91 300e problems because of the rain? - Page 2 - PeachParts Mercedes-Benz Forum

300holst · #16 08-07-2007, 12:05 PM

My '86 300E has not given mr trouble from moisture in the distributor cap but several other cars of mine have done so. In all cases, the car would start, I'd drive a short distance, stop the car, and then have trouble restarting it. I believe that the moisture inside of the cap would evaporate from engine heat, then condense on the top of the cap near the spark wire terminals. This then shorted out the spark path.

I was able to eliminate this problem by smearing silicone grease around the edge of the distributor cap where it bolts to the engine. I also removed each spark wire on the cap and put silicone grease on the inside of the rubber boot to seal out moisture. I did the same at the coil as well.

I have found a big increase in electrical reliability by using that silicone grease on all electrical connections. In fact, there was a TSB in abour '93 or '94 from Volvo telling their dealers to do this whenever a car was brought in for any service. This is a good way to prevent problems with those fuses in the older MBs too. Same fuses in the older Volvos were a problem.

I but a large tube of 'SylGlide' brand silicone grease and use it on everything but my morning toast.

david s poole · #17 08-07-2007, 05:36 PM

now surely the only reason that you don't use it on the morning toast is that you don't want to have to go buy more?

mbzr4ever · #18 08-07-2007, 07:46 PM

Quote:

Originally Posted by 300holst

My '86 300E has not given mr trouble from moisture in the distributor cap but several other cars of mine have done so. In all cases, the car would start, I'd drive a short distance, stop the car, and then have trouble restarting it. I believe that the moisture inside of the cap would evaporate from engine heat, then condense on the top of the cap near the spark wire terminals. This then shorted out the spark path.

I was able to eliminate this problem by smearing silicone grease around the edge of the distributor cap where it bolts to the engine. I also removed each spark wire on the cap and put silicone grease on the inside of the rubber boot to seal out moisture. I did the same at the coil as well.

I have found a big increase in electrical reliability by using that silicone grease on all electrical connections. In fact, there was a TSB in abour '93 or '94 from Volvo telling their dealers to do this whenever a car was brought in for any service. This is a good way to prevent problems with those fuses in the older MBs too. Same fuses in the older Volvos were a problem.

I but a large tube of 'SylGlide' brand silicone grease and use it on everything but my morning toast.

Sound good - worth a try. Just put the SylGlide on my shopping list!

300holst · #19 08-08-2007, 10:36 AM

Quote:

Originally Posted by david s poole

now surely the only reason that you don't use it on the morning toast is that you don't want to have to go buy more?

I knew that I was pretty cheap but I didn't think that was known clear to Texas!
Actually, the flavor is pretty blah. Now if they come out with a strawberry flavored Sylglide.........hmmmm.

crhenkel · #20 08-08-2007, 11:27 AM

It is a good idea to use a good dielectric ( non electrical current conducting) grease on the boots of the wires, the sealing edge of the cap, and sometimes even on the ceramic portion of the spark plugs when you are having spark and electrical current issues. One- it makes the wires easier to pull off when needed. Two: it helps to keep the electricity from following the path of least resistance and seeking a ground other than the route the electricity is supposed to take.
An old trick on old poorly shielded spark wires on muscle cars was to take a lead pencil and make a heavy pencil mark all along the ceramic portion of the spark plug, from the electrical tip to the engine block. If you got the lines heavy enough and just right, you would cause the electtrical current to follow the pencil line to the engine block instead of the spark plug tip, or at least degrade the power of the spark. It would cause a dead cylinder or poorly running engine and your buddy or not so much a buddy would look forever to find the problem. Sometimes this is basically what can happen with bad wires, cap, rotor, or plugs. Tiny breaks in plastic, carbon tracking, degraded wire sheathing, etc can let some or all the electrical current travel to where it shouldnt or ground out, with or without moisture, depending on the damage. Also, sometimes, wires break down internally and only leak voltage or ground out after they heat up. Fine when cold, but after getting hot the wires can cut out, ground out, or short and cause misses, bad or no acceleration, or stalling due to the drop in resitance. Always consider changing old spark plug wires. The high cost of the wires is nothing compared to the benefit good wires give your engine. Good luck

mbzr4ever · #21 08-11-2007, 04:48 PM

300holst (or anyone),

Where did you find the SylGlide? Did you buy it online?

mbzr4ever · #22 08-18-2007, 12:46 PM

OK, found it at napa.

CamelotShadow · #23 09-28-2007, 07:55 PM

Quote:

Originally Posted by crhenkel

It is a good idea to use a good dielectric ( non electrical current conducting) grease on the boots of the wires, the sealing edge of the cap, and sometimes even on the ceramic portion of the spark plugs when you are having spark and electrical current issues. One- it makes the wires easier to pull off when needed. Two: it helps to keep the electricity from following the path of least resistance and seeking a ground other than the route the electricity is supposed to take.
An old trick on old poorly shielded spark wires on muscle cars was to take a lead pencil and make a heavy pencil mark all along the ceramic portion of the spark plug, from the electrical tip to the engine block. If you got the lines heavy enough and just right, you would cause the electtrical current to follow the pencil line to the engine block instead of the spark plug tip, or at least degrade the power of the spark. It would cause a dead cylinder or poorly running engine and your buddy or not so much a buddy would look forever to find the problem. Sometimes this is basically what can happen with bad wires, cap, rotor, or plugs. Tiny breaks in plastic, carbon tracking, degraded wire sheathing, etc can let some or all the electrical current travel to where it shouldnt or ground out, with or without moisture, depending on the damage. Also, sometimes, wires break down internally and only leak voltage or ground out after they heat up. Fine when cold, but after getting hot the wires can cut out, ground out, or short and cause misses, bad or no acceleration, or stalling due to the drop in resitance. Always consider changing old spark plug wires. The high cost of the wires is nothing compared to the benefit good wires give your engine. Good luck

Good point about the dielec grease have to use it on the wires & distrib.

