bfb 1.8t cylinder head compatibility

richard hare

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hi guys thanks for reading this...a few months ago i posted that i suspected the head gasket had gone...turns out it has...anyway even though the audi engine is still in one piece at the moment an opportunity came by to purchase a passat with an apu engine 90000 miles £150 for the whole car engine wise seems sound...ive tried doing some research on head compatibility but its got my head in a spin(just in case the bfb head is cracked) i bought the passat with the intention of using the apu head...have i made a smart move or have i made a boo boo....thanks....
 
Why not put a hole engine instead of messing with a head that might not work
 
this is now what im thinking might be the best solution...thing is i think the apu is the older style engine(slightly different layout regarding pipework and air filter among other little things) can anybody advise me on any potential problems...for instance...can i retain the wiring harnace and ecu from the audi...any advice however small or trivial would be much appreciated....thanks....richard
 
The Apu doesn't have secondary air injection on the head (to clean up emissions at start up) however it does have drive by wire. The loom will be different as it will have one connector too many for the saip.
You could use the APU engine, ECU and engine harness but even then you would need diagnostics to pair the ECU and immobiliser.
It might be easier to source a cylinder head, any with SAIP will fit.
 
Why not look out for a smashed tt with a bam code engine then you've got every thing you need to do a engine swop plus bam engine has 220 bhp standard
 
thanks for the replies...have i read on the forums about people getting rid of the sai anyway and wouldnt this make the connector redundent..

is it going to be case of the bfb ecu and wiring not working with the apu engine...because i dont have vcds (nearest audi dealer is in bristol) pairing the apu ecu with the audi immobiliser could be problematic...
engine swap is only worse case scenario the audi head might be ok when we take it off...im just trying to get as much info just in case.....cheers....richard
 
I'm sorry I never answered that very well. Yes you can use the APU head on the BFB bottom end. Some people do get rid of the SAIP anyway but this will trigger a fault code, this one,http://wiki.ross-tech.com/wiki/index.php/16795/P0411/001041
This can be written out if you have your car remapped. As regards using the whole APU engine, the extra connector for the SAIP would probably mean that the ECU pinout would be different meaning connections going where they shouldn't = non start. The APU ECU and harness could be used but it would need the immobiliser matched or defeated.
Hopefully the BFB head will be okay and none of this will matter, best of luck.
 
thanks for that...i did sort of get you the first time but im clutching at straws trying to find ways and means around the problems..reason being the bfb has done 160000 miles but is in a nice condition audi while the apu has done 90000 miles in a skip of a passat..so you can see where im trying to go..
ive got a months mot on the skip left(drives rearly nice to be fair) to try and figure out the conundrum...cheers....richard
 
just another thought...if i go with the compete swap..engine,harness and ecu would it be a feasible option to send both ecu units to a specialist(if one exists) to reprogram the apu unit to the audi immobiliser...im not too clued up on the computer side of things....
 
Try get hold of a full car if your doing a engine swop then you've got everything you need to make it work .. no need to get ecu reprogrammed as you'll have the right ecu for the engine
 
ah right so the immobiliser isnt programmed to the engine via the ecu...ive got the whole car (passat)...a bit confusing regarding the audi immobiliser...
 
If you do an engine swop and you have a doner car you swop everything out of the doner car wiring looms .. ecu .etc etc .. as your using the ecu from your doner car with the engine from the same car the ecu will see nothing has changed so won't need coding
 
The immobiliser coding is between the instrument cluster and ECU.


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Ecu can be coded in no problem. If you get the ecu loom and engine in and to a point where the car starts then cuts out again that would leave just the immo coding to do.

I can do this if you post both ecus or can defeat the immo completely if you send the passat ecu.

Hope this helps.
 
If you use APU engine and ECU and engine wiring loom that would be the best option.
 
this is a great help guys...me and my mate have done a few engine swaps many moons ago...rs turbos... old golf gtis ..ect.. but as you can appreciate this is a bit more involved on the electrical side of things...im sure it will be fine(whats the worse that can happen anyway)
ill keep you posted on progress when we start hopefully i wont have to ask too many questions but if i do i know where to come..
thanks again and happy motoring....richard
 
You're using the APU engine wiring loom, ECU and engine, it should all be plug and play. Just the ECU immobiliser coding and you're done.
 
what sort of money are we talking about for the ecu recoding...also looking at the two cars there seems to be more room around the rear of the vw engine bay the coolant flange is quite easy access (seems a few inches forward)if that makes sense...any known problems regarding gearbox mounting or am i just looking at less obstructions on the rear of the vw head...
 
Saip valve takes up a bit of room, dunno how much for recode or immob defeat, pm previous poster who offered for a price est, shouldn't be too much though.


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christ man why are you complicating things?

Fit the APU head to your engine. You'll need to retain your existing VVT tensioner as the APU doesnt have an adjustable one.

The entire APU engine wont fit, as its an 058 block, and the B6 uses an 06B block. There are also some big changes with various aspects of the ECU programming that means you dont really want an APU ECU in a B6, for instance the cooling fans are ECU controlled on the B6, but they arent on the B5 platform.

If you do get a replacement 06B engine, retain ALL of your existing wiring harness and ECU, manifolds, anciliaries, brackets etc etc and just swap the physical engine over. there is NO need to swap looms and ******* about with recoding immobilisers.
 
