Bench Testing Webasto

bryanhes · November 27, 2009, 04:27:47 PM

I am trying to bench test my Webasto. I have the circuit diagrams but there is one that is an early canadian version and the other is present version. I have run the wires to what the early version shows but as soon as I hook up the negative to my battery it blows the inline fuse. Anyone that has a good knowledge please give me a call. 918 408 8917.

Is that you Nick?

Thanks,
Bryan

Nick Badame Refrig/ACC · November 27, 2009, 05:10:51 PM

Hi Bryan,

Second jack from the left on the module has a Black, Red, and Brown wire. Tye the red and black to positive, and the brown to negitive.

This will power up your unit and start a purge cycle first, then ignition, then fuel.

Do Not fire up the unit with no coolant in the heat exchanger!! You will melt the fuseable link at the top of the exchanger..

Swing open the burner, pull out the round venturi out of the exchanger, secure the venturi to the burner with clamps so that

the venturi is not inside the heat exchanger. Then you can bench test the burner. Oh, hook up the fuel line too...

You should have a circular flame pertrudding from the venturi about 6"..

Good Luck
Nick-

bryanhes · November 27, 2009, 05:38:46 PM

Nick,

I have my circulating pump hooked up with feed and return lines going into a seven gallon container of water. Do I need to prime the exchanger first by jumping the pump to fill it first? I have the brown to negative. The black is on the unit side of the toggle switch with the red going to positive and a fusible link between then a lead to the opposite side of the switch. This should do the same thing when I flip the switch right?

Thanks,
Bryan

Nick Badame Refrig/ACC · November 27, 2009, 06:51:51 PM

Hi Bryan,

Yes, it will do the same thing.

Since you have coolant hooked up you can also test your limit switches so leave the burner in the exchanger and bleed and air from the coolant system.

Use a thomometer that will read up to 220+ degrees and submerge it into your bucket. Your unit should cycle off at about 180 deg's then

cycle back on at about 140 deg's. This is done with the two limit switches on either side of the fuseable link at the top of the exchanger.

Does the unit still blow a fuse? or did you correct the connections?

bryanhes · November 27, 2009, 06:54:53 PM

I tried it the way you mentioned as well. The control board just clicks. Any way to test the control board? I did try to prime the water circulating pump. I think the impellor may be bad as it pushes very little water. I am just using garden size water hose.

Thanks,
Bryan

Nick Badame Refrig/ACC · November 27, 2009, 07:08:49 PM

Ok,

Clicks in the module are good signs.... This means it's working.

You'll have to start testing... First get a continunity meter and test the fuseable link at the top of the exchanger. It screws into the

center between the two limit switches. It will have two white wires connected to it. If it's open, it's bad.. Same with both limits..

if any are open, they are bad. Next, test the blower motor in the burner. [this is the most common problem with Webastos] The

blower will either be stuck, or the motor will burn out from being stuck... If blower doesn't turn with power, remove the module,

ignition coil, and remove the black plastic cover on the burner to expose the blower wheel/motor. Gently free up the motor by moving

it back and fourth without damaging the wheel or the gear that drives the fuel pump. If it frees up, your in good shape.

Good Luck
Nick-

bryanhes · November 27, 2009, 07:49:51 PM

Nick,

They all zero out on my ohm meter. So they are all closed. The motor turns freely. I just stuck a long screwdriver into the head and could turn the blades easy.

Any other ideas?

Thanks,
Bryan

Nick Badame Refrig/ACC · November 27, 2009, 08:24:44 PM

Ok,

Next see if your system had any external safty's. Does your second jack from the left [module] have any more jacks connected to it?

Like the two green wires? All should be open or not connected Also check the cad eye next to the burner nozzle. It should read

< (less than) 1600 Ohms when burning and over 20,000 when dark. If all tests ok, then we can point twards the control module.

Nick-

bryanhes · November 27, 2009, 08:50:40 PM

It did have B3 still plugged in but it was only for control light. I took it out. Only pins in place are B1 on/off switch, B2 Batt Neg. & B4 Batt Pos.

I am not sure what to make contact with on the photo eye. there are two wires on one spade and one on the other. I tried just touching the two spades but it just showed open. Unless I did it wrong.

I did contact the igniter tips and they showed 8.48 if that helps $:-\$

Thanks,
Bryan

bryanhes · November 27, 2009, 11:00:51 PM

I am about 98.5% I found the problem. I decided to take the protection cap off and check the motor connections since everything else seemed to check out ok. I even jumped the coils and had spark at the ignition electrodes. Once I pulled the cover and looked at the end of motor shaft and there it was. One of the field magnets apparently had come off during most likely its last run and was kicked sideways and worn down nicely on the corner (see photo below).

I did clip it back into place and hoped for the best but the controle module just clicked again as I thought it would.

So now what am I going to have to replace? Can I get a replacement field magnet? Probably not I am guessing

So much for a good working take out

Am I stuck buying a new motor. It looks quite different from the newer units.

Thanks again Nick,

Bryan

stevet903 · November 28, 2009, 11:00:40 AM

That looks like the brush for the motor to me. You could try taking the other side out and shaping the worn brush in the picture to match the curvature of the intact one. Once the brushes wear in, they should have a uniform "C" shape to them where they contact the curvature of the armature on the motor.

If you apply 12 or 24 volts (depending on the system) the motor should spin.

Here is a selection of manuals:

http://www.techwebasto.com/thermosystems_rv.htm#DBW_Series

Unfortunately I don't see brushes, only a motor in the parts list. Is there a manufacturer/model on the motor itself?

bryanhes · November 28, 2009, 12:49:25 PM

Steve,

It is one of the brushes. It was about 12:30 in the morning when I found this so my brain was a little foggy

The motor is a Bosch. It does have what appears to be a part number. I wondered if I could take the brush off and put it on my grinder wheel but was not sure if I could get it close enough to work. I guess I can not hurt it anymore than it already is

I have the service and parts manuals and the only option I saw as well was the complete motor. If it is not to expensive that may be the way to go since it is an older unit. On the other hand it does not appear to have been used very much.

Thanks,
Bryan

Nick Badame Refrig/ACC · November 28, 2009, 03:29:26 PM

Hi Bryan,

Try what Steve suggested... I have done this in the past with other motors but not the bosch.

It couldn't hurt since the Bosch motor is in the $300 range..

Good Luck
Nick-

Stormcloud · November 28, 2009, 03:32:37 PM

Ive also shaped odd brushes with a grinding wheel to fit various motors over the years and been quite successful at it. The trick is soldering together the two copper stranded wires.
and I got my Webasto installed and working....I bought this one from Nick on eBay recently.....makes lots and lots of hot antifreeze...seems to work well.

Best of luck..

Mark

Nick Badame Refrig/ACC · November 28, 2009, 07:08:13 PM

Quote from: Stormcloud on November 28, 2009, 03:32:37 PM
Ive also shaped odd brushes with a grinding wheel to fit various motors over the years and been quite successful at it. The trick is soldering together the two copper stranded wires.
and I got my Webasto installed and working....I bought this one from Nick on eBay recently.....makes lots and lots of hot antifreeze...seems to work well.

Best of luck..

Mark

Thanks Mark!
I'm glad your happy!
Nick-