When I first looked into getting an additional fuel filter for these I of course found NRWs & Euro power motorsports kits, the former cost ~£335, which I think is just a ridiculous price! And the latter costs $239+VAT, import duties and shipping (in a quick look I didn't find it for sale here in the UK). Anyway, aside from both being over priced, I also don't like the fact they're installed in the engine bay. The engine bay is already cramped enough, and now you'd be adding something else to get in the way of access to the plenum chamber and spark plugs etc!
Also, if the kit springs a leak (due to incorrect fitment, if nothing else) then it's going leak pretty much straight onto the exhaust manifold, not ideal!
Another possible problem, although maybe not significant, is extra pipe/filter body area for heat to soak into.
They do appear easy to fit though!
Oh and I only spent £90 on my kit!
If my instructions aren't clear at some point, lmk!
TLDR
Get the filter and BMW fuel filter clamp bracket etc as per my parts list near the end. Make up or buy an extension plate so that the fuel filter sits tight to the sill, you'll need to drill an extra hole in the underbody bracket & have 3 holes in the extension plate so that you can bolt that plate with 2 bolts.
Cut the fuel line about 2cm from the pipe support brackets (use blades designed for stainless steel), debur and clean the ends and flush the fuel lines of any debris.
Fit the compression coupling fittings to the end of the pipes (tighten hard!), and screw the hosetails into the couplings. Use PTFE tape on all threads, I had to wrap them 3-4 times.
Fit the fuel hoses and tighten the fuel hose clips, cable tie hoses midway to a pipe. Mind the front hose doesn't rub on those unused studs.
Turn the ignition on (at least 20s)/off 3-4 times to prime fuel system & check for leaks, if ok, then run it (at least 20 minutes?) and check for slow leaks.
Fuel filter location and mounting
BMW installs an inline fuel filter on e9x diesels and Chinese petrol versions under the floor on the left side front. My own e90 330d has one there. Whilst this isn't as easy a place to change the fuel filter (for a DIYer with no lift), it avoids all the above problems of an engine bay filter.
I bought a genuine BMW fuel filter clamp (a 2nd hand one from ebay, these are fitted to X1s, 1 & 3 series, e8x & e9x diesels over here. And they're made from stainless steel, so no worries about rust!). Initially I was hoping to simply bolt this clamp straight onto the floor where they go on the diesels, but sadly the fuel and brake pipes are routed differently & the floor longitudinal members are different too (I don't think it's just e90 vs e92 differences?). Having read Andrihallik's post over at Jvictor's DIY engine bay fuel filter thread about his underbody fuel filter instal, I decided I would fit it in the same place as his.
The BMW clamp more securely holds the fuel filter than Andri's bracket as it wraps right around the fuel filter (although tbf to Andri, his looks fairly secure anyway), but no need to make a fuel filter bracket anyway as the diesel filter clamps are 2 a penny here in the UK! I'm not sure how many will be available in the US, but I know you guys had the 335d, so their should be some 2nd hand availability. If not, they're not expensive new (£35-40 here).
I did need to make a very simple clamp bracket extension though, so I could mount the fuel filter to the underbody mount at the right distance (right by the sill, which is where you have the most depth). I happened to have 2 spare horn brackets lying around (flat plates with 2 holes in, about 1" wide). [Hmm, I didn't note how long, I'll have to do that]. So I used them both, drilled an extra hole in them and also drilled an extra hole in the underbody bracket. I had to slightly straighten out the fuel filter clamp's leg so that I got the right angle for it, but other than that it just bolted on with 3 M6 bolts & nuts (I think mine were 25-30mm long, but that was overkill tbh, it's just what I had available), 2 bolts holding the extension plate to the body bracket.
Fuel filter choice
When I first looked into this, people were discussing the Chinese e9x cars having an inline filter, and whilst I found the discussed filter in realoem.com, this filter is only for the non M Chinese petrol cars, at least as far as I could tell, even their M3 doesn't, or it's not listed on realoem. And the non M Chinese cars have a fuel return pipe from the fuel filter, so this is no good to us.
