Hello all,

I have been working on one of my rx-7s, an 88 turbo 2, and will soon be putting in a newly rebuilt engine.

I got this car earlier in the year, it has 72,000 miles and is in awesome condition throut, everything is stock and original.

Everything is out of the engine bay, dissasembled and every part is cleaned to showroom condition, ready for the replacement engine block.
The rear rotor had low compression, and upon dissasembly, awhile back, when I finally got down to the rotor I was really surprised.

This engine had not been taken apart before. The previous owners verified,etc.

---- I found that an oil side seal had been cut in half and used in place of one of the apex seal springs. ------

There is no other conclusion that this was done at the factory, when the car was built.
The previous owners have told me the car usually had ran very well, in the past, and started ok,most of the time. Other times it had hard starts, and lower power at lower rpms, but at higher rpm's it ran great.

the wrong part for the apex seal spring probaly caused the apex seal to not seal properly, and that led to the apex seals breaking. The broken apex seal was the one with the homemade apex spring under it.

Has anyone ever heard of this happening before? Just wondering if so.

 

I've seen some strange things come from the factory, but that takes the cake. Did you buy the car from the original owner? To me it sounds as if the engine was apart before, and someone did a quick jimmy job. If it were from the factory, I doubt ver much it would have lasted 16 years. These low mileage cars always have me courious. FYI-I have a '89 TII I purchased new with 172,000 miles. I mean the car is mint. The CarFax report shows 8 miles and a title date of May '89. That's it. I could turn the speedometer back to 60,000 and noone would be the wiser, unless they checked with Mazda for history of warranty work.
Just my $.02

 

I've never heard of anything remotely like this, nor do I think it's a good possiblity. Have you ever been to an actual assembly line setup? The guys on the line have no equipement/supplies that aren't part of the piece they're working on, which means it would have been a lot more work for them, since the assembler would have a bin of a certain spring, and they would have to find the other seal, cut it down to exactly the right size, most likely heat it up and bend it. And I don't think that the side seal would take the pressure of holding up the apex seal. The seals aren't meant to flex like a spring, and their composition makes me think that there would be brittle failure long before 16 years..

I think you might be getting taken for a ride on this one...

 

the side side seals are naturally curved, it wasnt heated up and bent, it naturally formed a perfect spring,and it can still be flexed easily. I still have it. It looks like the same material, only the peice they substituted is wider. Actaully it looks and feels stronger than the other normal ones.

The piece i pulled out is a side seal, that holds the compression, so its built to last and flex/move. It lasted 16 years and still worked, only a corner of the apex was chipped.

Its not the wavy thin, hairlike piece that is a spring for the side seals.

The previous owners live next to me. Like I said, the engine hasnt been out.

Other engine internals look new. This car will definately be kept stock and not modified. Rx-7's this original and nice are a rarity.

 

I'll be tearing down my '88 TII engine aswell. wonder if I'll find anything a bit odd...

 

idk ive heard some crazy stories from the factory, my friends old rustang came with a hi lift kit and some other goodies under the hood.

 

No way man...the previous owner either doesn't know or is full of ****. Theres no way that was put in there at the factory.

-Joe

 

bs...


a side seal is not made of spring steel like the apex seal spring, if you were to try bending the seal at a 180 degree angle the spring would snap in half in 1 or 2 tries, an apex seal spring would take about 50 tries to finally break.

what drew you to this conclusion?

if there is in fact a side seal in its place then the motor had to have been apart before, it wouldn't have made it 70k miles, if you have smog in your state it would never have passed nor would it run very well.

 

Yeah not possible. I am an engineer at a factory facility. And only the right part is used for the job. If they run out of parts to complete the set-up the line is shut down. or more parts are brought out to complete it. You are either getting a line of **** or the previous owner doesn't know and got taken for a ride just like you. whether or not the piece would work or not is not the case.

How do you know that the motor has never been disassembled? If the motor is that clean, it would lead ME to think that it has been previously disassembled.

