problems with the car We met at the Revolution, I went there with the guys from mirotaryclub, I'm Neit with the Black/Red FD

 

Hey, Neit! I've been laying kinda low since this smoking started. I had run quite a bit of smack about how reliable my car has been (and it has), then this happens. I've tried to troubleshoot it on the QT, but wasted 300 bucks on a new air/idle control valve that Sesi Mazda thought would fix the prob. So I decided to go public with request for help. Hope you are enjoying the beginning of summer, and I'm looking forward to getting together with the locals!!!!!!!!!!

btw, my best guest is that the smoke is from a coolant leak in the intake system. I don't yet believe it's deep internal. Keep finger's crossed! A MI Rotary club member has offered to come out later in the week.

 

There is no coolant in the intake system that could leak into the engine. None.

 

https://www.rx7club.com/1st-generation-specific-1979-1985-18/getting-worse-smoke-429428/

I saw this thread when I was doing my initial research and noted lots of discussion there about possible coolant leaks through the intake side of things. This is thread is about a 1st gen, but some folks have posted there that the 13b had similar tendencies. I don't know if the 13 b is the same as 13b-rew, which is what I have. Any thoughts after reviewing the linked thread?

 

The easiest way to rule out a coolant leak is to take it to a radiator shop and have them pressure test the system

 

I work on all generations and variations of engines as a builder adn installer. There are no o-rings on the 13brew, or any other coolant control device, that could let coolant into the intake path.

The only engines that have coolant o-rings on the intake are the 13bt 87-91, and a failure of those orings will not let coolant into the intake, just let coolant out onto the block/turbo. The guy in that thread just doesnt know what hes talking about (as evidenced by his grammar skills) which is often the case with people on this forum.

 

Assuming the smoke is from coolant, and that this coolant has discolored my plugs, would the only conclusion be that the engine has to be removed from the car to further diagnose?

One more question.... what does the air / idle control valve have to do with the flow of the coolant? A local Mazda mechanic had suggested that a bad valve or seal here would let coolant into the intake. I would not be surprised to find out he was completely wrong about this. Was he?

 

dealor mechanic? You may want to pass. Specialist in rotary is worth the time and money.
dealor's exchange, they dont repair to fix......most that is.

 

I dont understand why you seem so intent on this being an intake/coolant leak. First off, there's no such thing. I'll say it only once more...there is nowhere, on the REW intake system, that coolant can cross into the intake pathway. Secondly, you'd see coolant LOSS from the cooling system/buzzer if you were burning/losing coolant. Finally, coolant doesnt turn plugs dark, if anything it'd clean them up a bit. Carbon deposits come from burning fuel or oil or a combination of the 2.

 

Well, because I was previously given some bad information, I've had to sort it out with you, and it may appear I'm not comprehending. On the contrary this is just my way of sorting it all out. I took careful note of your previous statements that coolant can't get into the intake path. However, you didn't state that it couldn't get into the combustion cycle from some other path. I don't know the inner workings, but remember hearing something about seals of the water jacket possibly going bad. Is there a coolant seal between the rotor housing and end plates that could go bad and leak coolant into the combustion chamber? This is the scenario I had envisioned in my last post where I suggested that the engine might have to be pulled. Water jacket seal? Water jacket crack?

In your last post you stated some spark plug appearance considerations. Well, if that's the case, then I ought to be thinking this is fuel related. THis problem started happening when I filled her up with 112 leaded. I didn't think this could cause smoking, but maybe I'm about to learn that it can. I'm been running very rich, and when I went to 112, I didn't make any fuel pressure adjustments or system adjustments. I don't recall it ever smoking when I ran 110. I ran 110 leaded many many times. When I went to 112, it started smoking, but I just thought that's when the possible oil/coolant leak started.

Maybe the thing to do (seriously) is to drain the race gas and put pump gas in and see what happens. If it still smokes, drain anti-freeze and fill with water and see if I notice difference is odor of smoke. Any thoughts??? btw- I really appreciate the time you've invested helping me... thanks!!!