W210 E320 CDi not starting on very cold mornings

[JimM]

Hi pals.

For about a week my E320 CDi would not started in the morning from totally cold on the 1st try as it usually does, but on the 3rd try.

After that first start she is always fine all day through many short journeys, starting on 1st try within 1-2 seconds.

Early this week it was noticeably colder and it wouldn't start at all and I stopped trying after 6-7 tries and called my mobile mechie.

I left it alone until he arrived the next afternoon and we took a good look around, the glow plugs are heating, there is no air in the visible fuel line, there is fuel right up to the rail with no bubbles at all, and there are no leaks anywhere round or on the fuel rails or the fuel filter or pump.

It started on the 2nd try.

He offered to replace the rail seals but didn't think there was any need so we postponed that for now. He suggested to change the fuel filter next as it is a routine replacement anyway.

The last 2 days it started on the 2nd or 3rd try again.

Then today it wouldn't start again. It was bitterly cold this morning.

Could it be the fuel is freezing a little? I've seen -6C to -15C quoted as possible freeze points where the diesel fuel might start to gel but I don't think it was that cold in Berkshire last night/this morning?

I will replace the fuel filter, it's not been changed since I had the car, about 3 years now. It might have water in it which would possibly freeze.

Has anyone got any pointers please?

 

[mersum1es]

I guess injectors are leaking (tank line)...

 

[Naraic]

When mine did this it was a seal in the high pressure pump. Take it to an MB specialist.

 

[toby1]

It won't be the fuel freezing, we're not in Siberia. Could be injection pump leaking but take it to Star in Caversham and they'll sort it.

 

[malcolm E53 AMG]

The symptoms you describe are typical of air ingress into the LP fuel lines between fuel filter/low pressure pump. I did all mine this year (3 in total) consisting of plastic pipes with o ring seals at each end. They are a poor design as the o rings loose their sealing ability over time and either let air in or fuel out, if you haven't changed them and the car is over 10 years old it is the prime suspect. Buy the pipes from MB they are £80 all in.

HP fuel pumps start to develop leaks due to the integrity of the seals around this age as well so keep an eye on it mine is going into our local diesel specialist beginning of next year for them to be done as they are weeping when the car is stood.

Hope this helps!

 

[JimM]

Thanks for the pointers guys, I'll check them out and report back when I get a fix.

 

[JimM]

Well, we did another exhaustive eye-ball and prod around, no air present at all.

I replaced the fuel filter, the fuel was slightly misty but no water in there. There was a bit of metal sediment in the bottom of the filter can, so my pump may be on its way out.

That was quite easy, the only hard part being to unscrew the cap from the filter can, and to tighten it adequately after. I put some vaseline on the filter can threads but the tightness is between the cap's screw ring and the cap, and I couldn't get any lubricant in there at all. Maybe I could try some spray grease sometime.

She failed to start again, and after 8-10 tries the starter motor was slowing down so I stopped and put it on charge over night.

The next day I was truly amazed.

She spun about twice as fast as she usually does, and fired up within the 2nd try. i allowed not to start on the 1st because I had replaced the filter and maybe needed to pull up a bit more fuel.

So it seems that the cause is that my battery had slowly drained, because I really had not noticed the spin speed dropping or being slow before, probably because she did always fire up on the 1st try.

Yesterday she fired up on the 1st try as normal, within 2-3 seconds.

I'm not sure if the low battery is a permanent fix/cause, or if it's the cold weather distorting the fuel lines or seals very slightly and causing a small air leak, as we couldn't find any air on inspection.

Has anyone else experienced non-start due to turning over too slowly on a diesel?

I didn't think that this was possible, since in my days at Big Boyz' Skool I was told that diesel ignites on just being compressed?

 

[CRH71]

I was always lead to believe that a diesel needs to spin at a minimum of 100rpm to generate sufficient heat from compression of the air to ignite the fuel.

