Hello all. I am going to be rebuilding a spare S5 NA engine I have so I can having a daily driver again. I have tore countless engines apart, this will be one of my first rebuilds.

I got the engine and I couldnt turn it all the way over, so I thought it was bad. Turns out after I tore it apart it just had some ice in one of the rotors. Also though there was some weird scaring going up the housing after the exhaust port, so I am just going to replace that.

I am going to be keeping :
Apex seals
side seals
corner seals
both high comp rotors
1 rotor housing
all plates
eshaft
all stationary gears and bearings
and metal oil rings.

What I think I need is :
Pineapple coolant seal kit ( including the water jacket o-rings, front cover o-ring (and backup washer, if needed), dowel o-rings, rear stationary gear o-ring and oil pedistal o-rings )

(getting below from my mazdaspeed account)
12 FD corner seal springs
12 rubber corner seal plugs (do I need these?)
12 FD side seal springs
6 FD apex springs
6 FD outer apex springs
8 springs for the oil inner outer front and rear rotor seals

Is there anything else I need for this minimal freshen up?

Thank you.
~Tweak

 

At the very least you need to purchase some proper measuring tools and the RA rebuild video if you plan on re-using all those parts. It will save you a ton of trouble. Being NA you can reuse the apex seals more so than if turbo. Just know that the factory apex seals are very brittle and can break very very easily. Personally I would replace those with the newer 2 piece. You don't want to risk the top peace of the apex seals flipping out of the rotor groove and killing the engine. Tearing rotary's down is easy. Putting them back together correctly is a art.


The corner seal plugs are meant to help keep the compression higher. Since you reusing a lot of parts, get the plugs. Any extra compression you can make is a plus. Only reason people tend to not them is if they port their intake ports to the point they fall in. No need to replace the oil control o-ring springs either. I rebuilt my own engine re-using pretty much everything. I basically put together my own aftermarket gasket kit for very cheap. Saved me a ton of money. I only replaced the apex seals and slightly refreshed one of my damaged housings. I've got about 17k on it over these past two years.

 

Yeah I have already watched a couple how to rebuild videos. WOW they are boring haha. Anyways I am confident I can do it. I have a lot of tools, and I have "feeler gauge" ( I think that is what it is called) to get the side seal clearances perfect. I WISH I would have taken more time tearing down this engine like I have in the past, where I labeled and marked where each seal (side and apex) came from. But sadly I did not. It is going to be interesting getting the side seals to fit. Luckily I have 8+ rotorsworth of side seals so I should be able to find some that fit. I can always make the sides seals smaller to fit, I hope I have some that are too big.

I MIGHT order some apex seals, but I really doubt it. This is just going to be an extra daily driver for me. I REALLY doubt the motor will be driven hard at all. I will however get the plugs if there is a chance it will help the compression. EVERY motor I have torn down has had useless side seal and corner seal springs. I can't wait to have fresh ones of those, and possibly over 80 compression. I have never had an engine over 75ish compression.

Anyways looks like that is what I am going to be ordering. IF I was to get apex seals, would you recommend atkins 2 piece? From my research I have heard that they are softer and would help speed up the wear in processes and allow for higher compression sooner.

I still need to get a S5 NA housing, and getting new apex seals would take this nothing special rebuild from about $350 to over $570.

BTW how do you refresh a rotor housing???

 

I'd save your money and buy a nice engine. If you reuse just one rotor housing and one new one, and mix and match apex seals (especially since you didn't label them) your compression is going to be all over the charts. I'd at least replace BOTH rotor housings, apex seals, soft seals, etc. You're going to end up with an unreliable engine trying to make junk work with new parts...

One way to refresh a rotor housing is to send it to JHB. It'll cost you the same as a new one, but the Cermet coating they use will (theoritically-sp?) last longer than the factory chrome. Let me throw out a disclaimer to you here: I'm not a rotary engine builder (yet). I'm still green, but from the information that I've gathered from this forum (and previous knowledge from my piston engine escapades), I know that I'm not going to be using junk in any engine I'll build. If you're going to spend over $500 anyway, just save up and do it right, or buy a running engine with low miles from the classified section. It WILL save you some money in the long run and a giant headache when it goes.

Here's an idea-list some of the parts you have lying around for sale in the classifieds. Use the cash you get from that with the rest you're planning on spending on the engine and you just might have enough for a lower-end pro job or a nice used low mileage engine. I'm not trying to tell you not to build your own engine if you're dead-set on it, just don't plan on it being your daily driver for the next five years if you're reusing all those old parts. By all means, build your first rotary with what you've got lying around and with minimal expense as an experiement-but don't bet on it lasting a long time. Keep assembling and tearing down and checking clearances until you're confident that you can do it with new parts the right way and then spend the cash on 'em...

