Xantia V6 broken exhaust (update: and rough low rpm running)

[CitroJim]

Gosh, at that price it's worth getting one and a spare just in case you ever need one again...

[myglaren]

They probably give you a free car with that.

[andmcit]

Bit late in proceedings here but maybe this kind of thing may be of use considering the differing diameters on offer:

http://www.ebay.co.uk/itm/Renault-Peuge ... 2a22ff6dd1" onclick="window.open(this.href);return false;

[Mandrake]

Simon

I reckon there's two ways to go with this...

1 (no cost!) - remove the silencer and cut the end off its inlet pipe. Cut 2 or 3 slots in it, slide it back on and crank up an exhuast clamp on it. This is effectively the method used on the HDi repair pipe and should make a permanent solution. You will need to modify any future replacement silencer to suit though....!

HDi repair pipe ? Is that a kit available somewhere ?

Sounds like a plan, although the silencer pipe is in two sizes with the end enlarged to accept the inner sleeve of the cat pipe. If I cut that enlarged section off the end (which isn't that long) then whats left won't slide over the other pipe. (Athough that then opens up the possibility of sliding an intermediate tube over and clamping on both ends)

I really need to measure the various pipe diameters exactly to know what is going to work.

2a (costs a bit....!) - Not sure which part of the joint is on the cat and which on the silencer. If it is the bellmouth on the cat then you could buy the HDi repair pipe, cut the end off, slot it if necessary slip it on the cat and weld it into place. This would give you the 'original' arrangement, and any future centre silencer would still fit.

I don't know which way around the joint is either, does anybody know ? There's not enough of it left to tell

Also sounds like a good idea if I can get more info on this HDi repair pipe.

2b (Costs more) - if the other way around (eg bellmouth on the silencer) then you will need to buy a silencer (eg a rear box - mind you I got one for a Picasso HDi for £30 so maybe not that dear!) cut the lip off, and weld onto the cat as before.

My thought is that 1 will work no problem at all and saves having to remove the cat from the car.

I am at home this weekend (sans family!) but will be head down - arse up tiling the porch floor. However, you're welcome to come and use my facilities (ramps, grinders etc) and I can provide welding as required. I'm back on Thursday, drop me a PM and we'll arrange something.

Thanks for the offer, alas I'm working this weekend and have Thursday/Friday off instead. (Did I mention how much I hate shift work... )

I still have to bodge it first anyway as the car is completely immobile at the moment, so I couldn't get it to your place without first effecting some sort of repair. (Its sitting on high up on car ramps like a beached whale the last 2 days ) I'll go ahead with the temporary clamp, hose clamps and sealant fix for now (the clamp has arrived already) and that should get me mobile then I can work on a more long lasting and leak free fix.

Edit - of course if you are desperate, there is always Citroen:

Part Number Description Quantity Price excl. VAT Price incl. VAT Total incl. VAT
0000173177 CATALYST MUFFLR 1,192.52 GBP 1,431.02 GBP

Thanks very much, so do I get a free car supplied with every catalytic converter ?

[Mandrake]

Bit late in proceedings here but maybe this kind of thing may be of use considering the differing diameters on offer:

http://www.ebay.co.uk/itm/Renault-Peuge ... 2a22ff6dd1" onclick="window.open(this.href);return false;

Not too late at all, that looks very promising in fact for a longer term repair that I could fit myself...

I see they have various internal diameters - 45, 50, 55, 60mm, at the moment I don't know what diameter I need, or whether I'm going to need two different diameters for the two halves. (And if so whether the joint in the middle is compatible between two slightly different diameters...)

It's not clear to me whether this would be compatible with the V6, as I'm assuming that the one of the joints would have to be part way along the inner sleeve...

Or should I just choose a size that matches the diameter of the inner cat sleeve and fit it at the end of the inner sleeve, cutting off the larger diameter portion of the centre silencer ? If it turns out that the smaller diameter section of the silencer and the cat sleeve are the same diameter, I'm not sure what this extra joint buys me over and above a straight piece of pipe with slots at both ends that I can slip over and clamp with two conventional clamps ?

