merchauser

While under my car I noticed the ends of my frame to engine ground strap could use a little cleaning. I have read many posts regarding a variety of electrical problems resolved with cleaning and/or replacing the ground strap.

I took the strap off to clean and then started the car and went for a drive. I was hoping that the car would either not start, run rough, or have some issue that I could pinpoint to the ground strap and, to my disappointment, the car ran fine and presented no effects with the strap completely off.

what's up with that???

Taguid

Pretty sure I read in the workshop manual to never do that because it may cause irreparable damage to the computers.

merchauser

Geez, thanks for letting me know.....never heard of that one??? won't be running again like that!

linderpat

That is one of the more important ground connections, and yes, my understanding is that running the car without it can cause damage. There are many instances of irregular running conditions due to that ground not making good contact at both sides. Much like the one in the rear battery compartment (and of course, the car will not even start without that rear strap being secured). I am surprised that you saw no ill effects. Nevertheless, clean it well on both ends, as well as the contact point on the passenger side engine bay and the block, reattach, add dialectric grease to it after it is first connected dry, to insulate the connection from road dirt and you'll be good to go.

merchauser

thanks for the input Ed,
for less than $20. I have decided to buy a new strap and will clean all points and use dialectric grease on contact points

still would like to know why my car ran fine without the strap?

wondering if the car will be different with the new one?

Mrmerlin

Its possible that the grounding was done via the throttle cable,
try running 12v through a wire, what comes to mind?
Hint look inside an incandescent light bulb..

I have had an instance where a solid engine to chassis ground was not made in another truck,
and i was fitting a spring to a throttle return on a carburetor to the firewall,
I started the engine and the spring turned red and smoked the coating off of it

dr bob

There are multiple possible ground paths from engine to chassis. On mine anyway, there are grounds from the coil to the cam cover area, for instance. Still, I wouldn't depend on those. I'm not sure why folks are worried about computer damage. The alternator output won't exceed VR setting (~~14V) relative to the block when engine is running. If the ground is not perfect, less than that will be transferred to the system. Perhaps we are thinking about running without the battery ground strap, which does offer serious risk of controller damage from overvoltage?

On your "... use dielectric grease on contact points." remember that dielectric grease is an insulator. It has high dielectric strength, so is exactly NOT what you want to use when assembling an electrical contact. Clean and assemble the connections, tighten them. If you feel a need to protect the connections from corrosion or contamination, coat the assembled connections with spray battery terminal protectant. You could use Vaseline or even the dielectric grease on an already-assembled contact, except the ground strap runs under the exhaust -- grease will melt off. *** That heat is why we generally don't replace that exposed factory cable with an off-the-shelf insulated 2ga marine battery cable. There are some instant cold galvanize sprays that might make us feel better too, but the tin-plated connectors on the factory ground strap are already pretty immune to casual contamination. Make 'em shiny, make 'em tight, and you'll be fine.

*** The option of a fine-strand tinned marine 2ga battery cable for this duty would probably be fine if the insulation on the cable had a bit of FireSleeve or similar thermal barrier for protection from the exhaust heat.

dr bob

In my less-diligent younger days, I discovered that the metal spiral sheath inside the protective sleeve that made up the throttle cable in my fresh MG TF restoration was a partial barrier to starter motor current. It took only seconds for that to glow red and melt. 6-Volt high-current load for the starter, that little cable housing didn't stand a chance. It was a very inconvenient but well-remembered lesson.

Landseer

Avoid using the hood latch receptacle as a ground point when jumping.
Its not grounded well. The cable will cook stuff quick.

linderpat

exactly Dr Bob - that is what I mentioned in my post too, altho I agree that applying the grease at that point it may not last that long. But yes, diaelectric grease is an insulator, and most folks get that wrong. It is a decent protectant after the contact is clean and tightened dry.

Snark Shark

A bad ground can cause stray voltage in your coolant. Easy to test for. http://www.ve-labs.net/electrolysis-101/how-to-test

Alan

The biggest risk without this engine ground strap installed is starting the car, you could damage the grounds that remain that are there primarily for additional noise protection - not to provide starter current.

In general it is of course not a good idea to remove any primary supply wiring. It is expensive - so you can be sure it is there for a purpose. While you can't start the car without the main battery ground strap - once started you could remove it - the car would likely run on the alternator alone - however this would be a terrible idea - the voltage regulation of the alternator is very poor without the battery load as a ballast (and essentially also as a spike filter).

If the primary wiring looks bad - fix it because it is very important that it work 'normally'.

Alan

Adk46

I had a friend who bought a new Fiat, in the 1970's. The clutch often worked poorly right after starting. Turned out the only ground to the starter was the clutch cable, which ran through a housing with a plastic lining.

Years later, he busted through a snowbank in his driveway, driving snow under the exposed (!) timing belt, causing an expensive clattering noise.

I've always felt bad about these and other problems he had with that car: I had referred him to a very favorable review in Road and Track. The review should have ended with "But keep in mind that this is a Fiat, so don't buy one."

dr bob

In that same period I had an imported GF who had a 124 Spider that she loved for the image. Both she and the car were very high-maintenance so that didn't last long. I thought I was smart when I traded both in on an older model equipped with an Alfa 1750 spider and a Sunbeam Alpine. The ride was much more comfortable, and I only needed to keep one of her cars running at a time.