I need a motor tech
Thread Starter
|
Senior User
Joined: Sep 2002
Posts: 126
Likes: 0
From: staunton
I need a motor tech
I have a 400 in a 77 F-250. the motor had little to no compression on the front two cylinders on the passergers side. I pulled the motor out and took the head off the passengers side of the motor. Everything looked good, the cylinder walls were not scared up and the valuves were not burnt, BUT the 3rd push rod from the front was badly bent and broke and was not in use it was laying at the bottom of the head..
My question is, what would make this rod break?, can I just put another rod back in and hope everything will be right?. (This motor set for a few years) Could this boken rod have been causing the lose of compressing on both of the front 2 cylinders? or maybe the rings are stuck?
My question is, what would make this rod break?, can I just put another rod back in and hope everything will be right?. (This motor set for a few years) Could this boken rod have been causing the lose of compressing on both of the front 2 cylinders? or maybe the rings are stuck?
Posting Guru
Joined: Apr 2004
Posts: 1,127
Likes: 2
From: Lewistown, PA
If a pushrod is broken, then it won't open the valve. If the valve doesn't open, then there is not much air (or fuel) to compress, hence no or little compression.
I'm sure there are several things that can cause a push rod to break. Over reving a worn out valve train comes to mind, or inadequate lubrication.
I'm sure there are several things that can cause a push rod to break. Over reving a worn out valve train comes to mind, or inadequate lubrication.
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Timing chain could be stretched, valves could be bent, or 9 other reasons why a pushrod would break. I would turn the motor by hand and check that everything was moving as it should. Then I would take the timing cover off and replace the timing chain. Then I would take both heads to a shop and get them cleaned, sonic checked for cracks, valve guides checked, valves reseated. Then I would reassemble the motor checking the valve train for wear, or just replacing the rockers and pushrods.
