Peugeot 406 Coupe - 3.0L V6. Complete refurb... very slowly
Discussion
Chasing down the usual electric gremlins from a german electrical system in a french car put together by italians, but mechanically she's been rock solid.
Debating making some tubular wishbones right now as the poly bushes are getting ready for a rebuild anyway...
Debating making some tubular wishbones right now as the poly bushes are getting ready for a rebuild anyway...
Edited by PhillipM on Sunday 20th August 14:20
Was up near the dyno guy the other day so felt it'd be rude not to slap the car on quickly while he cleaned me some injectors 
Last time it was at that dyno it made 212bhp (with the backbox knocked straight through, cam timing advanced, bit of porting work to the inlet manifold/throttle and a foam cone filter on it).
This time around with the new air intake, new 2.5" exhaust system, the lightweight flywheel and a little tickle on the crank sensor to get a tiny bit more ignition advance it made 232bhp, so pretty happy with that.
It definately feels like it could take more timing though, gonna have to work out how to make something to adjust it better....
It made most of the gains up top in the last 1000rpm so it's not really much of a difference on the road, but it's basically gained a bit everywhere, filled in half of the torque dip these have at 3k and the car feels so much faster to rev when you blip down through the gearbox.
That's kinda surprising as there's not much flow just blipping the throttle for a heel and toe - but I think there was a resonance issue where the old system cranked down to 2" for the midbox, probably why it has that dip at 3.5k too, the later cars don't suffer from it but they have VVT and they also have a much longer 2-1 downpipe system that merges right where the cat-midbox joint is on the early engines - so that points at something similar as there's a tuned length there to cancel the dip out I would think.
Either way, pretty happy, 20bhp up on an old N/A car without any serious work is nice.
Last time it was at that dyno it made 212bhp (with the backbox knocked straight through, cam timing advanced, bit of porting work to the inlet manifold/throttle and a foam cone filter on it).
This time around with the new air intake, new 2.5" exhaust system, the lightweight flywheel and a little tickle on the crank sensor to get a tiny bit more ignition advance it made 232bhp, so pretty happy with that.
It definately feels like it could take more timing though, gonna have to work out how to make something to adjust it better....
It made most of the gains up top in the last 1000rpm so it's not really much of a difference on the road, but it's basically gained a bit everywhere, filled in half of the torque dip these have at 3k and the car feels so much faster to rev when you blip down through the gearbox.
That's kinda surprising as there's not much flow just blipping the throttle for a heel and toe - but I think there was a resonance issue where the old system cranked down to 2" for the midbox, probably why it has that dip at 3.5k too, the later cars don't suffer from it but they have VVT and they also have a much longer 2-1 downpipe system that merges right where the cat-midbox joint is on the early engines - so that points at something similar as there's a tuned length there to cancel the dip out I would think.
Either way, pretty happy, 20bhp up on an old N/A car without any serious work is nice.
Edited by PhillipM on Thursday 21st September 13:54
Whoops forgot to update this thread
The coolant tank is the old one - it did the usual trick and split on the poor factory welds - so I printed the clamp/stress relief pieces you see either side there in nylon, made the jubilee-clip clamp, then applied a bead of silicone after cleaning the plastic welds out, flame treated the surfaces and clamped the two halves together with the jubilee.
However, because they're so hard to get hold of, I am currently making replacements in stainless steel - I've got a prototype mocked up already but I need to find time to weld it together.
The coolant tank is the old one - it did the usual trick and split on the poor factory welds - so I printed the clamp/stress relief pieces you see either side there in nylon, made the jubilee-clip clamp, then applied a bead of silicone after cleaning the plastic welds out, flame treated the surfaces and clamped the two halves together with the jubilee.
However, because they're so hard to get hold of, I am currently making replacements in stainless steel - I've got a prototype mocked up already but I need to find time to weld it together.
