Poor Starting TD with Bosch pump.

ohms · Post by **ohms** » 29 Dec 2007, 16:56

Hi all,

Am having a few problems with my Turbo D BX, at cold start it smokes it's head off(white smoke) and is as lumpy as hell. This eventually calms down as things warm up and then it becomes just ever so slightly lumpy at very light throttle openings and up to 2000rpm.

The car is fittted with a BOSCH pump and the correct 175Bar injectors and had new glow plugs fitted on Monday as a means of curing the problem.

I should also mention that the problems started as a reult of running the car on veg oil. It has the old canister type (Purflux) filter housing with a new filter inside.

Really miffed and not sure what the problem could be. When i replaced the injectors I didn't put new fire seal washers in, but ordered some from Citroen and did this yesterday as well as replacing all leaks off pipes. It's still no better!

Anybody got any ideas???

AndersDK · Post by **AndersDK** » 29 Dec 2007, 18:27

You have all the symptoms of bad coldstart devices : timing advance & preheating.

However : please note that below 15degC average ambient temperature, you are prone to get troubles starting & running on veggie. Its simply too thick flowing to satisfy normal operation conditions of pump and injectors.
The colder the worse.
The veggie gang here on board will soon comment on their experiences on which mix you can use this time of year.

Come in guys 8)

That said, you may still suffer mechanical problems :

1) Check the battery voltage tomorrow morning first off, before you try start the car or even turn on the ignition.. It MUST be checked overnight cold, as this will instantly tell you the condition of the battery - by the voltage reading.
The battery pole voltage MUST read at least some 12.5-12.6Volts indicating a healthy battery. Anything below 12.2Volts indicates a dead (empty) battery.
2) check the glow plug power by the voltage reaching the tip of any glowplug - when you have just turned the ignition on (not starting - but preheating). The plugs are held powered for some 15-30 seconds, in which time period you shold read a minimum of 10.8volts from plug tip to clean nearby engine earth. Simply flick the ignition key back off-on to restart a new timing period.
3) check that the coldstart cylinder is pulling the advance arm fully home by a tensioned bowden cable. Later with hot engine check that the bowden cable now has released the arm at least 6mm from endstop.

Adjust idle rpm's at hot engine ONLY. Set to a tad higher than any petrol - i.e some 900rpm.
The cold idle is not adjustable - but should be some 1100-1200rpm.
Remember the coldstart is NOT a choke (fuel enricher) but an injection timing advancer, thus clearly making the engine knock harder when idling at cold.

Martin Beevers · Post by **Martin Beevers** » 29 Dec 2007, 22:44

I used to have this problem with my 95 TD Xantia. When the glow plug light goes out count to ten before turning the key. Worked for me good luck.
I also run 75% veg without a problem this time of year.

Xaccers · Post by **Xaccers** » 29 Dec 2007, 23:36

Currently running 100% corn oil (only 54ppl at the local tescos) without problems.

ohms · Post by **ohms** » 30 Dec 2007, 09:52

I should mention that the car is running on diesel again now, and I always leave the glow plugs on until I hear the relay click off, then go at it again.

I tested the voltage across all 4 of the glow plugs when i installed them and even went to the trouble of cleaning all the contacts on the bridging wire to as new, so there's no problems with the glow plugs..

the other day when i cold started it, i cracked off the union to each of the 4 injectors to see if this stopped the smoking and sure enough the smoking cleared when the injector closest to the timing belt was disconnected. i then proceeded to swap the injectors around, but even with a different injector in the particular location it was still smoking from the cylinder closest to timing belt.

Could I have problems with the pump?? this is what i am thinking now. has anybody ever known a bosch to go bad???

Post by **CitroJim** » 30 Dec 2007, 17:18

There is one other thing that can cause this. Valve clearances.

As it's a BX I'm assuming it's a 1.7 XUD7 engine and these suffer worse than the 1.9s for having their valve clearances close up over time. A quirk of the XUD engine is that the clearances are tightest when the engine is stone-cold and as soon as some warmth gets into them, they open fractionally.

I had this problem on dad's 205D. All the summer it was fine but as soon as the weather got colder, it gave your symptoms. Three inlet valves were found to be very tight when cold and in fact, were barely closing. I'd say your injector swap experiment points to No.4 cylinder having particularly tight clearances.

Checking and resetting is not quite the

job it looks but you do need a good set of feeler gauges and a micrometer. Be prepared to have the cam out at least twice to do the job.

I have an Excel spreadsheet to assist with calculating new shim thicknesses.

ohms · Post by **ohms** » 30 Dec 2007, 18:40

An interesting idea, but why would this problem manifest itself almost overnight and when running on veg oil??

The car has been starting fine in much colder weather then we've been having over the last week or so.

Post by **CitroJim** » 30 Dec 2007, 19:52

ohms wrote:An interesting idea, but why would this problem manifest itself almost overnight and when running on veg oil??