Andri used the fuel filter for the e36 M3 (their are actually 2 types), and this turned out to be the perfect choice for me too as it's 55mm diameter exactly matches that of the diesel fuel filter, so it's clamp is just right for this petrol filter.
The 2 types of M3 e36 fuel filters are :-
One type that's fitted to the 3.2 ltr engine (euro 7/95 to 8/99 & Z3M to 2000), these are 340mm long and have snap on connectors. Whilst that would be nice to have, it would mean extra fittings & complication. Also the filter is a bit too long for the space available.
The earlier type is fitted to the 3 ltr euro M3s and all US versions (and apparently the V12 Alpina B12!). This filter has flared pipes (8mm) for hoses, and is shorter at 300mm long. (Part No in the price list at the end). See the Mann listing for it here for more info.
In case anyone is worried this smaller fuel filter won't flow enough fuel for the S65, don't be, the aforementioned Chinese e9x cars fuel filter (and ones with the 'outside fuel filter' option) are also fitted to the M3/4 & M5 f series cars, this filter is 250mm long and also has 8mm diameter pipes. See the Mann listing here for more info on that one.
Connecting hoses to the fuel pipe
The fuel pipe runs from the rear to the front with no joins in it (there's a connector in the engine bay, hence partly why the kits are fitted there. And the only other connector is to the pump. There is a short rubber section by the side of the tank, but there's no spare space there, that means the pipe has to be cut into & a section removed. I cut about 1/2" from the pipe support brackets, but this ended up being too close, I had to straighten the rear pipe section slightly to gain a few mm so I could clip the pipe in! I'd suggest cutting at least ~3/4", 20mm from the pipe support brackets (but you can't do it much longer than that otherwise the fittings will clash). You'll need to unclip the pipe from the body to get enough clearance to cut it (at least with a hacksaw).
The fuel pipe is made of stainless steel, this complicates things as it's much harder than copper or even mild steel. You can't use a regular pipe flaring tool, you need to use a hydraulic one, or at least a very strong mechanical one which is designed to be able to flare stainless steel, and then you'll need to remove the pipe from the car completely to do this. And those tools are very expensive, about £350-400 as I recall!
You can't, or rather you shouldn't simply push the hoses onto a plain fuel pipe and hold it on with fuel hose clips either, it seems there's a risk the fuel hose will creep along and then blow off one day! Perhaps multiple clips on a hose would stop that? But I don't know & I didn't want to chance it. Whilst it appears from his photos alone this is what Andri did, actually he managed to flare the ends of his pipes, so they're secure.
So that leaves compression fittings, this avoids the need to flare the pipes or weld anything on them. Simply* slide the compression nut on the pipe, then the olive, then the coupling on and tighten up (hard!), then screw in the hosetail to the coupling. Unfortunately their doesn't seem to be any available hosetail-compression fittings as a single unit available below 10mm hose pipe size, very annoying!
Attach the hoses with fuel clips, the front hose can be routed on top of the various pipes there, then cable tie to one, mind it doesn't sit too low & rub on the spare 3 studs attached to the floor (see pics). Cable tie the rear hose to the biggest pipe.
*I say simply, it wasn't quite as easy as I thought, well, it went on easily enough, but getting it to not leak took much longer!
This was partly because I've never used compression fittings before, so I didn't tighten them enough on the 1st go (they had to be murdered up!) and partly because I didn't use enough PTFE tape on the hosetail threads, and then forgot entirely for the coupling's thread! lol. Also I found a single layer of PTFE tape wasn't enough, I found I had to wrap it around 3-4 times. Once I'd done that, then finally I had no leaks. Btw, if you're just turning the ignition on to test it initially, you'll need to turn it on & off 3-4 times to prime the pipe, the pump only runs for a very short time (30s??) with just the ignition on.
To cut the stainless steel pipe though (assuming you're using a hacksaw or power saw) you'll need special(ish) blades, after some Googling I settled on 32 TPI bi-metal blades for my hacksaw. I bought a pack of 5 Bahco blades from ebay. 5 in case of breakages or quick blunting, although in the end 1 blade did fine. Cut it square, then file off the sharp edge, and use a drill bit (by hand) to remove burrs inside the pipe, then flush the pipes out with brake cleaner or petrol, be especially careful with the pipe after the fuel filter!
