13BTOY

iTrader: (1)

I have oil gushing out on top of the rear iron near the oil filter pedestal. Any ideas what went wrong and could of caused this? The motor is starts runs and idles fine otherwise. Leak of death or cracked iron? BTW I'm boosted and this happened after a high boost 3rd gear pull.

Thanks, Ed

Siraniko

iTrader: (13)

too much for the old bolts to handle. On your next motor, be sure to use the ones they sell at mazdatrix. They have the big bolt kit and the strong replacement that doesnt require re-drilling.

steve84GS TII

Mazda adressed this issue with more ribbing and thicker metal on the S5 and later engines.The S4 and older engines would crack near the pedestal when under high HP situations......like boosting in 3rd gear.Thats why a S5 or S6 rear iron is always on everyones list when building a high HP engine.What style engine is your build-up based on?

13BTOY

iTrader: (1)

I just finished cleaning the oil off my motor so I can pin point exactly where its coming from. I cranked the motor over just enough to build pressure and well like you guys said I found a hairline crack on top of the block near the pedastal.

My motor is a 4port using 12A plates with gslse housings.

Thanks, Ed

CrackHeadMel

iTrader: (2)

a similar problem happens with s4 cars from time to time, generly its a cracked iron around the top dowl which is right below the oil pedistal as you have described

Latin270

nopistons.com has lots of good info on this very subject. I take it this is caused by vibration?

13BTOY

iTrader: (1)

Its kind of tuff to see but heres where it cracked.

Thanks, Ed

steve84GS TII

Yep,dowel pin boss under the pedestal.

No pics,but a simple explanation here........
http://www.mazdatrix.com/faq/boost.htm

13BTOY

iTrader: (1)

Thanks!

Ed

Latin270

That explains why the s5 irons look the way they do.

Siraniko

iTrader: (13)

not really. The S5 TII streetported on the turbo duece cracked due to stress. Rebuilt it with new rear iron along with the oversizied bolt kit from mazdatrix. Thats an extra 500 bucks by the way plus re-drilling it.

steve84GS TII

Right.

At stock S5-S6 power levels, Mazda's method of simply thickening the iron fixes the problem.But above that,the cracking of the rear housing is not neccesarliy the fault of the iron.
As the Mazdatrix site explains,the reason the rear iron will crack is due to the tension bolts stretching and allowing the housings to push apart under boost.Its the rotary equivalent of cylinder head lifting.This causes the contact between the bolt and the iron,and the subsequent failure of the more brittle cast iron housing. A S5-later rear iron will make the housing more resistant to cracking,but the larger tension bolts will prevent the housing seperation altogether by resisting stretch when power levels are high.Of course,as Mazdatrix explains,youll just be moving the failure point somewhere else......possibly something more expensive than the rear iron,which is relatively easy to change.

Man_in_black49464

iTrader: (1)

I had a problem with that once i was able to weld the crack, and seal the oil in the crush washer on the end of the main housing bolts sealed good.

13BTOY

iTrader: (1)

Please explain!
Also whats this I hear about an oil bypass? Anyone ever hear of it?

Thanks, Ed

680RWHP12A

your motor detonated causing the housing to crack
pull some timing out and/or add more fuel

my 12a didnt crack from h/p until i reached the 450 mark.

steve84GS TII

Considering the ease of removal of the rear iron,I wouldnt trust a weld.
Due to its metalurgical properties,welding cast iron is very tricky, even under ideal conditions.And even if its done the best it can,it will still never be as strong as before.

Jeff20B

iTrader: (13)

Nitrided R5 rear plates have a small curved rib right there. Older non nitrided ones had a large straight rib like S5.

steve84GS TII

Sounds like a way to go,since he's running 1st gen style housings.

Jeff20B

iTrader: (13)

Carbed style side plates? Or GSL-SE side plates? I only ask because of the GSL-SE rotor housing in the pictures.

Jeezus

iTrader: (4)

4port using 12A plates with gslse housings.

Jeff20B

iTrader: (13)

In that case get a nitrided R5 rear plate.

Directfreak

iTrader: (2)

I am in agreement with everyone here. Just replace the rear plate and re-tune. You don't have to take the whole engine apart.

Also, as for the OVERSIZED Stud kit Wacky is talking about, there is another kind that they sell, that use STANDARD studs, that don't require machining (drill & tapping) the plates.

http://mazdatrix.com/studkit.htm


Those are more than adequate for reasonable power levels.

Siraniko

iTrader: (13)

yup, thats what is going in my next motor. Im a cheap *** so I will try to use 1 kit for 2 motors. That is replacing all the exhaust/intake side and a few on the driver side, and none for top and bottom.

The oversized stud kit is what we used in my bro's 3-rotor RX-3, mazdaspeed featured turbo duece and the bridge ported RX-4 (soon to be turbo).

13BTOY

iTrader: (1)

Thanks for everyones input. The motor will be pulled later this week. I have all winter to figure out what my next motor combo would be. I decided to park the seven for the season.


Ed