Probs starting when warm!

storm99 · Feb 11, 2009

ok, short story..replaced the head and new glow-plugs, clean injectors..lovely. 2.5 N/A diesel defender.

Now i've driven a 50 mile tour to work, hopped out at petrol station, filled up, paid, jumped in...and didn't bother pre-warming, only been turned off 2 mins, and the bugger nearly didnt start, had to pre-warm 15 seconds, TWICE, and the battery was beginning to show signs of not wishing to continue this silly game.

Now i've not had this problem before i changed the head, always started 1st time with no pre-warm, often up to a half hour after these long tours...

Any ideas?

CharlesY · Feb 11, 2009

Question ....

during this game, when the engine was turning over, was there smoke coming out the exhaust pipe, yes or no?

If NO, you have a fuel shortage and/or start-up injection TIMING flaw - probably the tickover is being controlled by the throttle cable instead of the proper wee lever. This causes the STARTING AIDS in the injection pump not to work. You MUST have plenty slack in the throttle cable, and if the engine then won't tick over, adjust the little lever that leans on the fuel outlet union till it does. DO NOT disturb any of the compound levers on the pump - that's the ones made in two parts bolted together.

If YES, it smokes, and you are sure the tickover is contolled by the little lever, are you holding the throttle down when trying to fire her up? If so, DON'T! This too disables the starting devices in the injection pump of a 2.5NA. It needs all the help to start it can get even when warm.

After that try lack of compression - first check valve clearances aren't too tight.

They might just be OK cold, but might be too tight hot. I've seen it happen.

Let us know what you find.

CharlesY

boydy1989 · Feb 11, 2009

that sounds like you have a fuel leak and you are allowing air into the fuel lines - a warm diesel engine with compression and fuel will run. It should start fine without heat up to 2-3 hours after being switched off.

boydy1989 · Feb 11, 2009

what he said in fact.

CharlesY · Feb 11, 2009

boydy1989 said:
that sounds like you have a fuel leak and you are allowing air into the fuel lines - a warm diesel engine with compression and fuel will run. It should start fine without heat up to 2-3 hours after being switched off.

I agree with that. My old 2.5 NA (Sherpa) 15J was a great starter IF but only if, it had been running earlier that day. First start of the day was a different business!

procedure
cold - no throttle, press glow button (no timer!) for a long time, 20 seconds at least, and turn the starter till either she runs, or the battery goes flat. The moment it runs, deck throttle to hoick the revs up.

warm engine - no throttle, no glow, turn key to starter, and she runs instantly.

but the injection pump starting aids DO NOT WORK unless the throttle is completely OFF, and the tickover is set correctly. Don't even look at the throttle pedal when trying a cold start.

CharlesY

storm99 · Feb 12, 2009

Thanks so far, i never touch the accelerator pedal until its kicked in...It starts great from cold! With a 15-20 second pre-warm.

Its the warm start...i can literally turn the engine off, wait 30 seconds, try to start, no throttle, no pre-warm and it will just crank the engine but not start...I have to give it 20 seconds pre-warm and thats just not right!!

I'm edging towards the air in the system theory...it runs perfect otherwise, as soon as she starts, off we go, 45 miles to work no probs..

CharlesY · Feb 12, 2009

storm99 said:
Thanks so far, i never touch the accelerator pedal until its kicked in...It starts great from cold! With a 15-20 second pre-warm.

Its the warm start...i can literally turn the engine off, wait 30 seconds, try to start, no throttle, no pre-warm and it will just crank the engine but not start...I have to give it 20 seconds pre-warm and thats just not right!!

I'm edging towards the air in the system theory...it runs perfect otherwise, as soon as she starts, off we go, 45 miles to work no probs..

Yes .... with your further good information let's go that way.

AIR.

I suspect the self-bleeder on the fuel filter head may be blocked. When warm the fuel flows very easily, and if there's any possibility of an air ingress, it will happen warm first. Once the engine is actually running the injection pump can cope with (clear out) a little air, but on the start-up, perhaps not.

There should be a banjo bolt on the top of the filter head. This is the self-bleeder. No moving parts - just a little hole. There should be two pipes on it - one comes from the injectors and fuel injection pump, and the other goes back to the tank.

