My 406 Break - bought it for work, but already love the car

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joydivision
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Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

I was spot on - the problem was created by the additional check valve I installed. Today I bought clear fuel line tubing (just to discover that it was too small in diameter, but then found the right one at another store) and a bit of black normal flexible tube, as it revealed completely impossible to install the black original rigid tube on the connections, it's far too small, I don't know how they fit it in the first place... also I wouldn't want that, as I wanted clear tube to be able to see the air, if any. So, after much hard fiddling and some improvisation (I wanted to take out that little straight piece of black flexible hose and the white junctions, so the line would go direct, but I couldn't get suitably sized union pieces anywhere... as I need the car, I was forced to recreate the original improvisation with the new tubing - the old black tube piece was in a bad condition, who knows if it wouldn't let some air in?). Before final connection I used my "bleeding" trick, the syringe with diesel to fill the tube and pumped the primer bulb, then joined them and installed clamps. Tested and yeah! The little remaining air from this installation was purged within like 30 seconds and some accelerations, from then on a almost constant solid fuel stream could be seen, just on some harder accelerations a few bubbles would appear but also disappear as quickly afterwards. I made a short drive and the car behaved absolutely flawless, perfect power and acceleration until higher RPM, problem solved!! :)

So, lesson learned: two check valves in series are a REALLY bad idea. Unfortunately this also means I'm back to stage 0 about the fuel running back into tank issue.

Still I bought a new fuel filter element and ordered the O-ring that is fit in the bottom of the housing against the fuel heating part from the coolant lines, as I've read it sometimes develops minor air leaks. This because although the check valve caused the problem, the air must have come from somewhere (which would also explain why the fuel runs back into tank when parked uphill). I think your idea of coming in at the fuel filter housing might be right, as with the check valve aggravating the situation, it was after fuel filter that the majority of bubbles appeared.

But I won't have time to do this so soon, I have a lot of work right now, also the installed fuel filter can make a few more thousand kms.

If that doesn't settle the fuel to tank returning issue, I have one last idea (but I'm not sure if it's valid): in the fuel return line to tank, there's a fuel pressure regulator installed (or overflow valve, I think it's called here), what if that one is stuck open? Could that, together with minor air entry somewhere in return path, allow fuel to run back through injection pump and return line into tank?

Thanks again for all the patience reading my posts and useful hints :)

On another note, as I now have the front wheel triangle issue solved and two new tyres on, the car is ready to go to MOT (it's this month), here in PT it's a little less demanding than in UK, but still I'm a bit nervous as this is the first time with this car for me. When it's done I will report back, hopefully it will pass just fine.
joydivision
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Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

Here's the photo that I forgot to attach.
IMG_20211103_130204578_.jpg
(693.45 KiB) Not downloaded yet
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Doggy
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Re: My 406 Break - bought it for work, but already love the car

Post by Doggy »

Good progress, well done!

I think it likely the fuel running back to the tank is due to a less than perfect seal at the filter or one if the pipe connections in that area but I guess it can wait.

The overflow/pressure regulator valve is probably closing OK (or at least well enough) if you can run the engine at maximum fuel demand continuously, (accellerating hard up a hill for example).

Good luck with the MOT
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (we shall see......)
joydivision
1.8 16v
Posts: 72
Joined: Fri Jul 02, 2021 7:18 pm

Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

Thanks.

Yes, that's what I'm thinking, too, but in fact this can wait, I don't even have any ramps here at home where I would park.

Ok, I didn't know the overflow valve was important for this, but yes, the car drives perfectly now, so this rules the overflow valve out, which is good (one less thing to verify).
joydivision
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Posts: 72
Joined: Fri Jul 02, 2021 7:18 pm

Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

Went to MOT yesterday. It didn't pass yet, two issues, one of them serious. But there's also good news: mechanically, emission-wise and electrically (except for one fog light, that's the minor issue) it is all fine! :) Now for the serious issue which made it not pass: it's that damn oil leak I've mentioned before. My mechanic got the additional smaller leaks settled (just some connections that needed tightening) and I got the overall oil smearing of the whole engine coming from top of it settled by changing the manifold rubber joints. But that one oil leak right under the engine is still there and for them it's too much, has to be solved. So I called the mechanic and on Monday first thing in the morning I'll leave the car there for him to solve this problem with enough time and also clean thoroughly afterwards. Hopefully it's just some pipe connection (he said that oil circulates with quite some pressure down there). Just hope it won't take him too long, then the most costly will be the labour...

