ML280 W164 - Seems to struggle to start

[TheArchitect]

Hello all,

Hopefully I've got the right section of the forum for this query.

Picked up my 2008 ML280 W164 couple weeks ago. I've noticed that it takes a few seconds longer to start up after it's been parked for a period. Starting after say 4 or 5 hours of last use seems to be fine, but when left overnight for example it will take longer for the engine to get going.

I don't think it's a battery issue as it turns over well and there's no hesitation, it's just the engine doesn't seem to get going as quick as it does after a shorter period of non-use.

Is this a common thing with this engine/car?

Thanks in advanced for any input.

 

[texterted]

Could be air leaking into the fuel system, allowing the fuel to drain back to the tank. You then have to pump it all the way back again to start.

 

[TheArchitect]

Could be air leaking into the fuel system, allowing the fuel to drain back to the tank. You then have to pump it all the way back again to start.

Assuming this isn't normal? It's not such a big deal for me but I'm worried it may lead to other issues or eventually drain the battery.

 

[grober]

How long since the fuel filter was changed?

 

[TheArchitect]

How long since the fuel filter was changed?

Honestly, no idea. I'd have to go through the paperwork. Previous owner had had an "A service" (I think that's what it's called) done just over 1000 miles ago, not sure if the fuel filter would be replaced as part of that.

 

[SMS]

I would check out the glow system, relay and plugs.

 

[grober]

Honestly, no idea. I'd have to go through the paperwork. Previous owner had had an "A service" (I think that's what it's called) done just over 1000 miles ago, not sure if the fuel filter would be replaced as part of that.

Would not normally be changed at an A service except under additional items.
Mercedes don't detail their individual service labour operations often now- just giving labour totals. Your best best might be to look for "fuel filter " under parts supplied.

 

[JohnDavies]

Had the same issue on my ML so changed the 5 'O' rings on the fuel line and the 4 on the HP pump. Sorted.

 

[JohnDavies]

Could be air leaking into the fuel system, allowing the fuel to drain back to the tank. You then have to pump it all the way back again to start.

Absolutely correct, common issue, O rings on the common rail fuel line and on the High pressure pump harden after time and crack allowing the fuel to drain back. Had the same issue on my ML270 so changed them all. Cheap as chips and only took me a couple of hours ( incl.tea breaks) End of problem.

PS; Make sure your battery is fully charged when the seals have been changed as you will need to pull the fuel through or use a vac pump.

 

[trapperjohn]

If you can, park it nose down overnight and see if it starts better in the morning. This will let you know if your fuel is drainiing back to the tank. Not an exact science but a fair indicator.

 

[SMS]

Had the same issue on my ML so changed the 5 'O' rings on the fuel line and the 4 on the HP pump. Sorted.

Absolutely correct, common issue, O rings on the common rail fuel line and on the High pressure pump harden after time and crack allowing the fuel to drain back. Had the same issue on my ML270 so changed them all. Cheap as chips and only took me a couple of hours ( incl.tea breaks) End of problem.

PS; Make sure your battery is fully charged when the seals have been changed as you will need to pull the fuel through or use a vac pump.

Different fuel system set up on the v6cdi, no O rings except on the small leak off pipes.

 

[JohnDavies]

Different fuel system set up on the v6cdi, no O rings except on the small leak off pipes.

Most likely it is the glow plug module then??

 

[TheArchitect]

Thanks everyone for the feedback. As SMS points out that this model wouldn't suffer from O ring failure, do you think its more likely to be the glow system at fault?

What would one ask the garage to look for in this instance and how pricey is it likely to be to set right?

Apologies for the basic questions, this is my first merc, first 4x4 and first diesel so I have a lot to learn it seems!

 

[TheArchitect]

came across this thread from a while back

W164 ML280 - Starting Problems - MBClub UK - Bringing together Mercedes Enthusiasts

Similar issue which was resolved by replacing the Glow Plug Relay Module. I think I'll go down this route and may even get the fuel filter changed just to eliminate that from the equation too.

 

[jonny705]

Hi , i blew the fuse on my feed to the glow plug, and took about 4 turns with key before it fired, normally first turn.

If the engine is fully warm it basically dosent need glow plugs to start so would start on first key although no feed to circuit at time- it only happened when first trying to start in morning, thought the module was kaput at £160 , but was the fuse .

But fuel leak thingy could also cause it as it pumps back up to pressure, can you not check the glow plus with a multi meter to see if they are getting a feed?


At least will alliviate that potential problem, as finding a air leak can be hard

 

[SteveFromAvantgarde]

Glow plug modules will show on a STAR diagnosis test if they have failed. The relay modules are modified.

 

[TheArchitect]

Hi

Did a test to try to narrow down the cause of the problem. after 3 days of not driving I went to start her up. But before I started up I let the fuel prime for about 10 seconds before the final turn of the key to fire up. Worked like a charm and started like it should.

Also checked the paperwork and on last big service (about 1k miles ago) they did change the fuel filter as its listed as additional items.

I don't have a multimeter unfortunately and if I did frankly I wouldn't know what to do with it. As embarrassed as I am to say this, it's true.

So with above info does it make the problem any clearer?

 

[jonny705]

If you let the pump pressurise the system for a few seconds then it fired up , iwould not have thought it would be a glow plug isssue so no multimeter required.

If the fuel filter was replaced ,maybe they did not put lines on properly? with proper crimp things? I put jublee clips on mine and it did leak so ended up using air line type crimps and tool which i had from years ago.

As it sounds like others said - if air is allowed in anyware in fuel system it will flow back into the tank, if this was the part that was recently changed and is to do with the fuel lines and problems you describe-it seems like a good place to check for leaks.

I think you can get UV dye for fuel to help you look for leaks - you can for oil and it helped me find a leak i could not see on dirty engine.