another Eberspacher thread... must be winter somewhere !

[rickycox]

Hi all....

My 412, based in the U.K keeps on blowing the fuses ( under the back seat associated with the Eber ). As far as I can see I've tested the glowplug etc and all works fine. But the first and original owner has made the blower on a seperate switch ( know I 've guessed that if this is not always on maybe the fuses are blowing because of overheating ) But even having the blower on ALL the time the Eber is on it still seems to blow a fuse.

I've read the factory blurb as posted on previousd threads but no luck in spotting anything. I have 3 ( three ) inline barrel type fuses under the seat alongside the relay's. These fuses look standard ( wiring looks like it wasdone at the factory )

Any ideas, comments , help greatly appreciated.....

[Lahti411]

I uploaded the Eber Trouble Shoot manual to rapidshare:
http://rapidshare.com/files/324397032/E ... t.pdf.html

Maybe this helps.

[MGVWfan]

Ah, the lovely Eberspaecher BA4 fuses !

Thanks for posting the troubleshooting manual, Lahti...note that the posted troubleshooting guide is for the Canadian version of the Eber, which has a different relay (and a two-speed hot air blower) from the "standard" version. I'm suspecting Scandinavia and Canada got that version "standard", along with the second battery under the right seat. The UK may or may not have...I know the US got the other version "standard", with the Canadian version as an option up in colder climes (like Minnesota, helped keep the Lutefisk and Lefse warm, doncha know... ).

OK, some preliminary stuff. From the description, you have a Variant/Station Wagon/Estate Car/Break (46x) body style, since the Sedans/Saloons (41x, 42x) have the relays and fuses in the engine bay. The silver ice-cube relay on the right (Driver's Side in the UK) is for the rear windscreen demister, and the fuse connected to it serves that function. That leaves two other fuses which both feed bits of the Eber. The fuse with green wires on one end is the fuel pump fuse, also called the "overheating" fuse since, if you overheat the Eber, the overheat switch will short out the fuel pump feed and blow the fuse. It's an 8A (white) fuse. The other is the Eber "main" fuse, it has red wires on both sides, and is a 16A (red) fuse.

I've had trouble with both fuses blowing when the overheat switch closes, instead of just the fuel pump fuse, that may be what's happening here. If the main fuse blows immediately upon heater actuation, you have something different going on. What's causing the fuse(s) to blow? Proceeding down the path that they blow after the heat exchanger comes up to "overheat" tempearature, maybe 5 minutes at 70 deg F, you probably hit it, the DPO's mods may cause the Eber hot air blower to not run when it needs to, and fire in the Eber but no air to take the heat away = overheat switch actuation. Low airflow through the Eber causes this, too. I had a hot air blower that was running slowly due to draggy bushings, and it caused the overheat switch to actuate after running about 10 minutes with the engine off. With the engine on, the fan + engine fan produced enough airflow to keep the switch from tripping. Eventually, the fan started pulling enough to blow the main fuse by itself due to the draggy bushings. I found another blower motor, disassembled it, cleaned the commutator, lubed the bushings, and it's still working after a year...

Are all three of the non-return flaps present? See the link to get an idea what I'm talking about...

http://www.bus-boys.com/aircoolsystem.html

They're the little square things on the bottom left and right. If these aren't present, the Eber booster blower's flow goes into the engine fan housing, never to be seen again. If the third, in the Eber blower's discharge, is not present, hot air from the exhaust heat exchangers backs up through the Eber blower when it's not running, causing lots of fun and games.

Another possibility is that the blower produces enough flow, but the air is leaking out at various places (there are oh, so many possibilities here) reducing the amount flowing through the Eber. Take a good look at the various bits that conduct the air from the blower to the Eber, and see what's up. Turn the blower on by itself (or jumper the blower's yellow wire to +12V for those with original wiring), and get under/on top of the thing and feel for air leaks. Here''s a link to Richard Atwell's T4-engined Bus site...

http://www.ratwell.com/technical/Heating.html

The 411/412 heating system is identical up to the buses' flapper boxes, so this'll give you an idea what to look for up to that point. His description of the little non-return flaps is pretty good, and he's got some good advice on leak elimination in general.

BTW, I would return the blower wiring to OE state, the blower must run after the Eber is turned off to cool down the heat exchanger, and if it's on a separate switch, it'll require you to sit there and wait 4-5 minutes and turn off the switch manually post-run. Most annoying.

[rickycox]

so far:

1. Checked the diagram you sent and all 3 flaps are present.

2. The fuse thats blows is the green wired one so " Overheating fuse ".

3. I do make sure the blower is always on ( no standard switch ) and still the overheating fuse blows. I've checked the lever movement and it appears the heatexchanger flaps are opening to allow heat into the car ( I can feel heat from the vents etc )

So maybe the flaps are not opening enough to allow more heat into the car, would that make the Eber overheat / blow fuse ?

I will return the blower switch to standard once I figure why and how it had been changed from standard.......

[MGVWfan]

OK Ricky, sounds like the overheat switch is closing all right. Does the fuse blow immediately, or after the heater's had a chance to warm up?

BTW, you get clobbered with the snow where you are in the UK? I've got BBC R. Suffolk on right now, they were reporting on the severe weather yesterday, sounds like you guys are digging out...

[rickycox]

its after about 5 mins ish it blows.... how do you mean the overheat switch is closing ?


