Question / Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cjj737 · 03-22-2013, 02:50 PM

I have 67 C10 LWB 250 CI.

The other day i was looking at my engine and ujust happened to grab my fan and give it a lil wiggle back and forth in direction of rotation. To my suprise it moved about half an inch in each direction. My guess is that the crank key has sheered and is alowing it to rotate.

Any suggestions.

Davemotohead · 03-22-2013, 03:16 PM

Think your fan hooks to your water pump and not the crank? It will also spin as the fan belt will slip.

cdowns · 03-22-2013, 03:39 PM

maybe buy yourself a service manual with pictures

cjj737 · 03-22-2013, 04:23 PM

i do understand that the fan will spin but. the crank pully moves when i move the fan and yes i know the fan is connected to the water pump.

Davemotohead · 03-22-2013, 04:29 PM

sometimes you can turn the entire crank easy if the fan grabs the belt,I often turn my crank by grabing the fan belt and giving it a pull, pull off the pully if you think the keyway is bad and check?

cjj737 · 03-22-2013, 04:33 PM

My guess is keyway i can move it with one finger.

haysonj · 03-22-2013, 04:50 PM

Quote:

Originally Posted by cjj737

My guess is keyway i can move it with one finger.

If is is spinning on the crank your alt light would be on and more than likely it would be over heating

cjj737 · 03-22-2013, 05:13 PM

my volt meter is still registering volts and it has not died yet.

Faribran there is a bolt in the crank pully not sure when it was put in. i picked up the truck last july.

haysonj · 03-22-2013, 05:25 PM

Quote:

Originally Posted by cjj737

my volt meter is still registering volts and it has not died yet.

Faribran there is a bolt in the crank pully not sure when it was put in. i picked up the truck last july.

That is probably why someone put the bolt in because the snout on the crank is worn. You could be lucky and the inside of the dampner is what is worn

Davemotohead · 03-22-2013, 04:36 PM

Take the Pully bolt out and then look at the crank when you spin the pully and see if its spinning on the crank?

faribran · 03-22-2013, 04:59 PM

there is no pulley bolt unless someone has drilled and tapped it... sounds like something is not quite right...

hyatt · 03-22-2013, 05:10 PM

I have seen what you are talking about before When you remove balancer keyway in crank will probally be bad Balancer will probally come off with your hands If crank is tapped for a bolt epoxie a new key in crank and replace balancer If not tapped see if you can tap it for a bolt Otherwise you will have to replace crankshaft The only other alternative (and not a proper fix)is to spot weld balancer to crank to get you by until you can pull engine and fix it right

cjj737 · 04-15-2013, 03:03 PM

Quote:

Originally Posted by cjj737

I have 67 C10 LWB 250 CI.

The other day i was looking at my engine and ujust happened to grab my fan and give it a lil wiggle back and forth in direction of rotation. To my suprise it moved about half an inch in each direction. My guess is that the crank key has sheered and is alowing it to rotate.

Any suggestions.

so sunday i decided to change water pump and hoses. and find out why my balancer rotates a half an inch each direction. this is what i found..

**Ol Blue K20** · 04-15-2013, 03:12 PM

Quote:

Originally Posted by cjj737

so sunday i decided to change water pump and hoses. and find out why my balancer rotates a half an inch each direction. this is what i found..

Yep.... that would do it, it should have been leaking alot of oil as well the seal has grooved the snot out of it.

cjj737 · 04-15-2013, 04:03 PM

oh yes she was covered in caked on oil i was putting about a quart a week in.

cjj737 · 04-15-2013, 04:08 PM

so can this crank be save any thoughts

**TBONE1964** · 04-15-2013, 05:20 PM

The crank needs to be repaired which means the crank has to come out of the engine and be welded and repaired by a machinist.

If you put a new balancer on that crank without repairing it, the same thing will happen again.

From the photo you posted, it already looks like someone tried to do a "get by for now" repair.

**Ol Blue K20** · 04-15-2013, 05:51 PM

That keyway looks to be wollered out. It also looks like someone tryed to peen it with a centerpunch to tighten things up. I hate to say it.. pull it out and get a crank or have that one repaired

cjj737 · 04-15-2013, 08:42 PM

yeah thats what i might have to do but not sure if a machine shop can fix that.???
also thinking of getting a rebuild one to drop in place but being active duty navy kind of hard on the pocket...

03-22-2013, 02:50 PM	#1
cjj737 Registered User Join Date: Dec 2009 Location: mohave valley az Posts: 23	Question / Help I have 67 C10 LWB 250 CI. The other day i was looking at my engine and ujust happened to grab my fan and give it a lil wiggle back and forth in direction of rotation. To my suprise it moved about half an inch in each direction. My guess is that the crank key has sheered and is alowing it to rotate. Any suggestions.