I've seen it many a time (with both my own vehicles and others') where a lazy starter, or failing battery, have failed to turn the engine over fast enough to allow starting, especially in cold weather.

 

[mersum1es]

Your aux fuel pump and hp-pump are mechanical, so if you have some extra internal leak in system, it may not be able to produce sufficient pressure to allow start of the injection... in my experience battery is very low if it can be seen in spinning at start.

 

[JimM]

I'm very happy to report that she starts within 2-3 seconds from stone cold again, every time since recharging the battery, and the engine spin speed is distinctly faster.

Back to her usual self. And she has a new fuel filter, and I removed some of the black death enamel too.

She must think it is Christmas. :mrgreen:

Have a Merry one everyone.

 

[JimM]

Spoke too soon. It was very cold two mornings ago, about -5 degrees C, and she refused to start.

I left her overnight and yesterday morning it was sunny and warm, and she started immediately.

So this is proof that there are no air leaks, or it would have taken some turns to get fuel up before she would start.

Now I am convinced I have a tankful of untreated diesel which is gelling at too high a temperature, it is the same tankful of fuel.

Unfortunately I don't remember where I bought it, but it was not supermarket fuel, I normally use Esso and Shell as there are a couple of stations of each brand which are only a penny more than the supermarkets.

We shall see. Curiouser and curioser!

 

[JimM]

Well, how wrong could I be?

This is such an intermittent problem only happening at below-freezing-point temperatures.

It happened again, and my friendly mobile mechie replaced all 6 O-ring seals on the fuel lines.

Thanks to everyone who mentioned them, I should have listened but luckily it wasn't too inconvenient on the days it happened.

She has been good since then, starting in the first try every time.

But I'm still not sure it's been cold enough since I was convinced before that it had been.

So I guess only time and a proper snowfall will tell really.

There is one difficult O-ring to get to, it's at the front left of the engine (as you look from the front of the car) behind the air filter intake pipe, you need to remove the filter pipe and remove the fuel pipe bolt, not so easy with cold hands.

Who decided to put it there? :roll:

 

[JimM]

Small update - still starting on the first try, but as above it's not been as cold as before still.

Keeping fingers crossed.

 

[malcolm E53 AMG]

Glad the car is running well and the problem appears to be solved.

Now that the LP pipes have been resealed with new o rings if the car starts to smell of diesel at the front end (especially when stood for a couple of days) it will be an indication that the seals in the HP pump require replacing, they were replaced on mine late last year (2000 reg)

Mercedes don't bother to advise on these issues unfortunately.

 

[Jamesw3622]

Hi Malcolm210 and all.

I am new to the forum and to Merc. I brought a 2001 w210 E320 estate in May 2015. Family bus! Excellent car, no rust, one owner from new, full service history + many items changed, all at main dealer, 98k miles now 115k (I do about 25k per annum). I am a fairly good mechanic (farmers son) and have access to a workshop and pit.

Car was running fine until the weather started getting colder. When left for more than 12 hours it starts then stops, then takes quite a lot of cranking to get it going again. Once it starts it will be fine for the rest of the day. The glow plug light was also staying on. Having read lots of posts and needing a car I decided to find a good Indi rather than have a go myself. NJS Solutions in Sevenoaks. In the first instance they checked the glow plugs and found faults in all of them so changed them all which fixed the glow plug light staying on, but the starting problem persisted. They changed all the low pressure fuel lines and O-rings at the next visit, but unfortunately this morning it did the same thing (gutted).

I am now thinking its either a dodgy injector or the high pressure fuel pump. Costs are starting to mount up, but I love the car and other than this little problem its a joy to drive, and brilliant for motorway driving. The indi said it would cost circa £90 to check the injectors and look over the high pressure fuel pump.

If the pump is found to be leaking, is swapping the high pressure fuel pump a DIY job because I anticipate it costing circa £700-800 (including a new pump) for the garage to do it. I have been advised the seal kit are not worth mucking about with, would you agree?

Has anyone else got any ideas of what it might be?

Thanks in advance.
J

 

[bembo449]

Hi Malcolm210 and all.

I am new to the forum and to Merc. I brought a 2001 w210 E320 estate in May 2015. Family bus! Excellent car, no rust, one owner from new, full service history + many items changed, all at main dealer, 98k miles now 115k (I do about 25k per annum). I am a fairly good mechanic (farmers son) and have access to a workshop and pit.

Car was running fine until the weather started getting colder. When left for more than 12 hours it starts then stops, then takes quite a lot of cranking to get it going again. Once it starts it will be fine for the rest of the day. The glow plug light was also staying on. Having read lots of posts and needing a car I decided to find a good Indi rather than have a go myself. NJS Solutions in Sevenoaks. In the first instance they checked the glow plugs and found faults in all of them so changed them all which fixed the glow plug light staying on, but the starting problem persisted. They changed all the low pressure fuel lines and O-rings at the next visit, but unfortunately this morning it did the same thing (gutted).

I am now thinking its either a dodgy injector or the high pressure fuel pump. Costs are starting to mount up, but I love the car and other than this little problem its a joy to drive, and brilliant for motorway driving. The indi said it would cost circa £90 to check the injectors and look over the high pressure fuel pump.

If the pump is found to be leaking, is swapping the high pressure fuel pump a DIY job because I anticipate it costing circa £700-800 (including a new pump) for the garage to do it. I have been advised the seal kit are not worth mucking about with, would you agree?

Has anyone else got any ideas of what it might be?

Thanks in advance.
J

before it gets that technical pal , try charging the battery , cleaning the earths to the engine , if your starter motor isnt spinning the engine over fast enough , she wont start , i have a nissan navara that was a pig to start when cold ! just cleaning up all the earths cured this issue ! my mate who also runs one , had crap starting all round , new starter motor and wump ! shes away first crank eveytime without fail , just a suggestion

 

[mersum1es]

I am now thinking its either a dodgy injector or the high pressure fuel pump. Costs are starting to mount up, but I love the car and other than this little problem its a joy to drive, and brilliant for motorway driving. The indi said it would cost circa £90 to check the injectors and look over the high pressure fuel pump.

If the pump is found to be leaking, is swapping the high pressure fuel pump a DIY job because I anticipate it costing circa £700-800 (including a new pump) for the garage to do it. I have been advised the seal kit are not worth mucking about with, would you agree?

Has anyone else got any ideas of what it might be?

Thanks in advance.
J

It would cost 50p to check injector tank leak, you need 0,5m plastic hose and clamp to block loosen fuel line

http://i298.photobucket.com/albums/mm248/tr4dude/photo2-1.jpg

hp-pump is difficult to test without SDS, but again if alternatives are buy new or even refurb pump 500£?, and seal kit it 15£... I would give it a try. Changing the pump is easy, see thread
http://forums.mercedesclub.org.uk/showthread.php?t=105316

You need to remove fan shroud and perhaps tilt the rad because of longer engine and limited space.

Edit; I just re-read start - stop issue may be due to jamming pressure regulator valve (in the end of rail), and then there is also one o-ring, check it too. If it is faulty, Try find one from breakers or use actual part number to find new regulator valve only.

 

[malcolm E53 AMG]

My advice would be to find a good diesel specialist if the problem persists. The work you've had done ie.glow plugs and LP fuel lines is money well spent. It still sounds like you have air entering the fuel lines, so worth checking that all the seals were done correctly (new pipes are best) but it could be injector or fuel rail pressure related. I use County Diesels in Leicestershire for all the fuel delivery problems and they refurbed my HP pump last year for £450, the pump was leaking fuel.

Hope this helps!

 

[om613]

With the drop in temperature, my money's on the battery failing.

All the other suggestions are good ones.

 

[nyx]

these old mercs seem to really play up when the battery is on its way out.