Citroen Dispatch Misfiring when cold xud9te

[dudarus1]

Hi There

Hope some one on here can help i have a citroen dispatch 1.9td well the engine blew up in the van so i fitted one out of citroen zx and since fitting the new engine its always been a poor starter starting on 3 cylinders once warmed up runs perfect. I put this down to glow plugs and never got round to fixing it but with this colder whether its been getting harder and harder to start. I changed the glow plugs this evening and now its seems better but still running on three cylinders when cold. i have checked the fuel line and theres no air there. what is next to check ?

Thanks in Advance
Jake

[RichardW]

Check the valve clearances - exhausts have a tendency to close up, leading to a loss of compression when cold. Sadly, if they're wrong, changing them is a camshaft out job, and getting the right shims to correct it is an expensive occupation....

[dudarus1]

ok i will check this when i get a minute. if they are out and i leave thm out will this damage the engine further ?

[uncle buck]

Yes it will damage the engine if you leave them out.

You can't really leave them out as the clearance will then be too big (massively) so it will damage the camshaft or the bucket.

Not being funny... but checking and adjusting shims is a technical job so if you are unsure of what you are doing please get someone who knows what they are doing to check it over for you as you don't want to wreck a good engine do you!



Cheers.

[Mandrake]

Check the valve clearances - exhausts have a tendency to close up, leading to a loss of compression when cold. Sadly, if they're wrong, changing them is a camshaft out job, and getting the right shims to correct it is an expensive occupation....

I'm confused - how would too little (or no) valve clearance cause it to be worse when cold but get better when it warms up ?

For loss of compression the valve would have to be not closing, surely that would get even worse when it warms up and the valve stem expands ? (Hence the reason for cold clearance in the first place)

Would it not be more likely a sticking valve which frees up a bit when oil pressure arrives ? (note: I have no direct experience of any of the above so I could be talking bollocks )

[dudarus1]

Im hopeing that its not the valve clearances and its the injectors as i have a spare set of these.

[uncle buck]

@ Mandrake,
The alloy head expands more than the steel valve, shim & bucket so the clearance opens up a fraction when warm.


@ dudarus1,
Why not try the injector first as it's an easier job.

To do the shims you need to check each clearance and note it down. Then the camshaft has to be removed so each bucket can be removed in turn and the shim size noted. The shim should be marked with its size but you need to check this with a micrometer to make sure the size is correct as it's possible to grind shims down! (make sure the bucket goes back it it's original position)

When all of the measurements have been noted down you will then know the clearance & shim size for each valve.
If adjustment is required you can now work out what size shim is required using the measurements taken.

[RichardW]

The hard part is if there is no clearance, then it's impossible to tell how far out the shim is without taking the cam out and putting it back with no shim, then a known shim....

If the car is otherwise OK, you can check the clearances and if they are tight, then just leave them, as a long as you can put up with the rough starts. It may get worse I suppose over time.