Bench testing late BN2 eberspacher heater

[gbdub]

Trying to install a BN2 late model gas heater in my 74 super and want to bench test it.  Can anyone help with the wiring for the set up on the bench.  I have the heater and metering pump mounted on a work bench and the matching electrical plug for the electrics taken from a parts car.  the heater is complete and looks to be in good order.  I am picking up that the large red wire is the hot and the large brown wire is the ground going into the plug.  I also have to feed wires to a switch and to the pump.  Can anyone help with wiring these other components so I can try to start the heater on the bench.  I had it installed in the car but it wouldn’t light.  After a number of attempts and research I thought it best to take it out and fool with it on the bench. 
Any help would be appreciated.

[gbdub]

wow there has to be someone out there that can help??

[pittwagen]

You need to go here and find the appropriate info:

http://www.oacdp.org/ebersp.html#f3

I have reconditioned many BN2's both early and late so a few points:

- make sure all the wiring push on connectors are tight and making good contact.  These connectors tend to be brittle and may break if you attempt to    tighten them.  Replace any that are required.
- you will need an excellent fully charged battery to get this heater to fire up.
- decent used parts are getting hard to find particularly the fuel pump.
- the fuel pump can be partially taken apart and cleaned.  Here is a good tutorial.  It is for a BN4 pump but the innards are similar.  The pump part          starts at page 2.

http://www.thesamba.com/vw/forum/viewtopic.php?t=614419&postdays=0&postorder=asc&highlight=bn4&start=20

- you can test the pump by applying power to it.  Hook up the ground and just touch the positive wire to the pump.  You want to hear it click.  Do it       very quickly.  Do not apply continuous power to the pump.  You will ruin it.  Oh and if it isn't clear in the diagrams the positive terminal on the       pump is on the right when looking at the terminals from the discharge end.

- if you do not hear the pump click (it is a pulse pump so it does not run continuously) you will likely need to disassemble the fan housing and         clean/regap the points as well as cleaning the pump noted above.

My thoughts for now.

[owdlvr]

Not sure what your confusion is?

If you have the pump, the switch, the heater and the wiring harness...it's pretty obvious. I think there is only one or two free connections to be made, one to the power (fusebox in the car normally) and one to the ground. The rest is self-contained within the harness and heater...

My bench test:


-Dave

[pittwagen]

I'm not sure how good that first reference is for troubleshooting the late BN2.  The wiring diagram should be ok.

But to get to the wires.  Coming out of the heater harness you will have a red wire, brown wire, blue wire, green wire and a brown and white wire.  At least that's what my 73 Super has.  Blue wire goes to the switch.  Green (left) and brown and white (right) go to the pump.  You figured out the other 2.  Dave (owdlvr) may have the proper late BN2 service manual.  I can't find mine right now.

[gbdub]

thanks for the help folks.  I appreciate it.  I am now all wired up fine and the pump pumps fine ( I think) when I throw the switch.  I got it going once for a minute or so and then it quit.  Can't seem to get it to go again.  I have changed the glow plug and even tried a different heater but only that one short start up.  I will continue to fool with it.  Hopefully if I can get it to go and can run it for a while it would would be good but my problem now is getting it go.  Going to check the voltage at the glow plug to make sure it is getting enough power

[gbdub]

Update:  Got it going on the bench similar to Dave Hords setup.  Ran great and the pump continued to pump so everything seemed to work fine.  Ran it for 20 minutes.  Wouldn't start on its own until I jumped a wire directly from the battery to the glow plugs then it started up right away.  Measured the voltage at the relay and it was 9 volts and at the glow plug it had dropped to 6.  Not sure why it dropped so much but obviously not enough power to heat the glow plug enough to start the furnace ( I am assuming).  Now I have it in the car and it will still will not start.  going to get back at it tomorrow and see if I can jump it from the battery and see if it will ignite.  Lots of fun and I am not giving up on this  [

Any ideas why that glow plug won't ingnite the fuel until I jump it:

-12 volts at the red wire going into the plug and trough it
-9 at the relay heavy yellow wire
-6 volts at glow plug heavy yellow wire

[owdlvr]

I'm outta town and don't have my notes, but 6v at the plug sounds right. I think they might even be five. I do know if you hold 12v on them too long they burnout. In the car, they need lots of AMPS to fire. Many of us find the heater won't actually light unless we've got the engine doing over 2000rpm. I actually wait until I'm going uphill, under load, to turn mine on. Fires up every time.

