Teflon Coolant seals
 

Has anyone here used Teflon encapsulated coolant seals? The ones I got seem to have a smaller sealing area than the stock ones due to a round rather than rectangular cross section. They may be more robust but my concern is with their sealing ability.
Would appreciate any input on the pros and cons of using them.

Are you talking about the Hayes seals or from some other supplier? I found some in the McMaster Carr catalogue that were in bulk form. I am interested in where you got yours.

db

I have the Hayes seals in my 2nd gen. They get mashed down pretty far so sealing isn't an issue. I love them. You can even take them out and stick them in another engine later. Try that with the stock ones! The ones from McMaster-Carr are the EXACT same ones sold by Hayes. Hayes wants $100 a set. McMaster-Carr wants $10 apiece ($40 total) for them. Hayes has to make a buck somehow. Wish I'd have know about McMaster-Carr earlier. FWIW do not under any circumstances use the environmentally safe (orange or blue) antifreeze with the teflon/silicone seals. They literally dissolve in a matter of seconds! Stick to the good old fashioned Prestone type.

the McMaster-Carr part number should be listed so people could order them there without having to look all over their site, and order the wrong ones.

matt

I have it written down somewhere. When I find it I'll post the part number.

Rotarygod, thanks for your input. I got mine from rotaryaviation. If you can post the Mcmaster number, it would be great. That way I know I have similar ones. I measured the cross section width and it was 0.105" which is a 3/32" std o-ring. Can you tell me the width of the hayes ones? Well, you can imagine why I was hesitant using these. They occupy less volume in the groove than the stock ones but I suppose it would mesh down more than stock ones being circular in cross-section.

I have heard of a couple cases of o ring groove failure
using the Teflon encapsulated coolant seals, the seal
really fills the groove once it is squished down and
puts allot of pressure out on the o ring groove edge,
unless these rings are much cheaper I don't see any
point in going to them, if they are less, well its another
area where costs can be reduced.
or if you are racing and pulling apart the motor on
a regular basis to rebuild then you could reuse them
which would save even more inthe long run..

matt

Well, seems like it's pretty common for the aviation guys to use them so i figured they provided more reliability.

Did anyone find the catalogue number for McMaster Carr?

db

I talked with Bruce Turrentine a while back about the teflon seals and he said they were some of the best out there. The teflon is able to withstand alot of abuse. He recommends them. I value his opinion very highly.

I've been looking into making my own cooling seals for a while now... I'm kind of confused on the materials that I should be using.

Silicone can be used uo to 392 degrees, viton can be used up to 400, 500 for intermitant service.

Both of these can be spliced easily.

Teflon, 450 degrees, seals are only sold in a roll, where the others are sold by the foot. Also I can't find info on splicing teflon seals together..

Teflon Shore D: 50–65
Viton: Shore A: 70-80
Silicone: Shore A: 65-75

Any input?

Teflon seals look like they would be too hard to seal....

Brian,
we are actually talking about teflon encapsulated silicone o-rings. The silicone core gives "life" to the o-ring (term used in the sealing industry). They are used in very high tech applications like aerospace. Seems like they are popular among the 3rd gen crowd. My only concern is that the groove in the side plates is really suited for a rectangular seal but you can only buy the TEC silicone o-rings in a circular cross section.

I'd like to see that part # myself.
Don.

rxseven: Yeah, I just found the encaplsulated orings.. but if you are using a 3/32 oring the maximum diameter that the oring is made in is 9 3/4"

It seems small, I'll have to go measure up a housing to find what size we need

After much searching I have finally found the part number from McMaster-Carr!!! Part#9319K239

The big problem that I have seen from using these seals is during the building process. They are a serious bitch to keep in the grooves while you are assembling the engine. Use lots and lots of vaseline to hold them in!!!It burns off the first time you start the car anyways. I saw a 3rd gen engine that was built by Pettit that had to be redone after only 3K miles. When the engine was pulled apart it was discovered that whoever built the engine let part of one seal come out of the groove and get squished between the housings. Even though the area was small it was enough to cause a water leak and hence another rebuild. That engine had other build issues as well. The apex seals weren't all put in facing the same direction so a few had the triangular corner pieces on the opposite sides with no apparent pattern. Lousy built engine. I have 2 engine I personally built that uses the seals and I love them. No problems just be careful.

