7.3 IDI engine with 5 bent push rods on one side? - Diesel Forum - TheDieselStop.com
7.3L IDI Diesels (Not Power Strokes) Technical discussion of topics related to vehicles powered by the 7.3 Liter In-Direct Injection Navistar engines.

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Old 10-01-2006, 02:01 PM Thread Starter
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7.3 IDI engine with 5 bent push rods on one side?

I recently purchased a non running 1992 Ford F-series truck w/7.3 diesel engine, 90,000 miles and the drivers side valve cover was off and about five of the eight push rods were moderately bent. I have not checked under the other valve cover yet! Can anyone recommend the steps to take to find out why this happened? The Government owned the truck and they just turned it in for a replacement truck, it sat for a year and they don't remember what happened to it. Should I pull the head/s first? Why would so many push rods bend? water in the fuel? I think a leaking head gskt may cause one or two push rods to bend but, five? I would pull the heads but it may be better to leave them on to diagnose the problem? any help with this would be appreciated. Thanks!
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Old 10-01-2006, 05:42 PM
 
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Re: 7.3 IDI engine with 5 bent push rods on one side?

[ QUOTE ]
The Government owned the truck

[/ QUOTE ]

thats what happend to it ! [img]/ubbthreads/images/graemlins/smile.gif[/img]
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Old 10-01-2006, 10:04 PM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

My guess is that your timing chain is broke thus throwing your engine out of sync.

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Old 10-01-2006, 10:43 PM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

What timing chain? and where is it located.

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Old 10-01-2006, 11:15 PM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

Have you tried turning the motor over by putting a socket and flex handle on the front crank shaft pulley? The motor could be cavitated or it could have a cracked head. You may as well pull the head and see what the cylinder walls look like. If it's been sitting for a year with water in a cylinder it'll need to be overhauled anyway.


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Old 10-01-2006, 11:22 PM
 
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Re: 7.3 IDI engine with 5 bent push rods on one side?

[ QUOTE ]
What timing chain? and where is it located.

[/ QUOTE ]

they run a Chain??? I thought it was all Gears.

Front of the Engine, have to pull the water pump off, Harmonic damper and the nthe front cover can come off.

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Old 10-01-2006, 11:59 PM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

You're correct. All gears.
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Old 10-02-2006, 12:05 AM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

I would pull the other side and check them,replace the bent ones and any suspect rocker arms, drain the oil and change the filter and try to run it. I saw one that a guy used to start it and go cold and the excess oil pressure caused the lifters to pump up and bend some push rods. Turned out the relief was stuck, nothing else was hurt in that instance, good luck

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Old 10-02-2006, 12:56 PM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

I stand corrected. The GM diesel has a timing chain where the Ford is all gear driven. I would still start with timing marks and then go to the gears themselves. Push rods don't just bend from usage, they bend because they are not in sync with the cam.

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Old 10-02-2006, 03:38 PM
 
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Re: 7.3 IDI engine with 5 bent push rods on one side?

Bent pushrods are caused by two things one stuck valve in guides, but 5 valves,not possible second was to over rev engine and float the valves, if the govenor in the IP pump is working it should not overspeed, but that is where human error comes to play, like downshift in too low of gear going down hill will overspeed engine. Do a cylinder leakage test on the each cylinder make sure it did't hit any pistons or bend any valves, maybe you can get by with just replaceing push rods. Once started chech the governed speed make sure it works.
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Old 10-02-2006, 04:29 PM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

What is moderatly bent? I know I had 6-7 that I replaced because they wouldn't roll across my table saw top (flattest thing I could find at the time). I'm talkin maybe a 1/16".

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Old 10-02-2006, 06:54 PM
 
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Re: 7.3 IDI engine with 5 bent push rods on one side?

They bend because they hit the pistons. Your being new to these motors is not a problem. We all started where you are. First off the pistons clearance between the head and itself is .030... Now thats about 10 pieces of notebook paper. Not much room for anything. You will probably end up pulling the heads. If so pull the motor. Its so much easier. There is an easy way to remove the motor if you go that way. I wont talk about it now. Sometimes the lifters break up and cause the valves to kiss the pistons too. These lifters are roller lifters. The same type are in the early chevys and the powerstrokes. The best thing to do is turn the motor over by hand and see whats going on. Then post back what you see. Plenty of help here....
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Old 10-02-2006, 10:16 PM
 
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Re: 7.3 IDI engine with 5 bent push rods on one side?

[ QUOTE ]
If so pull the motor. Its so much easier. There is an easy way to remove the motor if you go that way. Sometimes the lifters break up and cause the valves to kiss the pistons too.

[/ QUOTE ]

I know this all too well. I have a set of new heads sitting in the living room. And looking at my current situation, yeah pull the motor. BTW-you can get the oil pan off while the block is in the truck. [img]/ubbthreads/images/graemlins/biggrin.gif[/img]
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Old 10-05-2006, 07:10 AM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

Hydrolock would cause your bent rods.The air breather is known for letting water in through the wing nut if the rubber seal is cracked or missing,the hood seals go bad as well which allows water to sit on the breather cover.It only takes a small amount of water to hydrolock and bend a few rods.

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Old 10-06-2006, 12:38 AM
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Re: 7.3 IDI engine with 5 bent push rods on one side?

Being as it was a gov truck I would side with over reving....could be someone tried to blow it up screwing around.


I would advise pulling the engine and checking things out......




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