Stiff turning engine after rebuild
#1
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Stiff turning engine after rebuild
Hey all. Thanks for reading. New here and couldn't find any threads that match my problem.
Just aquired an 89 NA with carbon build up. Ripped the engine apart (wanted to learn about the rot.) Now THAT was an interesting job. Well, got my new seals and put everything back together but the engine needs about 30 ft-lbs to turn. I've mic'd everything out and it was within specs. (apex seals, housings, side seals) but when I torq. the tension bolts to about 23 ft-lbs, it gets stiff. The apex seals aren't binding so I'm guessing side seals? I speant a week Cleaning the rotors and housings and you could eat off them. All rotor seals move freely. And yes, I oiled the gears and housings before rebuild. Nothing is warped or burned.
So should it take that much pressue to rotate the engine? I don't want to finish the install and have to rip it back out - as fun as it has been
Thanks for your replies.
Just aquired an 89 NA with carbon build up. Ripped the engine apart (wanted to learn about the rot.) Now THAT was an interesting job. Well, got my new seals and put everything back together but the engine needs about 30 ft-lbs to turn. I've mic'd everything out and it was within specs. (apex seals, housings, side seals) but when I torq. the tension bolts to about 23 ft-lbs, it gets stiff. The apex seals aren't binding so I'm guessing side seals? I speant a week Cleaning the rotors and housings and you could eat off them. All rotor seals move freely. And yes, I oiled the gears and housings before rebuild. Nothing is warped or burned.
So should it take that much pressue to rotate the engine? I don't want to finish the install and have to rip it back out - as fun as it has been
Thanks for your replies.
#3
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No, but I'm not that far yet. After the tension bolts are secured, (from what the repair manual says) the eccentric shaft should turn "freely". It just feels really stiff.
Thanks AJ
Thanks AJ
#4
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I can't give you a reason or a possible cause but it should not take that much torque to turn a fresh rebuild. Even if you had spark plugs in and it was building compression it should not take 30 ft.-lbs. of torque to rotate.
Later today I will see how much torque it takes to rotate the engine in my fresh rebuild with it in the car.
Later today I will see how much torque it takes to rotate the engine in my fresh rebuild with it in the car.
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The odds might be good that you dropped a side seal on the bottom side of a rotor. Did you check the rotor bearing and stationary gear bearing clearances? Di you use all the hard parts ouf of the orignal motor or did you replace some?
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Thanks for all the great ideas... but believe me - I've done all that. Checked every seal (broke it apaprt twice) every thing is in proper placement. Nothing damaged or broken. What I may end up doing is take all the side seals out and put it back together. If that don't work I'll do the inner and outer oil seals. etc. Once it starts turning good it will give me an idea of what might be binding it.
Thanks to all !
AJ
Thanks to all !
AJ
#9
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Originally posted by fstopped
Thanks for all the great ideas... but believe me - I've done all that. Checked every seal (broke it apaprt twice) every thing is in proper placement. Nothing damaged or broken. What I may end up doing is take all the side seals out and put it back together. If that don't work I'll do the inner and outer oil seals. etc. Once it starts turning good it will give me an idea of what might be binding it.
Thanks to all !
AJ
Thanks for all the great ideas... but believe me - I've done all that. Checked every seal (broke it apaprt twice) every thing is in proper placement. Nothing damaged or broken. What I may end up doing is take all the side seals out and put it back together. If that don't work I'll do the inner and outer oil seals. etc. Once it starts turning good it will give me an idea of what might be binding it.
Thanks to all !
AJ
corner pieces on the apex seals broken off?
you know how the little corner part is glued on the
the larger part, as you torque the tension bolts they
should break off, if this isn't happening i would bet
money that is what is causing it to be hard to turn.
you may need to reglue the small bit on in a way
to make the seal longer so when you torque the bolts
the corners break off.
matt
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If the engine is stiff you may also have not put the tension bolts tight in the right order, or you have a shitty torq wrench that's screwing you up.
Another thought is that if you replaced the main rotor bearings and pressed them into the rotors at home, you might have put one or both of them in at a slight kilter.
If you did, when you tighten down the tension bolts the eccentric shaft will actually bind against the main rotor bearings and this would also make it stiff.
Another thought is that if you replaced the main rotor bearings and pressed them into the rotors at home, you might have put one or both of them in at a slight kilter.
If you did, when you tighten down the tension bolts the eccentric shaft will actually bind against the main rotor bearings and this would also make it stiff.
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