It's a few months later with regard to this thread, but I discovered that both of the passenger side (RHS) ground connections behind the headlight were so corroded that they snapped when I lightly turned the nut. I inspected them because of flickering headlight issues on that side and some various random electrical anomalies with the car.

I drilled two new holes and put steel bolts of the same size and thread pitch so I could clean and re-use the original nuts. I put large washers on both sides of the frame, cleaned everything really well and used liberal amounts of dielectric grease. The headlight is steady now and thus far no electrical gremlins, but it's only been a short time since the repair.

Two questions for some of the veterans.
1) The ground connections were several inches apart originally, but in order to drill new holes without removing the headlight (and thus bumper) I had to put the holes much closer together; about 1 1/2 to 2 inches. I'm no eletrical engineer so, does this closer proximity present any possible problems, or is it insignificant?

2) I used standard steel bolts, washers and nuts from the hardware store. The original studs appeared to be steel, but it seems more logical they were aluminum. Will the use of steel bolts grounding wires to an aluminum body panel present possible problems? Reference the aforementioned "I'm no electrical engineer" comment above.

Thanks,
Jeff

 

Based on what I've read, regular steel (not stainless) and aluminum are "relatively compatible," but over time the aluminum will suffer from galvanic corrosion because it is more anodic than steel. Counterintuitively, stainless steel is even less compatible with aluminum. You may want to replace your steel bolts with aluminum ones at some point. McMaster-Carr carries aluminum bolts (search "aluminum screws" at mcmaster.com).

Cheers,

Don

 

According to my receipt the bolts are SS, but the washers and nuts (which are the only thing separating the wires from the aluminum frame) are made of zinc. I checked the mcmasters website and they don't have aluminum bolts like these in metric sizes. I guess I could NOT re-use the nuts and just get all new hardware in an SAE comparable size. I emailed them regarding the metric sizes, so we'll see.

We have driven the car approximately 60 to 70 more miles, with no electrical anomalies and steady (non-flickering) headlights.

This would be an excellent DIY checklist item for anyone with a newly acquired X350; it could account for so many other problems.

Since everything is working fine, I will just trust that the distance between the ground connection points is not an issue.

 

The document at the link below is helpful in evaluating the potential for galvanic corrosion:

https://www.fastenal.com/content/fed...0Corrosion.pdf


It appears that your zinc-plated washers and nuts will probably be compatible with the aluminum wire terminals and the car's body, but depending on the type of Stainless Steel in your bolts, you may want to replace them. The document says type 410 stainles is never recommended for contact with aluminum, and other types of SS will "marginally increase" corrosion of the aluminum.

Google "metric aluminum machine screws." There's bound to be a company with current inventory who will sell you metric screws in small quantities. You should be able to just re-use the original aluminum nuts and washers.

Cheers,

Don

 

The entire body is the ground electrode. If your aluminum stud has failed, you need to be to bare aluminum. This is where star washers are your friend. I would also recommend, as I did in another post, using OX-Gard in your ground connections to the body. Just sayin'...

 

when working single handed with a nut that might drop ....

lay a piece of masking tape across the box end of a ratcheting wrench
stick side towards wrench

place nut on plain side of the masking tape

push into box

actually works best with sockets though.

 

plums,

I like the masking tape tip for holding the nut, but it can interfere with the operation of a ratcheting box end wrench, and it doesn't solve the problem of there not being enough resistance for the wrench to ratchet, and there being no room to get a finger on the nut to hold it still so you can re-**** the wrench. That's the purpose of the long rod, to immobilize the nut so when you have to ratchet the wrench the nut doesn't loosen and undo what little clockwise rotation each stroke of the wrench imparts.

Cheers,

Don

 

I have to admit, learning about these metal compatibilities is very interesting. Don, the link to the PDF was fascinating. Here's my bullet points.

-- The bolts I bought have 01vk 8.8 written on the head. In my experience, 8.8 is a strength rating for metric STEEL bolts, not stainless steel, but it may be used across different materials I suppose. According to the info I read the SS bolts should have A-2 (most likely) on them and not 8.8. I am wondering that even though the receipt is charging me for SS bolts, maybe they gave me steel bolts.

-- Box, I used a dremel (sp?) to remove the paint from around the new bolt hole I made. I then put a thin coat of dielectric grease on the exposed metal and tightened a large flat washer onto that exposed metal spot with a nut, thus leaving the rest of the bolt sticking out as a makeshift stud for the wires and original nut to be attached.

-- Just to have a warm fuzzy about everything I am trying to source aluminum replacement components for everything. Am I safe in assuming (dangerous word) that if my wife is driving this car for a few weeks while I find the time to source replacement bolts, no significant and/or irreversible damage will occur? The connection is obviously electrically sound since all of the gremlins have been evicted, but of course I don't want to find in the future that I've corroded part of the aluminum frame.

Thanks for all the time and advice on such a minor little repair. Like I said, I am surprised by how interesting I find all of these compatibility issues. I used to put sacrificial zinc blocks on my boat to protect the critical metal components, so this is similar.

 

Just be mindful, dielectric grease is an insulator. OX-Gard is conductive. We don't want insulating grease in the ground connection, what we want is conductivity.

 

I think you'll be fine driving the car for a while as it is, but if you replace the steel bolts with aluminum, my personal recommendation would be to not apply dielectric grease to the body and other parts before you tighten the nuts, but instead to install the parts clean and dry, then apply dielectric grease after you have assembled the wire terminals and tightened the nut.