As for the minor issue, the fog light, I just fixed it today, was an oxidised connection, not a blown bulb. :lol:

So, next week I'll post updates.
joydivision
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Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

Just came back from MOT, it's done, it passed! :cheesy:

My mechanic found the origin of the oil leak and fixed it yesterday, then gave it a thorough clean. The oil came from upwards, behind the engine block, it was the seal of the valve cover, was in really bad shape. So it fortunately was an easy and inexpensive fix. I will still keep an eye on the ground under the car over the next weeks, as one never knows, it might very well still have some other minor leak, but I hope not.

So, I'm really happy with this and can now focus on the very few things that are still left to fix or that I want to improve on the car, listed in order of priority (though none of them is really urgent, which is great progress):

-1. change the air inlet piping, as it has that critically dangerous location behind the the fog light into the the wheel arc, way too low for the kind of floods we sometimes experience here. I already ordered a suitable pipe and have a clear idea of where the new inlet location will be.

-2. solve slight cold start difficulties and the "fuel running back into tank when parked on hill" issue (still needing some further investigation)

-3. fix RPM gauge not working (this one I tried to fix already, as you know, it's a tough one, but I will get it done one day!)

-4. change thermostat, as it MIGHT be stuck open or (more likely) not closing totally, as engine runs a little cold. Now with cold weather it can be noticed more clearly. Still have to do the pipe feeling test, haven't had time for this.

-5. Buy one of these "chinese" remote central locking units and install it, so that I can have working remote central locking, I always wanted this (my previous car, although from 2004, didn't have one) and this 406 supposedly had a remote, but the remote unit is broken (tried to fix it with no luck) and I don't even know if the receiver works, so this seems the most economical and easy fix.

-6. Next spring or summer, if I have time (or a little money spared), I will fix the two or three places on the paint work where there's deeper dents that have some rust. I might even do the job myself, I've done some (amateur, but acceptable) paint work before.

And that's it, looks like slowly I'm getting there 8)
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Doggy
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Re: My 406 Break - bought it for work, but already love the car

Post by Doggy »

Well done getting it through the MOT.
Sounds like you have most of the important/urgent issues under control.
Many of us miss our beloved 406's - enjoy yours!
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (we shall see......)
joydivision
1.8 16v
Posts: 72
Joined: Fri Jul 02, 2021 7:18 pm

Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

Oh yes, I'm enjoying it, since the start, but now that I've got everything important done, even more :)

I've also been enjoying this forum, although not having much movement, it's a place full of useful information as well as helpful and nice people.
joydivision
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Posts: 72
Joined: Fri Jul 02, 2021 7:18 pm

Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

Finally found the time to post some updates here.

- had an unpleasant surprise the other day: discovered, by luck, as I saw a part of it hanging down to the ground below the engine, that the auxiliary drive belt had split into half and one of the halves had wound itself up on the shaft of the alternator. So I had to call the recovery vehicle to have the car towed to my mechanic to put on a new drive belt. It went all fine and was quick and well done, also cheap (I myself bought the correct belt before going there). On that day in the morning I must have driven with the split drive belt a few kms, which is just scary... It must have split before, though, as in the morning for the first time I found myself almost unable to get the car started, then it finally started and made some weird noises which then went away (must have been the split belt making it difficult to start, then it freed itself). Now as for why this happened after only 9000 km (at the time all was done new, including tensioner), I'm convinced it was caused due to a little mistake made by my mechanic later, when at the time of installing the A/C compressor he put the drive belt slightly misaligned and I noticed it only after some time, then some more days passed and it made some kilometres like this, only then he and I had time to correct it. I think the belt must have suffered with this and only made it until the other day. Let's hope it's just this and that the new belt will make normal mileage.

- did the air intake mod today, haven't had the chance to try it out extensively but I'm quite happy with the result, now air gets in through a flexible 72mm pipe which ends on left side close to front grill, more or less close to the alternator. No more fear of driving through reasonable deep water when it rains (the original intake entry is located really very low, just behind the right fog light). I'm convinced that the slightly warmer air due to pipe heating up from engine bay heat won't be a problem, due to this being an engine with turbo and intercooler, but obviously I can only confirm that it works fine after driving some time. Hopefully it will be fine. Will follow up with some photos when I find the time.
During the process I fixed a problem with the oil breather hose, btw, which had a loose clamp, I think it would even leak some oil from there.

- speaking of oil leaks, unfortunately it still drips a little, less than before (in fact there was oil coming from the top of the engine before, in the start even from the intake manifold rubbers, which I then fixed, then my mechanic discovered the rotten valve cover seal, which was fixed, so from the top it probably isn't coming anymore), but under the engine, right in the middle, there's a black plastic pipe, there the oil drips from (but it's not from that pipe, it just collects there). My mechanic says it can be a oil pipe connected to the Turbo, which has pressure. Hard to get there. So this is postponed for now, will deal with this later, until next MOT I have more than 11 months.

