Side seal clearance issues? Blow by?
03-01-13, 05:35 PM
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Side seal clearance issues? Blow by?
I recently had to pull my motor apart due to severe blow by under boost. I am running the ALS side seals at factory clearances. I am thinking of reusing the same side seals but using new 93 side seal springs. Should I be running 0 clearance instead of oem specs? Any help is appreciated. Thank you!
03-01-13, 06:09 PM
#2
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What clearance were you running? OEM clearance spec is rather wide.
What is your side seal groove clearance? I've never seen an issue there (heck, I rarely if ever measure it) but things happen.
What corner seals?
What is your side seal groove clearance? I've never seen an issue there (heck, I rarely if ever measure it) but things happen.
What corner seals?
03-01-13, 09:27 PM
#4
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OEM side seal/corner clearances for an FD is .002"-.0059" iirc (2 thou to 6 thou basically).
I wouldn't run 0 thousandths of an inch clearance personally. You're going to need *some* room for expansion while breaking the engine in else you're probably going to significantly increase the chances of breaking something.
On my build we ran on the stupidly tight side of OEM specs, and I'll be doubling up the premix amounts and being EXTRA careful for my (1000 mile) break-in period as a result. My side seal clearance is about as tight as one should go (not giving out specific tolerance due to the request of my builder/friend) and we're not touching on 0.
Also, just use the OEM (longer) seals for everything but apex seals. There really isn't any reason to go away from them.
I wouldn't run 0 thousandths of an inch clearance personally. You're going to need *some* room for expansion while breaking the engine in else you're probably going to significantly increase the chances of breaking something.
On my build we ran on the stupidly tight side of OEM specs, and I'll be doubling up the premix amounts and being EXTRA careful for my (1000 mile) break-in period as a result. My side seal clearance is about as tight as one should go (not giving out specific tolerance due to the request of my builder/friend) and we're not touching on 0.
Also, just use the OEM (longer) seals for everything but apex seals. There really isn't any reason to go away from them.
03-02-13, 08:11 AM
#7
While I am a huge fan of Edgar and the ALS seals, I don't see the need to run aftermarket side or corner seals for your goals. OEM stuff along side ALS apex seals can take some serious abuse. You will hear audible detonation well before the OEM side or corner seals will let go.
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03-03-13, 08:34 AM
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I picked up the ALS side seals because they were cheaper than oem at the moment. Everything is ready to get assembled. I am however hesitant to close this motor myself as this will be my first time. I am thinking of having a reputable builder close it and double check everything. I'm on the fence.
03-03-13, 01:18 PM
#9
blowby isn't always attributed to side seal clearances. worn endplates can allow pressure to push past the oil seals also.
look at when a rotor is over the intake port and you will realize that the rotor sides are not always sealed inside the chambers. the oil seals are exposed to intake pressure for about half of the engine rotation cycle.
if side seal clearance is an issue you will usually see carbon traces leading directly from the edges of the side to corner seal abutment. tighter is almost always better in this case, mostly when using new seals clearance them to near 0 to the point that they do not bind.
look at when a rotor is over the intake port and you will realize that the rotor sides are not always sealed inside the chambers. the oil seals are exposed to intake pressure for about half of the engine rotation cycle.
if side seal clearance is an issue you will usually see carbon traces leading directly from the edges of the side to corner seal abutment. tighter is almost always better in this case, mostly when using new seals clearance them to near 0 to the point that they do not bind.
Last edited by RotaryEvolution; 03-03-13 at 01:22 PM.
03-06-13, 08:47 AM
#11
blowby isn't always attributed to side seal clearances. worn endplates can allow pressure to push past the oil seals also.
look at when a rotor is over the intake port and you will realize that the rotor sides are not always sealed inside the chambers. the oil seals are exposed to intake pressure for about half of the engine rotation cycle.
if side seal clearance is an issue you will usually see carbon traces leading directly from the edges of the side to corner seal abutment. tighter is almost always better in this case, mostly when using new seals clearance them to near 0 to the point that they do not bind.
look at when a rotor is over the intake port and you will realize that the rotor sides are not always sealed inside the chambers. the oil seals are exposed to intake pressure for about half of the engine rotation cycle.
if side seal clearance is an issue you will usually see carbon traces leading directly from the edges of the side to corner seal abutment. tighter is almost always better in this case, mostly when using new seals clearance them to near 0 to the point that they do not bind.
Also, when you tear down a Mazda built engine they have all kinds of slop.
03-09-13, 12:49 PM
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It seems that the front rotor has one apex seal that had too much play side to side and opened it up too much? Could that have been my issue? The ALS apex seals now have sharp edges on one of the sides. Also 1 of the side seals was bent, go figure.
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