Edited by PhillipM on Sunday 11th February 15:44
On the same topic as the above, a few more people asked about replacement tanks (they've not been available for a while and they're all faulty from the factory in the same ways) - the stainless one on mine is a no go as it takes some serious work to form the ends nicely, machined tube fittings, and the clamp where it attaches to the car has to be heavily modified and welded to, to attach a v-band clamp.
So, as an alternative, I did some CAD work, made some improvements to the design along the way to strengthen some areas, reduce stress concentrations by removing sharp corners, and changing the fault prone ultrasonic weld joint for a bolted, o-ringed flange connection - plus some internal improvements for better flow, I had a prototype in hand.
This isn't the final material, some cheaper stuff I had to check the process in - but I'm intending to use a similar material to the OE, albeit more water resistant (about half the saturation of the OE plastic) and using chopped carbon fibres instead of glass fibres, to give me a bit more strength, since it's not worth the few pence saving when you aren't making thousands, and it'll help compensate for the inherent strength disadvantage vs injection moulded parts.
Got a few tweaks I want to make but I'm pretty happy with that for the first attempt.
Gotta check the other half now but should go just as well I think, and give me a finished part that resembles this:
So, as an alternative, I did some CAD work, made some improvements to the design along the way to strengthen some areas, reduce stress concentrations by removing sharp corners, and changing the fault prone ultrasonic weld joint for a bolted, o-ringed flange connection - plus some internal improvements for better flow, I had a prototype in hand.
This isn't the final material, some cheaper stuff I had to check the process in - but I'm intending to use a similar material to the OE, albeit more water resistant (about half the saturation of the OE plastic) and using chopped carbon fibres instead of glass fibres, to give me a bit more strength, since it's not worth the few pence saving when you aren't making thousands, and it'll help compensate for the inherent strength disadvantage vs injection moulded parts.
Got a few tweaks I want to make but I'm pretty happy with that for the first attempt.
Gotta check the other half now but should go just as well I think, and give me a finished part that resembles this:
Edited by PhillipM on Tuesday 13th February 01:52
TGCOTF-dewey said:
3D printing really is a game changer.
That looks superb Phil. How's the eye BTW?
Also where is the buggy at - not seen an update in a while?
My eyes are good, they're still not perfect - I really struggle with them adjusting quickly in the dark, but they're getting better all the time for it, so hopefully it keeps going.That looks superb Phil. How's the eye BTW?
Also where is the buggy at - not seen an update in a while?
The buggy is still going I've just been way too busy with looking after family, travelling and job hunting to do much over winter, but Ed's still cracked on with it, got most of the maintainance out of the way, and the gearbox came back the other day with the short ratio 3rd and 4th fitted so I need to get up and give him a hand to get that in.
We didn't really plan a lot of work over winter this time as Ed was busy working on a new race car for a friend anyway.
k off" 
shalmaneser said:
The nylons can be bad for moisture absorbing too imo, get very flexible after a few weeks just left on a desk.
Yea the modded PA12's are better for that, this tank should hit equilibrium around 3-4% rather than the 8% ish of the old PA6.6 tank, and retain a lot more strength. I actually conditioned them by boiling them water for about 6 hours and they're still very stiff compared to the OE tank.Specs here for some of the better HTNs these days:
https://essentium.com/wp-content/uploads/2020/08/T...
https://www.3dxtech.com/wp-content/uploads/2021/05...
I'm just running modified P1S's for the stuff that needs a chamber, better nozzles, insulated chamber, etc, etc, nothing too complex - and a couple of my older duel extruder machines that are setup mainly for TPU production parts. The biggest think with end use parts tbh is making sure they're annealed properly which can be tricky.
Edited by PhillipM on Saturday 17th February 15:13
Okay, before I got off timeline with the exhaust and other bits, I was documenting the work I think shortly after doing the rear brakes and modding the stereo to work properly.
Anyway, I was hunting down a bit of a misfire, which I traced down to a leaking pipe on the idle control valve, unfortunately, that pipe is not available any more *AND* it converts between two different fitting sizes, and because the ICV sits right by the side of the manifold, there's no room to link adaptors and off the shelf pipe together....so I 3d printed one of those too. Once you have a hammer, everything looks like a nail....