Take off the banjo bolt, and examine it very carefully. There should be a very small hole through it, passing from the bottom end up to a cross-drilling where the actual banjo union joins it. This is the SELF-BLEEDING aperture.

The idea is that the little hole will allow quite a lot of AIR to pass through and be vented safely back the the tank, and once there's no air left, it will pass only a tiny amount of fuel, so little it won't matter. If all is well, air and fuel (which arrive mixed from the tank especially when the fuel is low due to sloshing about) reach the filter, and get strained, and allowed to "calm down". The air separates from the fuel and rises very quickly into the filter head where it passes up through the wee hole in the banjo nut, thus clearing the fuel filter of air. This should mean that air-free fuel flows to the injection pump.

If that TEENY WEENY aitr bleed hole is blocked, clean it out, and try again. Make very sure it is a free passage for air.

And they DO tend to block up over time. If the hole is blocked, any air in the system WILL be sent to the injection pump .... and that's when the trouble starts.

You never can tell. It may be as easy as that.

CharlesY

richardjeaton · Feb 14, 2009

CharlesY said:
Yes .... with your further good information let's go that way.

AIR.

I suspect the self-bleeder on the fuel filter head may be blocked. When warm the fuel flows very easily, and if there's any possibility of an air ingress, it will happen warm first. Once the engine is actually running the injection pump can cope with (clear out) a little air, but on the start-up, perhaps not.

There should be a banjo bolt on the top of the filter head. This is the self-bleeder. No moving parts - just a little hole. There should be two pipes on it - one comes from the injectors and fuel injection pump, and the other goes back to the tank.

Take off the banjo bolt, and examine it very carefully. There should be a very small hole through it, passing from the bottom end up to a cross-drilling where the actual banjo union joins it. This is the SELF-BLEEDING aperture.

The idea is that the little hole will allow quite a lot of AIR to pass through and be vented safely back the the tank, and once there's no air left, it will pass only a tiny amount of fuel, so little it won't matter. If all is well, air and fuel (which arrive mixed from the tank especially when the fuel is low due to sloshing about) reach the filter, and get strained, and allowed to "calm down". The air separates from the fuel and rises very quickly into the filter head where it passes up through the wee hole in the banjo nut, thus clearing the fuel filter of air. This should mean that air-free fuel flows to the injection pump.

If that TEENY WEENY aitr bleed hole is blocked, clean it out, and try again. Make very sure it is a free passage for air.

And they DO tend to block up over time. If the hole is blocked, any air in the system WILL be sent to the injection pump .... and that's when the trouble starts.

You never can tell. It may be as easy as that.

CharlesY

Bloody brilliant!!!

My Landy has been starting great when cold - I just give it 20 seconds glow plug preheater and don't touch the throttle until it fires which is normally a couple of turns.

I had been worried about switching it off though as warm/hot starts seemed to take forever. Funnily enough I had a similar situation at a petrol station last weekend. I'd been out for about 4 hours (not switched car off at all) and then switched off to refuel. Got back in and it took ages to get going, was really worried it wasn't going to go at all this time!

Anyway, having read this post I decided to take a quick look at the banjo bolt. Removed it easily enough and in the side of the bolt there was what looked liked a tiny tiny hole that I couldn't even tell if it was blocked. My local Landy guy had mentioned before that these should ideally be drilled out to 1mm as apparently these engines run much better with that done. Armed with a drill and 1mm bit I did the mod and refitted the bolt. The Landy was cold and fired up fine as usual, phew

I then left the car running for about half an hour until it was warm and switched off again. Crossed my fingers and tried to restart it and amazingly it fired up after half a turn

It now consistantly starts straight up when warm with no preheater or throttle at all - fantastic!

Who would have thought such a simple thing would make such a huge difference!

Thanks again for the post

Richard

CharlesY · Feb 14, 2009

My consultancy fee invoice follows .... !

(plus vat)

But the REALLY clever parts are these.
1. you were smart enough to ask for advice.
2. you were smart enough to take that advice.

Not a lot of 'experts' can do those things.

Glad to have helped!
CharlesY

CharlesY · Feb 15, 2009

Well, be sure to report to the Forum after your start-up (attempts) this morning!

Did it start up nicely ?

Fingers crossed!

CharlesY

Probs starting when warm!

storm99

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