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Thu Jun 19, 2008 6:15 am

Greetings

Thought I would share photos/info on our latest beetle project.

Now perhaps this is not the best time of year to talk about Gas heaters for Bugs, but I'm not about to start a project like this when I really need the heat.

I am in the final stages of rebuilding an Eberspacher B2 Gas Heater. Its a 12volt unit so it won't work in the 6 volt 64 Bug, buts its still sort of fun. As I go along I'm trying to document the process into a technical manual. I've been real lucky so far in that all the original components are in great shape and I have not had to replace any.(Just fuel lines)

The process so far is...
1) Take lots of pictures
2) Completely dismantle and remove everything
3) Rebuild/replace parts/clean and isolate/test each component separately.
3) Clean and derust all metal (case fan housing etc)
4) Make everything esthetically pleasing. (Spray paint) Used a "hammered" type of spray finish. Looks great and comes real close to the original paint

Of course the technical manual goes into a lot more detail than the above.

At this point in time I just finished finished cleaning and testing the fuel pump. It works great. The diaphragm has no rips or holes.

I'm also waiting for some 5mm and 7mm hose lines and crimp style connectors. (Not the worm gear type) :(

These 3 pics show the removal of the existing hose connectors

The ends of the hose barb has surface rust and will be removed

These are pics of the B2 unit partially assembled...

This shows the temp hose lines that were used for testing the fuel pump

Detailed wiring and components

If you have thoughts or comments, sure would appreciate them.

Thanks

Thu Jun 19, 2008 6:38 am

Awesome. I love details threads like this with pics.

The paint on the heater looks to be in pretty good shape. Why not just apply a coat of clear paint over it and preserve the original finish on it?

Also, for closeup shots, like the two of the hose fittings in the vice, you may want to consider adjusting the camera's focus so that they are not blurry.

I've never messed with heaters before, but I'll be keeping an eye on this. Good luck with the project and keep us posted! 8)

Thu Jun 19, 2008 7:57 pm

Maybe you should become the new "heater repair man"? The "other" guy has apparently disappeared and stopped working on heaters, which is no big loss... He wasn't very friendly to begin with!

Thu Jun 19, 2008 8:58 pm

Glad to see this thread! I'll be starting my own B2 rebuild very soon. I have a VERY complete unit that I plan on installing in my '70.
I'm especially interested in the fuel line fittings. Do you plan on installing them in the gas tank, per original? I've been told that those lines always leak and to just install a "T" underneath the tank, but then I'm not sure what to do about the return line.
Please keep us updated and post lots of pics.

Fri Jun 20, 2008 5:00 am

Thanks for the tips and questions. Keep them coming.

Woreign...I have a long way to go before I can earn the title of "Heater Repair Man" but thanks for the vote of confidence.Hopefully sometime soon. For obvious reasons I'm focusing on the B2 for the early Beetles

scott s....Perhaps we could use this thread to document any tips and tricks, to share our experiences. Unless their is a better forum.
I've had the same thoughts about the fuel pickup lines. I would have to do some testing, but I wonder if the old style fuel pump would have enough head pressure to suck the fuel from that far down below the tank.
FYI

"Head pressure". "Head" is simply defined as any resistance to the flow of a pump. When pump manufacturers list the head pressure, they are referring to the vertical discharge pressure head. Described in very simple terms, a pump's vertical discharge "pressure-head" is the vertical lift in height (usually measured in feet of water) at which a pump can no longer exert enough pressure to move water. At this point, the pump may be said to have reached its "shut-off" head pressure. When you look at a flow curve chart for a pump, the "shut-off head" is the point on the graph where the curved line becomes horizontal as the flow rate at that point is zero. The higher a pump's head pressure, the more powerful the pump.

The issue that you identified is what to do with the overflow from the jet carrier. Could it be run into the filler neck of the gas tank some how? Does the fuel tank need to be a closed system or is it under some pressure?

I beleive the later models of Eberspacher ie the BN2 have added a fuel metering device which may eliminate the overflow tube. Needs more research on my part.

