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I've never taken apart an entire rotary engine, so I wouldn't want to needlessly disturb a short-block.
:-) neil
RIP DAVE!
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We’ve all seen the leaky front cover gaskets in the past rotary RX7s. So has Mazda, apparently, as they have redesigned the RX7 gasket for the new Renesis RX8 engine. The new RX8 renesis gasket is now made of metal and has a crush ring around it; far superior to the old RX7 paper gasket. The purpose of this is to help you take advantage of the newer RX8 gasket style and use it on the older RX7 engines.
*This modification works for all 2nd gen 13B, 13BT RX7 engines and all 3rd gen 13B RX7 engines.
The first thing you might notice on a 13b-rew gasket (93-95 3rd gen RX7) is that most of the bolt holes line up. Cool! The next thing you might notice is that not all of them do.
To make this gasket work, we’ll need to do some cutting. It is metal, but some sturdy scissors or tin snips will work just fine. I’ve marked the cut points in red.
Just remember to stay on the outside of the crush ring when cutting for the bolt hole!!
You’ll notice part of the gasket is now free-floating on the water pump stud. You can attack this in a few different ways: either add just a touch of super glue or RTV spread very thinly to glue it onto the front side housing so it doesn’t fall off. You can leave it off entirely, use a washer/spacer from an s4, or you can cut the other “spacer” section of the gasket off and use the original spacer from the REW motor. Any of these ways are fine.
The last thing you need to think about is the front housing-to-front cover o-ring and nylon washer. I simply laid the o-ring and washer down with the gasket on top of it…piece of cake.
Last edited by M104-AMG; Oct 17, 2008 at 10:26 AM.
I hope my engine had a metal front cover gasket installed when it was rebuilt...
I read through all the archives, and everyone who has taken apart factory remans, have said paper front-cover gaskets still.
In fact, the stock Mazda gasket kit does NOT include the metal gasket, it still uses the paper one.
We can only hope, that they made some "assembly line" changes, like they did with the current (10/08) supposedly "new" 13b-rew engines where they did away with the oil-pan gasket, and are now using a silicone/RTV-type sealer (aka, The Right Stuff / Honda-Bond).
The metal front cover gaskets are for some reason a Japan-only part. If you get a NEW engine from Ray, they do use the metal gaskets, as they were built in Japan.
I've done a few motors with the metal gasket - works VERY well, I strongly recommend it. If you get an already-built motor with the older style gasket, I'd hesitate to recommend swapping it out, though. It's easy to goof up the front cover stack and crush a needle bearing if you're unfamiliar with those components (not necessarily directed at you, Neil, but for other readers of this thread).
The metal front cover gaskets are for some reason a Japan-only part. If you get a NEW engine from Ray, they do use the metal gaskets, as they were built in Japan.
I've done a few motors with the metal gasket - works VERY well, I strongly recommend it. If you get an already-built motor with the older style gasket, I'd hesitate to recommend swapping it out, though. It's easy to goof up the front cover stack and crush a needle bearing if you're unfamiliar with those components (not necessarily directed at you, Neil, but for other readers of this thread).
Dale
Can you see a paper vs. metal gasket on a short-block ?
If so, maybe that's a good way to see if at least your supposedly "new" 13b-rew is from Japan.
Dale is 100%. Read this before pulling your front-cover:
I’m using an rx8 gasket in my 76-78 13B. I had a machinist make a custom recess filler to the exact dimensions of the oring recess and from what I can see it’s working very well. I explain a bit more in detail in this video
oh yea.... i did this as well in my rebuild. yea, just be careful cutting it. the long part that extends out on the turbo side, i didnt cut. after i bolted down the cover, i just flattened the part. everything has been fine. when i break my motor back down, i will reuse it.
The cosmo 13b-re gasket is a direct fit for a 13brew , and its metal.
the earlier metal gaskets for the 13B RE are a decent amount more than an RX-8 gasket. The RX-8 gasket is just cheaper and more readily available in more places. To cut mine I just used a really good pair of scissors that are normally used to cut composite fabric. Cuts right through like butter https://www.mazdatrix.com/product/ga...-gasket-13bre/
Most builders are using the metal 13b-re gasket, not the rx8 gasket.
pay the extra $1 and no grinding/cutting
not sure who “most Builders” are, but I’ve really only seen the rx8 gasket being used and can’t say I’ve even heard the 13B RE gasket mentioned at all (not that it’s not used, it’s just not something that’s seen or heard of as much).
The 13B RE gasket is also about $17 more than the rx8 gasket btw, not much, but I’d prefer to save $17 if the only difference is some unnecessary cutting
Mazda deleted the front cover O ring in 1996, and instead they use the metal gasket, N390-10-502, the Rx8 is also without the O ring, but it adds the water pump housing, which is nice
Mazda deleted the front cover O ring in 1996, and instead they use the metal gasket, N390-10-502, the Rx8 is also without the O ring, but it adds the water pump housing, which is nice
I haven’t seen a version of the rx8 gasket without an oring included. Can you give some detail here? I’m not sure how the oil pressure in my 76-78 13B is being held otherwise
I haven’t seen a version of the rx8 gasket without an oring included. Can you give some detail here? I’m not sure how the oil pressure in my 76-78 13B is being held otherwise
see pic, the Rx8 and 96+ FD (N3F1 vs N3A1) have the O ring land flat, and it only uses the gasket, no O ring. see pics it actually appears that if you buy a replacement FD iron, the O ring land is machined, but if you tore apart a factory built engine with an N3F1 iron it won't be
Had great success and zero problems using it. I can't remember if I put an O-ring in there as well or not. I want to say the sealing part of the gasket hits the outer land of the O-ring hole so it has area to seal against.
Not sure if using the RX-8 gasket would be worthwhile.
see pic, the Rx8 and 96+ FD (N3F1 vs N3A1) have the O ring land flat, and it only uses the gasket, no O ring. see pics it actually appears that if you buy a replacement FD iron, the O ring land is machined, but if you tore apart a factory built engine with an N3F1 iron it won't be
ok I see what you mean, I just misunderstood. There no actual oring, but rather in integrated oring in its place