Isn't the B6 A4 newer engine 06A, the only 06B I found was for A3 1.6?
 
Last edited:
06A is the transverse mounted version, used in the A3/Golf etc. 06B is the longidudinal version used in the A4/A6

They're both available in 1.8T, as well as other sizes.
 
conflicting information...so the earlier apu entire engine wont fit in the b6 car...but the head will fit on the later engine(with a few mods)...
im not trying to complicate things...i was just hoping to utilise the two platforms to get the audi back on the road but get as much info before i have two useless engines out of two cars..but its sounding like i messed up buying the passat..at least it was cheap....still great info though guys before i go ruining two...well 1. 1/2 good motors...
 
Let me know how you get on with this, I have a BFB head spare, I don't really want to sell it but if you need it I will. I'm sure a head skim and new head gasket and bolts will see you right though.
 
good man QC...im gonna try..more ambitious projects have been done...i just liked the idea of an engine with 40/50000 miles less to keep the audi going for years....cheap..
 
If you like an engine with low mileage why don't you buy a recon engine or a newer car
 
so after removing the head it turns out the head gasket had indeed deteriorated... but not cracked anywhere...it had seperated like a sandwich into three separate layers if that makes sense...got lucky with the head...tested and all come back fine....but did notice when removing the head the bolts werent torqued down vert tight...whether this is a natural expansion and contraction thing i dont know.......anyway for those who are interested the total costs are thus...
head testing...£10(through a friend who works on helicopters)...make of that what you will..
head gasket from local indi part shop....£18 plus vat
head bolts...£21 plus vat
larger oil filter£9 plus vat
cheapest 5/w30 fully synth oil(comma) just to run it up and will be changed next week...£16 inc vat
few o rings which i already had from a kit from screwfix
about 2 hours scratching heads and ***** but altogether about 5-6 hours labour
it already had a new timing belt and water pump so no sweat there...
guys...honestly if you can hold a spanner and have the time and space this is not an impossible task for an amature...it can be quite daunting looking at all the pipe work but if you have too stick a bit of masking tape on them and number them this is what we done (probably sounds silly to a pro) once the air box and coolant reservoire is out of the way you will be surprised how much you can see and access..
one thing to add we had to buy a long head bolt tool for about£12...i had one but it was a tad too short for the front bolts...
i have to say thank you for the advice and ideas from you guys....i got lucky....so now hopefully the audi can live on for a few years and also the passat can be re motd and do someone else a favour....
 
so after removing the head it turns out the head gasket had indeed deteriorated... but not cracked anywhere...it had seperated like a sandwich into three separate layers if that makes sense...got lucky with the head...tested and all come back fine....but did notice when removing the head the bolts werent torqued down vert tight...whether this is a natural expansion and contraction thing i dont know.......anyway for those who are interested the total costs are thus...
head testing...£10(through a friend who works on helicopters)...make of that what you will..
head gasket from local indi part shop....£18 plus vat
head bolts...£21 plus vat
larger oil filter£9 plus vat
cheapest 5/w30 fully synth oil(comma) just to run it up and will be changed next week...£16 inc vat
few o rings which i already had from a kit from screwfix
about 2 hours scratching heads and ***** but altogether about 5-6 hours labour
it already had a new timing belt and water pump so no sweat there...
guys...honestly if you can hold a spanner and have the time and space this is not an impossible task for an amature...it can be quite daunting looking at all the pipe work but if you have too stick a bit of masking tape on them and number them this is what we done (probably sounds silly to a pro) once the air box and coolant reservoire is out of the way you will be surprised how much you can see and access..
one thing to add we had to buy a long head bolt tool for about£12...i had one but it was a tad too short for the front bolts...
i have to say thank you for the advice and ideas from you guys....i got lucky....so now hopefully the audi can live on for a few years and also the passat can be re motd and do someone else a favour....

Great news mate, glad to hear that, well done!


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cheers qc ...i know it was a long shot with the apu but it was most helpful when the two cars were side by side...as i said i got lucky...i realy do appreciate the input and help...dont know whether the post helped anybody regarding swapping heads though...from my point of view it was a non starter...(anybody googling or searching head swap) im sorry im no help...
 
Hello everyone. Newbie here. Hoping this thread can still be active. I have a quite similar case with Richard. Except my cylinder head and piston (CYL4) got wrecked due to hard acceleration when I was trying to isolate which ignition coil was misfiring :( did quite a few runs reving to 6500rpm and the last run engine quit and wont even crank. Am thinking I may have over revved and timing belt jumped a few teeth during the process. Timing belt is still ok and undamaged.

Anyways.. someone locally selling an APU head and wanted to inquire from you guys a couple of things. Someone from another group said the APU will fit the BFB and added pulley needs to be changed and also recommended to upgrade the exhaust valves.
Questions..
1. When using the APU head and its corresponding camshaft, valves, springs, etc., any anticipated issues? Hopefully lift and duration of both engine codes are the same.
2. Which pulley should be used when switching the heads? APU camshaft with APU pulley? or APU camshaft with BFB pulley?
3. One piston is clearly damaged. Is an APU piston the same as the BFB?
4. Unsure if there might be damage or strain with the BFB camshaft so I'm more leaning to use the APU camshaft.

Any help, comments or suggestions highly appreciated. Btw I'm from the Philippines
 

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