Links to pics :-
Looking up - https://photos.app.goo.gl/7gZEsGY9rvXxR4Qt9
Close up of fittings - https://photos.app.goo.gl/CUVP2VgNWSZ26TK69
Back view of filter showing level to sill - https://photos.app.goo.gl/B7pdjvJkPitnahpP6
Side view of filter and bracket - https://photos.app.goo.gl/jtfPFCPDSALfW9ns7
Front view of filter before hoses fitted + bracket (and before correcting filter direction!) - https://photos.app.goo.gl/eR3BLu1i1tyfk6Nt6
Back and side view of filter + bracket - https://photos.app.goo.gl/fpjJ3rmMCcMwAE5W9
Undertray back on - https://photos.app.goo.gl/2JNZVEZbmuGFFBVu5
Parts and cost
Fuel filter, Mahle KL 66 - £14.56 (alternates BMW 13321740985, Bosch (F5905) 0450905905, Valeo 58714, Mann WK516/1)
Fuel hose, ID 8mm (5/16"), 1m long - £7.41
BMW fuel filter clamp bracket (used) - £20 (part no 13328513540 . I saw Synter listed a new one as costing £35+delivery a few months ago).
Stainless Steel F Stud Coupling 8mm x 1/4" BSP PF (compression) x2 (these come with an olive each, but you might want a couple spare should you need to disassemble them at a future point).
Screwed Stainless Steel Hose Tail Adaptor 1/4" BSP TM x2
Cost of above stainless steel fittings and 4 spare olives - £41.73
Bahco Sandflex 12" 300mm Bi-Metal Hacksaw Blades x5, 32tpi - £6.49
*4 fuel hose clips 13-15mm (don't use jubilee clips!)
*2 horn bracket/flat plates.
*3 M6 bolts & nuts
*PTFE tape
Total £90.19
*I already had these.
(I bought these parts over the past few months).
Service interval for the fuel filter TBD, does anyone know its service interval for the e36 M3?
[edit, wow it seems to be impossible to find the official service schedule for e36 M3s, or any e36! But sources suggest on the Inspection 2 service, or the 2nd Inspection II service, which is 40k or 80k miles. I'll go for 40k].
Also, if the kit springs a leak (due to incorrect fitment, if nothing else) then it's going leak pretty much straight onto the exhaust manifold, not ideal!
Another possible problem, although maybe not significant, is extra pipe/filter body area for heat to soak into.
They do appear easy to fit though!
Oh and I only spent £90 on my kit!
If my instructions aren't clear at some point, lmk!
TLDR
Get the filter and BMW fuel filter clamp bracket etc as per my parts list near the end. Make up or buy an extension plate so that the fuel filter sits tight to the sill, you'll need to drill an extra hole in the underbody bracket & have 3 holes in the extension plate so that you can bolt that plate with 2 bolts.
Cut the fuel line about 2cm from the pipe support brackets (use blades designed for stainless steel), debur and clean the ends and flush the fuel lines of any debris.
Fit the compression coupling fittings to the end of the pipes (tighten hard!), and screw the hosetails into the couplings. Use PTFE tape on all threads, I had to wrap them 3-4 times.
Fit the fuel hoses and tighten the fuel hose clips, cable tie hoses midway to a pipe. Mind the front hose doesn't rub on those unused studs.
Turn the ignition on (at least 20s)/off 3-4 times to prime fuel system & check for leaks, if ok, then run it (at least 20 minutes?) and check for slow leaks.
Fuel filter location and mounting
BMW installs an inline fuel filter on e9x diesels and Chinese petrol versions under the floor on the left side front. My own e90 330d has one there. Whilst this isn't as easy a place to change the fuel filter (for a DIYer with no lift), it avoids all the above problems of an engine bay filter.
I bought a genuine BMW fuel filter clamp (a 2nd hand one from ebay, these are fitted to X1s, 1 & 3 series, e8x & e9x diesels over here. And they're made from stainless steel, so no worries about rust!
