jbherri2

iTrader: (1)

...and now I have "Smokin' in the Boy's Room" stuck in my head.

Anyhoo - on to the question. I have a 1985 12a in S trim, 75,xxx miles, only modification is the removal of the cold start assist system. I've noticed what I thought was a burning rubber smell for sometime now. I've looked around and can't find any sort of rubber-on-hot-surfaces issue going on. And, the more that I think about it, the more I think I have a "very hot metal" smell going on. Not really sure how to describe it.

So yesterday, after a 5 mile 70ish mph drive down the interstate, I parked and noticed smoke coming from under the hood. I pop the hood and I see smoke coming from the "Snorkel" part of the air intake. Nothing dramatic, but smoke nonetheless. Is this normal? Is it from the burning of oil as it is injected into the carb? I haven't noticed any power loss, although I'm convinced my oil pressure isn't as high as it once was (judging by the factory gauge - which I realize is probably a whole 'nother discussion).

Trouble brewing? Or, something less?
thanks!

t_g_farrell

iTrader: (1)

That snorkel a has hose that goes down to the exhaust manifold for getting hot air during cold
starts. Not sure what kind of smoke you are seeing but if something is leaking on the exhaust
manifold and burning off this might be your smoke source. Sounds like you still have the stock
manifold and probably the shielding around it. I would check to make sure you don't have a
coolant or oil leak above the manifold someplace.

Common coolant leak is at the intake manifold. Common oil leak would be around the dowel
pins but I think those are on the other side but there be one the intake side as well.

Cookboy

iTrader: (10)

Or Metering oil pump hoses.

midnight mechanic

or busted front seal....if so you will see a little oil pool on top of the engine. mine ran like that for 6 years, only thing is it could be a fire hazard if too much oil residue collects on the heat shields. since you are a conscientious owner, you'd clean the heat shields annually.

oil stop leak helps.....and aluminum based radiator stop leak could help it is a coolant leak. the cheaper stuff (****) will clog your radiator.

midnight mechanic

or busted front seal....if so you will see a little oil pool on top of the engine. mine ran like that for 6 years, only thing is it could be a fire hazard if too much oil residue collects on the heat shields. since you are a conscientious owner, you'd clean the heat shields annually.

oil stop leak helps.....and aluminum based radiator stop leak could help it is a coolant leak. the cheaper stuff (****) will clog your radiator.

Nicholas P.

iTrader: (1)

make sure your not running lean too.

ray green

iTrader: (14)

As I recall, you recently replaced your OMP. I'm not sure what the connection might be, but the oil smell showing up soon after you did the OMP work might be more than coincidence.

Have you checked the OMP and it's lines for:

1. Leaks?
2. Proper oil delivery rate, according to the procedure and specs in the FSM (might be over squirting)?
3. Actual oil delivery into the carb barrels as indicated by evidence of oil weeping from the delivery holes (if nothing, holes could be blocked).

Banzai

iTrader: (13)

I've never had an FB so I don't know for sure, but do they still use the heat shield around the exaust mainfold? I had an SA that would smoke through the intake snorkle and traced it to the heat shield. The inside of the shield is lined with an abestos material and swandwitched between the outer skin and an perforated inner skin. The inner, perforated material had rusted away in places enabling the abestes layer to delaminate and poke through. It would smolder against the exaust manifold and even start to burn, creating an almost electrical burning type of smell and smoke that came up through the flexable hose and out the intake snorkle.

rotornoob

iTrader: (2)

Yes the fb does come with a heat shield around the exhaust manifold.

jbherri2

iTrader: (1)

The OMP seems happy - I can even see the oil as it travels up the lines after I crank it; if the car has been sitting for a while. There is very, very minimal oil around it, but more along the lines of "damp" than any apparent leakage. If that makes sense? You are correct, I did replace the OMP not all that long ago.

As to the possibility of a front seal, I do have a puddle that forms on top of the engine, but this is most certainly coolant. It's watery and has some grease mixed in, but I'm fairly certain I have a leak around the exhaust manifold gasket. I think....

ray green

iTrader: (14)

Could it be the intake manifold gasket and O rings, leaking coolant on top of the engine and down onto the exhaust manifold?

If you have a puddle of coolant on top, it's got to be coming from somewhere.

And baked coolant can make smoke, especially when mixed with a bit of oil and spilled on a hot exhaust manifold.

Cookboy

iTrader: (10)

Ray, I concur. Intake gasket/orings. Relatively easy.

jbherri2

iTrader: (1)

Okay - coming back to this. Like most people, I've been busy w/ Christmas, Family, and frankly it's c.o.l.d. =)

Anyway, I think I do indeed have an intake gasket / o-ring issue. I have the replacement intake gasket and the replacement o-rings. I've searched the forums, but I'm mostly finding "I removed my rat's nest" types of posts. How do I get the intake off so I can replace the o-rings and gasket? I'm pretty much all original here, so lots of vacuum hoses and such. I've taken the airbox off before, and I've removed the air pump before (when I was replacing the OMP so that I'd have room to work) but that's about as far as I've gotten in the "taking stuff and putting it back on" department. Any pointers?

