so, i finished tearing down my engine this afternoon.
the car had very little compression on the front rotor.
ended up being a stuck apex seal.
the engine was rebuilt 3 miles ago, and the previous owner never got it to run right (he did not rebuild it himself, he sent it off to get rebuilt by a "highly regarded builder" on this forum)
needless to say, the car sat in his garage for over a year, and i just bought it last month.
so, i compression checked it, 110 rear, 30 front.
pulled it out, and started tearing it down.
of course, as i suspected, one of the front apex seals was stuck. no biggie.
what REALLY got me, was the fact that NOT ONE OF THE CORNER SEALS HAD AN INSERT IN IT!!!!
now, these are not solid seals. they are the stock style seals that require the little rubber inserts, but they were not there. not one. all twelve were missing.
now, im new to the FD section, but ive never seen, nor heard of this on an FC. is it something you FD guys do, or did this "highly regarded builder" forget something?

 

my engine did not have the inserts in them either when i tore it down, almost every single corner seal was shattered, definatety use the inserts

 

wow dude.. have you contacted the builder? Hopefully he has enough integrity to stand by his work, whatever state it may be in.

 

Strange. That is definitely not something we "do" here. That is a mistake for sure, as there is no logical reason to leave them out. Other than to have the engine prematurely fail that is.

 

Sabotage!


Sorry, I had to...

 

I think a "mistake" would be if the plugs were forgotten in one or even two corner seals. Seems like it had to be intentional when they were left out of all twelve.

 

perhaps a "friday error"

thats where you have 9 things to do and you forget to grab those 12 pieces and put them in, and once its together... you say "**** it... its friday, i'll fix the mistake on monday" then never do.

Its times like these that I realize why I am single now.

 

yeah, the thing is, when you put the corner seals in, youd have to see that they were missing the insers. so i think it may have been done intentionally. the thing i can figure out is, why?
didnt have any new ones left, and he needed to get the engine out asap?
didnt feel that they were necessary? (if so, why?)

 

i think the most important part for this community and for yourself is to disclose the details about how the builder is taking care of this problem for you.

and then for the community: Which builder is this?

 

well, here is the thing.
the builder owes me nothing.
i bought the car, knowing that the engine had low compression, and was full well aware of the potential problems that i could face with the "rebuild"
the previous owner claimed that the engine was rebuilt by "Blank Blank"
so, when i got the engine out, i verified it indeed was VERY freshly rebuilt (all the gaskets came right out, hadnt even formed to the engine yet, they were so new)
so, the engine does only have like 3 miles on the rebuild.

for the community, i would like to say who the builder was, but i cannot because this is word of mouth from the previous owner. personally, i respect the unsaid builder and his or her abbilities. they are very well respected on this forum, and if by chance the previous owner did not get the engine from him, or there was some mix up, or SOMETHING (who knows) i would prefer to not ruin his rep.

 

well, that is a respectable stand on this matter.

So are you going to get some inserts and put her back together? :P

sounds like you came across a great deal if that is all your problem is.

 

I didn't have any of the rubber plugs either when I tore my motor down. I remember checking into this when I found this, and I remember finding a few saying that it is okay to leave them out. Supposedly they are for idle quality and gas mileage I think? I don't see any reason to leave them out though, they are super cheap and doesn't take anymore work to put them in.

 

https://www.rx7club.com/showthread.p...ner+seal+plugs

I really can't say anything about the pros and cons of not using them, but I guess some just leave them out.

 

thank you for that.
and, yeah, im going to get a few more things, maybe port it, and "throw" it back together
yeah, heck of a deal!


thanks for the link.
and, thats kind of what i thought (what aaron cake said) was for the prevention of chatter.


im not sure if im going to get the inserts, or just order solid corner seals.

 

it is common not to use the plastic inserts in the corner seals

 

Yeah sure i think i got this now. I mean who wants idle quality and gas mileage. That was probably done for a racing motor. You know weight reduction. It'll rev faster that way. jk...lol

 

We have seen this alot, the engines always come from the same builder. Customers get tired of their poorly running budget rebuild and send them to us to be gone through correctly.