This is just a suggestion by the way, I'm nobody important. Just figured I'd throw my two cents in and hope it may save you a bit of cash in the long run...

 

Since your going the really cheap route (like I did), the side seal springs and corner seal springs can be bent back just like the apex seal springs. I too had an used assortment of extra side seals to pick and choose from. During assembly just make sure the side and corner seals purtude the reguired height above the rotor and have good spring back with-in the grooves with no binding. That's what I did to my 91 NA vert engine. I also like to clearence the side seal to corner seal to .002.

The softer Atkins apex seals are a really good choice for an NA set-up and will break in fast like you described. The refinishing I am talking about is what I did to my rear housing that was goulded from the previous broken apex seal. I was lucky to not have any real damage on the compression side of the housing. I wanted to smooth things out a little bit so I took my die grinder and installed a sanding disc. It's the kind that has the sand paper in evenly cut loose strips and is the diameter of the rotors main bearing. I basically just went around the housing sanding the surface trying to smooth out some of the scratches. It worked really good so I did my undamaged front housing the same. It gave the surface a nice smooth/textured appearance. I felt this would give the oil something extra to adhear to under operation. Glass smooth surfaces dont help the apex seals seal all that well do to the lack of oil retension. When I put everything together and back in the car, I did a quick compression test with my piston tester. The compression tested an even 90psi front and rear on all faces . Keep in mind I didn't use any extra assembly lube at all. The housings were basically dry with only jelly holding in the corner seals for assembly and it also had brand new rock hard RA apex seals. The engine fired right up with absolutely no excessive cranking.

Overall, we cheap bastards just have to be slick.

 

See my above post. That engine of mine has over 17k on it. You can do a lot with junk parts if you know what your doing.

 

Yeah I think I am going to go with V-ton on this one. But since the springs and such are SO cheap, I am just going to pay the extra for the peace of mind. I don't think I would be able to fix my housing, although I really wish I could, that would save a nice chunk of $. 17k miles is more than I have ever got with my high mileage used motors so haha if mine lasts that long I would be very happy. ( I think it will last quite a while though.)

If I can find a decent price for a decent shape s5 NA housing, I think I will buy the atkins seals. It will really add $ to this cheap rebuild, but who knows how old this motor is. All the bearings are in great shape showing no copper so it might be somewhat fresh. The shape of the good housing also suggests it is not a 100,000 mile motor.

Anyways, thank you both for checking my work. Sounds like I have everything I need (minus an engine stand) to do this semi minimal rebuild correctly.

~Tweak

 

Engine stand???? LOL I use a work table to assemble the engine. Here's one more tip for you. I like using the table for the simple fact that when I put on the oil pan, I can rest the engine on it while the silicon dries. The oil pan and engine mounts are always the last thing I put on the engine b4 putting it in the car. The added weight of the engine helps to more evenly spread the silicon around the pan surface creating a much tighter seal. I call it the smush effect. I let the engine sit this way overnight making sure the silicon is 100% dry. Using this method, I have yet to have an FC/FD oil pan leak.

Oh yea my engine gets 28mpg on the highway too with some other little mods I did.

Peace!

 

Keep your eyes on the 2nd gen classified section or just post a WTB add for your rotor housing. You'll probably find somebody that has a good used one in about the same shape as your other. Good luck on the build-I hope it lasts you a long time...

 

I just called mazda motorsports and put my order in, and he asked if I wanted the green rotor seals.... O.o I don't remember a green "rotor" seal, so I said no. Do you guys know what he is talking about?

 

The only thing that I can think of thats green and is a seal, are the oil control ring o-rings.

 

Yep those are the green stock oil control o-rings. I like to use the re-usable viton rings myself as they are perfect for people like me who like to repeatedly break the engine down.

 

Ok, so does someone have a picture of this thing? I think I understand what I did now. I ordered the springs for the oil control rings, but forgot the actual seals! haha I failed again. What are these special oil rings you speak of? Link to order them?

 

From my 20b rebuild list of parts.


Viton oil control inner #9464K125 1 pack of 5 good for one 13b leaving 1 extra.
Viton oil control outer #9464K116 buy 2 packs as you get 2 o-rings each

Go to Mcmastercarr.com and put in those part numbers. These o-rings are very durable and reusable but they are a bitch to install. If you use them, make sure you use another oil control o-ring seal and the thick side of one of your feeler gauges to evenly press them in. You will not be able to just force them down with only pressure. This tip is where the RA rebuild video comes in handy.