I had the same intermittent problem.... I got to see the Starter repair place take apart my starter.... the three small screws in the end .. which hold the ' cage' for the brushes... had vibrated loose... after only 30 years of use...
so the brushes were sometimes in contact and sometimes not....
The actual brushes ( pieces of carbon ) on these starters are very Robust... huge...

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Same in my 1985 300D. I had the cluster pulled out. When I cranked the engine, I noticed smoke coming from the speedometer cable. Knowing that meant the large starter current was using that as a ground return path, I searched out the "engine to body" cable, which is from transmission-engine bolt on driver's side. Unbolted, sanded, and coated w/ silicone grease. It didn't even look corroded, but that fixed it. Aluminum quickly oxidizes to white powder. That caused many house fires when they tried it as cheaper wiring in the 1960's.

My U.S. cars run BAT- to the engine block, whereas M-B ran it to the body. Thus, need a thick cable from engine to body. Similarly, I once had an alternator that wasn't charging, which turned out to be from a little oxidation of the aluminum case, which is the return path to the engine block (both my U.S. and M-B cars).

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Do not. I repeat do NOT by reman starters from World Parts or Advance Auto. Lesson learned. The one that crapped out was from World Parts (via my commercial account via the Advance Auto commercial desk) That was the second one from them that lasted less than 18 months. Ended up at Pat & Chucks. I think they’re in Des Plaines. The car was towed there at 2:00 in the afternoon. They got a reman Bosch from Napa and had my son back on the road by 5:00. Cannot speak highly enough of them. One of the owners (Chuck) personally took care of my son’s car. $250 labor. $250 starter. 24 months 24,000 mile nationwide warranty. Hopefully this one is better quality than the two I got from World Parts. But definitely can’t complain about how quickly on last minute notice they took in the car and got my son on the road and took payment over the phone from a complete stranger. Thanks again for all your responses. - Doug

Bill, could I use Silicone Spray Lubricant on the engine/transmission bolt for the grounding strap?

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I would suggest NOT..
but can't give any physics reasons...
there is a silicone used as a dielectric for some electrical items between them and the heat sink...
but if it is not the same kind it could work as an insulation..

https://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

No. Do not use that silicone spray lubricant. Go buy some dielectric grease at any auto parts retail store. Use it on any electrical connection. Bulb sockets. Wiring connectors. Any and all. Our techs use it for all electrical connections when we replace any electrical component on cars that come in for repairs at our dealership. I run the service department at an Alfa Romeo new car dealership.

Take this man's advice. He should have plenty of experience with electrical problems.

I always made it a habit to treat any automotive electrical connection before putting it back together. It eliminates even airborne humidity creating issues over time. Actually car manufactures did eventually adopt this practice themselves. Unfortunatly not on all connections though.

On connections having corrosion or oxidation. When you clean them up you may remove the original protective layer. If this occurs leaving them unprotected will become problematic sooner. That protective coating can already be either gone or be much thinner by the sacrificial nature of it.

Something I never see anymore. In Canada pennies where copper when we had them. Now long discontinued from circulation. We used to put a couple on top of our batteries as sacrificial metal. Small pieces of copper from any source would do no harm today. The pennies turned quite green with all kinds of white stuff present on them as well. Possibly oxides of lead? Indicating that acid does accumulate on the top of batteries.

I do not think there was even one time. I had to go back for a bad previously treated connection over all the years and cars we have owned. Although I do redo or renew the battery terminal connections protection from time to time. Not once have I ever got a loss of contact between the battery posts and the cable connections if they are treated. After I started doing this all those years ago.

Now many times If I had something like heavy grease only. I knew the coatings on wire do not like petroleum based product. I felt it was better than nothing. Typically would have been ground straps and other heavy cable connections. I see the coating you apply not as increasing electrical conduction. Instead protecting what exists and preventing new oxidation occurring. Vasoline at one time was recommended for automotive battery terminals for example.

This subject reminded me that the wives car battery terminals will need treating soon. Silicone type products might be the best. You need them to have enough viscosity or body to not get washed off easily. In places like exposed ground straps.

How it works in the real world is simplicity itself. If no oxygen from the air can get at the metals. They cannot oxidize. Also the exclusion of moisture helps substantially as well.


That said you can still perhaps have dissimilar metals reactions . Just far less active perhaps. The protective hard coatings manufactures apply to terminals can become sacrificial itself over the years. Last but not least. An electrical connection that has resistance will heat and cool or be subject to thermal cycling. The less resistance in a connection the better.

A very good example is leaving the original type aluminium fuse in the heater blower circuit of the 123s. It forms a substantial resistance at the points of the fuse connections.

This lowers the amount of voltage to the blower motor. As well as heats up so much it can damage the fuse box. It is better to change all those fuses for copper ones. Or if you do not want to do that at least change the blower motor fuse from the original aluminium type. It is just a cheap fuse type.


It is more a good habit to develop and treat older electrical connections before you put them back together. Than the time it takes to do it. Especiallly in rustbelt areas like mine where a lot of factors are working against maintaining electrical continuity.

Dielectric Grease is non-conductive, therefore you wouldn't want to use it on electrical connections. For example, you could use it on battery terminals after you make the connections, just don't use it on the actual connections.

It depends on the dielectric grease you're using. The stuff you should be using for electrical connections generally IS conductive and typically has additives to help break up and prevent corrosion.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

LOLOL
Second only to Lucas in British Cars.....

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

My father... a fine leathercraftsman... but NOT a mechanic.... once decided to clean up the battery terminals on the car ... and then applied chassis grease...and reinstalled the connectors......... I promise you that is not the right thing to do.

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

If you’ve ever discovered a small amount white or yellowish compound around wiring connectors and butt connectors on your Mercedes when changing things like headlight bulbs or turn signal bulbs or other under the hood components, I believe you’ll find that was dielectric grease applied at the factory when the car was built. And it has simply turned color over the years due to age and drying out. Here’s the article by many considered to be the ultimate word on “greases” for electrical connections Dielectric Grease vs Conductive Grease

Not sure of the cost. An alternative if silicone based grease is not readily available where you live. Or too expensive. Using the grease specifically designed for the aluminium feeder cables on electrical systems may be far more economical.

Available at most if not all electrical supply places. It is a clear silicone grease I believe of a simple non metallic nature. Used to protect dissimilar metals as well as similar ones. Just blocks moisture and air from the connections basically.

I have old stock but a probable six ounce supply in a nozzle bottle is still around five dollars. E bay may be a good source of really cheap silicone grease.

Okay looked the silicone grease up on ebay. A dollar will buy you thirty grams of the type that has ground metals in it. Delivered to your door. The conductive type. Comes in a large syringe. You do not need a lot on a connection remember.

Personally you have to remember this is the conductive type so use it only on single connector items. Like ground straps, Battery cable connections, fuse terminals etc. If you are doing electronic connections use the non conductive type. Again just a dollar gets a useable 30 gram supply on hand delivered to your mailbox. I think the larger syringe it is in is a good way of dispensing it as well. Or really get into the money and order one of each type. Living financially closer to the edge.

Actually removing, cleaning up and greasing. Just the ground straps can brighten headlights, increase starter speed etc. If corrosion over time has weakened the conductivity. Thirty to forty years is a long time for a connection exposed to the elements essentially. To maintain the original conductivity.