Anyone think those clamps pictured on ebay might work or is it just more complexity for no real gain ?

[RichardW]

I'll be there on Friday, Simon....

Jubilee clip round the cat pipe in front of the weld lip, pull the silencer back up and wire the two together will get it (nosily!) mobile.

The HDi repair pipe can be seen in the Bosal catalogue - it just means you can repair the back section of the pipe without having to replace the cat - looks like it is smaller bore than the V6 exhaust though. I see what you mean about the enlarged section now, but that is not that much different to the repair pipe in length. I reckon you could do it with an angle grinder with the pipe still on the car! No real need to cut the flange off, just slice through it.

[Mandrake]

Well I guess the weather gods have not smiled kindly upon me today:

The weather report looks good tomorrow though, so fingers crossed. I'm impressed at how long the suspension has stayed up, its been in high mode on the ramps since Sunday...

I'll be there on Friday, Simon....

Jubilee clip round the cat pipe in front of the weld lip, pull the silencer back up and wire the two together will get it (nosily!) mobile.

I've got an exhaust clamp to clamp on the cat tail and some jubilee hose clamps to pull the two clamps together, plus I'll put a bit of sealant in the overlap region - while the outer cat sleeve (or whats left of it) is certainly not a tight fit on the silencer pipe, the inner cat sleeve is a reasonably tight fit in the enlarged section of the silencer sleeve since its job is to support the weight at the joint...so with a bit of paste it might seal quite well, for a while at least.

Remind me where you are again Richard ? It's unlikely I could get there on Friday as I'm almost down to the petrol warning light with no money to spare on petrol until the end of the month (yes its been one of those months where everything stacks up) - hence doing the simplest cheapest bodge I can until payday. Some time early next month is a different story though, especially if you have a cunning idea on how it might be fixed permanently.

When I've had a thorough look over it tomorrow and done a temporary repair I think I'll have a bit better idea of what might work as a permanent (but cheap) repair...and I'll take some more photos with the two sections apart and also after my temporary repair.

[RichardW]

I'm in Lanark. Weather looks better for tomorrow - good luck with getting it gas tight again.

[Mandrake]

I'm in Lanark. Weather looks better for tomorrow - good luck with getting it gas tight again.

Weather report looks good, hope I get time tomorrow now, our boiler just blew up tonight (literally - it blew the main circuit breaker in the house and there is a strong smell of burning from it...) so I'll probably spend all tomorrow morning on my precious day off waiting in for the boiler repair man to arrive.

It's an old model that they always have trouble finding parts for, so this could be interesting...most likely a few days without it if its what I think it is, and our landlord could be looking at finally having to replace it...I'm sure my luck must be on its way back up after this.

[Mandrake]

Well it looks like my bodge job is a success.

I've been able to get a perfectly gas tight seal and it seems mechanically quite secure. The car is certainly a lot quieter now, there must have been a small leak ever since I've had it.

The inner sleeve of the cat tail seems to be in perfect order, no rust or deterioration, so it bodes well for having a new outer sleeve fabricated and welded on later:

This picture shows what was left of the outer sleeve of the cat:

Most of the pipe coming out of the silencer (up to the original clamp) is actually intact.

(continued...)

[Mandrake]

I gave the inside of the enlarged section of silencer pipe and the outside of the cat tail a smear of Halfords exhaust putty (man is that stuff sticky!!) and pushed it together, adding the jubilee clips. Because the putty is so sticky it took quite a bit of wriggling to actually get it to slide fully on, but eventually I had the good part of the original cat sleeve butted up against the weld ring:

With both hose clamps tightened up the joint is solid and doesn't even wiggle. Even with the exhaust putty still soft and yet to harden there was no leakage at all when I first started the engine...and I've done a few miles now and all seems ok.

You can see on the other side just how much one side had burnt away:

My only concern with this temporary repair is that there is quite a lot of strain on the jubilee clips, so I'm not sure how long they will hold up. If I had something a bit more substantial to pull the two clamps together it would be a bit more permanent as its otherwise mechanically strong and so far gas tight.

