cold start problem with 1996 E300 S124 (OM606)

[tonym911]

Hello all, first time poster. I'm the happy owner of a late ('96) S124 estate with the OM606 3.0 diesel. It's just about to hit 160k. A few weeks ago I had all the glow plugs replaced along with the glow plug relay. All was well until last week when the car developed a problem from cold starts. When the glow plug light goes off and I turn the key the engine fires but then immediately dies. I then have to crank the engine for 20-30-secs with the throttle pedal down before it will eventually start. Once it starts it runs fine and there is no issue with warm starts. I wonder if anyone has experienced this and has any helpful advice to offer? Thank you.

 

[johnsco]

The OP says that there is no problem with warm starts, this suggests that there is an issue with the glow plugs or glow plug relay.
Was there a starting problem before these components were recently replaced ?
If not, then that's where I would look first.
Does the OP have access to a scanner ? Preferably STAR ?
Poor starting on these OM606 engines can result from air in the complex system of plastic pipes around the diesel injector.
Has any of this been disturbed ?
If not, then I would be looking at the glow plugs or relay.

 

[Ted]

I would start by looking to see if there is air leaking into any of the fuel pipes.

 

[Smiley]

It does sound like an air leak in the fuel delivery system - the oring seals on the fuel delivery pipes would be where I would start; these suck air in rather than leak fuel out so can be tricky to diagnose - if you have lots of bubbles in the fuel in the pipes that is a clue but ime there was always a bubble or two in there. If you can't see the fuel because the pipes have gone a dark yellowy brown colour then it is a fair bet that the seals are gone. The next place I would look would be the small gauze fuel filter (not the main canister filter) and check that is clear AND the condition of the seal on that filter - even check that a seal has been fitted because it is a separate part number to the filter.
The beauty of these cars is their simplicity and lack of electronic control systems so there is little else it can be.

 

[tonym911]

Thank you guys for these very helpful suggestions. As mentioned in my first post the glow plugs and relay have all been replaced in the last few weeks. If the new relay has failed might that explain it? Only asking because the plug light comes on and goes off in the approved manner and as I say it does start initially but only runs for a split second before dying. It does run perfectly once it starts.
Anyway, the car is going in for some welding tomorrow so I'll add this to the job list and pass on your thoughts to the garage. I will let you know what they find to add it to the forum knowledge bank.

 

[johnsco]

The next place I would look would be the small gauze fuel filter (not the main canister filter) and check that is clear AND the condition of the seal on that filter - even check that a seal has been fitted because it is a separate part number to the filter.
The beauty of these cars is their simplicity and lack of electronic control systems so there is little else it can be.

I remember having problems with the seal on this little fuel filter.
The seal can be a fiddle to get seated correctly.
It is important to use a new seal rather than try to re-use the old one.
Cleanliness when seating the new seal is essential.

I agree with all the comments above.
I had two E300TD cars and the OM606 are great engines.
Hope you get starting problems sorted.

 

[91dm]

I would say it's the fuel seals in the top of the injector pump most likely. There's 6 of them and can be done DIY with a special socket.

After that there's a small o-ring on the prefilter delivery pipe that lets air in.

Also check the rubber pipes on the bulkhead that connect to the steel lines.

 

[tonym911]

Thanks to the last two posters 91dm and Johnsco. I've decided to leave it off the list of works for now as so far I'm able to 'catch' it on the throttle on that first cold start to get it going. If it gets worse I'll book it in and pass these info nuggets on as leads.
I love the car and hope it will see me out.

 

[91dm]

Try parking it with the front pointing down, this used to help prevent the fuel draining back and save the battery/starter until fixed.

 

[tonym911]

That's really interesting you say that because I did feel that the slope of my drive was making a difference, based on nothing other than a feeling!
While I'm on and among obvious experts, does anyone have a suggestion for freeing off the hinges on the third row seats? I've had the car for a few years now but have never seen this back seat.

 

[Smiley]

Those rear seat hinges do seize up if left unused. All you can do is try to spray some lube on them to free them off. I think that they suffer because most of the estate cars suffer from damp problems - culprit number 1 is the front corner of the rearmost window in the tailgate area - it can look fine on the body but remove the window seal and there will be rust and a hole in that corner - then the water creeps all over into the rear footwell and then into the front footwell.......

 

[Smiley]

btw if you can hold the rust at bay then this car will outlast you; I eventually sold mine after I did over 300,000 miles in it and it still drove not far off the way it did when it was new.

 

[tonym911]

Thank you Smiley, the trouble with lubing those hinges is that they are so well hidden most of it goes on the carpet!
My E300 hasn't been free to run recently (glow plugs done, new wing going on today) but I figure it's still a lot cheaper than signing up to a new car rental (which is what a PCP deal is in my opinion) or forking out a hell of a lot more cash for a used car that matches it on practicality or style. Selling your one must have been quite a wrench. Do you miss it?