Diagnosctic help needed

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Jun 29, 2021 | 08:19 PM

1L243

Thread Starter

Laughing Gas

Joined: Aug 2003

Posts: 836

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Diagnosctic help needed

I have a 1999 7.3 F250 2WD it ihas 229,000 miles. The original transmission.

I'm getting a little clunk sound from a start. It's a sight sound but you can almost feel it. Also if i'm moving along at speed and take my foot off the gas same thing and when I give gas same thing. The transmission shifts smooth with no apparent problems.

It sound like it coming from behind the transmission but no way to know for sure. I was thinking maybe the center drive shaft bearing?

Thoughts?

Jun 30, 2021 | 02:08 AM

85e150

Super Moderator

Joined: Apr 2004

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Check the bearing. Check the u joints. Check all slip splines. Does your transmission have a slip yoke or a fixed flange?

Jun 30, 2021 | 03:22 AM

1L243

Thread Starter

Laughing Gas

Joined: Aug 2003

Posts: 836

Likes: 7

It's a long bed it has a front slip joint that then a section of shaft to a center bearing U joint. Then the front of the rear shaft looks like another slip joint covered with a rubber dust sleeve then to the rear U joint.

A visual inspection shows nothing obvious.

Jul 1, 2021 | 12:34 AM

85e150

Super Moderator

Joined: Apr 2004

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Lock brakes, chock wheels, find a TRUSTED assistant. Have them shift P to R to N to D as you observe the drive shaft, cross members, differential etc. Repeat until you see a problem. No problem? Drive it.

Jul 2, 2021 | 05:29 AM

JWA

Fleet Owner

Joined: Aug 2010

Posts: 21,253

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From: Reynoldsburg, Ohio

^^^Or even better find a lift that contacts the frame and do that same process with wheels off the ground. Otherwise the emphasis would be on TRUSTED assistant.