Yeah lots of snow, I'm in Surrey at the moment but off to family for Christmas on the Norfolk Broads !!! so need lots of heat in the car to keep my other half happy

[MGVWfan]

That is definitely the overheat switch closing after the heat exchanger heats up to its trigger temp. Is it a defective overheat switch, or low airflow, that's the question. Here's a picture of the switch in its installed location...

http://manuals.type4.org/ba4/ch5/ba4_15a.htm

It's a little "Klixon" disc-type thermostat, triggers at about 400 deg F. It's in a silicone rubber boot that fits in a hole in the outer casing, and "sees" the infrared radiation from the inner heat exchanger, and is somewhat cooled by passing heated airflow. BTW, DO NOT RUN THE EBER WITHOUT THE OVERHEAT SWITCH, there, I said it. It's the only thing that keeps the whole mess from melting down and setting fire to the car in case of runaway combustion and other faults.

With the engine running at about 1500-2000 RPM, does the switch still close and blow the fuse? At those engine speeds, the engine blower is forcing a good torrent of air through the Eber, and you should feel a strong airflow from the inside vents (not a weak dribble of air). If the switch does not trigger while running the engine, the problem is either air leaks or a slow-running Eber hot air blower (worn out commutator, bushings, like that). If the switch still triggers, we get to scratch our collective heads a bit and have a cuppa tea/pint of ale/cuppa java and consider the problem further...most likely still air leaks, but they'd have to be pretty massive to cause trouble with the engine revved. At that point, if you have a spare overheat switch, I'd install it and try things again. I've not had trouble personally with the switch failing, but others may have.

Merry Christmas then, with all that snow! Last I was in England, Mother USAF had me at RAF's Mildenhall/Lakenheath/Alconbury/Bentwaters/Woodbridge doing comm system engineering. No snow, but lots of Greene King Ale and other Suffolk/Cambs. delights. Methinks you'll need that Eber on the A1(M)...

[raygreenwood]

Yes, spot on. Its the overheat or high limit switch. This can also be caused by running too hot meaning too much fuel...as an airflow resctriction....or a thermostat in the body duct that is way out of spec or has been wired around.

Also...check what fuse is in the black fuse holder that the high limit switch goes to if memory serves....it might be a 20-30 amp fuse. Its the olive green wire with the single fuse holder.

If your heater blower...the turbo...not the auxiliary is heard to run slow when cold until warmed up...it needs to be opened, cleaned, brushes and commutator checked and greased properly with a non-graphite based grease.

As MGVW fan noted in a previous post....even this should not overheat you as the fuel supply is proportional to speed.

Also check that the overheat switch is properly installed. If either flag connectro contacts metal as it heats up...it will blow the fuse. Also if your auxiliary fan is not working at low speeds like in traffic...it can overheat. Ray

[MGVWfan]

BTW, if you go to Lahti411's link, pg 19, it'll lead you through the same sort of troubleshooting procedure Ray and I have outlined...pretty neat when the factory was thinking the same way you do. That overheat troubleshooting's not in my version of the BA4 troubleshooting booklet, interesting.

[rickycox]

Thanks guys.... very helpful....

I'm off for Christmas tomorrow so will see what happens on the drive up country. I'm gonna try just using the Eber once up to A road speed 40mph + and see what happens... But i'm guessing as you rightly say its when used at idle or slow moving in trafic it overheats bla bla bla..

Regarding the overheat switch, i've seen the photo etc in the manual but still struggling to locate it on the car ( position etc ) Is this me being short sighted or is it tricky to find ?

BTW I went to many an open day at Mildenhall.... great hot dogs and root beer

[MGVWfan]

Root beer, eh? Quite the Yank thing, that.

Yeah, that's how I dealt with it, only activated the Eber once up to speed, then shut it down (using the thermostat on the fascia) before decelerating until I found a replacement blower motor. If it's leaks or airflow at idle, that should keep you from tripping the overheat switch while in transit.

The O/H switch is a little hard to see, it's kind of back and to the right of the ignition coil, just visible from the inspection opening in the rear deck. It's encased in that rubber cap thing, with the wires exiting at a right angle.

Maybe Father Christmas will bring you a new Eber blower!

Good old Moldyhole, lots of aircraft spotters hang out there due to the variety of transient aircraft they get to see. And excellent "open days", yeah! Beck's Row still have that little pub, can't remember the name, the "something and bush"...? Stayed in the Smokehouse Inn when the VOQ was full (which was most of the time). Loved East Anglia, actually, some thought it too quiet and "rural", I enjoyed the little towns and local pubs, the nice folks. It's all a matter of perspective. Of course, that was the early 80's...getting old, eh?

[wshawn]

Nothing to do with getting your Eber working, sorry, but I have some vague memories of nights out on a certain US base in the late 80s related to attempts by myself and a few colleagues to relief the disco of the sparkly mirror ball, attempts that for some reason the USAF Police took a stern view on... a few weapons pointed at oneself soon sobers you up to the point of returning the said ball and escaping to your own base rather quick

Thankfully as RAF Police we shared a good relationship with the guys on the US base and nothing was reported to superiors

[MGVWfan]

Shawn, you rascal! Must have been a few pints of something involved in that deed...

[wshawn]

Shawn, you rascal! Must have been a few pints of something involved in that deed...

What makes you say that?

[MGVWfan]

Happy Boxing Day, Ricky (and Shawn, too!)...hope the crowds at the shops don't jam up the roads too badly. We're off to see Granny now ourselves. Hoist a pint or two for us, then!