I'm my driveway, I have to hold the engine st 2,000rpm to get it to fire.

That's consistent with Bruce and many others. So I haven't looked for a "problem".

-Dave

[BUSDADDY]

-12 volts at the red wire going into the plug and trough it

Not enough, you need close to 14. Also consider the glow plug is powered through a resistor so you'll never see battery voltage there, and if any ground or power terminal is loose or corroded (particularly the ones on the yellow wires inside the shell) it'll be really hard to start.

[gbdub]

Thanks to all for the help guys and gals.   So here is the latest. Installed the heater and pump in the car and the heater started twice on its own in the car with the car reving at fast idle or above. Very happy and the heater blew great. Again if it won't start I just touch the glow plug for a second with a lead from the batter and it fires up right away.   Has anyone increased the guage of wire going to the heater and did that make a difference.  Also I was thinking of connecting a direct wire to the glow plug from the battery or a  hot terminal and running it through a horn button to give it a shot when I want it to start and it won't on its own.  QUESTION:  Any ideas for increasing the amperage so it will start up every time,  I know Dave you said you left it alone but I am looking for a fix to the starting?

[pittwagen]

So what voltage to you see when the car is running?  Is there a drop at the heater?  If there is a drop that may be part of the problem.  The heater alone needs 200 watts which is close to 17 amps.  Hope your charging system is in good shape.

There is no need for running larger diameter wire in the heater.  If the wires/terminals are clean, tight and not corroded there will be no problem.  Have you tested the glow plug and does it glow red after a minute like it says in the manual I referenced in a previous post ( section 4.3 1-2). Disconnect the pump, pull the plug and test it.  If it doesn't meet the test, get a new one.

When was the last time the glow plug was changed?  They do wear out and if you keep applying 12 volts to the glow plug whatever life was left in it will be no more.  It gets 6 volts max.  The correct glow plug for your heater is a 187GS.  They cost between $60 - $100 depending on where you buy them.

By way of comparison I have the same heater in my 73 and it has given me almost 42 years of service.  And yes I have changed the glow plug a few times.  Never had a problem starting it unless the glow plug was on its way out.  As well I have 2 spare BN2's and both will fire up (not attached to a car) with a fully charged battery on a consistent basis. Both have new glow plugs.

[gbdub]

Thanks for the reply pittwagen.  Not sure how old the glow plug is (probably 25 or 30 years) but I will check it out further today.  When I checked them on the bench they seemed fine but I was putting 12 volts to it to see if they lit up.  That may be the problem.  I have two glow plugs so I will check both out and see if one glows brighter than the other when being fired by the car with the gas line pinched off.  I will also check the voltage at the plug when the car is running to see if it is getting 5 or 6 volts.  When I checked it on the bench there was 5.8 volts at the glow plug and it still didn't start on its own on the bench without giving it a little jolt so I am assuming the voltage should be fine

Where did you buy the glow plugs from??

[pittwagen]

Bought the last one from Geoff.  Think it was about $60 which was a good price.  They come up on the Samba and Ebay but with the US dollar add 30% and shipping?  You can try some of the Espar dealers in the UK.  They have NOS plugs and the UK pound to our dollar has been reasonable.  Just make sure you get the right one.  Most of the ones I have are Beru.

On the wiring and I know it is a pain but clean, tight connections and proper flow of the current is an absolute must so take the time, do it right and check everything including the wiring under the tin cover.

[gbdub]

Will do.  Thanks again for the advice.  Will post updates

[gbdub]

update on the the heater.  As I said before the heater is in the car and now seems to be starting up fine when I have the revs up or are driving on the road in r 3rd gear.  I am happy to date so will leave it alone. 

Cheers.

[Bruce]

That's how I treat my B2 heater.  I only start it when the engine is running and I hold the rpms above about 2krpm.  Headlights must be off during startup.  Every tenth of a volt is important at the heater.