Binder Planet
BinderPlanet

Go Back   Binder Planet Forums > General Forums > General IH Tech




Reply
 
Thread Tools Display Modes
  #1  
Old 07-17-2012, 01:17 PM
phurst phurst is offline
Farmall Cub
 
Join Date: Apr 2011
Location: Richmond, VA
Posts: 112
Default Causes of bent pushrods

Ok, bone headed dropping of a lifter into the valley aside, I was mucking about under the valve cover because of a banging noise, and a miss. The culprit was a bent pushrod. Before I slap a new one in and call it a day (assuming I ever retrieve my lifter), I'd like to figure out (or at least make a good guess) as to why the pushrod got bent in the first place. So, what are some common causes of bent pushrods?

My 196 has less than 50k miles on it, rocker arm assembly appears to be in great shape with good oiling. No scarring on the tube the rocker arms are on, and it was installed correctly, with the holes pointing up (9 stand, welded rockers). The only thing that comes to mind as far as abuse is that the PO somehow switched the #3 and #4 wires on the cap, which obviously made it run very poorly, backfiring out the carb, etc. No idea if something like that could cause a bent pushrod. What else should I be investigating before I button it all back up?
Reply With Quote
  #2  
Old 07-17-2012, 02:27 PM
RD Durham's Avatar
RD Durham RD Durham is offline
High Wheeler
 
Join Date: Oct 2001
Location: Colorado Springs, CO
Posts: 1,090
Default Re: Causes of bent pushrods

A number of items can contribute to a bent push rod.

Most common is a sticking hydraulic lifter which can end up with enough of a gap between the top of the lifter and the push rod that the push rod can get sideways and end up bent.

Metal fatigue over the years can also cause a push rod to bend.

Pretty rare but it can happen when you have a bad engine backfire. Especially on a Scout V8 numbers 5 and 7 sparkplugs fire on after the other and though rare you can get a cross fire between the spark plug wires. Shop manual specifies that number 7 sparkplug wire be routed around the carburetor and then to number 7 sparkplug while number 5 sparkplug wire goes in front of the carburetor. You can also get a sever engine back fire in a four cylinder IH engine if you have a burn out exhaust valve. The 196 I had several years back had a burned out exhaust valve and would really backfire when the engine was turned off, a few times it bent a push rod when the engine tried to run backwards after turning off the engine.
__________________
R. Dale Durham
Colorado Springs, CO

1980 Terra
392IC V8
T19 Wide Ratio
Dana 300 T-Case
Four wheel disc brakes
SOA w/2" body lift
Warn 8274 winch
On board air and welder
Optional rust, custom dents & multi-color body parts
Reply With Quote
  #3  
Old 07-17-2012, 02:41 PM
phurst phurst is offline
Farmall Cub
 
Join Date: Apr 2011
Location: Richmond, VA
Posts: 112
Default Re: Causes of bent pushrods

Ok, so I guess I really should get that lifter out to check it out. It is my understanding that it is "bad juju" to replace a lifter though. Something about it causing rapid cam wear.
Reply With Quote
  #4  
Old 07-17-2012, 02:42 PM
phurst phurst is offline
Farmall Cub
 
Join Date: Apr 2011
Location: Richmond, VA
Posts: 112
Default Re: Causes of bent pushrods

Here is the offending rod, by the way.

Reply With Quote
  #5  
Old 07-17-2012, 03:05 PM
jauringer's Avatar
jauringer jauringer is offline
High Wheeler
 
Join Date: Mar 2011
Location: Tyler,tx
Posts: 1,485
Default Re: Causes of bent pushrods

Quote:
Originally Posted by phurst View Post
Ok, so I guess I really should get that lifter out to check it out. It is my understanding that it is "bad juju" to replace a lifter though. Something about it causing rapid cam wear.

It's "bad juju" to install a new cam and run the old lifters. It's fine to install new lifters with an old cam.

Might as well pull them all and either clean and check, or replace them while you're in there. Check the bottoms for cupping as well.