As mentioned above, I'm documenting the rebuild process into a technical manual with pics. It's a work in progress, and if their are a couple or more of us that want to share info, it could benefit everyone.

I've collected a number manuals already (digital form) from links I've come across here in the forums/technical areas as well as external links. These cover the whole range of Eberspacher models.

So much to learn, so little time.

Keep those comments coming. I'd be interested in any problems you may have had in the past, either installation or part issues. I can log these in the technical manual in an Appendix, ultimately with solutions

Thanks

Fri Jun 20, 2008 5:59 am

I had a B2 in my '66. It was easy enough to tap into the fuel lines at the bottom of the tank for the pick up and into the filler neck for the return. The neck was on the same side as the heater.
However, with the '70, the filler is external and on the other side of the car.
Is your gas tank already drilled for the factory Eberspacher pick-up/return? Do you have a plan to drill it without removing/draining the tank?
You can see where it goes into the tank in this pic.

Fri Jun 20, 2008 8:09 am

Been looking for a complete B2 for my 66 for a long time. Maybe I'll pick up a rebuildable one and get some help from you guys. Gotta get it done before winter tho, gets cold here in PA and I have no stock heat. It sat last winter cause all I could find was those damn BN4 or a NOS B2 in unopened box for like $850!

Sun Jun 22, 2008 2:04 pm

Just keeping this one alive.
What do you plan to do about re-crimping the fuel hoses? There's a hose/rubber supply house near me. I had them make some brake lines for my girlfriends motorcycle a while back. I thought about seeing if they could make up the fuel lines when the time comes.
And like I asked before...where are you running the return line? Is your tank already cut for the fuel pickup/return?

Sun Jun 22, 2008 4:50 pm

I've ordered some lengths of cloth braided fuel lines from www.germansupply.com in Toronto. They have permanent crimp type connectors that do not hurt the hose.
http://www.germansupply.com/home/customer/product.php?productid=17342&cat=&page=1
They are crimped with a pair of side cutters

Their are 3 hose lines that are 5mm ID and 1 line that is 7mm ID. I have the lengths documented if you or any one else needs them.

The original lines are rubber with a metal braided outer. I could not find a source that was affordable. The Performance auto places were the only source and way to expensive. Were your brake lines very expensive?

I'm not sure that the heater would be worth the added expense for steel braided lines

German supply recommends the cloth for Gas Heaters.

Pickup/Return Lines:
Option A:
I was thinking of obtaining an aftermarket gas cap and drilling the center out of it to accept the OE Pickup unit. However, on my 64, their does not seem to be a lot of head room between the top of gas cap and the inside bottom of the trunk lid.

Option B:
Another thought was to tie into the the cars fuel line below the tank for the pickup line and drill a smaller single hole into the side of the filler neck for the return/overflow line.
Not sure that the fuel pump will have enough pumping "guts" to suck the fuel up that far though. Any thoughts?

Option C:
The last and obvious solution is to install the OE pickup into the cars fuel tank.

Did some more work on the unit today, by cleaning and derusting the fuel pump. Tried to locate some really thin rubber to replace the diaphragm rubber, but no luck yet.

Also since my Bug is 6 volt and the gas heater is 12, I'm looking at some alternatives to run it on my 6 volt system

Option 1
Purchase and replace the 12 volt equipment with 6 volt. ie Fan, fuel pump and light. (The glow plug will run directly off 6 volt but you don't need to use the resistance coil.

Option 2
Continue rebuilding the unit as a 12 volt, sell it and buy a 6 volt unit for rebuild.

Option 3
Make the unit a combo style by connecting a 6 volt to 12 volt DC step up transformer, for only those components that need 12 volts. I still need to do some voltage/ amperage calcs to determine the current draw. Its possible that the total current draw of the componets may exceed the current output of the step up transformer. I know they exist, cause I have one for my little 40W stereo amp that feeds the mp3 player. The other issue is would I be bypassing the safety mechanisms built into the heater. I know that when the heater overheats the safety switch shuts off the fuel pump. Also the fan goes into a slower speed for a short while after the unit is turned off to purge any residuel heat out of thecombustion chamber.

