TheSamba.com :: View topic

Sat Nov 21, 2015 2:27 pm

Fellas,

I think I might have the right idea, but I just wanted to run this by you more knowledgeable folks before I start buying things.

My bus gives me a terrible time starting in the rain (or even when it's abnormally humid). Runs like a champ in dry weather.

I read some info on here and, as a result, popped the distributor cap after trying (and failing) to get the bus running today. There's a fair amount of moisture on the inside top of the cap: small drops and a sheen of wetness.

Time for a replacement cap, yes? Anything else you guys would recommend to keep in mind at this point?

I appreciate your help.

Sat Nov 21, 2015 2:46 pm

Howzit? from the other side of Oahu.

I would guess that you are getting condensation when not in use and/or moisture from leakage when it rains. Some distributor caps fit better than others and a new cap might moderate the problem. A better seal might help.

Is it possible that the moisture is coming from inside the engine? i.e. water in the oil that evaporates from the crankcase and condenses on the inside of the distributor cap?

I had Datsun 510's for many years in Kaneohe and had wet distributor problems only once after plowing through some deep water. LPS spray removed the water from the distributor and wiring and I was on the road again.

Malama Pono
Aloha
tp

Sun Nov 22, 2015 1:19 am

These things came with a plastic shield what sits below the rotor and cap. I bought several from Bus Depot a few years ago by describing what I wanted over the phone. At that time at least they didn't show the part in their online catalog but did stock it. Here you go:

http://www.autohausaz.com/search/product.aspx?part...oCN_vw_wcB

You could also drill a hole in the top of your cap off toward one side so that it will ventilate. If this isn't enough to solve the problem glue a plastic nipple into the hole and then connect the nipple to your fan shroud with a hose using a small orifice to restrict the air flow, you want to create a very light flow through the cap to remove moisture, not a torrent.

Sun Nov 22, 2015 3:01 am

Wildthings wrote: These things came with a plastic shield what sits below the rotor and cap. I bought several from Bus Depot a few years ago by describing what I wanted over the phone. At that time at least they didn't show the part in their online catalog but did stock it.

If you dig through a few hundred pages of the results for "cover," you'll find it too! :?

http://www.busdepot.com/1230500147

I've never tried one on a -70 vacuum only distributor, but Old Volks Home lists that part number being the same from '71 through '85 Vanagon. They also fit 009s.

Robbie

Sun Nov 22, 2015 5:13 am

WD-40 :wink:

Sun Nov 22, 2015 7:52 am

That shield is a dust shield. It "may" keep some moisture from the points....but its the moisture in the dome of the cap that causes shorting between the cap contacts.

There are usually....if you look....a pair of small vents on the bottom of side of the distrjbuter body to allow condensation to evaporate away as it warms up.

You could put a small amount of RTV around the base of the cap as a seal just in the corner of the cap. Let it,dry before you install it. You are making the equivalent of an o-ring....not trying to seal the cap to the distributor. You can also plug the two vents in the bottom. This can keep condensation out.....but also doesnt allow moisture out. So jn your humid environment treat all surfaces lightly with WD40 before sealing up and occasionally open it up to check for surface rust becaue you will get some moisture in through the drive shaft. Ray

Sun Nov 22, 2015 8:50 am

raygreenwood wrote: That shield is a dust shield. It "may" keep some moisture from the points....but its the moisture in the dome of the cap that causes shorting between the cap contacts.

Since no moisture is going to be coming through the walls of the cap the shield is not going to prevent any moisture from reaching the points nor will it prevent much of any dust from reaching the points either as almost no dust is generated within the cap. The shield will slow the rate at which moisture and dust that enters the base of the distributor reaches the cap, but will not stop either totally. Think of the situation of driving through a violent rain storm or when fording a stream with water splashing against the distirbutor. A bit of water may enter the base when this occur and then quickly drain back out through the drain holes, at these times the shield will significantly reduce the amount of moisture entering into and condensing in the cap and prevent stalling.

Years ago when I did a lot of 4 wheeling, I got to laugh at a lot of folks who would try to follow me across streams and other wet areas. They were always stalling out in the places where I would have no problem and the main difference between their rigs and mine is that they had tossed those bothersome little shields in their dizzies that had not obvious purpose. One time when I did have an engine stall crossing a stream the water level was just below the level of the points in the dizzy. I dried the cap and rotor and reinstalled the parts including the shield and was able to start and run the engine. Had I not had that little shield in place there is little chance I would have gotten that engine to start let alone keep running.

If the cap is positively vented the shield is just another piece that will help keep the inside of the cap clean and dry.