Thanks!

ray green

iTrader: (14)

Well JB, this is definitely a learning opportunity, time to roll up your sleeves, get out the FSM and go to work. Believe me, it will transform the way you look at life.

So you need to remove all those tubey things and remember where they go. That's Step 1. Do it once, commit to memory and now you're a 12A Regular.

Then you need to get the carb off without removing the rat's nest. This is tricky, you'll need a special homemade bent 12 mm wrench to get at that rear driver's side 12 mm nut and you need to get real familiar with the other three nuts. But once that's done, you're a 12A Master. Nikki's are your friend, on and off in 20 minutes.

After you get the carb off, it's all gravy and Nirvana, just dig in and extract that intake manifold. Make sure you have the correct nuts and bolts removed before you use a pry to break the manifold loose from the engine block. A common rookie error is to still have a bolt in place somewhere, which means the manifold will break before it let's loose (ask me how I know; I have a spare manifold you can have if needed).

By the time you get everything apart, everything will be perfectly clear and you can put it back together with a great deal of satisfaction. Leak fixed, brain filled with valuable information.

Go for it!

rwatson5651

iTrader: (5)

Ray, you really make an excellant case for getting out there and getting it done!!!

Hint, Hint......

ray green

iTrader: (14)

Yeah I know Robert, charity begins at home, I really should be more kind to my own RX-7, roll up my own sleeves and get my butt out there!

jbherri2

iTrader: (1)

Thanks, I follow what you're saying. Can you provide a little insight into:

" you'll need a special homemade bent 12 mm wrench to get at that rear driver's side 12 mm nut.."

ray green

iTrader: (14)

Hey JB, you need the bent 12 mm wrench to get down under stuff and snag that rear left (driver side) 12 mm nut that's holding down the Nikki. This one is the hardest one to get. There's not enough room with the rat's in place to use a straight wrench.

So take one of your spare 12 mm combo box/open end wrenches, put it in a vise about half way up and wack it with a hammer until you have a 30-40 degree bend in it. Now you can put the box end down on that 12 mm nut and get it loose. Then spin the nut off with your fingers (helps to have small fingers).

Also, for the rear right 12 mm nut, do yourself a favor and take that little dashpot that's held down with two 10 mm bolts off first, makes it a lot easier to access the carb nut.

rotornoob

iTrader: (2)

Ive always heated the wrench before whacking it with a hammer, but definately easiest to do this job with a bent wrench. I have a few different sizes made up for different carb applications. My bent wrenches are craftsman, but thats because i couldnt justify the drive to harbor freight for a cheap wrench. All my other wrwnches are snap on so bending thwm is out od the question.

Just make sure to measure how much wrench will fit in there before you make your bend.

justinfox

iTrader: (3)

put a little bit of silicone around the edge of the o-ring and make sure the port is dry before sticking it in there then don't run the car for a while so the silicone can dry.

Cookboy

iTrader: (10)

What's the big downside of removing the manifold with the carb attached? I haven't done it, but in this case it seems more expeditious.

Anger

iTrader: (1)

Wish I had this info before rebuilding my Nikki.
Have a bunch of funky wrenches in my box from that project.

jbherri2

iTrader: (1)

Okay. I have three of the four 12mm nuts off. My buddy is working on bending a wrench for me (I didn't have a torch - might have to remedy that!).

'another question - will I need to replace the carb base gasket?

ray green

iTrader: (14)

Not bad for a first time removing the carb JB, it only took you a month to get those first 3 nuts off! It will go much faster next time.

(just kidding, now I'm going to get a citation for harassing the newbies).

Here's a tip. I'm assuming you still need to get that rear left (driver's side) nut off to remove the carb. Always start with that one first, with the other three still tight and holding the carb flush to the manifold, this will make loosening and removing that rear left one (the hard one) a lot easier. After you get the left rear one off the same goes for the others as well, just break them lose a little bit until they're all loose and can be removed with a little finger spin.

Also, if you have access to a bench vice, you don't really need a torch to heat the wrench before bending. Just put the 12 mm wrench in the vice about half way up the shank and wack away with a hammer. Unless it's a wrench you spent way too much money for, like one of those Snap-On units, it should bend after a few wacks.

And no, do not replace the carb base gasket, there is not supposed to be one between the carb and the manifold. That plastic spacer that sits between the carb and manifold serves this purpose, if you add the gasket that comes with the carb rebuild kit it can screw things up (so I've been told).

Are you going to have that beauty ready for DGRR this spring?

jbherri2

iTrader: (1)

Ray, thanks! I did manage to do all three in one evening, instead of spreading them across one month!
DGRR is on my radar, yes. As for the carb, this exercise is an effort to remove the intake manifold and replace the leaking intake gasket. I had not planned to rebuild the carb, as it seems like it's okay. <slightly worried> should I have invested in a carb rebuild kit? My intention was to remove the carb, remove the intake manifold and replace said manifold gasket and replace the carb.

Oh, this leads me to more stuff - I did manage to get a 1984 Factory service manual off of FleaBay. My car is a 1985, but I'm thinking it's pretty much the same thing. So, the arrival of the manual may answer more questions for me, but in the meantime - do I just put the intake nuts back on, or is this something that should be torqued to specs?

As always - thanks!