I'm not sure if I'm making this more complicated than it should be. I just do a lot of thinking. :roll:

I sure would appreciate your thoughts on all of this.

Thanks

Sun Jun 22, 2008 5:51 pm

For the fuel, I did "Option B" on my old '66. It seemed to work fine that way. BUT, I have a '70 now and there is no filler neck there to tap into.

Sun Jun 22, 2008 10:44 pm

http://classicvw.org/eberspacher

Sun Jun 22, 2008 11:02 pm

64Bug wrote: .
Not sure that the fuel pump will have enough pumping "guts" to suck the fuel up that far though. Any thoughts?

Option 1
Purchase and replace the 12 volt equipment with 6 volt. ie Fan, fuel pump and light. (The glow plug will run directly off 6 volt but you don't need to use the resistance coil.
The amount of effort the pump has to apply to suck gas from the original Eberspacher pickup location (at the LR of the tank like in my pic above) is exactly the same as if you tie into the hose that feeds the engine below the tank.
I recommend you tap into the fuel line below the tank. It's much easier to install this way. I know of several installations like this and it works fine.

Converting a 12V heater to 6V is foolish, IMO. You will need to locate a bunch of 6V parts, which will likely be attached to a 6V heater. The glow plug isn't as easy as you think. The glow plug operates at 4V. So if you convert to 6V, you will still have to use a resistance coil of a different value. One you will get from the 6V heater you will need to buy for parts.

Mon Jun 23, 2008 4:04 am

Bruce, what do you do about the return line on a later model tank? On my '66, I just tapped into the filler neck, which was right next to the heater. But on the '70, it has the external filler on the other side of the car. I guess I COULD run a line over there, but that doesn't seem like a good option to me.
If I can get the local hose shop to make some new hoses, what's wrong with runnning it like you have it? I think you warned me against it because all the old hoses leak, but if they were new......
Lastly, I know you can't weld on a gas tank w/o draining and flushing it, but what about drilling the hole for the pickup? Possible to do in the car?

Mon Jun 23, 2008 4:58 am

Unfortunatley I can't offer to much advice on the return line because I don't have a later model Bug. As you mentioned scott s you COULD run it over to the other side. I would definitely put in a new line though.

Bruce thanks for the clarification on the "4 volt" glow plug running at 6 volts. It stands to reason a resistance coil would still be needed.

So the question still remains, what can you do with the end of the return line hose?

Thinking outside the box, how much fuel is really returned from the jet carrier? What are the implications if the return line were to be routed back into the pickup line before the fuel pump? or....tie it back into the same line below the fuel tank. That way you have two fuel pumps, the engines fuel pump and heater fuel pump, both drawing on any excess overflow from the gas heater.

To contradict my second point above, what happens when the heater is off. Does the return line fill with air and subsequently cause an air lock in the main fuel line to the engine?

I'm not sure I would want to experiment with the changes above, but I gotta ask the questions.

I know that Eberspacher engineered it that way and they did it for a reason. I suppose thats why improvements were made in the newer models.

More food for thought. :roll:

Mon Jun 23, 2008 5:25 am

The BN4 heaters, like on the Thing, tapped into the main fuel line below the tank. And there was no return line either. Might have had something to do with the fact that the heater's fuel pump was mounted below the tank, so the pump was gravity fed/primed. Where is the B2's fuel pump mounted compared to the fuel tank?

Mon Jun 23, 2008 5:48 am

The B2's fuel pump is mounted right on the side of the heater. I think, and stand corrected, that by going to a fuel metering device on the later models, that the retrun line was no longer required.

Mon Jun 23, 2008 9:43 pm

scott s wrote: Bruce, what do you do about the return line on a later model tank? On my '66, I just tapped into the filler neck, which was right next to the heater. But on the '70, it has the external filler on the other side of the car. I guess I COULD run a line over there, but that doesn't seem like a good option to me.
If I can get the local hose shop to make some new hoses, what's wrong with runnning it like you have it? I think you warned me against it because all the old hoses leak, but if they were new......
Lastly, I know you can't weld on a gas tank w/o draining and flushing it, but what about drilling the hole for the pickup? Possible to do in the car?
Well, you can clearly see the return line for my heater in my pic :wink:

The other installations I was refering to that draw fuel from under the tank have their return line connected up down there. The return hose won't back up, excess fuel will just flow back into the tank. The height of the fuel in the return line will be exactly the same as the level in the tank, always changing with consumption.

