Heater repair

[boelle]

hi..

dont know if i can help, i have the much older bbw40 unit which compared to the thermotops are much more simple to do fault search on

look at the manual a few steps up one thing came to mind... the glow plug / flame sensor... if i do not take much mistake a fault here could leed to the truoble.... let me put it like this:

the unit fires up... and then because it does never see the flame it shuts down and maybe retry it a few times and then locks with an error code (hence it works ok if power has been taken away for 10 secs or more).. the glowplug is descriped on page 8 on that pdf...

below is the parts list manual which may not look like much but when held together with the workshop manual it does provide a little more detail in to all the small bits that makes up the complete system... it is only usefull when the faulty part has been found and you need the correct part number.

only thing i missed is how to diagnose the the individual parts (what their correct value are) but on the last page there is a diagnose tool... i'm sure you can order it if you just provide the dealer with the part number... but i have never used it since my heater is way to old.. i have to do the diagnose the hard way

the software for the diagnose unit can be found directly from webasto: http://www.techwebasto.com/heater_main/ ... g_2_07.zip

the unit itself can at the moment be found on ebay here:

http://cgi.ebay.co.uk/WEBASTO-AIR-TOP-T ... 2eaa3f24f7

EDIT (just to keeep track of links):

Service and Repair Manual:

http://techwebasto.com/heater_main/tech ... 63378A.pdf

Parts list manual:

http://techwebasto.com/heater_main/5000918A.pdf

Troubleshooting:

http://www.techwebasto.com/heater_main/ ... g_Tree.pdf

Manual for the diagnose software:

http://techwebasto.com/heater_main/ther ... .07_GB.pdf

[ChrisB]

Handy bunch of links there boelle.

My problem is flame lift and flame out on the burner, thus once this starts is can trigger the flame sensor and thus it shuts down, I still suspect fuel flow to be the main issue for my one, now that could be due to fuel contamination or the pump being faulty ?

ChrisB

[boelle]

i can only speak regarding to the bbw type i have...

it's easy for me to say what it does when because they where so kind to include a timeline thing that shows it... as i can see it is not included for the thermotop series... sadly as it also helps a lot to do fault finding..

btw mine is from 1998

i even managed to find this functional diagram in the net... page 12 on this pdf http://www.telusplanet.net/public/gary2 ... /bbw46.pdf

go 2 pages back and it's descriped in words... since it can do a flame the dose pump is ok.. there is no way it can do a flame without that... just try to disconnect the dose pump and fire it up... if you can locate the dose pump try to fire up the unit and grap the dose pump... after about 20 sec you should feel it pulse... it will take one hour to pump 0,5 liters.... what could be wrong is air in the fuel line.... but as i remember it they use hard plastic lines and the diameter inside the line is arround 2 milimeters.. of course these lines become old and get small craks... but i guess you cant smell anything ? but the cracks can be so small that you cant smell it... anyways if there is air bubbles in the line it will prevent it from feeding the burner fast enough and it will stop and lock the unit with an error... and you then need to pull the fuse or power to the unit...

hmm... chekcing the full lenght of the fuel line is an option but looking out my window makes me think you think i'm crazy.... even here its sub zero.... one way to test if it pumps fuel enough could be to disconnect the fuel line at the burner and put that in a ½ liter cola bottle or something like it and then disconnet the wires to the dose pump and via a relay connected to the turn signal have it pump fuel...

what else could make the damm thing stop? if the 12 V drops below 9.5 it will also stop... try messure the voltage... just to rule that out....

what could help us is to know what value the temp. sensor should have at 20 degree c etc.... thse could go bad an indicate 78 degress even before its 30 degress.... the result would be almost the same.... it will stop heating...

for the moment i cant think of any other possible sources of errors... the diagnose unit would be a lot of help

// bo

[ChrisB]

Checked all of the above with my only concern being a possible lack of fuel from the dose pump

I have'nt actually measure it TBH

Just seems odd that it can run fine for ages and then just seemingly randomly go out

I'm still of the conclusion its crud/water in the tank blocking the intake/filter, I keep meaning to strip the tank out and clean it out in the summer, but of course the summer comes and goes and I forget

Can someone remind me this year

ChrisB

[boelle]

sure.... but would be more easy if you entered that in the calendar on your phone... i use it and a few days ago it surpised me with the birthday of my girlfriends dad