Alternative coil for BA 4 Eberspacher?

[wshawn]

Does anyone know of an alternative coil for the BA 4 Eberspacher fitted to a 412.

I have run through a test of all the compaonents, long overdue, and reached the conclusion the coil is dead.

The coil recieves power to terminal 15, a steady 10.5 volts, but will not produce a spark when tested as per the 4mm screw inserted into the ignition lead and held from earth as directed on here

http://manuals.type4.org/ba4/ch3/ba4_13c.htm

All the other bits check out, fans all blow, fuel pump is delivering fuel through new hose (what a job that was, I have some seriously skinned knuckles) glow plug gets hot and has the correct 5 ohm resistance.

Hopefully replace the coil and it should go whumpf again!

[david58]

Note:
If there is no spark, measure the voltage at terminal 15 of the ignition coil with a voltmeter. The voltage must be at least 10 Volts. If the measured voltage is lower, check whether there is voltage when the contact breaker is open and no voltage when it is closed at terminal 1 of the ignition coil with a voltmeter or a test lamp. If the voltmeter needle does not move, even when the contact breaker is open (contact breaker is not shorted), the ignition coil has open circuit and a new coil must be installed.

Is the voltage changing on terminal #1?

[raygreenwood]

Did you check the trigger points for the coil and fuel pump? That is usually what it is. Ray

[wshawn]

My electrical know how is very limited so bear with me.

As no spark was present when checking the coil I touched the screw with a volt meter and it read the same as the input power so would this suggest the coil is faulty? In my limited understanding of a coil I thought they converted the input power upto a high voltage to produce a spark so if this step up is not happening I thought it meant the coil was dead? I could well be wrong though

I seem to have not looked at that page Ray. Would checking them require the unit being removed from car? And if not is it just a case of usually cleaning these contact points with a bit of sand paper?

[raygreenwood]

Yes. There may be an electrical way to see them operate...but being that they open and close at a rate of either every 15 or 30 revolutions of the shaft (cant recall which)....and the fan runs like about 3000 rpm....which works out to one breaker point cycle of either every .8 seconds or every 1.6 seconds.....its worth it to open up both sets of points and clean and grease them. They gao at .016"
The 1.6 seconds sounds about right.
You remove the blower unit from the heater and there is a cap under the rubber covered end (outer). You must first remove the huge "E" clip under the rubber cover. I think the cap either comes right off or uses several long screws. There is a single set of worm geared points under that with an inductor. At the other end....there is an aluminum cap with an opening in theend with the turbine underneath. It may pop right off...or need to be pried off. Either way, there is an o-ring that goes around the oiutside that must be replaced. iseal everything back together and lube the outer o-ring with permatex copper which is good to over 600F.....clamp it into the unit tight and let it dry overnight before using. Failure to properly reseal the blower will result in ugly gas fumes.
Under that turbine cover aluminum cap.....make a note of the gap between the back of the turbine and the housing. Then with a small allen wrench....through the access hole...remove the turbine. The whole motor unit slides out of the aluminum housing. You can now release the end cap on the turbine end and access the points for the coil.
One set of points fires the coil...one fires the fuel pump. Ray

[david58]

Ray I sent you a PM

[raygreenwood]

To answer Davids PM on the site..and his nifty video showing a quicky coil test...yes...a coil test like that should work just fine.
But...what I was getting at...should 100% be done before passing go.
Every single unit I have worked with eventually ended up needing point service. They are no diferent than regular points. They do tend to carbonize a little more and are heavily greased at the worm gear so they can actually get sticky and not work.
Plus...you will have to remove the blower to actually turn 15-30 revs to get to the point opening stage...or even see the cam. Ray

[david58]

Here is what I sent Ray
Click the pic


Wouldn't this same test work on the BA 4 Eberspacher heater to test the coil?

[david58]

So if you want to see if the points are triggering the coil I would recommend using a dwell meter because I don't think you will be able to see a test light blink at those RPM's. That way your not taking anything apart. The dwell should be 30 degrees if the gap is .016.

[raygreenwood]

Thanks David.....Its a quick way to test the coil.....but the blower should be disassembled anyway. About every two years. The points need to be filed and cleaned and the crusty lube cleaned out...or else they will fail when you least can afford not to have heat. Been there too many times.

Also, once you take the blower out, you need to service the o-ring or fuel condenses and leaks out giving fumes that get into your system when idling at lights...and are almost impossible to track. There will never be visible fuel when you look for it. Ray

[MGVWfan]

Ah, the lovely Eberspaecher BA4!

Here's a link to a copy of the factory service procedure on the Type 4 website...

http://manuals.type4.org/ba4/

It'll get you started. This is the ignition coil test page from the above link...

http://manuals.type4.org/ba4/ch3/ba4_13c.htm

Here's a link to the dealer service training materials for the BA4, from when it was first introduced with the 411...

http://www.thesamba.com/vw/archives/man ... heater.php

Remember some of the temperature control parts will be different from later BA4 installations.

