Fumes and running rich?

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Philip Chidlow
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Fumes and running rich?

Post by Philip Chidlow » Fri Jun 09, 2006 10:33 am

My BX has quite a few miles under its belt and would benefit from the valve seals etc. being done. It does use a bit of oil and it sometimes will puff out a little smoke on warm start ups or under hard acceleration. This I can understand. I will have to bite the bullet and get the engine done.

But...

The engine is 'fumey' and I do get some soot around the tail pipe. Someone (I think it might've been Ian) at the FCS mentioned it might be something to do with fuel air mixture. If my car's running rich, would this have such an effect? How to I check or indeed get ti checked - and how do I rectify the problem? It doesn't smoke from the oil filler. But I was wondering about a split breather pipe (how do I find that?) or some other problem like a leaking exhaust/manifold... but I'd hear that I guess.

Anyone else with an 8v GTi of high miles experiencing the same? Any advice welcome.
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Post by jeremy » Fri Jun 09, 2006 10:58 am

Electronic fuel injection works very nicely if everything and I mean everything is in good order. Leaky breathers may cause problems as they alter the manifold pressure and all the carefully calculated airflow metering may not do its job properly.

The other things that can affect it are things like temperature sensors - for example the cold start one which may lead the ECU to think the engine hasn't warmed up - and so its running with the choke out as it were. the radiator theromstat may cause problems as well - if the water's too cold - as far as the ECU is concerned the engine hasn't warmed up!

Worth a good inspection of all hoses and electrical connections first. Also worth checking that none of the air inlet hoses have collapsed or that the air cleaner is OK. (I found a squirrel had filled my brother's MX5 air cleaner up with hazel nuts!)

tim leech

Post by tim leech » Fri Jun 09, 2006 10:59 am

Whats the fuel economy like Phil? Maybe worth getting its emmisions tested, a cheap way is having a MOT done at one of thjese MOT only places for £25. Ians 4x4 was running quite rich and needed tweaking for its MOT, probably why it was using so much fuel.

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Post by Jaba » Fri Jun 09, 2006 11:39 am

Phil,

If it is running a bit rich you would not notice this just as being a 'fumey' engine. It would tickover lumpily as well. It would also fail the CO emission test.
With the mileage you have done and the age of the car as well the valve stem seals willl be well past their use by date. If your nose is sensitive enough you can smell the burnt oil in the exhaust and see it too.

I had to do mine twice on my first GTi at 125k and then again at 250k. I replaced the piston rings as well as the big end bearings for good measure - all can be changed with the engine in the car.

My guess is you are running a bit rich and burning some oil too - both will leave a telltale black deposit on the end of the tailpipe. But using it for short runs only can do this too.
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Post by Philip Chidlow » Fri Jun 09, 2006 11:42 am

I get up to 31 mpg on a run. I will be getting the engine done later this year. It's got an MOT coming up so I think I might as well wait and see! I am glad the engine's going after 156k so expect a little oil use!

Thanks for the advice, chaps.
• COMING SOON... 1992 Citroen BX TZD Turbo Hurricane
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• Xsara Picasso 1.6 16v
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Post by DLM » Fri Jun 09, 2006 1:44 pm

If it's the valve stem seals then engine braking (e.g. manually selecting a lower gear going downhill for 10 seconds or so) should see your exhaust puffing out lots of blue smoke with that characteristic oily smell once you return to a more normal gear and press on the accelerator. In those circumstances you're creating a pressure differential between head and cylinders that forces oil through the seals on the overrun if the stem seals on the way out.

You'll also be aware of that same oily smell when reversing with the driver's window open.
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Post by jeremy » Fri Jun 09, 2006 1:48 pm

The state of the valve seals can be gauged by the oil consumption. Citroen themselves state 'oil consumption could reach 1/2 litre per 600 miles, after a running in period of at least 3000 miles.

Quite what this means I don't know but I wouldn't have thought that say 500 miles per pint was going to interfere with anything.

You may be able to replace stem seals yourself with the head on the engine. The trick is to fill the cylinder bore with thin rope and wind the piston up to trap the valve while you do the job. Alternatively you can get compressed air fittings to go in the plug hole and do the same job if you have an air supply.

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Post by Philip Chidlow » Fri Jun 09, 2006 1:53 pm

I do notice it when reversing. Yes. Now, if I'm going to take my car to the Citroen specialists I have in mind (and they're listed on this website for this area), what can I ask them to do? Valve stem seals, yes. What about head off, piston rings, bearings - the 'works'? My philosophy might be 'in for a penny, in for a pound(s!)' get it all done, renew hoses while we're at it and so on. But maybe not. I should try one thing at a time...
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• Xsara Picasso 1.6 16v
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Post by Ian_Fearn » Fri Jun 09, 2006 5:12 pm

I guess it all depends how long you want to keep it Phil.

The engine in yours sounds so sweet that i'd be tempted to just have the head off, do the valve stem seal and possibly valve guides, get the valves re-lapped in and refit the head after a skim if it needs it.

If you plan on keeping it for some years to come then maybe its worth having the engine out and getting the whole lot re-built.
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Post by Philip Chidlow » Fri Jun 09, 2006 5:26 pm

Thanks for that Ian. I will follow the course you suggest, because I don't think there'd be much cost vs. effect benefit from a big engine rebuild. I'm sure once the work's done I'll notice a difference in fumes. Especially as I'll fit a new exhaust downpipe and centre section at the same time.

As for how long I'll keep it? As long as it wants me I guess :lol: :lol: (or until the air con packs up - phew! wot a scorcher!). I imagine a good couple more years to come...
• COMING SOON... 1992 Citroen BX TZD Turbo Hurricane
• COMING SOON... 1998 Citroen Xantia 2.0 16v auto Exclusive
• Xsara Picasso 1.6 16v
and some Ford tat lol

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Post by Ian_Fearn » Fri Jun 09, 2006 5:49 pm

Today was a bad day to go to work in the 4x4. phew....
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tim leech

Post by tim leech » Fri Jun 09, 2006 6:29 pm

What you need is a convertable!