And since the ICV itself seemed to have a lot of play in the bearings, I swapped it out for a new one. But not the Peugeot one, which you can't get any more. What you can get, ironically, given how many 406 ended up dressed up as them, is a Ferrari 360 control valve, which after a bit of research into various parts, I found was electrically identical and plugs right in, and has almost the same airflow rating, close enough anyway. Only problem is the valve inlet is 90* out compared to the OE one. So I printed a 180* U-bend in polyurethane and fitted that to convert it too
While I was under there I also found that some of the nylon breather hoses under the inlet manifold had gone brittle and split, so I popped the manifold off, replaced them with silicone hose instead (again, no longer available) and then because I was there anyway and the inlet manifold to head piece wasn't all that well port matched - the ports were misaligned a fair bit, I blued up and ported both that, the inlet manifold/plenum itself to that part:
...and I also reworked the throttle body, because it was designed for a very, very soft off idle response curve and as such had a large ramp covering about 1/3rd of the throttle body area.
That made rev matching very lazy and the whole engine response at low throttle openings a bit sluggish. Great for old ladies cruising around town, not what I like, anyway a bit of work with a diegrinder and dremel and everything looked far better, I cleaned up a lot of flashing on the inlet trumpet side in the plenum too, while I was there.
And since it evidently needed a little bit of a service, it got new plugs, a new NGK coil pack, new OE leads (aftermarkets are hit and miss on this and it uses one coil to fire two plugs so they need to be good), and I decided to treat it to a cambelt kit too.
It's a good job I did, because I found a cracked through exhaust cam pulley where someone hadn't torqued it properly:
One new belt, waterpump and tensioner later...
Which wasn't too easy, it's a tight fit, the engine mount has to come out, oh, and you can't get the original hydraulic tensioner any more. So you have to grind a bit of the engine block away and fit a new style sprung one. Oh and there's 3 different sizes of waterpump, and the bigger one mine has runs into that new tensioner. So you have to grind the tensioner to fit it too.
Aren't these cars fun?
Anyway, as the more eagle eyed amongst you will have spotted, the inlet cam timing got advanced a bit too, to bring a bit more midrange torque to the table.
After reassembling it all, the engine was night and day different, nice, clean response to a stab of the throttle, maybe a little on the slow side but very linear now, and pulled harder up top to the redline, it really felt like it didn't like being strung out much past 6k before that.
Unfortunately, everything really stopped there, the same day my grandad had a heart attack and my mother had a stroke while we were waiting for the ambulance with him, my grandad took a while to recover and I spent I think 10 days by my mothers side without sleeping because I had to watch her for choking on fluid in her lungs constantly, she never woke up and the car just got left for probably half a year while I sorted things out, didn't really have any enthusiasm for it, and I ended up with nerve damage in my left shoulder that meant I lost my grip randomly in my left hand for a year or more which really compounded things. Whilst I did some bits and pieces, speaker upgrades, seat repairs, general servicing and few other bits and pieces and repairs, I didn't document anything really, wasn't in the mindset for anything bar the odd distraction for a long time, as you can guess.
Oh, and the bin collection lorry drove into the back arch of the Coupe and all but wrote it off because it wasn't worth repairing at values at the time, just to seal the deal, I think I got a payout of 600-700 quid or something, even after arguing it for being a rare car with documented work. I just took a payout from 'em and pushed it out myself.
Anyway, I kept trawling amazon for things at night when I wasn't sleeping and dropped on some serious bargains, and slowly built up this lot for about 200 quid I think. which finally motivated me to get back under the car and do something, so it got new front springs, new top mounts front and rear, top mount bearings, new droplinks front and rear, KYB front dampers and Bilstien rears, new front balljoints, and new front arb bushes too:
That was pretty much most of the wearing bushes and parts on the suspension side refreshed by then.
While I was under there I noticed some of the air con hose and water hose bushes were very tired too, to the point one kept falling out its bracket - and well, hammer and nail, remember?
