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post #1 of 10 (permalink) Old 07-06-2017, 01:11 PM Thread Starter
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Bad cam 7.3?

People that I have spoken with about the problems my truck is having say that they have never seen a bad cam in a 7.3. Not getting any compression from one valve. Seems like the cam could be wiped - Lose almost all the way around then when it gets to the top it finally tightens up
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post #2 of 10 (permalink) Old 07-06-2017, 01:40 PM
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Re: Bad cam 7.3?

I'm not too familiar with the 7.3 but I'm assuming it's got hydraulic lifters? That's probably more likely, but it could be a bad lobe.

If the lifters is fine and nothing's bent, then yeah, the lobe is shot.

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post #3 of 10 (permalink) Old 07-06-2017, 02:12 PM
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Re: Bad cam 7.3?

I would inspect the push rod first. Then I would pull the head. I don't think you can get to the lifter with it on. Does the valve stick up as high as the others.

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post #4 of 10 (permalink) Old 07-10-2017, 01:32 AM
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Re: Bad cam 7.3?

I vote push rod as well, a little more common than a cam.

I've only heard of a cam breaking once, and it broke in 3 places, as well as the crank, and the block...


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post #5 of 10 (permalink) Old 07-10-2017, 02:50 AM
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Re: Bad cam 7.3?

And if it is a wiped cam what caused it to wipe most likely has a head problem. Ie stuck valve that is most common cause of cam failures.

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post #6 of 10 (permalink) Old 07-10-2017, 04:05 AM
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Re: Bad cam 7.3?

The 7.3 has the same lifters as the 6.0 and 6.4. They have been know to wipe out a cam. The main reason is the cam profile is pretty aggressive in the 6.0 causing the lifter to jump and start to break the roller. I've never heard about a 7.3 having that issue but it's possible.

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post #7 of 10 (permalink) Old 07-10-2017, 04:27 AM
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Re: Bad cam 7.3?

I vaguely remember reading somewhere the lifter for our 7.3 is the same in a LOT of v8 engines out there, most commonly being the Chevy 350.


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post #8 of 10 (permalink) Old 07-10-2017, 04:28 AM
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Re: Bad cam 7.3?

Although wiping out a cam lobe is fairly rare, it does happen. I've seen it several times, usually from a roller seizing up or lack of oil or both. I've only seen one cam break, but that was do to not torqing in the correct sequence.

It's a fairly simple process. Pull the valve covers, if nothing's bent then turn the engine over, by hand or cranking and watch the rockers. Find the one that doesn't move and get some eyes on the lifter. If it's pumped up, you got a bad cam.

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post #9 of 10 (permalink) Old 07-10-2017, 04:35 AM
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Re: Bad cam 7.3?

Quote:
Originally Posted by Sbluke55 View Post
The 7.3 has the same lifters as the 6.0 and 6.4. They have been know to wipe out a cam. The main reason is the cam profile is pretty aggressive in the 6.0 causing the lifter to jump and start to break the roller. I've never heard about a 7.3 having that issue but it's possible.
Yeah i have seen 6.0l wipe cams when lifters fail but have never seen it in a 7.3l I have seen valve failures in 7.3l. But there's always a first time for anything.


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post #10 of 10 (permalink) Old 07-10-2017, 04:50 AM
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Re: Bad cam 7.3?

Someone mentioned installed height. That's a really good point, pay close attention to that because it's very hard to see the difference sometimes. Though I suspect a hanging valve would do some very noticeable damage in a diesel, but still look out for it. It could be hanging a tiny bit.

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