So i tore apart my engine today because of the bubbling coolant. It was bubbling out of my overflow and out of... well, everywhere that was opened to atmosphere. See a video of what it was doing here http://www.youtube.com/watch?v=if04UbTdlO8

So the back housing and plate looked ok but when i got to the front i found this...














And my army stained rotors...



..can anybody tell me why they are stained that color (its not carbon on the surface)? Also i should mention that my car was not smoking much, just bubbling.

Time for new front plate i suppose.

 

Clean off and mic out your rotor, it's prolly fine.

You might want to check the other housings very closely for cracks. (It's a guess :P)

 

yeah I have two plates that look exactly the same. Anyone know where to get replacements? Oh yeah, and if my car is an s5 with my end plates looking the same, can i use s4 for replacements?

 

jesus, looks like the housing itself has been busted off. Feel that rotary power!

 

NA rotary power?

 

Hey NA's can have their moments of glory as well.

 

thats cute, looks like for the price of a junk yard motor you'll be running again.

 

cute? junkyard motor?

 

Replace that Iron...

 

Hey, you might also want to check everything else to see where that huge chunk of metal went to! I'd hate to rebuild my motor only to have that sucker lodge in an oil passage or go to the water or oil pump and **** EVERYTHING up... lol. Good luck with the rebuild!

 

 

WOW!!! Does anyone know what happened to cause that?!

Holler at me when you piece that together!!

 

Thats very True!!!!

 

Corrosion, overheating, it could be a number of things that could cause it.

IIRC, the path where that coolant seal failed is the hottest area of the motor.

 

a lot of s4 irons ive seen have this problem. i havent seen any s5 irons fail like this yet. its usually just because the wall is so thin that over time and the corrosion bust the wall out and it forces the o-ring out. this is very repairable though. it cost me 25$ to fix a pair of irons i had that had a beautiful port job on them. he welded up the one piece that broke through and reinforced a few other spots. then we milled it down and i hand filed the groove back into shape. motor now has 15k miles on it and not one symptom or issure. also when doing rebuilds, use the RA water seals. they seem to hold up better than the mazda or atkins water seals and are less prone to blow out like this did.

oh yeah and if your motor is torn down and you have it pretty clean then i wouldnt worry about that chunk of metal. it cant reach an oil passage via water passage...

 

yes, junkyard motor because many rx-7s with good engines find their way to the crusher. Look for an engine that is in a car that was hit hard in the rear. Make sure the engine spins over and makes hissing and sucking noises. such a motor is a good candidate for a rebuild, especially if you already have another engine for parts.

gluck with the build

 

I am in the process of looking for the pictures now, but I had the same problem. I had bubbling coolant on my J-Spec. I tore the engine down, and saw a total of 3 missing pieces of cast iron of the water jacket groove. I decided to experiment a bit and weld extra material into the groove then machine it out. I tigged the new material in, but couldnt machine it. It was too damn hard, if there ever is a next time I would use a filler rod with a little less nickel. Anyways, I then surface ground the iron to a 15Ra with a flatness tolerance of .0001 from one side to the other. The water jacket groove had to be ground out after this. The iron looks like it is brand spanking new. There was quite a bit out work that went into it, but I am sure the iron will never fail there again. It is the current engine in my car right now which I expect to have running very shortly after several more parts come in. I will post my results.

 

Ok I am having the same issues with my s5 FC that was overheated, so I can have this taken to get fixed or do it myself with welder and a mill? If not how much are good used irons typically, and can I use my s4 NA irons from my s4 that had a blown apex seal? or should I just start my own thread?

 

mine did that in the exact same place! everything thing was fine except the front iron

I would just get a new-used iron, you can find them on ebay. I paid $80 for mine shipped, s5 also.

 

How is a piece of metal that broke on the coolant passages end up in the oil passages or oil pump

 

yah i dont know, this thread has got outa whack. i never asked what to do about it. im going to replace it not weld it. i was just showing how bubbles do mean something without smoke

 

Thats exactly what mine looked like, but on the center iron of an s5 engine. Mine never really had much smoke either, and barely had bubbles. It just pressurized the coolant system.

This is what most cars that burn coolant will look like on the inside, I think.

 

easy. It can get stuck somewhere, then fall into some hole on your freshly rebuilt motor... say the intake runners for example. Sometimes, you just dont notice untill it's too late, and often, little things like this can ruin that "perfect" setup the first time you fire it up. Just wanted to be helpful.

 

So, any more pics?