So if the dielectric grease in non conducting it should be used on the outer portions as a stop barrier & moisture barrier.

I was reading someone put in on the ends on the fuses & contacts
evidently this would inpede conduction therby making contact harder...
So do I rightfully conclude that you should not do that?

Thanks

300holst · #24 09-29-2007, 07:56 PM

The purpose of putting silicone grease on the end caps of fuses and on the pins of electrical connectors is to prevent air and moisture from corroding the metal contact surfaces. The grease doesn't prevent electrical contact because the grease is wiped off of the metal surface at the point of contact. The grease which was wiped from the point of contact just piles up next to the contact and acts as a further barrier to air and moisture. The normal 12 volt power in the car is well able to conduct through what little grease is left on the metal when the connection is made.

The only exception I know of is the connector for the Oxygen sensor. The output of the sensor varies but is less than 1 volt always. It is not recommended to put any grease on this connector. Volvo came out with a TSB in about 1994 directing dealers to grease all electrical connectors EXCEPT that oxygen sensor connector.

mbzr4ever · #25 10-23-2007, 12:01 AM

The new plugs, wires, rotor, cap and various other pieces just arrived today, thanks to Phil's exceptional service.

I also just bought the right size spark plug socket.
What would be the recommended order of installation?

I was going to do plugs, rotor/cap, then wires. Is this ok, or is there a better sequence of replacing these parts?

At what points do I use the slyglide?

Thanks again for any input from those who have done this before...

300holst · #26 10-23-2007, 10:42 AM

The sequence you have figured out seems right to me. I would apply the Sylglide as follows:

1. To the gasket where the distributor cap seals.
2. inside the rubber boots where the wires connect to the distributor cap.
3. Inside the rubber boots at the spark plugs. Sometimes I install the plug, then grease the connector end and the white porcelain part, the push on the wire and boot.

You don't need a lot of grease on the boots.

I don't know if you are replacing the ignition coil but all rubber boots and electrical connectors at the coil should be opened and the silicone grease applied. On the connectors, I fill the female part with the grease so that the male part pushes the grease out when the connection is made. This effectively fills all voids and seals out air and moisture.

mbzr4ever · #27 10-23-2007, 03:47 PM

300holst,

Thanks for the directions. Didn't order the coil yet, was going to see if these parts did the trick first.

Before I start, I think I have all the supplies, but forgot to ask if there were any other special tools, besides the SP socket and gap measuring tool, that I might need (besides your general wrenches, etc)?

The plugs say to torque to 15 lbs, which does not sound like much. What is that approximately after snug with the socket wrench? 1/4 turn?

mbzr4ever · #28 10-24-2007, 12:11 AM

Here is a summary of what I did today:

Disconnected the battery. Tried to get the old spark plugs off and they were on too tight. I know my limitations, so I skipped this part and went on to the wires. Will get those changed later by a shop/mechanic.

Changed all the ignition wires, using the sly-glide and put them in the new wire management piece that runs on top over the plugs. My only problem here was the coil wire was attached with 2 plastic clips that broke, they were so old. So I had nothing to attach my new wire to keep them out of the way. I used a small metal hose clamp to attach the coil wire to one of the clamps of the air filter housing, until I can figure out something else.

I discovered the black suppressor housing was broken on the bottom, in fact, the bottom screw was very loose. This might account for the trouble I was having, we shall see.

My old rotor was plastic and it was nice to see my one was metal, although I liked the old screws better, they did not strip as easily as the new ones. All in all, my new parts look very nice, it was almost a shame to use them, LOL!

The new suppressor housing fit perfectly into the rotor cap, used some more sly-glide and everything screwed together to make a nice snug fit over the rotor. Then the cover snapped on, like it should. My old one had fallen off and melted on the engine!

What a difference, it looked nice, anyway.

Connected the battery, started it up, maybe started a bit faster than before, but that was the only difference I could tell right now. Not bad for a girl!!!

The real test will be if I don't start it for a few days, especially if it has been raining, and see if it will start properly.

brewtoo · #29 10-24-2007, 01:59 PM

Quote:

Originally Posted by mbzr4ever

Here is a summary of what I did today:

Disconnected the battery. Tried to get the old spark plugs off and they were on too tight. I know my limitations, so I skipped this part and went on to the wires. Will get those changed later by a shop/mechanic.

I've always found that getting the boots off the spark plugs is the tough part...never had a problem getting the plugs out of the head. Hate to see you pay someone to do that since you were competent enough even to thread the wires through the holder and get them all to stay, which ain't easy either.

Good job! Hope it helps.

mbzr4ever · #30 10-24-2007, 02:29 PM

brewtoo,

Thanks for the encouragement. Patience is key, LOL!

In taking the boots off the plugs, I just twisted and turned the same time. What helped a lot is a pair of bent needle-nosed pliers. They were helpful in taking the boots off the distributor too, since it is kinda tight up front.

I'm wondering if there is a special tool for taking off the "frozen" plugs? I even sprayed them with WD 40 and let it sit a while. Tried the first two, then decided I did not want to risk breaking the plugs. At least the car would still run, which I really need right now, since my 240D has another ignition issue.