What to do about brittle plastic parts

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Aug 2, 2023 | 11:27 AM

CajunX

Thread Starter

Mountain Pass

Joined: May 2023

Posts: 121

Likes: 14

What to do about brittle plastic parts

So I'm playing around under the hood of my 7.3 Ex, and I notice the wiring harness connector that is located adjacent to the fuse panel is drooping. Upon closer inspection, the plastic that holds the connector has broken off. I check the other harness next to is, and sure enough, that plastic is brittle to the touch.

I poke the fuse panel. The plastic tabs that keep the lid on are brittle and some parts are broken and missing.

I just bought this Ex with 230k miles. My other 2 Ex's are V10's and don't have brittle plastic (yet). All are lifetime Texas trucks. I guess the diesel runs hotter and has taken a toll on the plastic.

Short of replacing it, has anyone else had this problem and come up with a DIY mod to keep this stuff together? I need to keep the water out of the fuses and keep the harnesses from flopping around.

Aug 3, 2023 | 05:35 AM

01__Excursion

Cargo Master

Joined: Nov 2017

Posts: 3,096

Likes: 534

From: Rock Hill, SC

Are you referring to the 42 pin big square plug at the rocker cover? Sounds like junkyard time.

Aug 3, 2023 | 07:58 AM

pirate4x4_camo

Lead Driver

Joined: Apr 2011

Posts: 8,259

Likes: 346

From: Northern California

Pic of the part in question will help,

if it’s the 42 pin harness you Will definitely want to address this ASAP. Strain relief is critical on all points of the 7.3 engine harness. The 7.3 engine harness is extremely robust butHeat and vibration take their toll, typically damage happens when someone is working in the engine compartment and not mindful of the harness. Not uncommon to have running issues crop up after working on something completely unrelated simply because you unknowingly bumped the harness and the brittle wire insulation cracks creating a random short.

typically the broken wire is within 6” of the connector. Motorcraft sells Replacement connectors and pig tails and new complete harness are available if rebuilding yours is beyond your skill. ( finding the quality components is the hard part as they are not run of the mill stuff available at retail. )

the fuse box lids are notorious. I’ve replaced mine twice but they just break.
Now I just leave it resting on top with some foil HVAC tape securing it.

Aug 3, 2023 | 10:41 AM

DrPepper 2

5th Wheeling

Joined: Apr 2021

Posts: 29

Likes: 17

From: NW, IL

Cajun, while you are under the hood check the wire harness that runs over the drivers side valve cover.
My 02 F350 started running like it only had 4 cylinders working on the way to work. I limped it to work and started checking the wire looms. The one on the drivers side had bare wires where the insulation wore off and was shorting out on the valve cover. I also found the plug for the injectors/glow plugs that go to the valve cover gasket was partialy melted/broken so I replaced both valve cover gaskets with Doorman gaskets which emilinates the plug and loom inside the cover.

Amazon.com: Dorman 615-201 Engine Valve Cover Gasket Compatible with Select Ford / IC Corporation / International Models , Black, Left, Right : Automotive