On 1985 and earlier 13B's The coolant O-Ring groove is located on the aluminiums.

On 1986 and later, the groove is on the irons.

I've heard that one wall of the groove on the irons is prone to cracking, and that the aluminium walls are a little more flexible and therefore don't crack.

Has this happened to anyone? Is it a frequent problem? What causes it?

 

my old motor had a crack. it was overheated..

 

I've seen one of those It was cause by Little Jimmy ******** using plain water and no anti-freeze. In other words *corrosion*. See the Mazdatrix FAQ page for more information.

 

Had it on my center plate, the previous owner overheated it bad. replaced it with a t2 centerplate

 

well mine really wasnt a crack....more like a huge piece broke off or corroded off.

 

In my experience its damn common with T2 motors on the front iron.

 

it's damn common on all S4 and on irons.

 

definately a common problem
i have had 2-3 motors that had to be rebuilt due to this

 

Which FAQ page? There's several tidbits of information scattered on their site, but they're all spread around in various sections. Could you link me please?

 

Aluminum ends up being the sacraficial "anode".
So guess which one fails more often?
Mazda did the right thing to move the groove to the steel side.


-Ted

 

http://www.mazdatrix.com/faq/sidehsgs.htm

 

Me too!!!

I mean it was like 1.5 centimeters that disappeared... and then the O'Ring kinda sloughed in upon itself, like two worms *******!!!!

Actually, i've seen it SEVERAL times in the exact same place with the exact same effects.. boiling coolant after you shut the car off Car hard as hell to start after it sits for about ten minutes, if it won't start, gotta change the plugs cause they're SHOT. But.. No white smoke.. just a very faint smell of freeze in the exhaust. Think it's because this "Crack" happens at the power stroke area of the housing.

 

those cracks / failures are usually only reason for NA FC's here in Europe to die, seen plenty of them and had few of plates fixed and used them again with no problems

 

How so? The Mazdatrix page says this problem only occurs on 1986 and later engines.

Although the electrolysis bit does kinda irk me. It's why I'm swapping my brass 1st gen radiator out for an aluminum 2nd gen one.

What'd happen if you shoved a thing of Zinc in one of the end tanks? Zinc could be the sacrificial anode.

 

Interesting idea.
In fact, I saw some special radiator cap that had a hunk of zinc in it that supposed to do just that...
I guess it didn't work, cause I don't hear of it anymore.


-Ted

 

or maby it worked so well, they pulled them off the shelf because no one needed repairs anymore, and the mechanics dident like that </consipracy theory>

 

So is the conclusion that the irons were made of inferior metal? Or is it just the corrosion from water that could damage any year or model iron?

 

We see this all the time, on S4 and S5 N/A front irons. failure pics http://www.banzairacing.net/winnie_breakdown_02-05.htm
Most of the time it shows up on cars that have low mileage with the original engine, meaning that the coolant has sat in the engine for long periods of time without moving. We have also seen it on TII and FD rear irons.

 

You just described my old fc exactly. 1986 luxury with only 78,000 miles, sat for like 3 years. Huge chunk of the water jacket just GONE.

 

i've seen them on all irons in all areas. it is due to improper chucking during the machining process and variances in castings, if you look at all irons the wall thickness is not symmetrical all the way around and some walls are very thin, these thin walls are often what breaks and the iron that i have seen break more often than any else is the center iron because it has 2 sealing faces hence double the chance to break than the front and rear. this is backed up by the reason i can hardly keep middle irons in stock.