Rough Start Help

rlatarche · Post by **rlatarche** » 07 Dec 2010, 14:14

Before anyone asks....i've read several hundreds of threads about this and I have done the following:

I've had my mechanic check the glow plugs (they were all replaced a year ago) and he says they are all working fine.

The battery is in tip top condition and is fully charged and is the correct rating for the car.

I've tried the trick of ignition on, then off then on again and then wait until the relay clicks to start.

All of which still leads my 1.9td SX (N REG) xantia to start like a bag of bones. It starts extremely rough when left for more than a few hours, with a HUGE plume of smoke. Give it 15-20 seconds and it purrs like a kitten.

I've tried to manually prime the system however the priming bulb never ever goes hard. I can hear initially the rush of diesel around the system so to me it sounds like air ingress. I've had the leak off pipes changed and the priming bulb. Anybody have any other ideas and also the size of the flexible fuel line so that I can change it for some clear line to try and prove the air ingress theory. I believe it has a bosch pump and has recently had a full service, oil, air and fuel filters etc etc.

lexi · Post by **lexi** » 07 Dec 2010, 14:52

If you had an air leak then you would have intermittent running when under way I think.

There is a symptom where the fuel drains back from the pump when left standing that may be worth looking at.. If glowplugs are good you can check that they are getting the current from relay with a Multimeter on the busbar strip that joins the plug.

That should shoot up to the 12v on turn on and then drop off again as relay closes when the required time settings are met.

rlatarche · Post by **rlatarche** » 07 Dec 2010, 15:02

Hmmm, not sure, if there was a buzzbar issue then surely everytime the car started i would have a cloud of smoke, this is not the case, anything less than a few hours and the car starts fine with little to no smoke. A small enough air leak would only present itself when the pressure externally was greater than internally...i.e when the car was not running. I strongly believe its an air leak but i need to know the ID of the fuel hose so that I can purchase some clear hose to look for air bubbles

Post by **RichardW** » 07 Dec 2010, 15:04

How did he check the glowplugs? Only way to tell for sure is to take the out and watch them glow. Given that this is such a dog of a job you might as well then throw a new set in. What plugs are fitted - if they are anything other than BERU then suspect they're knackered. Were all 4 changed - the one behind the pump often gets left as it's the hardest.

Otherwise, time to dig out the feeler gauges and check the valve clearances...my guess would be that one or more the exhaust valves is completely closed up when the engine is cold. Of course changing them is a complete PITA!

PS if it was an air leak on a Bosch pump (all Xantia TDs appear to be Bosch pumped) then it would be difficult to start, but would start cleanly once it did. The primers on these never go hard - give it 20 or so pumps, and if that doesn't improve starting then you can ignore air leaks for the time being.

rlatarche · Post by **rlatarche** » 07 Dec 2010, 15:11

Yes they are Beru's fitted (i researched into them before I had them fitted) not sure how they were actually tested so i'll find out. All 4 were changed out.

That's good news on the priming side of things I was expecting the bulb to go solid. I'll give it 20 or so pumps in the morning then and see what that comes up with.

spider · Post by **spider** » 07 Dec 2010, 15:23

Valve clearances only (in most cases) cause poor hot starting, unless they are horrendous.

Agree with glow plugs, you can check their current consumption and their resistance, but that does not tell you if they are actually working properly, you need to remove and bench (vice!) test them. Its not unknown for odd faults like glowing in the middle only

, which are not readily detectable when they are fitted. Removing and bench testing is the only reliable way to test them, including how long they take to actually heat up etc.

I still think air ingress is the cause.

If its not the leak off pipes (Lucas can do this but they are not as dependent as Bosch, but if they are really bad you can get issues) then its worth fitting a non return valve just before the pump (between pump and filter)

I did this and it fixed most of my issues at the time.

Air can get in anywhere, the most common one is the filter housing itself (either the lid or the seal underneath)

I would be tempted to fit a non return valve here too (just before the filter OR just where the fuel pipe is at its highest in the engine bay if possible before the filter)

rlatarche · Post by **rlatarche** » 07 Dec 2010, 16:02

spider - do you have source and a size for the NRV's and the ID for the fuel pipe. I too agree its a air/fuel issue.

evilally · Post by **evilally** » 07 Dec 2010, 16:12

Should be 8mm ID.

If you can hear fuel moving when you press the bulb, then I would bet it's air ingress. Once up to temperature, does it have any reluctance to rev hard? Leave it in 3rd gear and let it run all the way round to 4.5k, there should be no hesitation.

I have in the past connected an electric tyre inflator to the end of the fuel line and put it under light pressure (10psi or something). Then you can listen for air escaping.

First suspect is the fuel filter, I notice you said it had a new filter recently. Did this problem start around that time?

spider · Post by **spider** » 07 Dec 2010, 17:00

rlatarche wrote:spider - do you have source and a size for the NRV's and the ID for the fuel pipe. I too agree its a air/fuel issue.

Ebay is where I got mine. I've had them for a couple of years.

Random Ebay Link , nothing to do with me though, just that's what I have (different seller) , mine look identical

Caution: Do not buy the 6mm ones, I have a pair of these thinking they were OK but they are far too small

, ended up buying two of the 8mm ones.

rlatarche · Post by **rlatarche** » 08 Dec 2010, 08:34

well before i started it this morning I primed the fuel system, giving it about 30 pumps and it started with very very little smoke still sounded a bit chuggy - but then again it is well into the minus's this morning. Looks like a purchase of some nrv's and some new fuel line to try and stop the air ingress.

andy5 · Post by **andy5** » 08 Dec 2010, 12:46

spider wrote:Valve clearances only (in most cases) cause poor hot starting, unless they are horrendous.

Actually, my old BX with the non-turbo 1.9 diesel engine got very tricky to start, making smoke and so on, but was fine once warmed up, and fine restarting when wartm.

And it was the valve clearances, and reshimming or something like that did sort it out.

So sometimes it will be worth including a compression test in the diagnostic process.

Post by **RichardW** » 08 Dec 2010, 12:56

It's normally the turbo units....but, surmising what happens:

The valves sink into the head, closing the clearances up; when cold the head contracts more than the valve stem, and this holds the valve just open, leading to a loss of cold start compression; once warmed up the head expands and the valve closes properly (and a slight loss of compression is less of a worry once it's running).