Although the car is a lot more quiet the problems I mentioned in the engine noise thread still remain - the engine still stumbles quite a bit and seems unwilling when trying to pull below 2000rpm with an odd sort of shuddering noise (sometimes even a dry scraping noise like a noisy driveshaft bearing) accelerating at 1500rpm, and you can feel a definite shuddering on the actual acceleration. I'm beginning to think the engine mounts may well be faulty even though the top one looks ok. (There is sometimes quite a big thump when changing up a gear with no acceleration, also pointing at engine/gearbox mounts... )

Now that the middle of the exhaust is completely quiet I've also noticed that there is a LOT of boom from the tailpipe at low revs around 1000-1500 if you give the throttle a good poke, so much so that I'm thinking that the baffles in one or both silencer boxes must be rusted/blown out internally. Not having heard a Xantia V6 before it's hard for me to judge whether that throaty boom at low revs is normal or not, but it seems excessive to me.

(Could one cylinder misfiring also cause a boomy exhaust at low revs with wide throttle openings ?)

So despite the leak being 100% sealed all is still not well between 1000-2000 rpm, and it has certainly got me wondering what is going on given that the shuddering and poor running at low rpm has only been noticeable for about a month...

[CitroJim]

That's a nice bodge Simon and certainly one to remember when invariably it will happen on other V6s

As for the poor running...

Have you had the engine on a Lexia? You have symptoms there of a dicky MAP sensor as a quick guess...

[Mandrake]

No it hasn't been on a Lexia, I guess I'll have to add that to my ever growing to do list, if I can find one nearby.

The strange thing is I'm sure that this poor running at low rpm didn't start until after the first time I had the fuse box apart when I was doing reconnaissance for the starter mod. Naturally the battery was disconnected at the time. I can't really see the connection though. I do remember also pulling a few of the visible small plugs on the engine off and giving them a spray of contact cleaner but I'm sure that was AFTER the problem had already started...

Where is the MAP sensor located and what does it look like ? If I know I can at least check the electrical connection, although I guess there probably isn't much else I could do to it except replace it if a Lexia finds it faulty.

Are there any air intake pipe leaks that could cause similar symptoms ?

[addo]

You are most likely to be losing spark, if failure happened fairly smartly.

I don't think the coils can be tested with a meter; you need a signal generator or known good units to try.

[Mandrake]

Thanks addo, what sort of signal generator ?

I was testing the car on my lunch break at work today (yes, working on Sunday, grr) and what I noticed is that the idle is absolutely rock steady whether cold or hot, however as soon as I open the throttle even a tiny amount the revs actually drop and start fluctuating up and down quite a lot like its struggling a bit. It takes quite a bit of throttle opening before it will actually go above 1000rpm, and around 1200rpm there is a definite unevenness to the way it runs that suggests either missing or a problem with the mixture (?).

At any speed between about 1200-2000rpm if I hold the throttle steady I can hear the engine rpm going up-down-up-down-up-down in a cyclic fashion about twice per second, although it doesn't show on the rev counter.

A few weeks ago I had noticed the same thing on motorway driving cruising just below 2000rpm - this cyclic variation in engine revs up and down about twice a second.

If the car is idling and I give the throttle a quick stab to half way the revs drop down and it really stumbles quite badly then recovers, which I don't recall it doing before I started having these problems.

These problems are all fairly recent in the last 6 weeks or so, before that it pulled smoothly and well at low revs and rpm was steady.

Can someone describe to me what the symptoms of a faulty map sensor might be ? I presume it would cause the mixture to be too lean or too rich under certain throttle and load conditions ? Is the map sensor more about controlling mixture under static light throttle conditions or is it more important for heavy load / wide throttle conditions ?

What symptoms might help me distinguish between a cylinder missing due to a faulty coil, and a faulty map sensor upsetting the mixture ?

Finally, if I could get access to a Lexia to test it, I presume a faulty MAP sensor would be reported by the Lexia, but could it detect missing due to a faulty ignition coil or plug ? (I can't think how it might detect that...)

Any clues anyone where the map sensor is on the V6 so I can check and clean the plug ? Can it be measured with an ohm meter ?

PS, my exhaust bodge is still gas tight, it really is a lot quieter than before.