). Initially I was hoping to simply bolt this clamp straight onto the floor where they go on the diesels, but sadly the fuel and brake pipes are routed differently & the floor longitudinal members are different too (I don't think it's just e90 vs e92 differences?). Having read Andrihallik's post over at Jvictor's DIY engine bay fuel filter thread about his underbody fuel filter instal, I decided I would fit it in the same place as his.The BMW clamp more securely holds the fuel filter than Andri's bracket as it wraps right around the fuel filter (although tbf to Andri, his looks fairly secure anyway), but no need to make a fuel filter bracket anyway as the diesel filter clamps are 2 a penny here in the UK! I'm not sure how many will be available in the US, but I know you guys had the 335d, so their should be some 2nd hand availability. If not, they're not expensive new (£35-40 here).
I did need to make a very simple clamp bracket extension though, so I could mount the fuel filter to the underbody mount at the right distance (right by the sill, which is where you have the most depth). I happened to have 2 spare horn brackets lying around (flat plates with 2 holes in, about 1" wide). [Hmm, I didn't note how long, I'll have to do that]. So I used them both, drilled an extra hole in them and also drilled an extra hole in the underbody bracket. I had to slightly straighten out the fuel filter clamp's leg so that I got the right angle for it, but other than that it just bolted on with 3 M6 bolts & nuts (I think mine were 25-30mm long, but that was overkill tbh, it's just what I had available), 2 bolts holding the extension plate to the body bracket.
Fuel filter choice
When I first looked into this, people were discussing the Chinese e9x cars having an inline filter, and whilst I found the discussed filter in realoem.com, this filter is only for the non M Chinese petrol cars, at least as far as I could tell, even their M3 doesn't, or it's not listed on realoem. And the non M Chinese cars have a fuel return pipe from the fuel filter, so this is no good to us.
Andri used the fuel filter for the e36 M3 (their are actually 2 types), and this turned out to be the perfect choice for me too as it's 55mm diameter exactly matches that of the diesel fuel filter, so it's clamp is just right for this petrol filter.
The 2 types of M3 e36 fuel filters are :-
One type that's fitted to the 3.2 ltr engine (euro 7/95 to 8/99 & Z3M to 2000), these are 340mm long and have snap on connectors. Whilst that would be nice to have, it would mean extra fittings & complication. Also the filter is a bit too long for the space available.
The earlier type is fitted to the 3 ltr euro M3s and all US versions (and apparently the V12 Alpina B12!). This filter has flared pipes (8mm) for hoses, and is shorter at 300mm long. (Part No in the price list at the end). See the Mann listing for it here for more info.
In case anyone is worried this smaller fuel filter won't flow enough fuel for the S65, don't be, the aforementioned Chinese e9x cars fuel filter (and ones with the 'outside fuel filter' option) are also fitted to the M3/4 & M5 f series cars, this filter is 250mm long and also has 8mm diameter pipes. See the Mann listing here for more info on that one.
Connecting hoses to the fuel pipe
The fuel pipe runs from the rear to the front with no joins in it (there's a connector in the engine bay, hence partly why the kits are fitted there. And the only other connector is to the pump. There is a short rubber section by the side of the tank, but there's no spare space there, that means the pipe has to be cut into & a section removed. I cut about 1/2" from the pipe support brackets, but this ended up being too close, I had to straighten the rear pipe section slightly to gain a few mm so I could clip the pipe in! I'd suggest cutting at least ~3/4", 20mm from the pipe support brackets (but you can't do it much longer than that otherwise the fittings will clash). You'll need to unclip the pipe from the body to get enough clearance to cut it (at least with a hacksaw).
The fuel pipe is made of stainless steel, this complicates things as it's much harder than copper or even mild steel. You can't use a regular pipe flaring tool, you need to use a hydraulic one, or at least a very strong mechanical one which is designed to be able to flare stainless steel, and then you'll need to remove the pipe from the car completely to do this. And those tools are very expensive, about £350-400 as I recall!
You can't, or rather you shouldn't simply push the hoses onto a plain fuel pipe and hold it on with fuel hose clips either, it seems there's a risk the fuel hose will creep along and then blow off one day! Perhaps multiple clips on a hose would stop that? But I don't know & I didn't want to chance it. Whilst it appears from his photos alone this is what Andri did, actually he managed to flare the ends of his pipes, so they're secure.