Out came the printed parts again:
Anyway, I was hunting down a bit of a misfire, which I traced down to a leaking pipe on the idle control valve, unfortunately, that pipe is not available any more *AND* it converts between two different fitting sizes, and because the ICV sits right by the side of the manifold, there's no room to link adaptors and off the shelf pipe together....so I 3d printed one of those too. Once you have a hammer, everything looks like a nail....
And since the ICV itself seemed to have a lot of play in the bearings, I swapped it out for a new one. But not the Peugeot one, which you can't get any more. What you can get, ironically, given how many 406 ended up dressed up as them, is a Ferrari 360 control valve, which after a bit of research into various parts, I found was electrically identical and plugs right in, and has almost the same airflow rating, close enough anyway. Only problem is the valve inlet is 90* out compared to the OE one. So I printed a 180* U-bend in polyurethane and fitted that to convert it too
While I was under there I also found that some of the nylon breather hoses under the inlet manifold had gone brittle and split, so I popped the manifold off, replaced them with silicone hose instead (again, no longer available) and then because I was there anyway and the inlet manifold to head piece wasn't all that well port matched - the ports were misaligned a fair bit, I blued up and ported both that, the inlet manifold/plenum itself to that part:
...and I also reworked the throttle body, because it was designed for a very, very soft off idle response curve and as such had a large ramp covering about 1/3rd of the throttle body area.
That made rev matching very lazy and the whole engine response at low throttle openings a bit sluggish. Great for old ladies cruising around town, not what I like, anyway a bit of work with a diegrinder and dremel and everything looked far better, I cleaned up a lot of flashing on the inlet trumpet side in the plenum too, while I was there.
And since it evidently needed a little bit of a service, it got new plugs, a new NGK coil pack, new OE leads (aftermarkets are hit and miss on this and it uses one coil to fire two plugs so they need to be good), and I decided to treat it to a cambelt kit too.
It's a good job I did, because I found a cracked through exhaust cam pulley where someone hadn't torqued it properly:
One new belt, waterpump and tensioner later...
Which wasn't too easy, it's a tight fit, the engine mount has to come out, oh, and you can't get the original hydraulic tensioner any more. So you have to grind a bit of the engine block away and fit a new style sprung one. Oh and there's 3 different sizes of waterpump, and the bigger one mine has runs into that new tensioner. So you have to grind the tensioner to fit it too.
Aren't these cars fun?
Anyway, as the more eagle eyed amongst you will have spotted, the inlet cam timing got advanced a bit too, to bring a bit more midrange torque to the table.
After reassembling it all, the engine was night and day different, nice, clean response to a stab of the throttle, maybe a little on the slow side but very linear now, and pulled harder up top to the redline, it really felt like it didn't like being strung out much past 6k before that.
Unfortunately, everything really stopped there, the same day my grandad had a heart attack and my mother had a stroke while we were waiting for the ambulance with him, my grandad took a while to recover and I spent I think 10 days by my mothers side without sleeping because I had to watch her for choking on fluid in her lungs constantly, she never woke up and the car just got left for probably half a year while I sorted things out, didn't really have any enthusiasm for it, and I ended up with nerve damage in my left shoulder that meant I lost my grip randomly in my left hand for a year or more which really compounded things. Whilst I did some bits and pieces, speaker upgrades, seat repairs, general servicing and few other bits and pieces and repairs, I didn't document anything really, wasn't in the mindset for anything bar the odd distraction for a long time, as you can guess.
Oh, and the bin collection lorry drove into the back arch of the Coupe and all but wrote it off because it wasn't worth repairing at values at the time, just to seal the deal, I think I got a payout of 600-700 quid or something, even after arguing it for being a rare car with documented work. I just took a payout from 'em and pushed it out myself.
Anyway, I kept trawling amazon for things at night when I wasn't sleeping and dropped on some serious bargains, and slowly built up this lot for about 200 quid I think. which finally motivated me to get back under the car and do something, so it got new front springs, new top mounts front and rear, top mount bearings, new droplinks front and rear, KYB front dampers and Bilstien rears, new front balljoints, and new front arb bushes too:
That was pretty much most of the wearing bushes and parts on the suspension side refreshed by then.