I had a bad coil on my Eber when I got my 412 5-6 years ago, so I had to cross the same bridge you have, David. Yes, the standard ways of testing an ignition coil work with this one. It's an internally ballasted coil, which means you can hook +12V to Terminal 15, the trigger point line to Terminal 1, and your test spark plug to the HV nipple (called Terminal 4 by Bosch), no ballast resistor needed. If the coil sparks without breaking down in your test setup, it's either a wiring/12V feed issue, or nasty crapped-up ignition points in the combustion air blower. Use the troubleshooting chart in the link above to guide you. If the coil doesn't spark in the test setup, measure the primary resistance from Terminal 1 to 15, should be in the 3-8 Ohm range, and the secondary resistance from Terminal 1 to 4 (HV nipple), should be in the 2-20 K Ohm range. I'm betting if the coil doesn't spark in the test set, you have an open secondary winding, as I did. But first, make sure you've cleaned the points as Ray points out, I've also had lots of fun with that.

Replacement coil...well, you'll have a hard time finding an internally-ballasted coil with the same form factor as the original. I ended up using a flat epoxy-potted coil from a Mercury Tracer (lots of Japanese cars used this coil) mounted by one screw in the original location. It fits well. It is NOT internally-ballasted, and WILL destroy the points if you try to use it as-is. You will have to add a ballast resistor in the line going to Terminal 15 (the +12V line), either a real-live ceramic resistor from a points-type application (like a 1967 or so Dodge Dart with 225 6-cylinder, http://www.rockauto.com/catalog/x,carco ... ttype,7084 as an example), or get a 6 Ohm 25 Watt power resistor from Mouser or locally. I mounted a metal-cased power resistor on the combustion blower's air filter/flame trap housing, it was convenient, and the heat warms the incoming air some.

BTW Ray, it's the fuel pump points that are gear-reduced to close once every 33 revolutions of the combustion air blower shaft, the ignition points open once every revolution. And you are so right, both of them get nasty and can keep the coil or pump from working, so cleaning is in order if they've not been cleaned before. I use a strip of business card stock lightly saturated with contact cleaner or denatured alcohol (do NOT use contact cleaner and lube like for volume controls, it will really mess up the points and you'll have to remove them to clean them ) dragged through the points while they're closed. If they're really pitted and crusty, a point file may be needed to clean them up.

A little theory...the fuel pump and ignition are triggered from the combustion air blower for three reasons...one, in the late 60's when this thing was built, there was no other simple, cheap, reliable way to trigger an ignition coil or trigger a metering pump...second, the metering pump output (assuming constant volume per pump stroke) is directly tied to the combustion air blower speed, assuring the fuel/air ratio stays close to reasonable even when the blower runs slower (voltage sags, bearings getting worn, like that). Third, the ignition coil doesn't run unless the blower is running, minimizing the chance of uncontrolled combustion (explosion). Even if you consider doing something electronic (as I have in the past) to trigger the coil and pump, the last two considerations still apply, FYI.

[raygreenwood]

Very nice write up! I had forgotten that the coil triggered 1:1. Yes...you can actually use any coil that will fit as long as you ballast it properly. I had thought at one time about making a simple sheet metal bracket that uses the two original 6mm bolts to simply sling a standard short bosch coil down underneath the unit to be accesses easily and to have a readily replaceable one. Ray

[MGVWfan]

Thanks Ray. School of hard knocks on the Eber.

I need to write up my experiences of late with fuel supply to the "dosing pump" (as Eber calls it nowadays), seems bubbles are a consequence of the horrid fuel blends we get in Houston nowadays...and bubbles will completely shut down the pump.

BTW, where did you get your avatar, it's appropos now, I'm working on the new spacecraft, Orion, down here in Houston...that's what's kept me off the board for a while, lots of travel and late nights.

[raygreenwood]

I actually stole it from somehwere on line.... ....but you can get the manual:

http://www.amazon.com/s/ref=nb_ss?url=s ... &x=14&y=18

and the Spitfire

http://www.amazon.com/s/ref=nb_ss?url=s ... &x=16&y=12

And the Avro Lancaster
http://www.amazon.com/s/ref=nb_ss?url=s ... &x=17&y=20

And the ME 109


I had plucked the Avatar back in July during the aniversary of teh moon walk. About a mont hago...a friend at the office liked it so he started looking. Turns out the Apollo 11 shop manual....put out through Haynes is a set of drawings, stories, mission briefing and technical facts for the LEM. The Spitfire, Lancaster and ME 109 are exerpted maintenance manuals with outakes from a full restoration. These would be great reading in the loo Ray