Possible Glow Plug Problem
A couple of days ago the yellow pre-heater light started staying on for about a minute after starting. Today when I started up, the engine was running very roughly. It sounded so rough that it seemed better not to drive it.
Does this mean that one of the heater plugs needs replacing? Is it still ok to drive?
Thanks for any help or advice.
Hi the glowplugs would be suspect..that is what the light is telling you....not the easiest things to change as they can carbon up inside and this fouls the threads...best removed when the engine is hot......a failed plug will stop the related cylinder from firing at the same time as the ones with working plugs ..hence the roughness..it will clear if you rev the engine and hold the revs until roughness clears ( 50 seconds to a minute) depending on the ambient temperature....lots of smoke as the excees diesel burns out of the offending cylinder/s...best change all six at the same time and sooner than later.......
Hi the glowplugs would be suspect..that is what the light is telling you....not the easiest things to change as they can carbon up inside and this fouls the threads...best removed when the engine is hot......a failed plug will stop the related cylinder from firing at the same time as the ones with working plugs ..hence the roughness..it will clear if you rev the engine and hold the revs until roughness clears ( 50 seconds to a minute) depending on the ambient temperature....lots of smoke as the excees diesel burns out of the offending cylinder/s...best change all six at the same time and sooner than later.......
Two or even more glowplugs are finished
best change all six at the same time and sooner than later.......
Hi Heater plugs can be bought for as little as 10euro each."NOT from MB" .....MB labour estimate used to be 2 hours (@ 130euro / hr) so if MB supply and fit it could cost a minimum of 350/400euro......
They are actually an MB truck service centre but seem to know Gs quite well.
I have heard that it is always better to get Gs, particularly the G300 TD, serviced at an MB truck/commercial service centre due to better expertise with that engine....
You can try cheaper variant. Find bad glowplugs and replace them (when engine is hot). Old glowplug could be even better than new one.
you don't have to go to a MB for something as simple and as common as glow plugs. any small independant garage that understands diesels will do it at a fraction of the dealer cost...always best to change all the plugs just remember to refit the vacume pipe. or you'll not be able switch the engine off.
you best get the job done asap. do not keep trying to start the car on faulty plugs. i did this and it 's just cost me a new starter motor.
Hi Mmm..firstly having the engine hot makes the heater plug removal a lot easier...drilling out a broken plug insitu leads me to wonder what happened to the broken bits and all the swarf generated by the drilling process?? are the bits sitting on the crown of the piston and is that the noise you are hearing? I cannot understand why the engine should sound seriously different after just changing the heater plugs ....I would ask the question as to what method was used to remove the broken plug ..and go on from there.because the head will have to come off ..and should have come off to remove the broken plug....
Ah, yes, I agree entirely with fixwin. Changing the glow plugs in itself would make no difference at all to engine running/noise. I would say (without hearing it to be sure) that a piece of an old plug has fallen in. I would be extremely disappointed with MB for a) breaking a plug and B) drilling it out in situ!!!!!!!! Makes me cringe. Would be a good idea to take it straight back to them.
Hi Richardc Your G' turbo could be totally destroyed if there are pieces of heater plug in a cylinder and one piece gets past the exhaust valve and into the turbo turbine blades...I shudder to think what is happening to the crown of the piston and the compression chamber......DO NOT RUN THE ENGINE until you can verify what broken heater plug removal method was used.....
I wouldn't run the engine at all, in case that possible bit of debris chips a valve or marks the liner. Any special tips or tricks in removing the heater plugs, apart from having the engine hot? My heater plugs are due for replacement and from what i here its very common for them to break in the head.
Hi With engine cold spray each plug base with a penetrating oil and leave for two hours then spray again then after further hour start engine and remove heater plug leads and allow engine to run up to 85/90c.with engine running and using the correct size socket and ratchet bar turn each plug anti clockwise one full rotation..shut down engine and remove old plugs..fit new plugs (after having them in the freezer overnight) and instal while engine hot..do not over tighten because they will expand slightly as they get warm.....
Do you think it’s possible that they’ve somehow altered the diesel pump timing?
I haven’t a clue to what extent electronics control your engine but something as simple as pulling a wire off a temp. sensor could also affect fueling.
Any alteration to fueling or timing would affect the tick over noise.
The heater light is where you started with the problem, it indicates a fault with the system. Something is still not correct
Hi ...If there was debris in the combustion chamber the first thing it would damage is the new heater plug which would result in the delay in the light going out... and a lumpy start with smoke when cold...I and most of the diesel engine related service/overhaul industry would welcome hearing specific details of the method used to remove the broken heater plug by drilling without getting swarf into the compression chamber and as a result not having to remove the cylinder head!!
Hi ..would be convincing if you had the old heater plugs in your hand..depending which plug position it was access to precision drill and tap a left hand thread deep enough to enable the broken plug to be removed is quite a challenge ..anyway your engine appears to be working as it should so "all's well that end's well" ......
Thanks very much guys.
I will be phoning my local MB dealer tomorrow. I guess it's going to be quite expensive?