Did you find that they fit well in the groove? This morning, I took an old seal, cut it, and used it to measure the diameter of the seal groove. I measured it at 29 1/2 inches circumfrence which calculates to 9.4 diameter. In looking at the catalog entries, it appeared that the K241 at 9 7/16 o.d. might be the best fit.

If you have used the shorter one with no problem, I will order a set tomorrow. I also plan to order the 3/32 inch square rope seal material to make the outer water seals with as well. I have spoken to people who use silicone gasket material to bond them together with no problem. Do you think at 250 degrees, they will live in the outer?

The Atkins videotape suggests using Hylomar to hold the seals in the groove during assembly. I have been using that stuff since the early 70's and have great confidence in it. At that time, it came in a yellow tube labelled "manufactured by Rolls Royce to Continental Aircraft specifications". It was more expensive then as well before Permatex bought the US rights to the stuff.

I have 3 engines to build before Christmas. This should help a bunch.

db

Thanks rotarygod. I cross referenced the ones I got from rotaryaviation and they are the same ones, dash # 175. If Mcmaster sells them for $10, they can be bought for around $8 from o-ring suppliers. i work for an OEM so I should get them at OEM prices not retail. BY the way you guys also realize the oil control o-rings which are sold for $90-$100 a set are about $2-$3 a piece for viton?

DaveB: When I first tried to install them I thought they were too short. After I started getting them in place where they stayed they actually just fit.

I have used both hylomar and vaseline when assembling engines. Vaseline merely holds the o-rings in place until the engine is assembled. When the engine runs for the first time it burns off with no residue leaving only the o-rings to do their job. Hylomar holds the seals in a little better and helps to seal. Which is better I don't know but I have used both with success in both cases.

Great!!

I will for certain order the Dash 175's.

I was also looking at the viton. Would the viton work better over the square silicone? I looked at both. I noticed that the viton has a better heat range. If I remember correctly, the viton is something like 43 cents a foot in bulk. 12 feet should do a complete engine. If you think 3/32 viton would be better than silicone, I would take your advice and order that as well.

My race engines will be done by Christmas at the nice price. This is good!

Thanks for all your help!

db

89 GTUs - ITS
89 GTU
87 Sport - ITS
74 260Z - ITS
72 240Z - ITS
71 MGBGT - Vintage racer
64 AH 3000

"They're a retirement investment, honey"

DaveB, I am not sure I fully understand. Are you saying use viton o-rings as water seals or the rest of the internal o-rings?

I was the one who misunderstood!

You were talking about the oil control rings on the rotors. I hadn't thought of that one. Duh......

Yes, I was planning to buy the material from McMaster for the outer water seals as well. The bulk material is also really inexpensive and is not that difficult to bond together. Some of the racers I have talked with use high temp silicone without any problem. I'm going to try it on a street engine as an experiment.

Thanks again for the help.

db

If the cost of the Teflon encapsulated coolant seals were
significantly cheaper then I would suggest them for all rebuilds.
The last inner coolant o rings that I got from the dealer
cost me 15 dollars Canadian each, it was said above that
the Teflon encapsulated o rings were about 10 dollars
u.s. which would equal about 14 to 15 Canadian.
No real cost savings there.
like I had said before unless you are rebuilding the same
motor often, as you might if you were racing, I really
don't see any point in using anything other than the
stock o rings.
the same goes for the outer rings I think the last ones I
got from the dealer cost me about 5 Canadian dollars.
Now if mazda puts up the price of these parts like they
have been doing with some of the rotary rebuild parts
this will become more of a point of interest.

matt

the inner water seals are $18 at mazdatrix so the teflon rings are much cheaper. But cost is not why most people use them. They are supposed to be less prone to failure and the aviation guys use them as one of the reliability mods.

After more research and measuring, I got the whole order together and placed it today. All water seals AND oil control seals, in stock, to be shipped immediately for just under $75. I got the oil control seals in viton and the inner water seals in teflon encapsulated. This was better than I had ever imagined.

If you want all the McMaster part numbers, I will be happy to pass them along.

Thanks for all the information that you have provided. It helped a bunch.

db