ThePOWERtoRULE

I've always liked the RX-7s. MY current ride is actually an XR-7... a 1970 Cougar XR-7... that the lady who I bought it from kept calling an RX-7... in fact, my insurance company INSISTED it was called a Cougar RX-7. But that's another story.

I went and looked at an RX-7 for sale locally. I know the guy selling it, but not very well.

I had some questions about it... the oil pressure... I searched and searched and finally found someone that had a 10 per 1000 RPM rule... which seems like it would starve the engine of oil, especially at lower RPMs. This one started up cold without a problem and idled above 1000 RPM for a second before dropping down just below 1000. The oil pressure sat right at about 30.

Another issue was at idle there was a slight miss that was not consistently timed. Plugs maybe? Cap, rotor? Or am I looking at a fuel related problem like a partially clogged injector or something?

The top had a few rips in all the wrong places, and the interior was apparently 15 years old, slightly neglected. But that stuff is pretty straightforward, and I've already done some research on the cost to fix that. The DOOR AJAR light seemed to be stuck on. The clock was dead.

My only other major concern was the transmission. Went into each gear fine. The shifter felt a little bit sloppy... do these have linkage shifters or are they direct into the transmission? It reminded me of the worn out cable linkage shifter on my '90 SHO. It didn't grind into any gear when I shifted it, but in lower RPMs in second gear it would sort of rattle and make this noise that sounded almost like a bad gear whine. Maybe throwout bearing, or a pilot bearing/bushing? I'm trying to tell myself the transmission isn't shot.

So yeah, I'm in pretty much new territory. I've done a pretty good amount of work on a variety of piston engines, mostly on Ford 5.0's, my Ford 351 Cleveland, My SHO 3.0 V6 (made by Yamaha, and a pain to work on), and a little bit of work on Chevy 350's. So someone mind helping me out a little on getting into the Rotary world?

tie pilot

I'll tell you what I know, in the order you asked, and leave the rest for more knowledgabel people to answer = )

oil pressure at 30 at idle is good. most people (including me) will tell you they range form 30 at idle to 60 at full acceleration.

the slight miss at idle, I can't help you figure out what causes it but almost EVERYBODY will report the same type of idle in their FC (including me). a stable idle just below 1000 with a slight miss is considered by many to be ideal.

If the clock is dead, check the A/C too and the power mirrrors. All three dead? check the 10A CIGAR fuse in the interior fuse box by your left foot.

Sloppy shifter could often be caused by worn out bushings. A new bushing set is $20-30 from www.mazdatrix.com and installation is a piece of cake.

good luck.

Snrub

iTrader: (1)

Welcome aboard. From the sound of what you've described the shifter issue can be fixed by replacing the shifter bushings. (easy, cheap) I believe it's a direct link shifter. The oil pressure should be a bit over 60psi when you're cruising along at a decent RPM or doing more than that.

Matt22

iTrader: (10)

i would get an series 4 or 5 gxl. they seem to be most ideal. because of the options they have. most importantly being a LSD> 30psi was that same in my 88 gxl. and that miss you speak of might jsut be the missfire with is oh som common and loved by us. Lates matt22

Jager

iTrader: (10)

Thought the GTU had the LSD? Correct me if I'm wrong of course.

ThePOWERtoRULE

I just realized I didn't give a specific year. It's a 1990.

Thanks for all of your responses... what about the transmission (I think) noise? That's a pretty major concern!

evileagle

iTrader: (1)

These cars don't have a cap & rotor, they use coil packs

So on the bright side you can rule those two things out!

ajsuper7

GTU's have open diffs, S5 GXL's have open diffs, Vert's have open diffs. Only the GTUS and Tii's had LSD for 89 - 91's.

boosted1205

iTrader: (9)

As long as th pressure doesn't drop too much. Take it for a spin and see what the gauge tells you. If it's sitting well below 60 at 3000 rpm, the o-ring or thermo pellet could be bad( easy fix).


A slight miss could be anything from bad plugs, wires, etc.



Interior parts are everywhere. People are always parting out their cars.
The logicon could be bad if lights are on or some are stuck on.
Is the clock, a/c and power mirrors working? If not to all, check the "cig" fuse at the drivers kick panel.


Take it for a spin and shift through the gears. If you hear a constant whine or have trouble going into gear maybe a pilot bearing. If it just grinds a bit on downshift or upshift
a fluid change may help to Redline MT-90 (good stuff).
The shifter does not have a cable linkage.