Sun Nov 22, 2015 9:00 am

VOA of Portland Or called them "ozone" shields-- due to the high O2 content given off by high energy spark in the cap- causing corrosion in the points-

keeps the dust and water out too. :!: :!:

Sun Nov 22, 2015 10:54 am

https://www.google.com/search?q=vw+waterproof+dist...BaQQsAQIJA

Sun Nov 22, 2015 11:05 am

Wildthings wrote: raygreenwood wrote: That shield is a dust shield. It "may" keep some moisture from the points....but its the moisture in the dome of the cap that causes shorting between the cap contacts.

Since no moisture is going to be coming through the walls of the cap the shield is not going to prevent any moisture from reaching the points nor will it prevent much of any dust from reaching the points either as almost no dust is generated within the cap. The shield will slow the rate at which moisture and dust that enters the base of the distributor reaches the cap, but will not stop either totally. Think of the situation of driving through a violent rain storm or when fording a stream with water splashing against the distirbutor. A bit of water may enter the base when this occur and then quickly drain back out through the drain holes, at these times the shield will significantly reduce the amount of moisture entering into and condensing in the cap and prevent stalling.

Years ago when I did a lot of 4 wheeling, I got to laugh at a lot of folks who would try to follow me across streams and other wet areas. They were always stalling out in the places where I would have no problem and the main difference between their rigs and mine is that they had tossed those bothersome little shields in their dizzies that had not obvious purpose. One time when I did have an engine stall crossing a stream the water level was just below the level of the points in the dizzy. I dried the cap and rotor and reinstalled the parts including the shield and was able to start and run the engine. Had I not had that little shield in place there is little chance I would have gotten that engine to start let alone keep running.

If the cap is positively vented the shield is just another piece that will help keep the inside of the cap clean and dry.

sure...it may help with droplets of water that get in...but its a dust shield.

That was its purpose....thats whats listed in most VW parts listings for the vast amount of cars that used them. Its neither water or vapor tight.

The OP is getting NOTICEABLE condensation inside of his CAP...not on his points. Moisture is known to cause arcing between poles in the cap. The shield may keep droplets off the points...but not being airtight...it will not keep condensation off the points. The shield does nothing for condensation. Its a totally different issue from splash water.

Its a common problem in places of very high humidity that have large changes of temperature between night and day. Dew point changes and you have condensation.

Moisture doesn't need to come through "the walls of the cap"...and neither did I suggest that it did. The cap to distributor body joint is not even remotely watertight, airtight or sealed in any way...which is why I suggested sealing it and the vents.

Ray

Sun Nov 22, 2015 11:39 am

raygreenwood wrote:

Years ago when I did a lot of 4 wheeling, I got to laugh at a lot of folks who would try to follow me across streams and other wet areas. They were always stalling out in the places where I would have no problem and the main difference between their rigs and mine is that they had tossed those bothersome little shields in their dizzies that had not obvious purpose. One time when I did have an engine stall crossing a stream the water level was just below the level of the points in the dizzy. I dried the cap and rotor and reinstalled the parts including the shield and was able to start and run the engine. Had I not had that little shield in place there is little chance I would have gotten that engine to start let alone keep running.

If the cap is positively vented the shield is just another piece that will help keep the inside of the cap clean and dry.

sure...it may help with droplets of water that get in...but its a dust shield.

That was its purpose....thats whats listed in most VW parts listings for the vast amount of cars that used them. Its neither water or vapor tight.

The OP is getting NOTICEABLE condensation inside of his CAP...not on his points. Moisture is known to cause arcing between poles in the cap. The shield may keep droplets off the points...but not being airtight...it will not keep condensation off the points. The shield does nothing for condensation. Its a totally different issue from splash water.

Its a common problem in places of very high humidity that have large changes of temperature between night and day. Dew point changes and you have condensation.

Moisture doesn't need to come through "the walls of the cap"...and neither did I suggest that it did. The cap to distributor body joint is not even remotely watertight, airtight or sealed in any way...which is why I suggested sealing it and the vents.

Ray[/quote]

The only way that the shield could stop water or dust from reaching the points is if those substances were coming from the cap, which is almost 100% unlikely. If the moisture and dust were coming from another source then the shield would in no way prevent them from reaching the points. I will agree with WilliamM ideas that the shield has something to do with ozone seems way more likely than anything to do with dust. A lot of manufactures use these shield even on dizzies with electronic pickups so I doubt that their main or sole use was to protect the points. Also just because VW names a part a certain thing doesn't mean it has anything to do with that use. The control and relief valves in the dual relief case are both poorly named as is the always full expansion tank used on Vanagon engines.

Many rigs use vented caps to prevent condensation and may even still used the shields, so in my mind the combo of these two systems, vent and shield, is the way to go.

Sun Nov 22, 2015 11:39 am

Both thesamwise4 and I live on Oahu. He is in Honolulu and I am in Kaneohe. My side of the island is the windward side and we have more rain than town side. He has a bus and I have a Vanagon. I've had Datsun 510's. Temperatures and temperature changes are the same, but we are wetter. Why does he have distributor problems and I do not?

