Long crank time when cold

[Technoholic]

Hi all

my new 2013 CLS 350 cdi is generally great, there are a couple of niggles though that I don’t know if are actually problems or just how it is, I’m new to Mercs so forgive me for asking.

This problem is related to starting when cold. When I turn the key, it seems to crank for a lot longer than any recent modern-ish car that I’ve had. Probably for about 2 seconds which doesn’t sound a lot, but if you actually count it out you’ll see it’s quite a long time for a crank.

after that the car starts up and all is fine. Then after turning off and starting again relatively quickly, the turnover is as I would expect it, fairly instant.

During the long turnover, it doesn’t seem to turnover slowly, as it would if the battery was dying, just does it for a long time.

Has anyone seen this before?

thanks

 

[mbzclk]

Glow plugs or glow plug relay. Had it when I had my CLK 320 CDI, once replaced the offending bit was near perfect for me. After 8 years old a fresh brand new battery made the world of difference too.

 

[Technoholic]

I’ve been looking at posts about the relay, looks like a relatively easy diy?

are the glow plugs diy too?

 

[OneForTheRoad]

I’ve been looking at posts about the relay, looks like a relatively easy diy?

are the glow plugs diy too?

I changed all 6 and fitted a new relay. Starting time still wasnt instant. I think its a characteristic of the om642 engine.i did try 2 ignition cycles and that seemed to improve things.

 

[zipdip]

The relay is a easy diy job I would caution about changing glowplugs,you can hit problems,might I suggest that when starting your car,look at the glowplug light on the dash and when it goes out wait a couple of seconds before starting,you might find it starts quicker.

 

[Technoholic]

The relay is a easy diy job I would caution about changing glowplugs,you can hit problems,might I suggest that when starting your car,look at the glowplug light on the dash and when it goes out wait a couple of seconds before starting,you might find it starts quicker.

I tried that this morning, I gave it a couple extra seconds and yes it did start potentially a little quicker although it might be the placebo effect. I’ve ordered a glow plug controller so will change that and see what happens.

 

[Technoholic]

Deleted duplicate

 

[mbzclk]

Glow plugs can get stuck so can snap when attempting to remove. Depends if it’s been changed before and how old they are. Mine got stuck; then the replacement failed after 2 years or so.

I changed the failed replacement out myself. It was easy you just have to be very gentle and not apply too much force.

I guess that’s because they had already been replaced and were not that old.

 

[Technoholic]

Yeah I think I'm going to do the relay myself (I've just had a look where it is and it looks like a 10 minute job most), but if that's not helped I will probably take the car to have the plugs replaced. I probably won't even bother to do it straight away, it's not like this is a major problem, so maybe get them to do it at next service.

I hope I ordered the correct Glow Plug Controller. Is there a way of verifying which one I need? I believe it's right, it's the Beru GSE116 I ordered

 

[mersum1es]

It may be fuel pressure issue as well (usually it is), injectors are leaking at cold, when tehy warm up they are better. Double ingintion cycle on other hand also primes the low pressure fuel lines better, which may point to lazy aux pump in tank. Most common culprit is injector leak. In case of OM642 glow plugs have some effect, especially if more than one is dull.

 

[Technoholic]

What’s the easiest way to check for leaky injectors?

 

[mersum1es]

Commercial leak test kit https://www.tooloutlet.fi/product_pictures/big/CommonRail+suutinten+testaussarja+BGS+8101-4244.jpg
Or DIY http://www.skg.fi/tile002/w163/pic/pic060.jpg

Edit: Note that test MUST be done at problem conditions (usually cold)

 

[poormansporsche]

Ditto mine. Always fine doing the double click or leaving for a couple of seconds before turning full chat.

Strangely mine got better after changing the pcv ?

 

[Technoholic]

Ditto mine. Always fine doing the double click or leaving for a couple of seconds before turning full chat.

Strangely mine got better after changing the pcv ?

What’s the double click and the PCV? I’m new to the Merc world!

 

[poormansporsche]

Like above, turning the key to position 2 til the glow plug light goes out then turning back off then back to position 2 again then starting.

The pcv is a oil breather valve which is a known weak spot on the 642. It shouldn't effect starting but I do not know why but definitely got better when I changed mine (mpg got better as well) . Well worth changing if done over 50k

 

[Technoholic]

Like above, turning the key to position 2 til the glow plug light goes out then turning back off then back to position 2 again then starting.

The pcv is a oil breather valve which is a known weak spot on the 642. It shouldn't effect starting but I do not know why but definitely got better when I changed mine (mpg got better as well) . Well worth changing if done over 50k

Thanks, yes I've seen the PCV is a crank case breather valve. Did you change this yourself?

 

[Technoholic]

I just replaced the coil plug controller, but need to wait till the engine is cold to test properly.

With regards to the leaky injectors issue, I can't see how this could be the case. It was said that when warm the injectors seal better therefore stopping the issue on restarting the engine when it's warmed up. However because leaving the key at position 2 for a few more seconds before any type of starting occurs seems to solve the issue, by definition the injectors can't be the issue, right?

 

[mersum1es]

They can be. With injector leak low pressure line can be 'empty', double ignition primes line better (less air) and car starts faster even injectors are leaking a little bit. Injector leak tends to escalate in time so next winter you will know for sure

Measure glow plugs first before starting first time. Yes, faulty plug should trigger coil light but if relay has failed due to faulty plug, it will fry new relay too.

Sometimes plug is not entirely broken, it may give a good resistance value at cold but hot won't work properly. That will cause not big problem, only lower heating performance.

 

[Technoholic]

They can be. With injector leak low pressure line can be 'empty', double ignition primes line better (less air) and car starts faster even injectors are leaking a little bit. Injector leak tends to escalate in time so next winter you will know for sure

Measure glow plugs first before starting first time. Yes, faulty plug should trigger coil light but if relay has failed due to faulty plug, it will fry new relay too.

Sometimes plug is not entirely broken, it may give a good resistance value at cold but hot won't work properly. That will cause not big problem, only lower heating performance.

im not referring to priming the lines twice by running through the ignition twice, I'm referring to single turn to position 2, waiting a few seconds, then starting. But I see your point, it's a possibility, so will see how I go and tackle that next if necessary. To be honest, this is a minor issue, and is the only real issue with the car so I'm not worried right now. it's just a little annoying more than anything

 

[mersum1es]

Ok, thanks fo clarify... basically key back and forth double might be the same thing than keep longer time in position 2 before starting (I cannot remember how long primer pump pumps or is it on continuosly when key turned).

Leak back test is rather easy, just one meter of suitable size clear hose, clamp wrench to block fuel line to filter. If I recall right WIS says 20 ml/min crank/run is allowed.