Their easy to work on when you get the hang of it. Change all the fluids and vacuum lines and it will treat you good.
Some people expect fluids and parts to last forever and expect the car to be trouble free. They forget these cars are 15+ years old. Most important on these rotary engines are oil changes. They inject oil into the combustion and the holes in the housing can get clogged if oil changes are neglected. Good luck

Jager

iTrader: (10)

Oh ok, thanks for clearing that up for me.

mr0pistons

I am surprised nobody corrected the mistake in the subject line...FC3C . It is actually FC3S.

gerbraldy

If you get that convertible, it would be a good idea to get a hatchback diff, perferably from a gxl or better. The vert's have the 3.9 , hatchbacks have 4.1, it's good for an extra second 0-60 if you swap em, plus the lsd.

Matt22

iTrader: (10)

the 86-88 gxls have the LSD and i thought the 89-91 also had the LSD but i could be mistaken. only the 88 GTU had a lsd, and they are a good car to get. as well as the 89+90 GTUs but i would agian get a GXL or a Turbo2.

gerbraldy

the only cars that didn't come with a lsd are gsl, and verts.

ThePOWERtoRULE

I'm going to try and get another look at the car either Saturday or Sunday. I'll be checking the AC, and asking the current owner some more aggressive questions about some of the noises it's making.

I got an idea at work today.... think maybe the transmission noise and feel could be a bad transmission mount?

I think I'm going to try and talk the guy down to $800, and buy it for up to $1000. He's currently asking $1200.

I think I'm going to have to get it regardless of what the transmission noise ends up being. It really does go into every gear smooth... with no grind. I'd be looking to just fix up alot of the little ****... broken switches, etc. It just seems like a hell of a deal, and seems to run descent. If worse comes to worse I'm sure I could sell it next spring without losing too much money.

Only other thing is the windshield is pretty badly cracked in a couple of different places. But I know I can probably get a pretty cheap windshield installed locally... for under $300 for sure.

Think of anything else I should check on my second visit?

eriksseven

iTrader: (6)

Check the compression with a slightly modified conventional tester. Search on how to do this. 100+ on all rotor faces should be decent #'s.

razorback

i think the fc3c is the convertible model. hence c instead of s (coupe)

ThePOWERtoRULE

This is the impression I was under. I'm going to see if he'll let me do a compression test on it then, I can do a search on that.

mr0pistons

Yea, forgot about that.

RX7_ZRO

FC3C is indeed what the vert model gets referred to as on a frequent bases. And personally, I say screw all the people telling you to go for this or that couple model. :P They're just trying to keep you from getting the fun version of the car.

ThePOWERtoRULE

Alright guys, went and looked at the FC3C again today.

All the interior lights mysteriously worked great this time. The DOOR AJAR light was not stuck on, and the clock was shining bright. But the factory stereo is apparently dead, he thinks it's not hooked up. He knows that guy who he initially sold it to (who he had to take it back from) put an aftermarket deck in there, and he thinks he didn't rewire the factory deck correctly.

The car starts up without smoking at all. The guy says he starts it up and lets it run every other day or everyday just to keep it loose. He says he lets it run or drives it for 15-20 minutes and shuts it off.

Today when he started it up we let it sit for awhile. One thing it did this time that it did not do last time was after it was sitting for awhile at idle, the car began to bog itself, and then recover. It would go lower and lower each time, but it didn't stall. I asked him not to save it to see if it would kill itself and once it stopped going lower and went about as low as it had the last time 3 times, I told him to give it gas.

The oil pressure is still up on my list of concerns. It sits about or jsut below 30 at idle, and goes up to around 60 while cruising. There was, however, no noise from the transmission this time.

It had new apex seals about a year and a month ago, done by the last owner personally.

Now, I'm going to spill the price (i don't think I have yet?)
He wants 1200 for it.

Think it's worth it? I'm really thinking it is at this point.

The idle issue reminds me of what my SHO was doing when the MAF started to go on it. Also, it STILL misses at idle... and while revving when the car is still (e.g. holding it at 2000). It's an inconsistent but minor miss. Someone ripped off the stock airbox assembly, and there's just an port on the air pump with no hose on it. Think this has something to do with the miss, or the idle fluctating? I cannot hear or feel it miss while I drive it, accelerating or decellerating.


Worth the investment?
What do you think these problems are?

Thanks.

JDUBrx7

Might wanna check to see if it has a cat on the exaust. If its gone that would explain the airpump thing. I dont run a cat currently, and my airpump hose is clamped pointing at the ground. I have a s4 though, you are looking at a s5. The s5's 5th adn 6th ports are controlled by the air pump i belive, so u might have a problem with your 5th adn 6th ports not openeing 4000K. The s4 5th and 6th ports are controlled by the backpressure of the exaust.

ThePOWERtoRULE

The factory cat was replaced by a Catco cat from summit. He has the factory cat. The unused tube on the airpump is the one on the very top of the pump that comes out and turns toward the passenger side of the car.

RotaryWeaponSE7EN

iTrader: (6)

Since I've had my fc, I've never been disappointed with it.

ThePOWERtoRULE

Make no mistake, I love the car, but what about things like the oil pressure???