Mk 1 Aux Heater

[new nige]

Read lots of aux heater posts and have a couple of queries, can anyone help?

 

The car is an Mk1 1998 AHU Ghia X aux heater pipes bypassed by previous owner, Aux heater has never worked, 3 cold children.

 

1) Am I correct this is a dumb unit with no controller and hence no VAG COM Connectivity to module 18

 

2) Blower works (no heat), is this separate from the unit you drop from under the car as per FAQ #1 page 6 or integral suggesting it has power.

 

3) As hoses are bypassed I was going to remove for a few weeks and strip, will this effect weathering to the car while it

[marinabrid]

welocme to the wonderful aux heater post,

my answers are gained from years of these,

 

1 yes the mk 1 is dumb no vagcom connect

2 the rear blower is inside the car at the back and is fed by water pipes from the aux heater no need to touch this blower unit

3 you say the hoses are bypassed, if the heater is just sat there then unplug the electrics and remove the unit i assumed by bypassed you mean someone has pulled both hoses off the heater and joined them ?

4 the cicuit is completed by crossing the sensor wiht a mini fuse

5 no run on pump fitted to mk 1 i dont know why and no one else seems to either

6 no 2nd battery unless you are lucky enough to have the one that has a timer and can be set to come on without the car running you can tell this if you have extra buttons on the overhead clock module rather than just the hours and min buttons

 

any further questions just ask or go to the faqs and you can see the pump rempved and stripped down by members i think its a mk 2 but its just the same.

[new nige]

Thank you for your comprehensive response, this clears up a few loose ends before I attack.

 

The previous owner has short circuited the heater coolant pipes thus bypassing the heater. When I got the car it had a water leak which I located to the water pump, now changed and leak solved. I assume the previous owner had a glow plug failure or assumed the rear heater matrix was the leak problem. I intend to drop and refurbish the heater which should be easy as it has been short circuited from the coolant system. I have checked fuse 12 as would have expected previous owner to cut power to the heater but this seems present.

 

I will keep you posted as things progress, probably slowly. Can you see any problems with removing it for several weeks? Also can i test it without water pipes reconnected presumably it won

[marinabrid]

to try and fix one on a bench you will need fuel supply and power etc.. a pal of mine who is a bus fitter took ours off and tried to bench test but as you need specialist test equipment to diagnose what is wrong you may spend many fruitless hours like we did .

we stripped it down and cleaned out the combustion chamber, swopped the glowplug and thats about all you can do. usually the bolts that hold the 2 halves together are rusted so you got to buy new as well as some gaskets, cost us around

[new nige]

will remove and try a glow plug and see how we get on.

 

cheers

[new nige]

Removed my aux heater but don

[marinabrid]

there are some on ebay but are the D5WZ units from mk2 , this is what i fitted 2 years ago, worked but not to full capacity as you need to change the metering pump as well this is what i am about to do but 2nd hand cant find and new price seems an expensive

[new nige]

did the d5wz work adaquately then? or is fitting this with the original pump not recomended? i am considering stripping down but the exhust outlet has sheared, does the exhust silance it much?

 

nige

[marinabrid]

from info i have gleened from this site and sgaf.eu the D5WZ will only work to 3/4 capacity as the mk1 pump doesnt give it enough fuel. mine has worked for 2 years ok but takes 20 mins to get reasonbly warm air when tickover, quicker if driving.

 

i was looking to upgrade the pump but they are

[marinabrid]

heres one on ebay at the moment the number is 110593366074 hard to know if its a good one but you should be able to get money back if not. you will need a new dosing pump. i enquired on a parts web site and now have the chance of 4 at around

[new nige]

i think i will have a go at refurbishment, parts dealer local, and cant throw money away, more curious than anything with such an old car! Like to get it going though. There are some interesting bench tests on youtube fyi. I will work out the wireing and get all the screws out. Do i remember you saying how much a gasket kit was?

[new nige]

As a separate question, anyone know how the previous owner might electrically isolate the heater? Never heard it fire up? Thermister in front of bulkhead operates ok however relevant fuses are not clear, (note mk 1) yet to check for voltage so could be a knackered unit.

 

Also still don

[George106]

IMHO on MK1 is fitted 3KW heater which may not require aux pump because of the lower power output.

[marinabrid]

thats an interesting point, ive run D5WZ for 2 years with no apparent problems execpt take a fair while to heat up, im now putting a 5kw dosing pump on to replace the old original 3kw so the heater will run a full power, im now wondering if i should put a recirculating pump in the line on a switch. however from reading the posts on the german site sgaf.de the people who have upgraded to the 5kw from the 3kw report only need to change the dosing pump, they never mentioned having to put in a recirc pump as well.

 

the gasket sets are around

[zorgman]

the run on pump on d5wz is for heat dispersal as its a 5kw so a lot of latent heat to get rid of and water is the best way to shift it. the reason or pump on bench is so that the overheat sensor doesnt kick in and shut it down whilst testing. with regards to water pumps theres loads about if you look for example merc vans have them fitted right on bulkhead took me 2 mins to grab it at scrappy. heaters are fitted to loasda cars eg merc vans, vx omega cars etc

[marinabrid]

mmm wondering now if i fit the 5kw metering pump to my 5kw heater will it suffer any over heat problems as the mk1 doesnt have the after run pump, i suppose if the heater had actually shut down due to the water temp bieng hot enough then it wouldnt matter but if it was on full bore during shut down it may suffer, i suppose i could put a switch to the heater and turn if off if it was running before i stopped the engine.

or then again it may work fine :blink: