Om651 not starting

[Uncle Benz]

I would perform a compression test on all cylinders first. Next steps depend on outcome of that.

 

[Kev555]

Is it possible to blank the egr on this van like some other vehicles uncle benz?

 

[Kev555]

That will be awkward to perform as i dont have any equipment to pressure test. sorry for being a pain but what do u suspect by that test or just to test piston valves and rings? I have got further here tonight than i have in 6 months thanks to you uncle benz and the other lads

 

[Kev555]

seen compression tester at handy money but nervous about taking heater plugs out if they are problematic . paid 170 quid to get that injector pulled and defo dont want to see that man back in yard again for a seized or broken heater plug

 

[Uncle Benz]

I'm old school I'm afraid. Any symptoms pertaining to an individual cylinder lead me to starting with the basics. Single cylinder faults will be caused by lack of compression, valve leakage, injector fault or valve timing. I would test in that order. The valve timing thing is very unlikely, but some modern camshafts are made of a shaft with the lobes pressed on. I have seen slipped lobes before. Very unlikely, but in my trade you never rule anything out until you have checked.

 

[Kev555]

I see your point uncle benz. im old school as well but that peaved off with this van i would be prone to taking a shortcut knowing rightly it wont pay off lol. The om651 is known for jumping timing if chain is worn from posts on internet, i cant say mine hasnt but there was no chain noises before it happened. i will do the compression test and get back to you, i dont think its a valve timing issue either as it was intermittant but cant rule it out either till ive had a look. Thanks for all your merc knowledge reading between the lines tonight, things are a lot clearer now. i will call back later after compression test

 

[mrmb]

I would plug the car to the proper diagnostic such as StarDiagnosis, if there is any issue it will tell you. If there is a problem with EGR, it should thrown the error and you can also test the valve. Same with injectors it will throw codes if there will be something bad. You can also code them again to the engine contorl unit. I think SD is the way to go, otherwise you will loose a lots of time trying to find out the issue and there is a possibility that you will not find the exact problem without StarDiagnosis.

 

[Kev555]

Thanks mrmb, star would be nice to hook up just to see whats what but nearest indie to me with one is 30 miles from what i know and i wouldnt pull that van 1 mile at the minute im that scundered with her. i have the compression test kit ordered and it will be here sometime next week. In the meantime when i have spare time tomorrow im going to drain the tank and see if some fresh diesel changes the non starting situation. if it starts or doest start i am going to take the egr out as well to see if its possible to inspect and clean. This may give me some extra room to get in at glow plugs as it looks nearly impossible without some stripping

 

[Kev555]

Just confirmed yesterday its not a fuel problem after draining tank and changing filter. same symtoms as before so concerned now that its a cylinder problem. Really tight to access glow plugs on the om651 but got the caps off the plugs yesterday and they are very rusty. spraying with wd40 now until test kit comes to see if it helps, unfortunately not able to warm engine up to help so going to be heart in mouth time when trying to release them. i think if any of them snap its curtains for me and the merc

 

[Uncle Benz]

Have you tried a sniff of easy start?

 

[Kev555]

No Uncle benz, hadnt got any yesterday. Im sure engine is igniting on 2 cylinders its that close to starting. i will try it if i get a can tomorrow. Not hopefull it will be any different outcome other than engine running for a few seconds like before. No codes as yet so i am drawing to the conclusion that its a mechanical problem the ecu cant monitor

 

[Botus]

re glow plugs - you need the engine hot and I'd be using plus gas... wd40 will do nothing... also a torque wrench is the best idea to not over do it... can't remember the torque value but it's TINY !!! 20nm is a long way overdoing if I remember correctly

FYI glow plugs and their control unit / relay, are service items and need doing around 60k miles

also read on here quite few times, people having issues with refurbed injectors (and that's with ones done by proper places)

 

[Kev555]

Hi Botus no way to get in around an om651 with any sort of heating equipment without doing more harm than good. I have been a mechanic in the past so i have a fairly accurate hand as what pressure to apply safely although your always tempted to apply a little more lol. WD40 over a number of days has always got me out of tight spots before including glow plugs. its always having to rush a job that gets you me into problems. time is one thing i do have but seriously short on patients

 

[star]

It may need bleeding properly via star

 

[Kev555]

re glow plugs - you need the engine hot and I'd be using plus gas... wd40 will do nothing... also a torque wrench is the best idea to not over do it... can't remember the torque value but it's TINY !!! 20nm is a long way overdoing if I remember correctly

FYI glow plugs and their control unit / relay, are service items and need doing around 60k miles

also read on here quite few times, people having issues with refurbed injectors (and that's with ones done by proper places)

LoL sorry Botus, my bad. I thought plus gas was some sort of handheld butane torch. ive never heard of it or seen it before to my knowledge but defo will give it a try if wd40 doesnt do the trick. just to add ive been using the wd40 fast release penetrant which i think is a slight notch up on the ordinary stuff

 

[Kev555]

It may need bleeding properly via star

Dunno nothin about bleeding through diagnostic star but it has a low pressure pump in the tank and a hose at filter which seemed to make bleeding very easy yesterday

 

[star]

So you bless to the filter, what about after? We don’t work on vans but cars with the same engine need a star bleed especially after doing timing chains.

 

[mrmb]

As star said it, after doing any work on injectors, pressure lines etc. you should do a bleeding process through a proper diagnostic equipment. In OM651 this is the only solutions to bleed the injection system, there is no manual way of doing it.

 

[Kev555]

Not possible to get it to a star diagnostic machine at the minute as i dont have a money tree in the garden lads. If compression test goes well i can afford to relax the purse strings a bit and maybe hunt down a star specialist or similar. If compression test fails its head off time, reconditioning or replacement lump which will test me to breaking point. last time injectors were out for black death repair mrmb, i really done no more to fuel system than this time and got her bled no bother. Please dont take mistake me as a smart ass because you guys know a hell of a lot more than i ever will or want to about mercs. i will always go on you guys recommendations when i have the money to do so.

 

[Kev555]

Got time to do the compression test today finally
Cylinder 1 22 bar 320psi
Cylinder 2 18 bar 260 psi
Cylinder 3 20 bar 295 psi
Cylinder 4 19 bar 275 psi
150,000 miles on clock
cylinder 4 is really awkward to access for compression test between rail and inlet housing. thankfully all glow plugs were easy removed except for one but a bit of easing back and forward and some more wd40 and i eventually got it out.
What do you guys think of them compression readings? good, reasonable or bad for this engine?