03-22-2013, 03:16 PM	#2
Davemotohead Registered User Join Date: Sep 2011 Location: rosamond ca Posts: 130	Re: Question / Help Think your fan hooks to your water pump and not the crank? It will also spin as the fan belt will slip. __________________ edited by staff Last edited by Davemotohead; 03-22-2013 at 03:44 PM.

03-22-2013, 03:39 PM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Question / Help maybe buy yourself a service manual with pictures __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

03-22-2013, 04:23 PM	#4
cjj737 Registered User Join Date: Dec 2009 Location: mohave valley az Posts: 23	Re: Question / Help i do understand that the fan will spin but. the crank pully moves when i move the fan and yes i know the fan is connected to the water pump.

03-22-2013, 04:29 PM	#5
Davemotohead Registered User Join Date: Sep 2011 Location: rosamond ca Posts: 130	Re: Question / Help sometimes you can turn the entire crank easy if the fan grabs the belt,I often turn my crank by grabing the fan belt and giving it a pull, pull off the pully if you think the keyway is bad and check? __________________ edited by staff

03-22-2013, 04:33 PM	#6
cjj737 Registered User Join Date: Dec 2009 Location: mohave valley az Posts: 23	Re: Question / Help My guess is keyway i can move it with one finger.

03-22-2013, 05:13 PM	#8
cjj737 Registered User Join Date: Dec 2009 Location: mohave valley az Posts: 23	Re: Question / Help my volt meter is still registering volts and it has not died yet. Faribran there is a bolt in the crank pully not sure when it was put in. i picked up the truck last july.

03-22-2013, 04:36 PM	#10
Davemotohead Registered User Join Date: Sep 2011 Location: rosamond ca Posts: 130	Re: Question / Help Take the Pully bolt out and then look at the crank when you spin the pully and see if its spinning on the crank? __________________ edited by staff

03-22-2013, 04:59 PM	#11
faribran Registered User Join Date: Jul 2005 Location: AL Posts: 1,828	Re: Question / Help there is no pulley bolt unless someone has drilled and tapped it... sounds like something is not quite right... __________________ "

03-22-2013, 05:10 PM	#12
hyatt Registered User Join Date: Dec 2012 Location: sparta tennessee Posts: 345	Re: Question / Help I have seen what you are talking about before When you remove balancer keyway in crank will probally be bad Balancer will probally come off with your hands If crank is tapped for a bolt epoxie a new key in crank and replace balancer If not tapped see if you can tap it for a bolt Otherwise you will have to replace crankshaft The only other alternative (and not a proper fix)is to spot weld balancer to crank to get you by until you can pull engine and fix it right __________________ 1946 car hauler 1948 surburban 1937 chevy sedan 1940 olds sedan (project) 1967 ss396 chevelle 1999 dually crewcab(24000 miles)

04-15-2013, 04:03 PM	#15
cjj737 Registered User Join Date: Dec 2009 Location: mohave valley az Posts: 23	Re: Question / Help oh yes she was covered in caked on oil i was putting about a quart a week in.

04-15-2013, 04:08 PM	#16
cjj737 Registered User Join Date: Dec 2009 Location: mohave valley az Posts: 23	Re: Question / Help so can this crank be save any thoughts Attached Images Last edited by cjj737; 04-15-2013 at 04:17 PM.

04-15-2013, 05:20 PM	#17
TBONE1964 Cluster King Join Date: Nov 2012 Location: Junction City, OR Posts: 5,263	Re: Question / Help The crank needs to be repaired which means the crank has to come out of the engine and be welded and repaired by a machinist. If you put a new balancer on that crank without repairing it, the same thing will happen again. From the photo you posted, it already looks like someone tried to do a "get by for now" repair.

04-15-2013, 05:51 PM	#18
Ol Blue K20 Proprietor of Dale's Corner Join Date: Nov 2012 Location: Vacaville , CA Posts: 16,245	Re: Question / Help That keyway looks to be wollered out. It also looks like someone tryed to peen it with a centerpunch to tighten things up. I hate to say it.. pull it out and get a crank or have that one repaired __________________ "Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man R.I.P. FleetsidePaul

04-15-2013, 08:42 PM	#19
cjj737 Registered User Join Date: Dec 2009 Location: mohave valley az Posts: 23	Re: Question / Help yeah thats what i might have to do but not sure if a machine shop can fix that.??? also thinking of getting a rebuild one to drop in place but being active duty navy kind of hard on the pocket...



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