Dielectric grease is an insulator (part of the definition of dielectric, along with the fact that it can store a static electric charge). Using dielectric grease adds some resistance to an electrical connection, so other than for light bulb bases, I apply it to grounds to seal out moisture only after everything is already tight. Others may have different opinions.

+1 on David's recommendation to use star washers, and the OX-Gard he mentions contains Zinc and Graphite, which are both conductors (though neither is as conductive as aluminum).

Cheers,

Don

 

depending on the available space, the tip of the middle finger
against the back of the nut should do it while the remaining
fingers juggle the wrench through the arc

years of practice and desperation

 

I know all about desperation! Available space is the problem here. There is very little of it between the rear of the headlamp housing and the end of the lower ground stud. My photos in post #9 were taken with a wide-angle lens, so they exaggerate the sense of space. With my medium-sized hands, I couldn't possibly get any finger on the nut and apply enough pressure to prevent it from turning while ratcheting the wrench. Thus, the use of the rod.

 

ahh!

in that case combine tape + curtain rod for the best
of both techniques

 

You guys rock! Don and Box (David?) have just given me an "aha" moment.

Probably about 5 or 6 years ago a kid in an auto parts store said "this grease will help improve your electrical connections", and handed me a bottle of dielectric grease. I operated on this UN-questioned presupposition ever since! Amazing, like Don said...it's IN the name.

But, please don't judge me by this guys, I am usually a pretty bright dude. This is just a good example of how we need to investigate every presumption when working on a problem.

I have been searching out the cause of a stumbling idle on my BMW for two years! Car runs great, but stumbles a little at stop lights. I had taken apart the C-191 plug (most likely culprit) and thoroughly filled it with dielectric grease, to "insure" a good signal to the fuel injectors. Wow! I just went to the garage, disconnected the plug, cleaned it as best I could and plugged it back in dry. The car runs noticeably smoother and on my test drive accelerated better as well! Two years I have been brainstorming that little problem.

Okay, I have gone on long enough. Tomorrow I will be buying some Ox-Gard and repairing that C-191 plug once and for all. Plus, I'll be re-doing lots of electrical connections on our cars.

Thanks again,
Jeff

 

Jeff,

It's a constant learning process for all of us, and learning from each other is why this forum is so helpful.

OX-Gard is fine for high power connections, but personally I am not an advocate of applying any compound to the terminals of sensor connections, since the voltages and currents involved are small and even a slight increase in resistance can affect the signal seen by the ECM or other module. Caig Laboratories makes products for low-level signals under the DeoxIT brand, and they are probably fine for cleaning connectors (though over-priced), but I question their claims of "enhancing connections."

I don't know of any compounds that are as conductive as the Copper, Silver-plated or Gold-plated terminals common in sensor and ECU connectors. Zinc is only about a third as conductive as Copper or Silver and half as conductive as Gold. Graphite is a few hundred times less conductive.

My preference is to clean the contacts thoroughly with zero-residue electronic contact cleaner spray (CRC is a commonly-available brand), allow them to dry, then apply dielectric grease to the outside only of the plastic housing of the smaller half of the connector. This helps seal out moisture and oil and eases future separation. Here's an example of this method on an O2 sensor connector:




Here's a link to photos of how I maintain the grounds on our '93:

Welcome to Jag-lovers - Members Photo Viewing Page


Cheers,

Don

 

TO ALL;

Never use a conductive grease (like OX-Gard) in electrical connectors. Connectors, like GM-Pac and Metri-Pac are self sealing and should all be assembled dry. The only place you want to use a product like OX-Gard would be grounding studs, battery terminals and compression splices of large current cables.

 

My experience with electrical connectors used on Jaguars (Econoseal, Multi-Lok, Amphenol, Lucar, Modu, Augat, Deutsch, AMP, Motorcraft, etc.) is that even on the ones that have seals, the rubber tends to harden over time and lose its ability to seal. A little dielectric grease on the outside of the smaller half of the housing, and the seal if it is accessible, can help supplement the old rubber seal and ease future separation.

Another thing to keep in mind is that in the low-voltage and low-current circuits such as those for sensors and electronic modules, the ground points are just as much a part of the circuits as the electrical connectors. Adding any resistance to those grounds by the use of conductive grease will add resistance to the entire circuit, so it's not something I would personally recommend. OX-Gard is really only suitable for "high-power crimp connections and stud bolt mountings," per their own literature.

Cheers,

Don

 

I hate these sort of months later followups...
I just used standard Autozone nuts and bolts after drilling a hole in the aluminium to replace the broken ali studs. No one ever said anything about galvanization, die-electric grease or whatever. I must say though that I have not had any grounding issues to date.
I will have to keep an eye on them and monitor their corrosiveness and the flicking of the lights.

 

trosty,

Sorry we didn't mention galvanic corrosion earlier in this thread, but you didn't mention you'd used steel bolt & washers either...

I know the topic of galvanic corrosion has come up in other threads. Here's one from last September:

https://www.jaguarforums.com/forum/x...nt-how-126855/


Cheers,

Don

 

Not sure if your x350 is RHD or LHD but for both the ground places for the front are quite accessible without removing panels. The most likely ground problems are the 3 ground studs directly behind the grill and under headlamps. For LHD there are 2 on the right side and one on the left (looking forward). On my cars they are painted body color and may have a bad contact to the body even if they look OK (one fell off when I tried to remove the securing nut even though it looks OK).

Hope this helps. Good luck.