760 turbodieselstarting and heating

Hi guys I am new, I have just brought a 760 turbodiesel (tic) but i have a couple of niggling problems
First it doesnt start very well when cold it takes about 8 seconds on the starter before it fires it had new glowplugs and filters and the relay is working fine with voltage, the engine has 174,000 miles and it doesnt smoke or breathe or use any oil or water, when the engine is running there is loads of power. (my old 740 used to start first turn of the key instatly and it was worn out burning oil)

The heater only blows small anout of air on fan speed 5 not much to the screen or floor, i have checked the vacume pipes and servos motors and are all working fine blower ok and it is also air con unit. thanks john

[Peter Milnes]

If your glowplugs have ALL been changed for new ones then you need to take a look at the relay as it's contacts are on the way out. The usual trick at garages is to change plugs 1 to 4 and leave 5 & 6 in place as they are quite tricky without the right tools for the job. The relay contacts have to pass around 55 to 60 amperes current to get the plugs hot enough to heat the swirl chambers. The only other cold start problem is to do with the cold start fuel device at the front of the pump. This needs a coolant feed to the thermal unit so that as it warms up the accelerator is alowed to relax towards the slow running stop. It is cable actuated by the thermal bulb inside the unit. If coolant does not flow through it the unit will not work and if the cable has not been correctly set it will not work either. You need access to the D24 Green Book or a diesel experienced pal with one.

The heater problem could well be the thermostat which is obtainable from German, Swedish & French from their website. You will also need the seal for the thermostat. Quoting 760 GLE Turbodiesel (with intercooler) will get you the right part. Most air-con problems are due to vacuum leaks in the unit itself, although heater problems can be down to the vacuum operated heater tap on the engine side of the bulkhead or blockages in the matrix, flushing may help to clear this.

Check the easier bits first before getting lured into the harder bits. A progress check will be welcome as will any other problems I can help you with.

All the bes, Peter.

Yes those heater plugs at the back no 5 and 6 are quite tricky, I have changed them all and current is going to the heater from the relayi put a test lead on it, and the thermostat was knackered so i relaced that to, now the temp gauge sit in the middle when hot, i also noticed that when i start up and look at the fuel pipe from the filter to pump, it has some air bubles in it,the heater works onvents ok but very little on screen and floor and loads coming out of the side window demisters, all vacume servos seem to be working . i took the bottom duct to the floors off and i could feel the floor/screen flap moving all the way both directions(iam just getting no airflow) motor is ok, thanks john

[Peter Milnes]

You will need to sort out where the air is getting into the fuel pipe from which is the bubbles. The filter has a tap on it's bottom which is designed to let out any accumulated water in the fuel supply. You need to slacken the screw or bolt) on the top of the filter housing then undo the tap until fuel comes out not water. Then do the tap up fairly tightly and tighten the screw on the top. If you still get bubbles you will need to investigate the fuel pipes. The banjos need to be tight and yopu may need to replace the banjo washers. The rubber type pipe joins the filter to the metal pipe which runs from the front to the tank. Check that it has no splits. The metal pipe should be OK unless it has had a previous knock somewhere along it's length which has punctured it. The flaps can get crossed up in their action as there are about four or five all operated by vacuum motors. The fan intake could be blocked from the windscreen wiper gutter across the top of the scuttle. I am sorry but it is an awkward job.

All the best, Peter.

[Ferg]

Make sure the fuel filter is also screwed on properly and is relatively new (less than 5years). I had an old citroen diesel which wouldn't start but ran great. It was because of a possible leak in one of the high pressure pipes, i couldn't trace it so I fitted a one way valve before the fuel filter. When the car was left overnight the fuel would drain back to the fuel tank- sucking air into the system. The one way filter stopped this. You could try this if you don't find the leak and the filters are about £10 from a diesel specialist or an acessories supplier (not halfords- they is useless).

[740-estate-nut]

hi there,
Did you get your problem sorted?? I was having HUGE problems with my 740 TD... Same engine..(basically)....
I replaced all 6 glowplugs... the glowplug relay, the fuel filter, oil change(with filter) and air filter.. and even the fuel pump... but this didn't help...
I noticed that my car was leaking diesel, but couldn't find from where...
So, I looked at the injectors... they're all interconnected with pipes.. these pipes return unused diesel back to the pump... on 3 of mine, the pipes were perished.. I replaced the pipes, and now my car starts first time, every time...
One little hint... When you turn the key to start.. wait for the glowplug light ot go out... THEN, wait until you hear a small clunk from the back of the car... This is the fuel heater... after you hear it clunk, then start... It just means that you have more power from your battery to start the car, instead of the battery feeding the starter and the fuel heater..
Hopes this helps...
Thanks
Simon