While I was under there I noticed some of the air con hose and water hose bushes were very tired too, to the point one kept falling out its bracket - and well, hammer and nail, remember?
Out came the printed parts again:
Edited by PhillipM on Monday 19th February 00:38
Okay, next bit of fun, well, I now had all new suspension on the front, albeit I wasn't perfectly happy with the front end, the bushes available for these tend to be a bit cheap and cheerful now the cars old, and even with new bushes I could feel the wishbones tweak the front around on rough farm tracks at speed.
However, I now had the two old front wishbones to hand....you know where this is going
I measured up carefully from the old wishbones, and drew up some polybushes to print... only with a difference, instead of the usual thing with polybushes where they have a cheap sleeve turned from some bar in the centre to rotate on (or in some cases just use the rough af cast pin on the wishbone) mine got designed to use proper ground 52100 bearing races in the centre, that press onto the wishbone pin and act as the bearing surface - and riding on that surface, instead of the soft, grippy polyurethane that leads to stick/slip and friction issues, is a nice hard acetal wear surface that's actually designed to be used as a bearing, complete with detents to hold lubrication and that's then encapsulated by the actual polybush around the outside to support it and take care off all the deflections and NVH duties:
It also has a grease pocked in the centre that feeds into the acetal bearing surface, and as you can see, there are sealing lips printed into the bush itself to keep water and dirt out:
Gave them a tap into the old housing with my very sophisticated manual press:
Vs the old rubber ones:
So now I had some nice firm polybushes for the rear of the wishbones (which is where most of the movement was/is on the standard setup), but ones that don't have the friction and squeaking issues that usual polybushes exhibit.
I fitted a set of good Lemforder rubber bushes to the front of them, which fortunately you can still get, and swapped the wishbones back around again
That tightened up the front end a lot, much less tramlining or wandering, less torque steer and really barely any change in NVH, it was maybe a bit noisier for the secondary ride on very rough roads.
However, I now had the two old front wishbones to hand....you know where this is going
I measured up carefully from the old wishbones, and drew up some polybushes to print... only with a difference, instead of the usual thing with polybushes where they have a cheap sleeve turned from some bar in the centre to rotate on (or in some cases just use the rough af cast pin on the wishbone) mine got designed to use proper ground 52100 bearing races in the centre, that press onto the wishbone pin and act as the bearing surface - and riding on that surface, instead of the soft, grippy polyurethane that leads to stick/slip and friction issues, is a nice hard acetal wear surface that's actually designed to be used as a bearing, complete with detents to hold lubrication and that's then encapsulated by the actual polybush around the outside to support it and take care off all the deflections and NVH duties:
It also has a grease pocked in the centre that feeds into the acetal bearing surface, and as you can see, there are sealing lips printed into the bush itself to keep water and dirt out:
Gave them a tap into the old housing with my very sophisticated manual press:
Vs the old rubber ones:
So now I had some nice firm polybushes for the rear of the wishbones (which is where most of the movement was/is on the standard setup), but ones that don't have the friction and squeaking issues that usual polybushes exhibit.
I fitted a set of good Lemforder rubber bushes to the front of them, which fortunately you can still get, and swapped the wishbones back around again
That tightened up the front end a lot, much less tramlining or wandering, less torque steer and really barely any change in NVH, it was maybe a bit noisier for the secondary ride on very rough roads.
Edited by PhillipM on Wednesday 28th February 00:10
shalmaneser said:
Really impressive stuff you're getting on with here, and it sounds like you've been through the wars with personal stuff too.
