what are my old spark plugs telling me?

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Linegeist
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Post by Linegeist »

I rather suspect Max that you might have a leaking vacuum advance capsule on the distributor. This is a device that uses inlet manifold 'suction' to alter the ignition timing in response to engine loads/speeds. If the diaphragm splits, usually through age, then not only do you lose the dynamic timing function, but the vacuum advance pipe delivers raw air into the inlet manifold, weakening the mixture slightly and causing rough running at low revs.

Easy to check - locate the 1/4" rubber pipe goes from the rear of the carb to the round disc-like object on the side of the distributor and pull it off gently at the carb end. Then suck on it.

You should feel a definite resistance as the diaphragm deflects against spring pressure. Suddenly releasing the suction should result in an audible 'click' from the distributor mechanism as it springs back. If you can draw air and there's no click, then you may have found the first problem.

The second one is getting a replacement capsule .................
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maxgreenwood
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Post by maxgreenwood »

mmm very interesting stuff i'll get poking and sucking!

it runs really quite rough if driving straight after starting, until it warms up a bit, then it is hesitant and not that smooth between 1000-2000rpm, with a light throttle. If you give it some juice it feels smooth, especially above 2000rpm. While it is first warming up, i notice the idle goes high for a while and exhaust smells rich, then it settles down after a few minutes - i assumed this was an automatic idle advance or something for when the engine is cold. I might try enrichening the mix slightly and see what that does.
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
Linegeist
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Post by Linegeist »

maxgreenwood wrote:While it is first warming up, i notice the idle goes high for a while and exhaust smells rich, then it settles down after a few minutes
I think you'll find that's the auto choke's fast-idle mechanism kicking in (and out) Max - and as normal as them plugs. :wink:
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maxgreenwood
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Post by maxgreenwood »

Not had time to check anything deeper but did notice to my slight horror that after it had come back from the garage post-octopus transplant that it had virtually no oil in it, just a little at the bottom of the dipstick, so must have been missing about 1.5 - 2 litres. I would have thought the garage might check it, which I will take up with them tomorrow. So with no major leaks I guess it must be burning oil - I estimate after a 400 mile journey to Cork and back the other day at a rate of about a litre per 1000 miles. There is smoke from the exhaust on harder acceleration, difficult to say if it's blue, more grey-blue but nonetheless I think it must be burning oil. Not necessarily the end of the world on an 80 k engine having done very little mileage in the last 10 years. But should I be concerned about engine damage from low oil level? The oil light pressure gauge was always ok and I'm hoping it had enough in the bottom ( capacity about 5 litres according to Haynes) to keep the pump drawing and things lubed. What action should i take now though - is thicker 15 w 40 oil advisable on a worn petrol?
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
citronut
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Post by citronut »

or instead ok doing kinky thing like sucking your car, you could pull the same pipe off at the dizzy end and plug it,


also if plugs are all diferent colours this usualy tells you the combustion is diferent in each chamber,

maybe caused by valves not seatting fully,

it might be worth doing a compresion test,


regards malcolm
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mat_fenwick
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Post by mat_fenwick »

I wouldn't worry about the oil level, even when it is at the bottom of the dipstick there is still a reasonable amount in there. The level is such to make sure the oil pump doesn't pick up air on hard corners/roundabouts (so as long as the oil pressure light didn't come on the oil will have been circulating as normal) and to give adequate cooling to the engine internals. With it being low, the remaining oil will probably have run hotter than usual, so some would suggest replacing. However, you will be adding a decent amount of fresh oil so assuming the engine hasn't been working hard when low on oil, I would be inclined just to top up and maybe change a little earlier than normal.

IIRC that 15w40 is still within the range of acceptable viscosities stated by Citroen, so should be fine. I'll try and remember to check the handbook to be sure, but higher still may be OK.
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demag
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Post by demag »

"or instead ok doing kinky thing like sucking your car,"

Malcolm, the mind boggles! :lol: =D>
Dave.

