@RedZilla any chance you want to take a side by side picture of the plug ends so when we can see the difference in size? Doesn’t have to be tonight 
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.7.3L spark plug/coil wire failure
- OP 🔹 Stonegrey20
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Just looked up spark plugs and wires for the Ford F53 motorhome chassis. Both the WR6164 (our trucks) and WR6167 wires are specified for the chassis depending on the application. Based on a number designation, there's two versions of the motorhome chassis and the plugs and wires specified for each are different. Both plug models and wire models have the same application date of 01/20/2020. The spark plugs are obviously different in appearance. Again probably the reason for the different size of heat shields.
There's a definite difference in the angle of he heat shield. The size of the spark plug boot end is not that much different, just slightly smaller on the truck version. And of course the spring in front of the boot on the chassis version. Also the rubber boot on the chassis version has a slight thicker wall and a different shape than the truck version. Obviously they put all these differences into the designs for a reason. Which one is more durable is a guess as far as I know. The engineers could probably explain it very clearly.
Thanks for the pictures!
I'm trying to follow along from home and I'm a little slow. Are the new wires that you just purchased the ones with the spring and the greater degree of angle? If so, the angle would seem to move the wire further away from the block potentially allowing more air between it and the engine.
Yes. The WR-6167 has the spring. Those are the ones @RedZilla just bought. They are found in some motorhome chassis 7.3’s.
You got it buddy. Actually both part numbers are still specified for Ford RV chassis, depends on the version. But the RV plug wires I received have a spring on the boot end.
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Thank you for the pics @RedZilla ! I want to add some additional clarity, however. This may be a bit nit-picky but the details are important in the designation between the various versions of plug wires. The "C" wires available through service (LC3Z prefix) are the ones designed for motorhome/chassis usage. The wires used in production with an "MB" suffix are not "C" wires. There is clearly some design evolution, certainly using some of the features from the chassis design. Comparing pictures supports this. The MB release level does appear to have an increase in diameter around the area of the bend, not exactly the same as the JB/C version but learning from that design. I don't immediately recall hearing about a failed MB, though I should reread this entire thread again!
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No, see my post above yours for explanation.
Maybe this will help clear it up… lots of part numbers and pictures being thrown around and it all gets confusing.
WR-6163 is the same as LC3Z-12286-A
See picture below. These plugs were installed on previous 7.3 trucks but are not the same as what our trucks are shipping with now. I do not believe these were the faulty plug wires. I believe these are the updated version that were used to replace the original defective wires. These 6163’s are seen in the TFL video. All of these wires have an “LB” designation on the plug wire.
WR-6164 is the same as LC3Z-12286-B
See picture below. These are the current wires being installed by ford on our engines. These wires have gone through at least one revision and possibly 2 since the faulty wires were used. All of these wires have an “MB” designation on the plug wire.
WR-6167 is the same as LC3Z-12286-C
These are another revision of the plug for the 7.3 that are only found on some select for chassis and motorhome platforms. None of our trucks have these installed from the factory. Reference @RedZilla’s picture on page 7 and you can see the bag with the part number and different plug inside. These wires have a “JB” designation on the plug wire.
@Modman : am I missing anything or do you believe this is all correct to help simplify it?
WR-6163 is the same as LC3Z-12286-A
See picture below. These plugs were installed on previous 7.3 trucks but are not the same as what our trucks are shipping with now. I do not believe these were the faulty plug wires. I believe these are the updated version that were used to replace the original defective wires. These 6163’s are seen in the TFL video. All of these wires have an “LB” designation on the plug wire.
WR-6164 is the same as LC3Z-12286-B
See picture below. These are the current wires being installed by ford on our engines. These wires have gone through at least one revision and possibly 2 since the faulty wires were used. All of these wires have an “MB” designation on the plug wire.
WR-6167 is the same as LC3Z-12286-C
These are another revision of the plug for the 7.3 that are only found on some select for chassis and motorhome platforms. None of our trucks have these installed from the factory. Reference @RedZilla’s picture on page 7 and you can see the bag with the part number and different plug inside. These wires have a “JB” designation on the plug wire.
@Modman : am I missing anything or do you believe this is all correct to help simplify it?
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Not having a full understanding of he design progression and what the numbers stood for, I guess my approach was to specifically purchase the items that were designated for the RV chassis (WR-6167) because I felt the problem of overheating plug wires/failure first showed up and was more directly being addressed in those applications. I certainly don't have a full understanding and am going off pieced together info from numerous sources. Mine is a bit of an experiment, maybe an investment, just in case my originals fail. I honestly don't anticipate a failure, but being my luck some likely would fail right when we are desert or mountain traveling with trailer in tow.
For the peace of mind of other 7.3 owners, it appears Ford has introduced a progression of a design change as far back as my truck build in Mar. of 2021. I hope this eases folks fears of still getting the original failed plug wires on their new orders. And if they do there is one additional part number available to try.
One other nuance I'm recognizing between the two plug wires I shared pictures of above. I will refer to them as truck wires and RV wires. The truck wire has a heat shield that seems to clip onto the outside of the spark plug. On the other hand the RV wire has an "alignment spring" on the front of the boot, and a slightly larger diameter aluminum heat shield. The spring serves to center the heat shield around the spark plug and prevent contact between the two for a thermal break.
Also the truck wire does have a taller heat shield on the wire side that provides a little more protection. The RV wire has a wider angle to the heat shield and is noticeably shorter in length. None of this really matters as long as they are both performing well, just my attempt to explain the differences we can visibly see.
Also the truck wire does have a taller heat shield on the wire side that provides a little more protection. The RV wire has a wider angle to the heat shield and is noticeably shorter in length. None of this really matters as long as they are both performing well, just my attempt to explain the differences we can visibly see.
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I think this is a very sound approach!
Agree completely. I still think I’m going to get these wires and run them. I’ll keep my current ones as spare. I’m not an engineer but still feel like the 6167’s were designed with better heat rejection and isolation characteristics in mind compared to the factory 6164 wires on our truck.
Again forgive me for trying to wrap my head around this, so you are saying that number9xd pictures of his 2022 wires are "not" the C type. ...a truck that was builkt in 2022.
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No problem it is a confusing topic for sure! His pictures are not of the "C" wires. The C's were specifically design for the motorhome/chassis applications which have a different underhood environment. My guess by looking at them is that they are more expensive to produce and released for just those applications in production. The latest production release for SuperDuty (MB suffix) have been improved with some of the same features. Study the pics provided by @RedZilla in post 144 and you can see the difference. @Tucsontremor has a good breakdown above as well...
i dont have these wires since i have the 6.7. however i have had wires similar to these on multiple vehicles and the metal shields were always a problem. spark jumps through any crack in the wire to the metal heat shield and to ground instead of going through the spark plug itself. i have always just removed the metal shield completely and never had an issue with the boots melting. if you were worried about the boots though you could use the fibreglass boot protectors. pretty sure this would be a permanent fix for this.
That's a good suggestion in theory, although unfortunately some have essentially experimented with this concept with poor results. Not by removing the metal shield from the OEM wires, but by replacing the wires with after market wires that only have the fiberglass shield over the boot and wire. A number of those have failed badly after a few thousand miles. Some have had better results, but all in all the failure rate is pretty high considering only a few people have tried this approach.