Oh there was even more than that, it's been a rough decade, we'd only just lost my other nan and grandad, and a couple of more distant relatives too, and I lost a couple friends to accidents right around the same time, it was hell - and I basically ended up as a carer for many years after to stop what was left of the family doing anything silly too. Not much fun. It's why the buggy revamp took so long too.Anyway, the tanks I posted up above that I'm making right now, I had prior form with - whilst on a long drive I suddenly started slowly loosing coolant. When I parked the car up there were no leaks - it only lost it when the car was hot and everything was up to pressure. That was a bit worrying as that's often a sign of a headgasket leak but there was no misfire or oil and coolant mixing - anyway, I doubled checked all the radiators and hoses, checked the hose clamps, couldn't find it, so I threw some UV leak detector in expecting a pinhole in the radiator, nothing showing, but I got a little shine right at the back of the engine bay, cue one degassing tank:
Now after some research I found they all start leaking and they're no longer available, so I started looking at why and if I could fix it - it turns out these tanks are made in two halves and ultrasonic welded at the seam.
Only they're welded very badly, to the point there's basically only a small flashline that's actually welded - they weren't done with enough pressure or for enough time at the factory, someone was obviously saving a few seconds of cycle time to crank them out faster - I've seen people saying they had 1 or 2 tanks replaced even under warranty when they bought the car new.
You can see how the weld had split and the tank opens up under pressure here:
Peugeot changed the design for later engines and went with a welded polypropylene tank instead of these Nylon 6.6 + glass fibre ones, however, the shape is different and so are the outlets and angles, so they won't fit in the stock location, it's very tight down at the back of the bulkhead down there.
Now, some might know this, but bonding nylon together is a nightmare even fresh, when it's aged, been heat cycled and absorbed coolant (it'll take about 8% of it's volume in water when saturated, it's a lot!) over the years it's nigh on impossible to bond with decent structural strength to the point I'd trust it with pressure and boiling hot coolant - and the inside was full of stress cracking and bubbles under the surface where the tank and fittings had flexed and coolant had worked its way under the surface:
So, if I can't get a replacement, I can't glue it back together, and I don't trust trying to weld it with heat and fresh nylon because of the internal cracking, I came up with the next best thing I could think of - clamp the two halves together onto a seal.
So I dried the tank at 100c for 8 hours to drive out as much of the absorbed moisture as I could, I sanded back the flanges where the two halves of the tank met, washed it down with solvent and then flame treated the flanges to get the surface energy up to try to help things bond - then put a good bead of 3M copper silicone sealant between them and clamped them down with a controlled gap (half a mm) so it didn't get squeezed out completely while it set.
Then to hold the two halves together against the pressure of the cooling system, I welded a couple of washers to jubilee clip to make a self centring clamp, and I printed two washers in PCTPE (a form of soft flexible nylon I had on hand for making prosthetics) to spread out any stress from the clamp given it would otherwise be on the flat area of the tank where it's the most flexible/weakest, et voila, one repaired tank:
Which worked pretty well for maybe 6 years or so, but given I've kinda spoilered this already - those internal stress cracks in the tank eventually worked their way through and it started blowing coolant out of the top instead last year
But hey, my seal never leaked!
....and yes, that does look like a polyurethane engine mount that it's sat on there....hmm, wonder why...
Edited by PhillipM on Tuesday 20th February 15:38
Cambs_Stuart said:
I'm really enjoying this thread! Your problem solving and technical skills are just brilliant.
Sorry to hear about all the non-car stuff. I suspect there are a few people on here (myself) included that use tinkering with cars as a release/escape from other stuff.
Yes, I think it's pretty common given some of the people I'm often talking to with race stuff, etc. It's a good distraction and you learn new stuff along the way, works well Sorry to hear about all the non-car stuff. I suspect there are a few people on here (myself) included that use tinkering with cars as a release/escape from other stuff.
Since I'm already talking about the tanks anyway, the replacements I was making this week fit perfectly, it's pretty tight in the OE clamp and fitting, you couldn't get a cig paper between the flanges and bolts and the clamp, pretty happy with that:
And the hoses fit perfectly too:
The layer lines look way worse on camera, my Pixel seems to oversharpen everything, Google need a kick
Edited by PhillipM on Tuesday 20th February 16:23
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