Worth a check at any rate. It's not at all difficult to check clearances and at least it'll rule them out as a possible cause if they're OK.

The fact that it's white smoke says the diesel is leaving the engine unburned. This is often a result of low compression. Valve seating is a prime candidate as is sticky rings.

Running veg can cause sticky rings through polymerisation of the heavy ends of the veg that do not vapourise and burn but remain liquid and form a plasticky compound similar to that seen around the exterior of old-style chip pans.

ohms · Post by **ohms** » 31 Dec 2007, 11:41

Could a fuel system cleaner bring and benefits? i must admit i've never been one for magic potions finding them to be next to useless for most applications.

Is loss of compression due to H/G failure another option?? Car is showing absolutely no symptoms of this however(|Pressuring vcoolant, oil in water, water in oil etc?)

i agree with you theory of lack of compression on this particular dylinder. i'll check valve clearances and report back.

Post by **CitroJim** » 31 Dec 2007, 12:16

ohms wrote:Could a fuel system cleaner bring and benefits? i must admit i've never been one for magic potions finding them to be next to useless for most applications.

I'm in your camp regarding magic potions but then again, it cannot do any harm and might just help. Most Diesel additives from reputable manufacturers do seem to have some effect.

ohms wrote: Is loss of compression due to H/G failure another option?? Car is showing absolutely no symptoms of this however(|Pressuring vcoolant, oil in water, water in oil etc?)

No, an HG failure sufficient to cause a big loss of compression would invariably give rise to other symptoms. Also, it would not improve as the engine warmed. You can happily discount that as it would be most unusual for an XUD HG to blow in a way that will not pressurise the waterways. I suppose there is an outside chance the fault could be caused by a cracked/burned swirl (pre-combustion) chamber.

jeremy · Post by **jeremy** » 31 Dec 2007, 12:28

Glowplugs only assist with the initial start and don't feature after the first minute of running (less with the earlier BX timer)

I had a head gasket fail between 2 cylinders on mine - but that was sudden and it just got me home before the thing became virtually undriveable. Ironically I'd just had the injectors cleaned and the thing was running better than ever before. When the head was removed it was found to be cracked and was replaced. Previously I'd driven it about 10,000 miles and it had never run hot or consumed water. Its mileage at the time was about 173,000 (or more if the car has been clocked)

The valve sinkage problem mentioned by Jim is quite common - and if caught in time seems to do little damage. As the engine warms the alloy expands more than the steel valves - so the valve seats!

The cracks can lead to a lack of compression at startup - again - engine warms - cracks close - compression restored! As the compression leakage is to the waterways - some bubbling may be noticeable when the engine is STONE COLD.

The fact you can identify one cylinder as the problem does rather point to an engine problem.

Air is the enemy of diesel systems - and can get in many places - including the steel fuel lines if they are nearly rusted through. (New steel ones are cheap £10 approx) from Citroen.

Why not replace the last supply pipe to the injection pump with a length of clear plastic pipe and you can then see if you have any air in the supply.

I would look for gas and check the valve clearances first then if I'd found nothing - put the clear section of pipe in and see if air is a problem.

ohms · Post by **ohms** » 01 Jan 2008, 10:57

A bit of an update.

I started the car this morning(happy new year BTW to all) and for the first 3 or 4 seconds the car ran perfectly, as if it was warm, but then started smoking and coughing and spluttering as usual.

From this i have deduced that everything on the high pressure side of the pump(at cold start up) is working exactly as it should, but as soon as the car has used up this small amount of stored fuel and starts running on the fuel drawn from the tank it runs like a bag of nails again. It looks to me as though i may well have an air leak.

I'm going to try bypassing the standard fuel filter jobbie and install an inline filter and priming bulb and see if this cures the problem.

Thoughts and opinions on all of the above appreciated!

jeremy · Post by **jeremy** » 01 Jan 2008, 12:03

93 BX should have the black plastic fuel filter over the thermostat. A search on here will show that the priming bulb can leak - and will show visual signs of perishing - the lid doesn't always seal after a filter change and that there is a thermostat in it which controls the water heating - which can leak as well. The thermostat is visible I think as the 1/2 inch diameter plug at the left hand back end when you look at it.

It might be that a well placed finger full of mastic sealer over the end of the plug could prove it as a source of leakage for diagnostic purposes.

ohms · Post by **ohms** » 01 Jan 2008, 12:45

Sorry, haven't updated my profile, it's a 1990 car with the canister arrangement by the LHM tank.

AndersDK · Post by **AndersDK** » 01 Jan 2008, 12:54

ohms wrote:Sorry, haven't updated my profile, it's a 1990 car with the canister arrangement by the LHM tank.

Go purchase a couple of meters fuel hosing and replace the lines you can acces in the engine bay. Its so cheap it aint worth chasing and hairpulling a leak problem in old hosing in your BX.

From memory its 8mm internal dia hosing you need. Any recent type fuel hosing is capable of withstanding petrol, diesel, veg & oil.