So that leaves compression fittings, this avoids the need to flare the pipes or weld anything on them. Simply* slide the compression nut on the pipe, then the olive, then the coupling on and tighten up (hard!), then screw in the hosetail to the coupling. Unfortunately their doesn't seem to be any available hosetail-compression fittings as a single unit available below 10mm hose pipe size, very annoying!
Attach the hoses with fuel clips, the front hose can be routed on top of the various pipes there, then cable tie to one, mind it doesn't sit too low & rub on the spare 3 studs attached to the floor (see pics). Cable tie the rear hose to the biggest pipe.
*I say simply, it wasn't quite as easy as I thought, well, it went on easily enough, but getting it to not leak took much longer!
This was partly because I've never used compression fittings before, so I didn't tighten them enough on the 1st go (they had to be murdered up!) and partly because I didn't use enough PTFE tape on the hosetail threads, and then forgot entirely for the coupling's thread! lol. Also I found a single layer of PTFE tape wasn't enough, I found I had to wrap it around 3-4 times. Once I'd done that, then finally I had no leaks
. Btw, if you're just turning the ignition on to test it initially, you'll need to turn it on & off 3-4 times to prime the pipe, the pump only runs for a very short time (30s??) with just the ignition on.To cut the stainless steel pipe though (assuming you're using a hacksaw or power saw) you'll need special(ish) blades, after some Googling I settled on 32 TPI bi-metal blades for my hacksaw. I bought a pack of 5 Bahco blades from ebay. 5 in case of breakages or quick blunting, although in the end 1 blade did fine
. Cut it square, then file off the sharp edge, and use a drill bit (by hand) to remove burrs inside the pipe, then flush the pipes out with brake cleaner or petrol, be especially careful with the pipe after the fuel filter!Links to pics :-
Looking up - https://photos.app.goo.gl/7gZEsGY9rvXxR4Qt9
Close up of fittings - https://photos.app.goo.gl/CUVP2VgNWSZ26TK69
Back view of filter showing level to sill - https://photos.app.goo.gl/B7pdjvJkPitnahpP6
Side view of filter and bracket - https://photos.app.goo.gl/jtfPFCPDSALfW9ns7
Front view of filter before hoses fitted + bracket (and before correcting filter direction!) - https://photos.app.goo.gl/eR3BLu1i1tyfk6Nt6
Back and side view of filter + bracket - https://photos.app.goo.gl/fpjJ3rmMCcMwAE5W9
Undertray back on - https://photos.app.goo.gl/2JNZVEZbmuGFFBVu5
Parts and cost
Fuel filter, Mahle KL 66 - £14.56 (alternates BMW 13321740985, Bosch (F5905) 0450905905, Valeo 58714, Mann WK516/1)
Fuel hose, ID 8mm (5/16"), 1m long - £7.41
BMW fuel filter clamp bracket (used) - £20 (part no 13328513540 . I saw Synter listed a new one as costing £35+delivery a few months ago).
Stainless Steel F Stud Coupling 8mm x 1/4" BSP PF (compression) x2 (these come with an olive each, but you might want a couple spare should you need to disassemble them at a future point).
Screwed Stainless Steel Hose Tail Adaptor 1/4" BSP TM x2
Cost of above stainless steel fittings and 4 spare olives - £41.73
Bahco Sandflex 12" 300mm Bi-Metal Hacksaw Blades x5, 32tpi - £6.49
*4 fuel hose clips 13-15mm (don't use jubilee clips!)
*2 horn bracket/flat plates.
*3 M6 bolts & nuts
*PTFE tape
Total £90.19
*I already had these.
(I bought these parts over the past few months).
Service interval for the fuel filter TBD, does anyone know its service interval for the e36 M3?
[edit, wow it seems to be impossible to find the official service schedule for e36 M3s, or any e36! But sources suggest on the Inspection 2 service, or the 2nd Inspection II service, which is 40k or 80k miles. I'll go for 40k].