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Post by johnbird »

i dont bother with any of the proprietary injector cleaners as all they basically are parrifin. i put a litre of parrifin in a full tank every second fill up or so on my car and it keeps the injectors clean. lately on the saab forums there has been much discussion on using thinners too so a litre of that a tank has been going in. its basically acetone tuolene and zllene-excuse the spellings its early and my spelling is not great- they are also used in octane boost products and cleaners for engines. both are cheap by the gallon too.
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maxgreenwood
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Post by maxgreenwood »

thanks for the advice guys, thats put my mind at rest. I'll be delving further into running issues when back off hols. The roads are terrible down here in Kerry compared to last year, i think last winter has really taken its toll, lots of potholes badly filled in, mind you last year i was in the XM, this year we're in the Saab, one noted for soft and one noted for hard suspension setups. We're coming back in August and i think i'm going to bring the BX which should be a bit more pleasant.
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
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maxgreenwood
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Post by maxgreenwood »

Bob, you were right i have a leaking vacuum advance capsule thingy. Sucked on pipe and got a chest full of petrol vapour, no resistance, no click, so i've plugged it at the distributor end. I take it i leave the air feed at the carb end un-plugged?

So i need a replacement, i'll get looking.

Max
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
Linegeist
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Post by Linegeist »

maxgreenwood wrote:Bob, you were right i have a leaking vacuum advance capsule thingy. Sucked on pipe and got a chest full of petrol vapour, no resistance, no click, so i've plugged it at the distributor end. I take it i leave the air feed at the carb end un-plugged?

So i need a replacement, i'll get looking.

Max
Hi Max,

You need to stop the engine sucking in fresh air from the open vacuum takeoff point, so you need to block the CARB side of things. I usually just shove a handy bolt into the pipe at the distributor end until I can fix the diaphragm.

The good news is that (if you can find a vacuum capsule) replacing it will perk up your performance no end.

And that of your engine, too. :wink:
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maxgreenwood
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Post by maxgreenwood »

I actually wonder if it has degraded since i got the car as the performance has seemed to wane a little. The car didn't have much use in the last 10 years and other rubber bits have gone like the octopus and little mounts in the engine, oil breather split etc. And that pipe that feeds the vacuum advance practically fell apart in my hands.

There is this one on ebay with distributor attached:
http://www.ebay.co.uk/itm/DISTRIBUTOR-C ... 1c1b2247b5
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
Linegeist
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Post by Linegeist »

There's more thsn one type fitted to the 1.6 motor - I got mine from Malcolm and, despite it being the 'wrong' type, it fitted with minor mods to the lead ends and has trnsformed the car.

That oe on Ebay looks good
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maxgreenwood
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Post by maxgreenwood »

as in smooth running and responsiveness?

i've just had a look at mine, this one is Bosch part number 0237 009 060, mine is 0237 009 617, so not sure if it will fit, Bob what was the part number difference between your old/new one?

the garage is saying the distributor is no longer available.

I'm ringing round
'92 16TXS (m), Dark metallic green, 74k
'90 16TZS (m), White, 86k
'89 19TRS auto, Olympic Blue, 133k
'88 Saab 900 8v Turbo (auto) 107k Red with Tan leather, lovely drive and well maintained.
'07 Hyundai Santa Fe 2.2 CRDi 85k (m). Practical family wagon
Linegeist
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Post by Linegeist »

Sorry Max - been away on business.

The part number .... haven't a clue. Malcolm (Citronut) is the expert there. (Beats the heck out of me....)

But most of the dizzies are interchangeable, and the small variations in timing profiles between models are insignificant compared to running with zero dynamic vacuum advance. My original dizzie was a Bosch and I bought a brand new Ducellier from Malcolm complete with cap and 'Verteilerfinger" (I can't remember the English word for the thing the fits inside it).

It bolted straight on, accepted the Bosch ignition sensor with no mods and just required the HT leads crimping to fit OVER rather than INTO the cap contacts.

The responsiveness of my 1.6 petrol was markedly improved with the new distributor, along with an instant stop to the pinking that occurred at anything above half throttle and below 3000 rpm. AND the fuel consumption improved by about 10%. :D
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