Does he have water in his oil that evaporates from the crankcase and condenses inside the distributor cap? If that was happening he should see moisture on the walls of the distributor body and mayonnaise in the oil filler cap.

Is the inside of the distributor cap contaminated with some hygroscopic material (zinc chloride, calcium chloride, potassium hydroxide, or sodium hydroxide) that attracts moisture?

Would cleaning of the distributor cap or replacement solve the problem?

Why does he have a problem?

Aloha
tp

Sun Nov 22, 2015 11:58 am

Wildthings wrote: raygreenwood wrote:

Years ago when I did a lot of 4 wheeling, I got to laugh at a lot of folks who would try to follow me across streams and other wet areas. They were always stalling out in the places where I would have no problem and the main difference between their rigs and mine is that they had tossed those bothersome little shields in their dizzies that had not obvious purpose. One time when I did have an engine stall crossing a stream the water level was just below the level of the points in the dizzy. I dried the cap and rotor and reinstalled the parts including the shield and was able to start and run the engine. Had I not had that little shield in place there is little chance I would have gotten that engine to start let alone keep running.

If the cap is positively vented the shield is just another piece that will help keep the inside of the cap clean and dry.

sure...it may help with droplets of water that get in...but its a dust shield.

That was its purpose....thats whats listed in most VW parts listings for the vast amount of cars that used them. Its neither water or vapor tight.

The OP is getting NOTICEABLE condensation inside of his CAP...not on his points. Moisture is known to cause arcing between poles in the cap. The shield may keep droplets off the points...but not being airtight...it will not keep condensation off the points. The shield does nothing for condensation. Its a totally different issue from splash water.

Its a common problem in places of very high humidity that have large changes of temperature between night and day. Dew point changes and you have condensation.

Moisture doesn't need to come through "the walls of the cap"...and neither did I suggest that it did. The cap to distributor body joint is not even remotely watertight, airtight or sealed in any way...which is why I suggested sealing it and the vents.

Ray

The only way that the shield could stop water or dust from reaching the points is if those substances were coming from the cap, which is almost 100% unlikely. If the moisture and dust were coming from another source then the shield would in no way prevent them from reaching the points. I will agree with WilliamM ideas that the shield has something to do with ozone seems way more likely than anything to do with dust. A lot of manufactures use these shield even on dizzies with electronic pickups so I doubt that their main or sole use was to protect the points. Also just because VW names a part a certain thing doesn't mean it has anything to do with that use. The control and relief valves in the dual relief case are both poorly named as is the always full expansion tank used on Vanagon engines.

Many rigs use vented caps to prevent condensation and may even still used the shields, so in my mind the combo of these two systems, vent and shield, is the way to go.

Sun Nov 22, 2015 12:36 pm

and do not plug the vents in the bottom of your distriubtor. When those vents are sealed off this is what happens next:

Ouch! Ozone is combustible and points emit frequent sparks!

Sun Nov 22, 2015 12:46 pm

Many Many years ago I lent my 1974 Super Beetle to a co-worker to do some job searching/interviewing. I knew the car's foibles quite well. and when she called to say that the bug would not start one damp morning I showed up with my "toolbox" in hand at her door. My tool box was a couple of kleenex. She was pretty impressed that I was able to get er running with just some tissues.

Sun Nov 22, 2015 1:02 pm

tasb wrote: ... Ozone is combustible and points emit frequent sparks!

From the internet:
"Ozone is not combustible, but pure ozone poses a serious fire and explosion risk by reacting with combustible materials."

O3 + oil vapor + spark = BOOM

Aloha
tp

Sun Nov 22, 2015 1:24 pm

Cut a ring out of foam, ID the size of the dist shaft and the OD to cover the vent holes. Oil it up a little bit.

Sun Nov 22, 2015 1:31 pm

williamM wrote: VOA of Portland Or called them "ozone" shields-- due to the high O2 content given off by high energy spark in the cap- causing corrosion in the points-

The spark jumping from the rotor to the dist. cap Ionizes the air molecule 02.
Ionizing the air charges oxygen atoms, enabling them to form toxic ozone molecules. Ozone in the air, which is a triple-bonded oxygen molecule of O3, can be a powerful oxidizing agent and toxic gas.

Tcash

Sun Nov 22, 2015 1:40 pm

The shield will no more prevent ozone from reaching the cap than moisture. My bet is its more likely an explosion was unburnt fuel than an ozone-oil explosion.

I suspect the cap is more to prevent debris from the rotor and cap falling into the points

Tue Nov 24, 2015 2:11 pm

Do some CLOSE reading (sorry educational term here) the plastic- sometimes aluminum shield has nothing to do with ozone build up. It's blocked vents in the bottom/side of the distributor and sometimes in the cap that does not allow ozone to escape/o2 in. Believe me, or choose not too- and ignore experience, the cap explosion was from ozone build up.