Schmooey

So I finally decided to find and clean the ground points on my '84 944 N/A and I have to say that I strongly recommend this to anyone who has been thinking about it. I found and cleaned the two up front under the headlights, the one in the rear of the hatch (easy to find), the one in the center of the firewall behind the engine up towards the top. I also cleaned the connections and cable running to the negative battery post. I then ran a new cable from the negative post directly to the block, as per some suggestions I've read online.

What is interesting to me is that I immediately saw two benefits that I was not even aware could be related to the grounds. The dome light came on when I opened the door, (as well as the light in the rear hatch - surprise!) and, the analog clock on the dash is now keeping time.... it had worked intermittently in the past and I was planning on taking it out and apart to clean it, but now that is not necessary. I just assumed the dome and hatch lights were bad bulbs and was planning on getting to them as they were low down on my list of projects, but now I can cross those off.

I wonder if there are other gremlins that are now also fixed but I haven't noticed yet....

AgLiftPilot

I have made two new charging and grounding harnesses now. Both sets of cables I pulled were in sorry shape and did nothing to help the car run.

My race car uses a 'floating ground' which grounds all components through a common grounding block on the firewall which is then grounded to the battery. The battery has a 1 Ga cable grounding it to the block where the DME/Engine Harness grounds. My positive cable reflects the stock setup which keeps the battery, alternator, and starter all connected via 1 Ga battery cable.

The 924S I just made new cables for is a little different since it still has all the rest of the stock wiring. Negative 1 Ga from the battery to the mounting bolt on the starter, then a smaller 2 Ga cable to the common ground on the block with the DME/Engine Harness and then a small jumper from the block to the chassis ground above it. I then rerouted the mess of positive cables that are unsightly and corroded on most cars at the battery to connect to the back of the alternator. This allowed me to cut off much of the corroded wires at the end, crimp new connectors, and run power right off the alternator.

KVDR

I just did the same thing - cleaning the grounds front and rear and applying dielectric grease.

My left turn signal was becoming intermittent. Opened up the front lens and discovered lots of corrosion on the bulb.

I also removed the tail-light bulb assembly and cleaned every terminal, ground, and bulb. Some were pretty oxidized. Also had a few loose/broken connections to fix.

FRporscheman

One important ground, which sadly is really hard to reach and even harder to clean, is above the pedals, fore of the fusebox, all the way up there.

Last year my NA had an intermittent no-crank, turned out to be dirty battery connections.

morghen

While you can surely see the good results immediately its also very important to seal the new exposed metal if you're sanding the connections as if you don't, in a couple of months you will get a worse situation than what you had before the "improvement" job you did.

Schmooey

this is interesting. Would you recommend a particular way to do this? Thanks.

morghen

Look for contact lubricants but be careful what you use.
To be honest if you don't have a specific problem with a contact or ground point I would not sand it or use contact improvement liquids of any sorts.
I've done that on my 924 thinking I'm doing good to the car but 3 months later the area I had "improved" worsened with new and more abundant corrosion. Inspecting the areas I found more corrosion that had accumulated for the last 30 years.
I had to re-clean the connections and seal them with some contact lubricant/grease.


That was the only time I went away from my general rule of keeping the 924, if it isn't broken, don't fix it.
Be aware of wearing parts and replace them with new ones if there is the risk of breakdown but other than that leave it be, its really good as it is.
Or if you really want to improve an ageing system do it properly.
There is no such thing as a cheap fix.

FRporscheman

What I do is coat the terminal / post with some grease after it's cleaned and fastened. You can use battery terminal grease, dielectric grease, silicone paste, wheel bearing grease, motor oil, cosmoline, undercoating... anything that's non-conductive.

Side note: it's not just electrical connections that are subject to corrosion. I just rebuilt an engine last summer, and this winter I saw all of my perfectly cleaned and tidy engine parts developing corrosion, like little white spots all over the aluminum parts. I guess that's why the factory coated the engines with that tan colored waxy stuff.

pfarah7

I've used dielectric grease with very good results.

FRporscheman

Ya, just don't make the same mistake I did - I thought dielectric grease protected against corrosion yet was conductive, so I put it all over the terminals before attaching them. That's the "dirty battery connection" I was talking about. I cleaned it all off, connected, and applied the stuff to the outside.

Jay Wellwood

This is a good topic and well timed for yours truly.

I've noted there are obvious copper based ground points and other ground connections that are merely bolted to the chassis. So it appears the consensus is dielectric grease?

KVDR

I've been reading a lot of conflicting opinions on dielectric grease. Some say it shouldn't be used in-between connections, however the manufacturers own directions indicate otherwise.

From Permatex website:

Directions for Connectors:

1. Make sure ignition system is off.
2. Clean surface with Permatex® Contact Cleaner.
3. Coat both parts of terminal contact with Dielectric Grease.
4. Reassemble, maintaining metal-to-metal contact.

I think two keys points in the above is 'clean both contact surfaces' and 'maintain metal-to-metal contact'.

So while dielectric grease is considered non-conductive, a super thin layer between properly tight metal connections should not increase the resistance.

The intent of dielectric grease is to prevent arcing (which contributes to corrosion, pitting) and also to keep out air, water, salt, etc.

I slathered all my connections and grounds in the stuff. I'll run my ohm meter across the connections when I'm in the garage later today.

KVDR

I emailed Super-Lube and got a response:

"Yes, you can use our dielectric grease on tight fitting terminals. After you coat the terminal and assemble the mating connector the grease will be displaced leaving the metal to metal contact necessary to complete the connection.

After the connector is tightened in place, you will be left with a very tight water and corrosion free seal"

i944

Thanks for this as it is at the top of my to do list. Got the grease.

FRporscheman

I had some very bad gremlins in my car until I cleaned the dielectric grease from the metal-to-metal contact surfaces of the battery posts and cable connectors. They should be clean, raw metal. Other things, like m6 ground bolts, probably don't carry enough current to need such good contact, but I'm not putting grease between contacts from now on. Just my 2 cents.