 

yeah, im assuming you are pretty well aware of who i am reffering to then.
its always a shame to see something like this, though.
especially for being "quality work"

 

Spill the beans already... Who's the ALLEGED... engine builder?

 

I think it would be a potentially libelous thing to do, to point out an engine builder that MAY have done this, without any proof. For all anyone knows, the builder could have done it correctly and the owner taken it all apart for some reason or another.
There isn't a good way to 'tamper seal' these engines, nor it is hardly ever done.

I've rebuilt a lot of piston engines in my life and can't imagine ever say...not putting in piston rings or main bearings....lol!

 

You guys are blowing this rubber corner seal plug thing way out of proportion. Yes they do help some with compression but not to the point that you will loose 70psi compression. When was the last time someone on here did a compression check on a 12a or 13b 1st gen Rx7? FYI the 1st gen rx7's didn't even have these plugs and these engines still made over 100psi compression and easily lasted over 200,000 miles. Those plugs are something Mazda added when the 2nd gen Rx7's came out to help improve compression a little bit more. If you only had 30psi, you need to check the condition of the apex seal springs and the rotor groove itself to make sure the seals isn't catching or binding. Also make sure your corner seal to side seal clearance is between .002-.006. A lot of people on here forget how important this clearance really is. I've personally seen compression drop 45psi simply due to improper side seal to corner seal clearance.

 

You are only partially correct here. 12a's didnt have rubber plugs, true. However they didnt have corner seals that were designed and machined to have rubber plugs. They were solid units. Common now. Mazda put those things in there for a reason. If you think that you are a better engineer than they guys that work for the factory, you might want to write them a letter about getting a job. Sure they made some sacrifices when building this car. But over the years, with the parts that they phased out, internally these engines are pretty sound. Just saying.

--Hank

 

So you think they were all solid units and I'm the one that's partially correct? LOL!!Based on what actual experience of yours? How many actual 12a engines have you pulled apart? If you say none, you may was well not reply back to this thread as all your doing is spreading misinformation. I currently have 2 12a's pulled apart right now (one from my 81 and one from my 84 Rx7) that have corner seals that are not solid pieces and are designed exactly the same as the corner seals in the 2mm based 13b that were found in the 2nd gen Rx7 and up. The only difference with my 12A corners is that they are designed for 3mm apex seals as that was the size of the 12a and 13b GSL-SE apex seals. Next time educate yourself before you call someone out.



I already stated as to why they did it! Did you not read my explanation?

?????? Based on my explanation, what point are you trying to make? I have over 17yrs of rotary related/ownership/rebuilding experience. What do you have? Bottom line it doesn't take a rocket scientist to read a compression gauge to know for a fact that there isn't much difference between the compression of an engine with plugs vs an engine that doesn't have them at all.

Lastly, since you challenged my knowledge of this subject, let me ask you something. Why did Mazda engineer the 3 piece apex seal just to turn around and revert back to the original 2 piece design from back in the 1st gen days?

 

I agree mostly with T-von on this. However I'm sorry T-von the rotaries after 1976 had the rubber inserts, including the 12a. Many times old age alone can deteriorate the rubber inserts to the point they are gone. I know on alot of my personal engines I leave the rubber inserts out due to the port shape not being able to reliably hold them in, and in bridge port engines should not use them either. The downside is BOTTOM end torque, aka below 1800rpms. Static compression will be roughly 5-8psi lower, dynamic compression after 1500rpms is virtually the same.

 

Don't apologise as I know I'm not perfect. You actually educated me on the subject. I've heard of the discintegrating, I just never thought they would discintegrate to the point that they would completely disappear. That's why I thought they wern't available on the 1st gens. My 84 12a only had 144k when I opened it up. No plugs! Yet my 94 Fd with 108k original miles had all the plugs. 36k isn't that much difference but I guess it's more of an age/material thing? Anyways, thx for adding to the thread and thx for proving my point about the compression difference.