Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

 
 Reply to this topicStart new topic
> Cracked crank, Yet more problems
jeffdon
post Jun 29 2014, 02:23 PM
Post #1


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
Put my engine back together in November, and have been driving since then. Couple of 200 miles drives, mostly around town. Itts a 2056, webers, cam, nothing super high power. This weekend it started an awful clunk deep inside, and I got it off the road and towed home.

Got her puller apart, and here is what I have found. Crank broke threw the rearmost counterweight. How does this happen? So I need a new crank. What else should I replace? Obviously all main bearings. Rod bearings too?



Attached thumbnail(s)
Attached Image

Attached image(s)
Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jeffdon
post Jun 29 2014, 02:40 PM
Post #2


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
Ok, 914 guy I know had me look the thrust surface of the flywheel end main bearing. Its chewed up, so maybe I f-d up my endplay?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Jake Raby
post Jun 29 2014, 07:35 PM
Post #3


Engine Surgeon
*****

Group: Members
Posts: 9,398
Joined: 31-August 03
From: Lost
Member No.: 1,095
Region Association: South East States
Was the crank magnafluxed at assembly? That fracture appears to have been a long time coming based on the coloring around it.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jeffdon
post Jun 29 2014, 10:02 PM
Post #4


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
QUOTE(Jake Raby @ Jun 29 2014, 06:35 PM) *

Was the crank magnafluxed at assembly? That fracture appears to have been a long time coming based on the coloring around it.


No, I admit to not doing that. The next one, for sure. Don't want to go through this again. I like to think I can build an engine to spec. Just seems I may have screwy parts. This time, i am going to get everthing checked out.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mark Henry
post Jun 30 2014, 07:05 AM
Post #5


that's what I do!
***************

Group: Members
Posts: 20,065
Joined: 27-December 02
From: Port Hope, Ontario
Member No.: 26
Region Association: Canada
Most likely your case is trashed, get a new core.
If you F-ed up your endplay you should see signs of the counter weight hitting a main web.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Matt Romanowski
post Jun 30 2014, 09:46 AM
Post #6


Senior Member
***

Group: Members
Posts: 878
Joined: 4-January 04
From: Manchester, NH
Member No.: 1,507
I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).

Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jeffdon
post Jun 30 2014, 11:22 AM
Post #7


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
QUOTE(Matt Romanowski @ Jun 30 2014, 08:46 AM) *

I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).

Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....


Looks like it hit the case. Marks that look like rough machine marks, but not even like machining. Deeper at the top. Is my case toast?


Attached image(s)
Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jeffdon
post Jun 30 2014, 11:38 AM
Post #8


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
QUOTE(Jake Raby @ Jun 29 2014, 06:35 PM) *

Was the crank magnafluxed at assembly? That fracture appears to have been a long time coming based on the coloring around it.


Jake - Regarding the coloring, I am not seeing any. I would think if I had tight endplay, and it got hot, I would see some blue/yellow somewhere. Could you expoind upon your color comment a bit?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
stugray
post Jun 30 2014, 11:41 AM
Post #9


Advanced Member
****

Group: Members
Posts: 3,825
Joined: 17-September 09
From: Longmont, CO
Member No.: 10,819
Region Association: None
QUOTE
Regarding the coloring, I am not seeing any


Due to the the poor lighting in the pics, it is hard to tell if that is corrosion inside the crack.
That would mean the crack was there for quite a while.

Although it is hard to tell in the pics.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jeffdon
post Jun 30 2014, 01:12 PM
Post #10


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
QUOTE(stugray @ Jun 30 2014, 10:41 AM) *

QUOTE
Regarding the coloring, I am not seeing any


Due to the the poor lighting in the pics, it is hard to tell if that is corrosion inside the crack.
That would mean the crack was there for quite a while.

Although it is hard to tell in the pics.


No obvious corrosion that I can see.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
colingreene
post Jun 30 2014, 02:20 PM
Post #11


Senior Member
***

Group: Members
Posts: 734
Joined: 17-October 13
From: Southern California
Member No.: 16,526
Region Association: Southern California
I have a spare factory 2.0 crank if you need it let me know.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jeffdon
post Jun 30 2014, 03:23 PM
Post #12


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
QUOTE(colingreene @ Jun 30 2014, 01:20 PM) *

I have a spare factory 2.0 crank if you need it let me know.


PM sent
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
stugray
post Jun 30 2014, 04:07 PM
Post #13


Advanced Member
****

Group: Members
Posts: 3,825
Joined: 17-September 09
From: Longmont, CO
Member No.: 10,819
Region Association: None
Youd be better off getting one of the complete crank, bearings, case that was for sale recently on the WTB: parts thread.

It was a great deal ofor ~$800 for all in a matched set.

http://www.914world.com/bbs2/index.php?showtopic=236879
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Valy
post Jun 30 2014, 04:39 PM
Post #14


Senior Member
***

Group: Members
Posts: 1,677
Joined: 6-April 10
From: Sunnyvale, CA
Member No.: 11,573
Region Association: Northern California
QUOTE(jeffdon @ Jun 30 2014, 10:22 AM) *

QUOTE(Matt Romanowski @ Jun 30 2014, 08:46 AM) *

I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).

Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....


Looks like it hit the case. Marks that look like rough machine marks, but not even like machining. Deeper at the top. Is my case toast?


Those marks will not trash the case. They don't look so deep that may cause structural problems.
However, you need to check the case bore. It looks to me that the bearing has some play along the crank axle, seen on the bearing seat in the picture. It might be just the camera but you better check.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jeffdon
post Jun 30 2014, 09:55 PM
Post #15


Senior Member
***

Group: Members
Posts: 1,094
Joined: 24-October 06
From: oakland, ca
Member No.: 7,087
Region Association: None
QUOTE(Valy @ Jun 30 2014, 03:39 PM) *

QUOTE(jeffdon @ Jun 30 2014, 10:22 AM) *

QUOTE(Matt Romanowski @ Jun 30 2014, 08:46 AM) *

I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).

Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....


Looks like it hit the case. Marks that look like rough machine marks, but not even like machining. Deeper at the top. Is my case toast?


Those marks will not trash the case. They don't look so deep that may cause structural problems.
However, you need to check the case bore. It looks to me that the bearing has some play along the crank axle, seen on the bearing seat in the picture. It might be just the camera but you better check.


They seem light-ish. I have another case. Guess I could send them both out and have a shop tell me which would be the best.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Standard · Switch to: Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 9th May 2025 - 05:16 PM
Invision Power Board v9.1.4 © 2025  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...