BTW: I went through the entire process of tearing mine apart, cleaning, and then putting them back together just to buy a new set for $100 and be done with it. IMO, it's not worth the effort being 40 year old lifters. (assuming yours are OE)

Jason
__________________
72 Scout II - Flame Red
SV313/TBI-7747/727-TF2/D20-Twin stick
Reply With Quote
  #6  
Old 07-17-2012, 03:57 PM
Afireinside2285 Afireinside2285 is offline
High Wheeler
 
Join Date: Nov 2003
Location: colorado
Posts: 1,613
Default Re: Causes of bent pushrods

The only one I ever bent was running very old varnished gas,which I guess caused the lifter to stick. I replaced it and drove the scout for many months after till I sold it.

Good luck
Reply With Quote
  #7  
Old 07-17-2012, 04:04 PM
Bill USN-1's Avatar
Bill USN-1 Bill USN-1 is offline
Moderator
 
Join Date: Dec 2002
Location: Whidbey Island, WA
Posts: 14,923
Default Re: Causes of bent pushrods

A sticking valve in the valve guide or a piece of carbon holding the valve open can also cause it.
A sticking valve is pretty common on an engine that has sat for a while.

If the bottom of the lifter is worn to a cup, chances are good that the cam lobe is bad also.
You can put a new lifter in but it won't last long and will just put more metal in the oil.

Best to just replace the cam and lifters, use break in lube and use an oil with plenty of zinc(ZDDP) or use a zinc additive in every oil change.
__________________
Bill USN-1


Click a link below that meets your needs! Either DIY or let me help.

COMMITED TO HELPING PEOPLE "PROPERLY" INSTALL EFI
Learn to do it right.


May be the answer to all your fuel injection needs!


WANTED-Holley Distributor
Reply With Quote
  #8  
Old 07-17-2012, 04:11 PM
Mark Pietz Mark Pietz is offline
High Wheeler
 
Join Date: May 2003
Location: Foresthill, CA
Posts: 1,174
Default Re: Causes of bent pushrods

Once I floated the valves on a freshly rebuilt 196. Pistons kissed some of the valves, and it took me a while to figure out while I kept dropping odd pushrods - some rocker arms (early style) had cracked and the damage was invisible until the loading from higher rpms opened the cracks, letting the rods drop into the engine. Of course, some of them looked like pretzels when I retrieved them from the bottom of the pan.
__________________
IC 196, 4-speed, 3.73 gears
Reply With Quote
  #9  
Old 07-17-2012, 04:43 PM
phurst phurst is offline
Farmall Cub
 
Join Date: Apr 2011
Location: Richmond, VA
Posts: 112
Default

Ok, lifter is out, and a new set of lifters and pushrods will be at the parts store in the AM. Is there an easy way to check for a stuck valve? Do I need a spring depresser?

Sent from my ADR6350 using Tapatalk 2
__________________
1969 Scout 800A, 196, 3 speed.
Gallery: http://s42.photobucket.com/user/pear.../library/Scout
Reply With Quote
  #10  
Old 07-17-2012, 09:50 PM
Bryan G's Avatar
Bryan G Bryan G is offline
Farmall Cub
 
Join Date: Apr 2007
Location: Federalsburg, MD
Posts: 244
Default Re: Causes of bent pushrods

Back around 1980 my Dad was goofing around in the Country Squire, driving fast up our gravel driveway then locking up the brakes and getting her sideways. In the process the engine shut off and when he restarted it he found it had bent a rod, or several as I recall. Never did get an explanation of just why.
__________________
1967 Impala 283
1974 '100' 258
Reply With Quote
Reply

Tags
100 , 196 , backfire , cam , cap , carb , carburetor , cylinder , engine , exhaust , front , gap , hydraulic , ignition , manual , number , rare , scout , shop , shop manual , top , tube , valve , valve cover , wires

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Ever seen where boat rocker pushrods too short? sdowney717 General IH Tech 3 01-15-2012 05:42 AM
345 Bent Pushrods Bicyclebob General IH Tech 33 04-02-2011 01:52 PM
bent pushrods buggerbear General IH Tech 4 10-31-2006 03:28 PM
Mandrel Bent Exhaust... Doug Shailor General IH Tech 4 12-01-2005 07:09 AM
Lifter Type (Broken Pushrods) PatL General IH Tech 2 12-27-2004 01:55 PM



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.

The IH logo, the "IHC" logo, are trademarks respectfully of the International Truck & Engine Corporation and the Case New Holland Corporation.
They are used for identification purposes only.

BinderPlanet® Copyright ©2011