Bent push rod

showcrop

Well-known Member
I have a bent push rod on my 172 diesel. I got it bent back to 1/32 - 1/16 out of straight. I know that it will not be as strong as perfectly straight if there is such a thing in a fifty year old motor, and I know that it will be slightly more likely to bend than a new one, and that it is still apart so why not wait a week for a replacement and so on and so on. But is it really something to worry about or is there 10 times as much strength as really needed built into them in the first place?
 
I would play with it a little more. A guy could get it to within a couple thou of being straight pretty easily.
Then run it and look for a used one for a spare.
Larry D would probably have one if you need it.
 
I have straightened a lot and reused them over the years on a lot of different engines. I don't see any reason not to give it a try.
 
(quoted from post at 17:20:56 04/14/13) What caused it to bend?

I would like to say it was a gremlin that slipped it out of place as I was tightening the rocker arm assembly down but it was actually wrench operator error.
 
Are they the same as the gassers?I got a parts engine out back that
i would gladly pull one for you and send free of charge.Email is
open.

Vito
 
(quoted from post at 20:38:58 04/14/13)
(quoted from post at 17:20:56 04/14/13) What caused it to bend?

I would like to say it was a gremlin that slipped it out of place as I was tightening the rocker arm assembly down but it was actually wrench operator error.
I've been in front of that mirror.
Doesn't feel good, but at least you don't have to wonder what
happened to cause it or worry that it may happen again. :)
 
(quoted from post at 17:53:37 04/14/13) Are they the same as the gassers?I got a parts engine out back that
i would gladly pull one for you and send free of charge.Email is
open.

Vito

Vito I checked the parts book, they are the same. That would be great if you could send it. I don't see your email address. mine is [email protected]

Colin
 
The push rod is loaded in compression and will fail by buckling (bending). Since the pushrod is pre-bent you can think of it as beginning to fail, similar to a part that is cracked.

If it was up to me I would replace the push rod. A 0.060" bend seems like a lot to me, 0.020" - 0.030" or less well...maybe in a tractor.
 
Been wrenching 40 years and have hammered on a few push rods myself... I don't remember ever seeing one fail .
Theirs nuttin wrong with replacing it if I had one are could easily get one.

My experience with diesels is very little if that makes a difference in this case...
 
My buddy just did the same thing on 4020 rebuild. He cranked the shaft down before loosening the rocker arms.
 
i'd replace it.

when mine bent on my gasser.. I had 1 i tried to fix as it was only bowed a hair.. it kept throwing of fmy adjustment. many i got salvage from john smith.. that last one cmae from cnh.

them later ones should be the round ball style bottom and cup top.. not the button bottom. should also be the wide ones.. 2 piece adjuster. I wouldn't mix styles..e tc.
 

From the "King of bent push rods" LOL, I'll take it. I was hoping you would chime in. I got two ordered from ebay. they are the same type.

Colin
 
at least with replaced ones.. you'l know.. and won't be wondering if you not getting correct valve movement.. etc..
 

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