I would NOT run the return line to the right side of the car and tap it into the filler. The hose would lay down on the floor of the trunk behind the tank, then rise up to the filler. This will cause the hose to fill with fuel, backing up to the filler possibly. The hose must not go uphill. Remember plumber's rule #1.

There's nothing wrong with what you propose. Make new braided steel lines, then crimp them onto the original fuel pickup. Then hog out a hole in your tank. A lot of work when the alternative is so simple. The only reason I did mine like in the pic is because 20 years ago I never thought of doing it any other way. I sure wouldn't do it that way today.

If you do, don't even think about trying it in the car. Pull the tank and drain it. IIRC, the hole is close to an inch in dia. I started small then from ½" up, I used a die grinder to open it up. All those chunks of steel are gonna end up plugging your pickup if you try this in the car. Not to mention the risk of making a spark with whatever tool you use.

Fri Jun 27, 2008 5:28 am

Bruce, I reread your post and what you say makes absolute sense. ( Takes me awhile)
Quote: The other installations I was refering to that draw fuel from under the tank have their return line connected up down there. The return hose won't back up, excess fuel will just flow back into the tank. The height of the fuel in the return line will be exactly the same as the level in the tank, always changing with consumption.

That would be much easier than cutting a hole in the fuel tank.

Thanks

Update:

Still waiting for the new fuel hose lines and hose clamps to arrive. The supplier told me the small 5mm hose clamps were back ordered and could be delivered today. (I phoned on Wednesday of this week)

Fuel Pump:

I figure after 40 years, the rubber diaphragm should be replaced. It is a little stiff, not brittle or cracking yet, so I’m looking for a suitable material for its replacement.
1) Obviously must be gas and oil resistant
2) Must be thin enough but strong to handle the constant vibration.

The original is actually two thin layers of material. The layer closest to the bottom of the pump is a thin piece of black rubber with the layer above it being orange and appearing to have a woven texture to it. The layers do not appear to be “glued” together but I guess over the years they have sort of congealed into each other.

So, in meeting with the above criteria, my quest for a suitable material begins…..

Thought I would try a piece of rubber from a car tire inner tube. Nope, too thick and impedes the up and down motion of the diaphragm plunger. Besides not sure it would be gas and oil resistant.

I remembered buying some fuel and chemical resistant rubber gloves a long time ago. Dug them out of the shop cupboard, cut them up and used different products to glue the two layers together. It worked for a while until the glue dried solid and shrunk the rubber. :( I used two layers together as the rubber was very thin. Unfortunatly I used up all of the glove material trying different glues, and correcting the size.

Side Note:
BTW the diameter of the diaphragm in a B2 fuel pump is 1 and 5/8”. To cut the rubber into circles, I used a rotary cutter and cutting matt. The same as what quilters and scrapbooking people use.

So off to the hardware store to purchase another pair of gas and oil resistant rubber gloves. The only ones they had were “flock” lined. Hmmm….not sure how that would react with the gas, but will give it try. Before I start cutting them up into little circles, I took a small piece and immersed it in a glass jar of gas. It is still soaking, so I’ll let you know in a couple of days what the outcome is.

Do you have any other ideas of what to use for the diaphragm material? Or if you know where I can get replacement ones, that would be even better. Would a shop that services pumps or hydraulics have such a material?

Fri Jun 27, 2008 11:57 pm

A carburator's accelerator pump diaphragm is the exact material. Try to find that.

Sat Jun 28, 2008 5:09 am

Bruce, not to be dense, but could you elaborate on the fuel lines under the tank?
The T for the intake is a no brainer, but what about the return? Just another T in the line or do you have a better way to do it?