shinka/10ae

As I was putting hylomar on the inner water seal for my rear rotor, I felt the seam give and ended up tearing the seal about halfway. I didn't want to risk my rebuild so I decided to stop until I could get a new seal ordered. However, since I had already completed the rebuild through installation of the center iron I didn't know what to do about the rtv between the front iron, front rotor housing, and center iron. I ended up installing the rear rotor housing and rear iron without the rotor so that I could tighten the tension bolts so that the rtv could set up properly.

My question is whether or not I now need to replace ALL my water seals or just the inner seal that I broke. My guy feeling is to just order a new set and be safe, but if it really isn't an issue I would rather avoid having to tear the entire engine back apart and starting over. Thanks for any help that you all can provide.

rxtasy3

iTrader: (2)

those seals should be replaced with new when doing a rebuild. old seals have alread been compressed and probably wont seal again if reused.

shinka/10ae

thanks for your help. I should have been more clear in my post that I was using new seals to begin with. I tore one of the new inner seals from the kit I got from racing beat. My question is whether or not the new seals that have already been compressed also need to be replaced along with the torn seal. I didn’t know if the fact that they are brand new means that I can compress them again.

fendamonky

iTrader: (6)

Definitely use new OEM seals for any rebuild. Also, I would not be adding hylomar in there.. totally unnecessary. If you need to keep them in place then I'd opt for a dab of petroleum jelly.

I want to say that hylomar was only really recommended for the early engines to help smooth out mating surface irregularities.

shinka/10ae

Thanks for your help. I did use new OEM water seals for my rebuild. However, since I tore one of the inner seals accidentally, I was just trying to determine if I could open the engine back up and replace just the one seal (that I tore) or if I needed to replace all 8 seals again.

This also leads me to another question. Are the 4 new OEM orings for the dowel pins ok to reuse or do I need to order a new set as well? Considering the engine hasn't been run yet I am thinking they are ok. However I still wanted to check with the knowledgeable folks on here.

fendamonky

iTrader: (6)

I don't consider myself a "professional" by any means. For my own motor, I replaced the water seals when I opened up a motor I built that was never run. It's cheap insurance imo, especially if the seals have swollen and/or been compromised at all.

I'd inspect them, if they're flattened or deformed at all then I'd swap them. Again, better to be safe than sorry. It's MUCH cheaper to replace them initially, than to find a leak and need to pull the motor and replace them after the fact.

shinka/10ae

Thanks again for your input. I ended up doing exactly what you described and bought a whole new set of both the water seals and dowel pin orings. At this point its not worth going cheap when I have put so much money into this rebuild already (lapping/hardening, rotor housing resurfacing, rebuild kit, new rotor, etc).

fendamonky

iTrader: (6)

I'd be cautious about the lapping/nitrating. I've heard stories about a popular shop having substandard QC practices and leaving some lapping paste behind. That results in trashed motors almost immediately.

I spent the $2k on brand new irons for my own motor for this very reason (also the reason I bought new soft seals for a stacked motor that was never even started).

BLUE TII

iTrader: (9)

Anytime your engine parts are back from the machine shop you have to clean the fk out of them with solvent, nylon flat brushes for the grooves and bottle brushes for all the holes.

I finish it off with high pressure wash in the oil drain and coolant passages.

The worst is when you see people use parts fresh from the powdercoater. Thats covered in a fine layer of silica dust from their sandblasting operations....

peejay

And here I am gluing my own coolant seals out of cord stock from McMaster-Carr and installing them with Right Stuff because it will fill in all of the corrosion pits in the rotor housings

I built two engines with Hylomar. Coincidentally the only two engines I built with Mazda seals. The first engine I did in 2001, and my stock-as-a-rock 12A a couple years ago.
Hylomar does NOT flow in a 40F garage.

BLUE TII

iTrader: (9)

But that is race car stuff peejay.

I did all the racecar stuff peejay did, but I never used electrical wire for inner coolant seals.

And if I would have, it would have been silicone insulated wire cause I had that in the scrap bin at work. Vinyl peejay?

peejay

Is it racecar stuff if you are driving it 20k miles a year on the street?

2.2mm Viton cord for inners, 2.0mm elastomeric for outers, just because Viton is like $2/foot and elastomeric is like 20 cents a foot, gotta save money where possible. Tested to 0F cold starts and 250F coolant temps...

BLUE TII

iTrader: (9)

Yes, because that is exacly what I did in my race car living in Cali and racing in Oregon every month.

BLUE TII

iTrader: (9)

Not a brag-

I have re-used stock inner coolant seals after a year.

I have used and re-used the giant Teflon encapsulated silicone o-rings.

I have used and re-used the Viton cord stock.

I have not used wire. Yet

Only rotary that probably ever lasted me over 140,000 miles un-opened was a stock 1986-88 NA 13B that was in at least 3 of my and friends different FCs, raced 4-6 seasons and the last season was after it had coolant o-ring failure and I CRC copper block welded it.

Sold the last FC that engine was in to a friend who knew all that. It was still running and not using coolant.

Sold because of shot oil control ring seals.
It smoked so badly cold I had to start it predawn on race days so neighborhood did not call fire dept.

BLUE TII

iTrader: (9)

Disclaimer- I have never built an engine for any one but myself.

Craiggar

With respect to the water seals for a long-term daily driver, Mazda OEM parts have worked really well on my original build and on my current rebuild. There is a lot of trial & error experience regarding water seals that is searchable on this forum and I seem to remember some similar conclusions.

With respect to Viton, it is a great material and one needs to do a bit of research to get the correct grade and diameter to correctly fill the gland and survive the elements (wrt fuel and/or additives, water, oil, pressures/temperatures around the rotor housing, etc - all depending on the o-ring job/ location in the engine). Another bit of advice is to ask the o-ring supplier for the manufacture certification that what you are buying meets your specifications. The other bit of investigation requires how to properly join the ends for longevity.
For example, here is a link to a supplier document that sells DuPont Viton with “some” excellent manufacturer information to help choose. Of course nothing sounds perfect… and that’s the risk. https://rainierrubber.com/wp-content...tion-Guide.pdf

peejay

As BLUE TII was noting, I have built a few engines using 18 gauge electrical wire as coolant seals. It works well as long as you don't try to drive the engine in below freezing temps, then the engine gets loose enough to burn the jacketing. (I only torque my tension bolts to 23 ft-lb, helps keep the rotor housings from getting damaged when the coolant temps are far off in never-never land because doing a 60 second long dyno-pull of a run every five minutes in 90+ degree heat. Be lucky to get water temps back down to 210F before the next run begins)

The Viton cord is more or less immortal as far as I am concerned. I do replace it if I have to tear the engine back down, but then I have spools of the stuff so it is no hardship to do so.

The 12A I have been driving has actual Mazda coolant seals and gaskets and such in it, because I felt like doing that again, and had some fresh side housings and uncorroded rotor housings to use. And the class I occasionally compete in strictly has No Internal Engine Modifications Allowed and I don't want to get caught out in a gray area.

Slides

This is pretty funny, guys in Australia doing full rear rotor rebuilds to replace hard seals or cracked early rear plates without going anywhere near the front rotor, including workshops. Plenty of people gluing reel viton, diagonal cut/join preferred for surface area.

A lot of guys clearly haven't seen statistics on maintenance induced failures on high duty equipment, if it isn't decades old and is working you are more likely to introduce a fault by doing unnecessary work than leaving it alone.