Plain Jane OEM nothing to see here rebuild

[JustJeff]

I'm dissapointed that when I took my engine apart I did not find a smoking gun showing a blown out coolant seal and am concerned that I'll put this engine back together without identifying why/where/how the coolant seal failed.

Ted circled a pic in a previous post showing where he'd bet the seal failed. My concern is all my iron surfaces look very similar and seem to be tied to hylomar staining. Here's some pics with areas having similar staining.





Unrelated to staining, look how thin the wall is at this point. It looks cast that way and doesn't at all feel like corrosion. Should I be concerned?

[RETed]

You can ignore the outer water jacket groove.
I've never seen a failure on the outside one unless we're talking severe corrosion problem or extreme overheating.
The majority of the punishment is done to the inner water jacket since it has to seal combustion!
More specifically, the area from 12 o'clock to 9 o'clock (or vice versa, depending on how you're looking at the housing) which is the area where you start the ignition cycle through the combustion cycle to the end of the exhaust cycle is most important.

Sometimes it's very hard to tell from just pics on where the coolant leak came from.
It's almost necessary to be there - in person - to get a good idea of what is going on.
I tried to the best job just by the pics you posted...

Another question...
Assumed you did torque the engine down in the specified order...
How much torque did you tighten the tension bolts down to?
What kinda torque wrench?


-Ted

[JustJeff]

Originally Posted by RETed

You can ignore the outer water jacket groove.
I've never seen a failure on the outside one unless we're talking severe corrosion problem or extreme overheating.
The majority of the punishment is done to the inner water jacket since it has to seal combustion!
More specifically, the area from 12 o'clock to 9 o'clock (or vice versa, depending on how you're looking at the housing) which is the area where you start the ignition cycle through the combustion cycle to the end of the exhaust cycle is most important.

Sometimes it's very hard to tell from just pics on where the coolant leak came from.
It's almost necessary to be there - in person - to get a good idea of what is going on.
I tried to the best job just by the pics you posted...

Another question...
Assumed you did torque the engine down in the specified order...
How much torque did you tighten the tension bolts down to?
What kinda torque wrench?


-Ted

You have been very helpful Ted

I figured the same thing about that thin spot, but thought it was odd that it had a thin spot.

I don't remember the specific order I torqued the through bolts down in, but I did it in a chris cross pattern. I used a beam torque wrench and did them down to FSM specs..though I don't recall what those numbers are at the moment. I get where you are going with this though and talked to a friend about it just yesterday. If they weren't torqued down correctly wouldn't I have had leaks everywhere. I didn't have any signs of coolant in oil or any outer leaks through the irons and into engine bay. BUT I did transport the assembled keg to a friends shop to use his air tools for the flywheel nut. I doubt the engine "loosened" during transportation....but is it possible?

[RETed]

Originally Posted by JustJeff

I figured the same thing about that thin spot, but thought it was odd that it had a thin spot.

I think the molds were just getting bad toward the end of the production that some of the irons came out like that.
I've seen a lot of them on tear-downs, and they look awfully like massive corrosion...
It's so common that I've just chalked it up to "bad" molds.
Oddly enough, I've never seen a failure in those areas.

I don't remember the specific order I torqued the through bolts down in, but I did it in a chris cross pattern. I used a beam torque wrench and did them down to FSM specs..though I don't recall what those numbers are at the moment. I get where you are going with this though and talked to a friend about it just yesterday. If they weren't torqued down correctly wouldn't I have had leaks everywhere. I didn't have any signs of coolant in oil or any outer leaks through the irons and into engine bay. BUT I did transport the assembled keg to a friends shop to use his air tools for the flywheel nut. I doubt the engine "loosened" during transportation....but is it possible?

I believe the Mazda torque spec is around 27 lb-ft?
I only use Snap On torque wrenches - click-type.
I run my rebuilds at 30 lb-ft.
It's slightly higher than stock spec, but it's not tight enough to interfere with the rotating assembly.
I know guys run them higher, but you run the risk of increasing friction.
I've seen an engine torqued down to 40 lb-ft that almost could not be rotated by hand!
I know Snap On torque wrenches are not cheap, but the ~$200 investment is a good one in this case.


-Ted

[JustJeff]

Originally Posted by RETed

I believe the Mazda torque spec is around 27 lb-ft?
I only use Snap On torque wrenches - click-type.
I run my rebuilds at 30 lb-ft.
It's slightly higher than stock spec, but it's not tight enough to interfere with the rotating assembly.
I know guys run them higher, but you run the risk of increasing friction.
I've seen an engine torqued down to 40 lb-ft that almost could not be rotated by hand!
I know Snap On torque wrenches are not cheap, but the ~$200 investment is a good one in this case.


-Ted

I've got a Craftsman. I doubt that the torque was off unless the wrench was faulty. I like the beam type wrenches more cause I can see with my own eyse type thing. Trusting a click in a wrench makes me nervous. I got very anal and almost OCD when checking torque on nuts and bolts. I went around the through/tension bolts several times, but don't remember what the torque was on them. I took notes and pics through the teardown and tolerance speccing, but then at the end for assembly I got more focused on getting the job done and note taking fell by the wayside.

[JL1RX7]

The click type torque wrenches are very accurate as long as they are not dropped and used for the final torque. Beam are the least accurate. I have seen so many fail calibration brand new out the box.
The snap on ones are expensive but they are very good. Used them in the Navy torquing bolts and CADS on the ejection seats. Figure if they are used for that then it is more than good for a car.