Strange sound from rebuilt engine...
03-09-2013, 03:19 PM
#392
Burning Brakes
Thread Starter
On initial inspection it appears the crankshaft is toast. Admittingly, I am using a crude measurement technique (digital calipers) but the journals appear out of round. The specification is 54.971mm to 54.990mm.
One sample measurement:
Journal Diameter Axis 1: 54.9x (within spec)
Journal diameter axis 2 (90 degrees from axis one): 54.2x (way out of spec)
One sample measurement:
Journal Diameter Axis 1: 54.9x (within spec)
Journal diameter axis 2 (90 degrees from axis one): 54.2x (way out of spec)
03-09-2013, 05:12 PM
#394
Burning Brakes
Thread Starter
03-09-2013, 05:19 PM
#395
Rennlist Member
It should turn very smoothly. The concern is if some small metal chips managed to get through the pick up screen and into the scavenge pump. The gears should look smooth when view through the ports as the shaft is turned.
03-09-2013, 05:29 PM
#396
RL Technical Advisor
Peter.
Yessir,......you will need another good, used std/std crank and a set of used rods.
I see some case fretting that should be closely inspected, too.
The oil pump should get disassembled and the case inspected for any scoring since these are Mg.
Yessir,......you will need another good, used std/std crank and a set of used rods.
I see some case fretting that should be closely inspected, too.
The oil pump should get disassembled and the case inspected for any scoring since these are Mg.
03-09-2013, 06:04 PM
#397
Rennlist Member
03-09-2013, 07:51 PM
#400
Three Wheelin'
03-09-2013, 08:01 PM
#401
Three Wheelin'
Well I Googled it,and I think he is concerned with the unusual wear pattern above the second crank bearing from the right. Could be a sign of hair line cracks or fracture. That's my guess anyway. Just trying to learn something new.
Emerald
Emerald
03-09-2013, 08:17 PM
#402
RL Technical Advisor
The case halves shuffled against themselves pretty hard in that area as well as some light fretting on others.
Race engines get shuffle-pinned in two places on each main bearing web to help prevent this, but that's overkill for street motors.
In this situation, it deserves a closer look and examination.
03-09-2013, 08:43 PM
#403
Burning Brakes
Thread Starter
I had to google it too. Photo supplied via the interwebs.
Fretting is a special wear process that occurs at the contact area between two materials under load and subject to minute relative motion by vibration or some other force.
Last edited by Vorsicht; 03-09-2013 at 10:09 PM.
03-09-2013, 08:47 PM
#404
Gordo
03-09-2013, 11:40 PM
#405
Rennlist Member
Peter, the IMS bearing looks beat (not related to anything you did) so a minor consolation in splitting the case is you avoided another tear down. Glad that suggestion paid off. Just one of those "been there done that" scenarios.