OM642 slow starting

[TheRevDrSyn]

Hi all, I hope you can point me in the right direction.

I bought my R320CDI knowing that it was slow to start and the glowplug light was staying on after it eventually fired. I changed the plugs without any improvement so I checked the fault codes with an icarsoft mb v2.0 and it told me cylinder 3 and 5 plugs were open circuit.

The glowplug relay was the old fashioned type with the brittle aluminium wires inside. I replaced this with a later Beru part and now the glowplug light goes out on startup and the scanner is no longer showing any codes.

The problem is that the car is still slow to start and still gives a puff of white diesel smoke when it does fire.

Once it is warmed up it is fine for the rest of the day. Having changed the plugs and the relay, I'm wondering if a leak off test on the injectors is the next step? The engine cranks strongly and live data shows the fuel pressure builds up within a second or two.

My only other concern is that my icarsoft scanner does not show the electric pump running in any live test that I do, though I am led to believe that the engine would stall if the HP pump was doing all the work alone, is this correct?

TIA.

 

[mersum1es]

yep if primer pump is dead, main pump shouldn't be able draw enough fuel for full blast... primer pump should engage when you but ignition on, can you hear it whirring?

Leak test is good idea, check also injector eletrical correction values if iCar shows them (note: NO voltage values).

 

[OneForTheRoad]

I used to give mine 2 ign cycles. Seems a bug for the om642 engine. Very common.

 

[Nicebutdim]

Mine is the same. I give two cycles and sometimes three if it’s below freezing. Also pause for a few seconds between cycles.

 

[TheRevDrSyn]

It doesn't seem to matter if I give it one heat or three heats, it still struggles to start.

I can hear a whir when the ignition is set to on. I do need to change the fuel filter hoses as they are perished. I'll test the LP pump when I have the hoses off the filter.

I've ordered up a leak off kit, I'll see where that takes me.

I know I can program injectors with the icarsoft kit but I don't know about reading the values. I'll have a look tomorrow if it's not raining as heavy. Me and swmbo have just spent the morning moving 6 tons of hardcore, gravel and sand from the front of the house to the back garden, so playing with the car is not on top of my list today!

Thanks for the help so far!

 

[Larkone]

It might help to read post 102 - you never know

OM642 PCV Upgrade | Engine

You could try a smoke test to check for any leaks - a lot of the pipework from the turbo via the intercooler is hard to inspect properly just visually. Cheaper than throwing parts at it and would eliminate one possible cause.

forums.mbclub.co.uk

 

[TheRevDrSyn]

It might help to read post 102 - you never know

OM642 PCV Upgrade | Engine

You could try a smoke test to check for any leaks - a lot of the pipework from the turbo via the intercooler is hard to inspect properly just visually. Cheaper than throwing parts at it and would eliminate one possible cause.

forums.mbclub.co.uk

For the time it will take me, it is certainly worthwhile having a go at, thanks

 

[Duff3103]

personally i always start with changing the fuel filter to make sure that's able to pull fuel through it with ease, might be good to get some live readings on the injectors or even get a leak back check done on the injectors to rule them out. personally iv never had any issue with the 320cdi with long starts but obviously its not unheard of. also maybe get a look around the fuel lines for any small leaks, any small leaks will mean it can draw air and that's a bad sign on a diesel

 

[TheRevDrSyn]

So, a bit of an update. I have been busy with the Mrs sorting out our lock-down garden but got around to doing the leak off test today. It looks like the injectors for cylinders 1, 2 and 3 are suspect, with number 2 being the worst of the bunch. It is probably not helping matters much that they are all on the same bank and rail.

I've ordered up three refurbed injectors and will take it from there. Duff3103, the Fuel filter is brand new, I replaced all the filters shortly after buying the car.

 

[Sicario]

I recently read about the nylon seals that you need to replace when you renew the crankcase pressure release valve, these can cause starting issues

 

[TheRevDrSyn]

I recently read about the nylon seals that you need to replace when you renew the crankcase pressure release valve, these can cause starting issues

View attachment 96583View attachment 96584

I've also replaced the PCV valve and hose for the later type and a new inlet oil seal. They didn't do anything to improve matters either!

 

[Sicario]

Worth a punt.. Which injectors do you have, the long metal ones or the short plastic ones at £250 a pop?

 

[Duff3103]

How long did you leave it running for? I’d have expected to see fuel in all the tubs at least then you can compare just how much extra fuel is being leaked off