Rotors Too Big?
06-02-2005, 10:51 AM
#1
Senior Member
Thread Starter
Join Date: May 2002
Location: California
Posts: 22,465
so my buddy put a mana motor into a customers FD, all the housings were new except it was a rebuilt engine. engine ran fine but used about 3 quarts of oil in the first 1200miles, then the oil pan started leaking so the motor was pulled to be warrentied.
he tore the motor down and all the housings look like you would expect, new. basically everything is new except the rotors, which look new but on inspection they arent.
the rotors have been machined on the flanks, theres a step around the outer oil rings where its been turned down about .003". you can see on the side of the rotor, about 1/2 way along the side seal, theres a shiny spot, on each face. also the rotor gear lands are black and chewed up. we measured the rotor, even the turned down spot the rotors out of this motor are still .003-.005" WIDER than a couple of other rotors we had lying around, even the machined part.
questions:
1. how the **** are these rotors WIDER than a couple other used ones?
2. who machined em? whomever did it still fucked it up
3. anyone ever seen anything like that?
he tore the motor down and all the housings look like you would expect, new. basically everything is new except the rotors, which look new but on inspection they arent.
the rotors have been machined on the flanks, theres a step around the outer oil rings where its been turned down about .003". you can see on the side of the rotor, about 1/2 way along the side seal, theres a shiny spot, on each face. also the rotor gear lands are black and chewed up. we measured the rotor, even the turned down spot the rotors out of this motor are still .003-.005" WIDER than a couple of other rotors we had lying around, even the machined part.
questions:
1. how the **** are these rotors WIDER than a couple other used ones?
2. who machined em? whomever did it still fucked it up
3. anyone ever seen anything like that?
06-02-2005, 11:42 AM
#4
Senior Member
Thread Starter
Join Date: May 2002
Location: California
Posts: 22,465
[quote name='banzaitoyota' date='Jun 2 2005, 08:24 AM']damn, shall I take a drive over to LADSON SC where the reman facility is and ask them WTF?
[/quote]
yeah, i dont really picture them machining rotors, and then b, how did they take metal off and end up with it bigger?
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yeah, i dont really picture them machining rotors, and then b, how did they take metal off and end up with it bigger?
06-10-2005, 08:04 AM
#10
Fabricator
Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
[quote name='j9fd3s' date='Jun 2 2005, 07:51 AM']so my buddy put a mana motor into a customers FD, all the housings were new except it was a rebuilt engine. engine ran fine but used about 3 quarts of oil in the first 1200miles, then the oil pan started leaking so the motor was pulled to be warrentied.
he tore the motor down and all the housings look like you would expect, new. basically everything is new except the rotors, which look new but on inspection they arent.
the rotors have been machined on the flanks, theres a step around the outer oil rings where its been turned down about .003". you can see on the side of the rotor, about 1/2 way along the side seal, theres a shiny spot, on each face. also the rotor gear lands are black and chewed up. we measured the rotor, even the turned down spot the rotors out of this motor are still .003-.005" WIDER than a couple of other rotors we had lying around, even the machined part.
[/quote]
questions:
1. how the **** are these rotors WIDER than a couple other used ones?
Rotors are different widths where they make no contact with anything. When building a screamer, you cut about .015 additional off the sides outboard of the oil scrapers to allow for crank flex. This is so the corner seal area does not touch the irons. More alarming is that seldom are the rotor housings the same width, and some are narrow enough that you need to keep one piece seals used in that housing separate from others (shorter).
2. who machined em? whomever did it still fucked it up
If damage was very light, grinding off this area might save a rotor. A lot of work to save a junk rotor. Mazda has had a poor reputation for rebuilt engines for years.
It sounds like much of this one should have been left in the dumpster.
3. anyone ever seen anything like that?
Anytime there is a major overheat of a rotor due to oil overheat or oil loss (cooling loss), the rotors grow as a function of the material they are made of.
Most often this will be the rotor getting longer since that dimention is limited by the rotor housing thickness the limit is when the gear face touches the iron.
The scraper land area will touch on the non gear side.
It is typical that an over reved rotor will walk out the gear and you will see shiny spots on the gear face. When you see this just press the gear back into the rotor and clean up the gear face with some oiled 400 and a smooth surface. Flip it over and do the non gear side as well.
When the engine is accellerated or braked hard the rotors may touch the oil film on the irons, as the 9 pound rotors cannot be supported by the seal springs. So it is normal for the two surfaces to touch.
If there has been a major melt down and the irons are blackend from lack of oil, just scrap the parts and start over again.
Lynn E. Hanover
he tore the motor down and all the housings look like you would expect, new. basically everything is new except the rotors, which look new but on inspection they arent.
the rotors have been machined on the flanks, theres a step around the outer oil rings where its been turned down about .003". you can see on the side of the rotor, about 1/2 way along the side seal, theres a shiny spot, on each face. also the rotor gear lands are black and chewed up. we measured the rotor, even the turned down spot the rotors out of this motor are still .003-.005" WIDER than a couple of other rotors we had lying around, even the machined part.
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questions:
1. how the **** are these rotors WIDER than a couple other used ones?
Rotors are different widths where they make no contact with anything. When building a screamer, you cut about .015 additional off the sides outboard of the oil scrapers to allow for crank flex. This is so the corner seal area does not touch the irons. More alarming is that seldom are the rotor housings the same width, and some are narrow enough that you need to keep one piece seals used in that housing separate from others (shorter).
2. who machined em? whomever did it still fucked it up
If damage was very light, grinding off this area might save a rotor. A lot of work to save a junk rotor. Mazda has had a poor reputation for rebuilt engines for years.
It sounds like much of this one should have been left in the dumpster.
3. anyone ever seen anything like that?
Anytime there is a major overheat of a rotor due to oil overheat or oil loss (cooling loss), the rotors grow as a function of the material they are made of.
Most often this will be the rotor getting longer since that dimention is limited by the rotor housing thickness the limit is when the gear face touches the iron.
The scraper land area will touch on the non gear side.
It is typical that an over reved rotor will walk out the gear and you will see shiny spots on the gear face. When you see this just press the gear back into the rotor and clean up the gear face with some oiled 400 and a smooth surface. Flip it over and do the non gear side as well.
When the engine is accellerated or braked hard the rotors may touch the oil film on the irons, as the 9 pound rotors cannot be supported by the seal springs. So it is normal for the two surfaces to touch.
If there has been a major melt down and the irons are blackend from lack of oil, just scrap the parts and start over again.
Lynn E. Hanover