Disassembled the motor again. Since trans parts are on order. Well the reused inner water seals look good and the super glue is still holding the ends together.

I'm sold on the inner ones. Still reusing the outer stock water seals. Cut to fit, no super glue this time. max torque of 30 ft lbs

car is not a daily just a slow track car and never sees temps over 175f. Just under the limit of the super glue. :lol:

If the water temps are 175, then the metal temps are going to be a lot higher.

I haven't torn down my first fabricated-cord engine yet. I KNOW that it's seen 240F+ coolant temps. That's not why I pulled it out, though.

good quality superglue has a 280F operating temperature.

i'm still not sure why this has all transformed into this from the FEP encapsulated coolant seal thread though, which i've seen numerous problems with those seals on over the years. i've been using viton coolant seals for at least 3 years and the viton seals are always fine unless a seal wall broke. in fact every single soft seal i use on the short blocks now is viton.

and as a side note over the past year and a half i have ordered over 500 feet worth of Dupont viton, meaning there is over 50 engines out there somewhere with those seals. i'm due to order another few hundred feet, adding self sufficiency to my shop versus ordering from other rotary suppliers and paying the 10 middle men in between here and Japan.

the encapsulated FEP mcmaster carr/RA coolant seals still only used for some applications, since i have seen so many tears in them and premature failures in street driven cars. they're simpler for drag racing or low use motors because i don't have to fiddle with putting the seal sets together.

:popcorn: the thread grew and gave excellent, cheaper, better real world alternatives that do soo much better when used with less than perfect parts

i havent had any issue with the viton besides the one motor that lost a coolant wall while i was still finalising the correct dimensions

i find the square oem stuff more of a pain .. and the generic copies worse.. with no white side to show a twist .. always makes you worry till the pressure test,, while the viton i have total confidence in

if your using the sizes i listed all those years ago then you will find the glue join is only secondary,, as squish between the plates puts compressive tension on the butted ends and the length is calculated/ guestimated/ trialled to keep them together with more force than what is in the water pressure

R/E are you using 15.8 x 2.4 CS .. or using 17. something by 1.9 CS for the oil dowels ??

no issue with the 15.8 for me ( yet ) although this is on the inside lip of the dowel land unlike the stocky ( 17 something x 1.9 )

the dowels i use an irregular size that is smaller/fatter that i pull over the dowels to install. i haven't actually measured the dimensions to use a proper fitting dowel seal as these work and i had hundreds of them already.

Good thread. :)

the dowels are size 111 shore 75 viton, not the size i would sell with kits(because they can't be installed in the rotor housings but must be installed on the dowels) but i haven't had any problems with them.

Hi BDC, I went to your website and tried some of the links but they don't seem to work.

I started a spreadsheet of the different seals discussed in this thread but not 100% sure of accuracy since there has been so many different part #'s thrown around. Can someone post a list of the consensus on what o-rings to use for what?

This is what I have thus far:
Outer water seal: 9464K537
Inner water seal: ?
Inner oil control o-ring: 9464K125
Outer oil control o-ring: 9464K116
Tension bolt o-ring: 9464K116

All of these are McMaster Carr #'s

Anything I missed or have incorrect?

Thanks for your help

Huh. When I assemble an engine, I put the dowels in the rotor housings first, then lay the housing down on the engine.

I've only built maybe ten-twelve engines over the years, so I probably haven't perfected a production-minded assembly procedure. Heck, after the first one on a stand, I do engines over a 5 gallon bucket, 40 liter drum, or a wheel...

Are these those square inner viton I suggested?

It was the round ones.

Just received some square stuff and will give them a try next go around. Must say I'm happy with the round stuff, just like trying new things.

i chose the different size because it seals to the dowel with a tension fit since you have to pull the o-rings over the dowel to install them. you could do it the way you described as well if you put the dowels in the housings and then slipped the o-rings over them to hold the dowels to the housings.

problem is the standard mazda seals are marginally fitted to the groove, which can allow them to leak prematurely, as we've all seen with the 12A engines.

the OEM seals are easier for novice builders, because they will stay in the housings with a dab of hylomar or vaseline and be installed prior to final assembly.

I just ordered some of these.

Will report how they fit.
X-Ring 175 FPM 70 228,27 x 2,62 mm - arcus Shop


They are not cheap. around 16 euro + tax. but they are Viton and if they are re-useable they might be a good alternative in case one does not want to get creative with viton cord and superglue.

Got them in.. they feel alot to fat for stock grooves. I think 2.4mm round is the fattest one should go.

they will altough work great if they would be available in thinner sections than 2.62mm or if someone with corroded groover machines the groove to 1.8mm deep

The 12A dowels leak because the oil non-cooler makes the oil temps skyrocket, and the dowel O-rings lose all elasticity and crack. If the O-ring was leaking, it usually comes out in at least three pieces and trying to flex it results in more, smaller pieces ;)

Update: I will also confirm that the 94245k52 round seals are perfectly reusable for the outer coolant seal as well as the square viton #2542t21 cord for the inner coolant seals. I installed these back in Oct 2013. A year later, I was able to finally put some miles on my 20b. My engine now has 4k on it and saw a 2,200 mile round trip to sevenstock last year. Even the jell paste superglue is still holding them together. Also, as an experiment, I also installed a couple factory inner coolant seals and they are not re-usable in this same time period. The above vitons are perfectly reuseable. :) Unfortunately, I had to break my engine down this past weekend as I previously pulled the engine a month a go to fix various intake leaks, eletrical issues and to test fit a CTS-V T56 I bought late last year to see if it would fit with my engine moved back. Good news is the t56 will still fit and I was finally able to fix all my intake leaks and electrical issues. Bad news, in the process of all this, I didn't cover up my exposed pp's and something fell in the center rotor without my knowledge. Needless to say, I now have a missing apex seal and zero compression after running the engine for a few minuets while still on my jack stands. :( Oh well, I needed to open the engine anyways so I could install the new Cosmo intermediate plate I bought last year due to my 20b's numerious broken coolant seal walls. I'm also ditching the old factory 3 piece apex seals and have a new set of RA classics on the way as we speak.