TROUBLE STARTING MY 460 DIESEL.
Hi having a nightmare trying to track down a starting problem with my 460 5 cylinder diesel G. she's about 20 years old with about 100k on the clock, have just changed all 5 glow plugs with merc ones, checked out the relay and wiring to the plugs, all is OK, got a new battery out of Halfords under warranty (ha ha they let me keep the old one as well, seems that it's fine anyway) starter motor spins the engine over OK although a bit sluggish when really cold although there is no noticeable difference with the new battery in starter speed, have changed the oil today with a semi synthetic oil which is thinner when cold hoping this will help, other than that all filters are changed every 4-5 k. One thing that i noticed when poncing around is that the manual primer pump when pumped leaks fuel, otherwise bone dry when secured and tightened- does this effect operation in anyway IE could this be allowing air into the system overnight and has anyone replaced the seals on this unit (if its possible) and if so could you let me know what spares might be required and what procedure was followed and any problems or short cuts there might be.
Many thanks in advance and kind regards Lynxman.
PS the only way to get her to run today was to tow it- she didn't like it much, massive amount of smoke and ran like a dog for a few minutes, once warm she starts on the button and runs smooth as silk, please help.
Hello Lynxman,
Sorry to learn of your problem. You do not give much history away to your predicament. Has the starting difficulty immediately started? Say, after changing of fuel filters. Or, has this been an on going problem, now worsened?
Naturally, you would know if you have fuel in your tank and is that above a good 1/8th of a tank or less? Whilst getting some one to crank the engine for you, crack-open each injector nut in turn, and watch for fuel delivery. Let, each injector leak by a small amount of fuel to flow and as soon, as this is achieved, tighten the nut and move on to the next injector. After, bleeding the injectors and verifying you have fuel delivery and the vehicle still will not start, either, do a compression test or check and adjust the vale clearances.
Check the fuel lines and hoses for any leaks or wet patches, if necessary renew fuel filters and seals (Main fuel filter and pre-filter).
If still no joy then you need the injectors, professionally looking at.
Before the starting failure, how did the engine start, Smokey (white or black), fired and ran fine or gradually came to life? On the Road, how did she run? Lacked power etc, etc…
Give more feed back please.
Regards,
Hi Lynxman you did not mention the amber light on the dash ...this should come on as you turn the key and stay on for a timed period 20/40 seconds...repeat the heating cycle twice more before cranking the engine and feel the heater plugs for any warmth.... from the smoke it looks like lack of heat but as per previous posts it could be other things.does it start as it should when hot?
Hi Lynxman the amber light should remain glowing for the duration of the heating cycle.. 5 seconds is not long enough in the current ambient temperatures.... the fact that you hear a relay click after 20 seconds does not prove that the heating cycle has been made for that period of time .the light only glows when the current is passing through the heater plugs......meter the plugs before and after the light goes out to prove the correct function of the black box.......
A simplistic, non scientific method is to turn the interior light on before you start the heating cycle. Turn the ignition to heat position, the light should dim due to the current draw, and start counting seconds until you see the interior light brighten which will indicate the end of the heating cycle. As fixwin38 says 5 seconds is way too short. Mine needs around 20 - 30 this time of year.
The above assumes the 460 does not keep the glow plugs energised after the engine is running, which is how my 463 operates.
hi thanks for the advice will give it a go, after the oil change yesterday she started on the button this morning (-3 overnight) so the thinner oil seems to of helped, also bought a new primer pump (£8 from a Bosch dealer) today and have fitted it so hope that if this air leak was playing any part in my starting problem this will also have helped, i needed to replace it anyway, problem i seem to have now is that after a 10 mile run on the motorway to get my new primer pump she really struggled to crank over at all, just managed to get her to fire, when i got back home and fitted the primer (about 1 hour later) she spun over like a trouper and started fine, so it seems that she doesn't like starting from hot or cold, i am mystified, maybe my starter is dying or would it exhibit slow cranking all the time, any thoughts?
kind regards Lynxman.
Check for bad ground/earth continuity...age. verdigris. and frayed or broken bonding leads can effect your starter output which pulls lots of amps as you turn the keyswitch.. and drains power from ancilliaries like heater plugs....hence the dimming lights when your heater plug circuit is activated.....
hi thanks for the advice, today i intend to grease the shafts so while I'm under her i will take off the earth lead and clean and grease the contact faces, also tried leaving the ignition on longer after the glow plug light went out, F*"K ME what a difference, thanks for that tip.
Kind regards Lynxman.
PS my throttle damper is shot and has been for a while is it necessary and would it smooth out a jerky ride? (when my wife drives her)
:( these are the problems that we can do without ,,,
over the last 2 months the sister inlaw , was having these same simptoms ( not a G )
she would go to her car and no dash lights nothing at all , did this twice ,, so ended up fitting a new battery ,, two weeks later flat battery , i hooked up jump leads to my car and left it to charge half an hour ,, then try to start ,, not enough power ,, so then removed battery lead , which sparked telling me a high power draw ,, 20 mins to charge the disconected battery , refit bat lead then it firred up , turn off undo bat lead no power draw :x , so told her to disconect battery when she was not using the car '3 weeks later it did it again , after just poping into a house for 10 minuets ,,
this time I started removing each fuse in the engine conpartment , a secondary heaterplug relay for 4 glowplugs to heat the water for the in'car heatting ( HDi's run cooler ) was sticking on , relay had been getting too hot ,, nothing at all to tell you that it was doing this other than a flat battery ,, all sorted now :) hope this may give you an idea :)
JOIN THE GWOA
This website and forum are provided for the benefit of enthusiasts and owners of all Mercedes Benz off road vehicles, in particular the G Wagen. The costs of development, upkeep and provision of the site are met entirely by the annual subscriptions of club members. If you are using the site and are not a member of the G Wagen Owners Association please consider joining. You will have access to areas on the site that are not open to non members, to club trips and meetings and to technical assistance. In addition your contribution (only £25 annually) will help us maintain and develop our website for future users.
Who's new
- cloudburst
- Mike242
- Brendan arroyo hondo
- WaspG
- stevessx
hi thanks for the quick responses, the problem manufactured itself about 2 weeks ago with poor starting hence the glow plug change prior to this every thing was normal, she has plenty of fuel in the tank about 5 gallons (i always use either shell optimax or bp ultimate sod the expense) she always starts with a puff of black smoke and never burns a significant amount of oil between changes (approx a pint) on the road she has always had a dirty exhaust trail not clear like my astra diesel but not excessive and always passed the smoke test during mot, hard to say if she lacks power because if anything she seems quicker now she has got this starting problem when stone cold, once warm she starts on the button and the glow plug operating light comes on for approx 5 sec's then goes off if you listen under the bonnet you can hear the relay click off after approx 20 secs. cheers and thanks for your interest all comment appreciated, kind regards Lynxman.