Will have the oil changed in a couple of days, it made 9000 km (and due to the oil leaks, I topped up with less than 1 lt, so engine is not consuming oil, which is good news). I've read in some places that the XUD engines should change oil all 5000 km and other places state 10000 km. Any comments on this? I'm thinking of settling on 7500 km for next oil changes, to be on the safe side and keep it economically viable (I drive quite a few kms per year).
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Re: My 406 Break - bought it for work, but already love the car

Post by Doggy »

You did well to spot the damaged drive belt - it is not unknown for a loose auxilliary belt to get behind the crankshaft pulley and cause a timing belt failure. Rare, but it has happened.

I have never had an XUD, but the later HDi's are very similar. Recommended oil change interval on those was 12000 miles / 19000 or possibly 20000 km. I tried to change mine a little bit early, roughly 8500 - 10000 miles as I did notice a marked change in the sound/smoothness of the engine after an oil change at the full service interval. (I think this was due to the hydraulic tappets not working as well prior to the change, not sure but I think the XUD has solid valve lifters). Engines in both of my 2.2 HDi's were still faultless at 200k miles. Work out a schedule that suits how you use the car, (I did mine in spring and autumn when the weather was favourable).

I don't know the recommended oil change interval for your car - in the late 1980's and early 1990's most petrol cars sold in the UK had intervals of 10000 miles and diesels were typically half that at 5000 miles. I suspect this was in anticipation that turbochargers would be a little more likely to fail due to poor lubrication than the rest of the engine. The difference in servicing costs harmed diesel sales for a time and the service intervals were soon extended. Lubricants have definitely improved since then, I would expect that your car would be fine with the same intervals as the later HDi.

My last PSA diesel, (2009 C5 2.0 HDi), had service intervals of 20000 miles/ 32000 km. I don't think the engine was changed in any way to accomodate extending the service interval. After that they got really silly like my BMW's variable mileage/condition based service intervals which mean some cars now go several years between oil changes.

If you can get from one oil change to another mostly without having to top up the oil you have little to worry about. Minor oil leaks are more an irritation than a genuine problem. Be aware that almost every intercooled PSA engine will have signs of oil on the intercooler, boost pipe or breather pipe connections, caused by oil mist from the crankcase and valvegear breathers being pressurised by the turbo / forced into the induction system where it condenses and can seep a little from any of the joints.
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (we shall see......)
joydivision
1.8 16v
Posts: 72
Joined: Fri Jul 02, 2021 7:18 pm

Re: My 406 Break - bought it for work, but already love the car

Post by joydivision »

Yes, I've also heard about that worst case scenario when auxiliary drive belt breaks, rare but terrible.

Thanks for the detailed input of your experience about the oil change intervals and different engine types, very educative.
Also what you say about harming the sale of diesels, it could explain why in some places they mention 5000 and others 10000 km for the same engine.

Let's see how it sounds tomorrow after changing the oil, but I'm also quite confident that the sound of the engine has gotten a little rougher since some two thousand kms ago, which would be about the 7500 km mark, that's why I'm planning to go with that mileage. I tend to drive more than the double of this per year, so maybe two oil changes per year won't be enough (that's what I did before with my Lancer, but that was a completely different scenario, I had it since 45000km in almost new state and that's when it was converted to LPG, which meant that even at oil change the oil looked almost new, so I could easily have done more than 10k between changes.), so I think I will settle at the intermediate 7500-8000 km mark.

Regarding the oil leaks, yes, I'm aware of that oil mist getting into intake manifold and other places, I've also seen it before on other older turbo diesels my dad had, but it's always a good idea to keep control of it, as it will not only make the engine bay a messy place but ultimately find it's way down the engine and to the floor and that's something they don't like at all at MOT. But in this particular case, there must exist some minor oil leak somewhere behind or under the engine, close to the Turbo, in some really hard to access place, unfortunately. That's where it comes from now. I suspect more oil exits there when I drive the car more hard due to higher pressure? (or do I see this wrong?) which then eventually much later finds its way down and collects, until it drips to the ground very slowly. This would explain why the mechanic, after fixing the valve cover seal, cleaning all up and having the engine run quite a long time on idle, wouldn't notice any oil dripping. Having improved oil spray leaks on the upper parts of the engine, it is now in fact only a very small amount dripping to the floor and it doesn't seem to grow at all. But it is still a problem which I will have to address in some way before going to the next MOT in roughly one year, otherwise it won't pass. :roll:
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