Good luck with that... hope it all works out

 

I was just about to say this. Side seals are very brittle. If you bend them, they will break.

The apex seal springs are quite a bit thicker then the side seal springs. And apex seal springs are thicker then side seals, but not as wide. You would have to cut a side seal width-wise in order to fit it in an apex seal groove.

 

I was going to say.

1) a side seal is probably 3mm or wider, no way it'll fit into a 2mm stock apex seal groove.

2) a side seal is very thin, and has a low breaking point when flexed. And even if they don't break, they distort so easily, they would apply next to no force on the apex seal. The apex springs are much stronger and will flex but not break.

Perhaps you have a ground-down 3mm apex spring that looks a little funny to you.

 

or it could be possible the motor had 3mm apex seals put in and some jackass installed a broken side seal thinking it was an apex seal spring.

 

But, 3mm seals use a single spring 90% of the time (unless aftermarket). There is NO WAY a side seal could hold up as a apex spring (especially for a more massive 3mm seal) for x number of years. Not a chance. It'd flatten out the first few rotations, and then the seal would be laying there limp, not making compression on 2 faces.

 

This...thread...is...useless...without...pics?


-Ted

 

Agreed.



anyone ever think it could just be a stock seal that had a manufacturing problem and was to thick?

More plasible then the original conclusion.

 

i never said it would hold up the apex seal, similar to the original post i made it would never have made it 70k miles with it in there..

 

Nope, I honestly don't. Have you ever put the seals in? We're talking a few thousands worth of clearance.. . The only way that would happen, is if it was 3mm apex seals, and that was ruled out a couple of posts up by Kevin and others.

Speaking of which - Kevin - get that computer all set up?

 

Yeah man, I finally got it all straight. I appreciate the help a lot.

 

Thanks for all your input, it has been interesting.

I have a friend with a telescopic camera lens and will take a pic of the piece that I found in place of the apex spring. It looks like a side seal, I cant prove it is one, although it looks like one.

The piece has a natural curve, gradual arc, matching the curve of the other apex springs. If I set it on the table, arc up, it will flex with pressure applied.

As far as the engine being taken apart. This post isnt about that question, although its a question im sure people will have. I appreciate their insight.

Mazda isnt perfect, and Im not knocking them for any mistakes. I have the highest regard for their products. They have their duds too, like anyone.

According to the previous owner, the car started well "most of the time" whether that was due to an apex is uncertain, especially with the turbo. There are tons of reasons why the car started hard for years.

The rear rotor had between 65 and 68 psi on the compression test, so I decided to pull the engine { no choice} , the front rotor was a happy 95.

In the end Ill have a better car, I havent decided to go with a mazda reman or one of the rotary specialty people. Ive replaced the turbo inlet duct, one end was a little hard, new injectors, fuel pressure reg, and thats about it.

Thanks all

 

Sweet You're welcome.

Mack123 - If you're not sure you want to tackle the reassembly, talk to the guy who posted right above your last one. Kevin (RotaryResurrection) knows what's going on

 

These engines are not built on an assembly line they are hand built by a tech, i have a video of them building Renn's

I guaranty you it is NOT a side seal as:

A: Side seals are made of sintered iron and will snap if bent much at all

B: a side seal is to wide to fit in the apex seal groove


It is far more likly that it is just a poorly finished spring that was cut to wide and the tech building the motor was to tired to care enough to use a differnt one.

The fact that the seal with the weird spring under it broke is probably just coicidence.


One a side note, on the motor thats in my car now, when i dissassembles it one rotor had the small apex seal not in its designated area, you could tell by the wear marks it was off to the side sharing the same land as the long apex seal spring,..damn lazy techs....

 

Sorry i ment spring. not seal.

 

I know, I was talking about the clearance of the Apex seal "slot" at the corners of the rotor... a side seal wouldn't fit down in there without filing/cutting/etc, and that would simply not be worth the work..

I thought you were goign to get us some pics?