Stop/Start Operation

[00slk]

On our 14 plate SLK 250 cdi it has the stop/start function which my wife has noticed doesn't work if the heater fan is running and sometimes when the car if first used.
Is this normal for one of these to work like this, seems a little odd to me and I would have thought it should work all the time and only if the button is switched off should it not operate.
Any one have the same issue?

 

[fabes]

Mine can be similar.
Both batteries need a little juice in them so from start youll need a couple of miles to get them into adequate condition

 

[EmilysDad]

there are many parameters that need to met before stop/start operate. The heater fan takes a fair bit of power & could very well be the tipping point for the car to not stop/start. At this time of year, there'll be a big demand on the charging system which will affect stop/start.

 

[00slk]

there are many parameters that need to met before stop/start operate. The heater fan takes a fair bit of power & could very well be the tipping point for the car to not stop/start. At this time of year, there'll be a big demand on the charging system which will affect stop/start.

Thanks for the replies, so sounds like this is normal.
On the last service in October the battery state of charge was 100%. State of Health 96% so nothing to do with the battery.
Can't say she noticed S/S wasn't working in the warmer weather, but then if the fan wasn't on.........

 

[Tony Dyson]

The recent cold snap will have had a detrimental effect on the batteries as well, SS will be looking for peak performance battery levels so it is one of the first tell-tale signs your batteries aren't quite 100%. Before the advent of AGM batteries which are (Allegedly) sealed for life and 'maintenance free' drivers had a weekly electrolyte top-up maintenance procedure then Maintenance Free came along and was a distinct advantage but I think we've all got a little lazy over the years, Maintenance free AGM batteries still use a liquid electrolyte and have you ever wondered what comes out of the 'Breather' tube connected to the common cell chamber at the top of the battery?
It takes the expanded gasses, which is essentially boiled electrolyte from a charge/discharge cycle and provides an exit to atmosphere, so over the Years electrolyte levels will drop within the battery along with the battery efficiency so 'Maintenance free' is a moot subject as you can take off the labels on the top of any AGM battery to access, with a little brute force and ignorance, the removable tops of the individual cells, top-up with De-ionised water as you would any flooded battery, De-ionised is better than Distilled, thereby improving the battery condition and extend life beyond manufacturers recommendations!
That's if you want your SS to start operating faster than it is doing! some wouldn't bother!

 

[malcolm E53 AMG]

My son has borrowed my S212 for the week as his W213 has a flat and what was the first thing I said to him don’t use Stop/Start - the engine killer IMO

 

[Gazwould]

 

[00slk]

The recent cold snap will have had a detrimental effect on the batteries as well, SS will be looking for peak performance battery levels so it is one of the first tell-tale signs your batteries aren't quite 100%. Before the advent of AGM batteries which are (Allegedly) sealed for life and 'maintenance free' drivers had a weekly electrolyte top-up maintenance procedure then Maintenance Free came along and was a distinct advantage but I think we've all got a little lazy over the years, Maintenance free AGM batteries still use a liquid electrolyte and have you ever wondered what comes out of the 'Breather' tube connected to the common cell chamber at the top of the battery?
It takes the expanded gasses, which is essentially boiled electrolyte from a charge/discharge cycle and provides an exit to atmosphere, so over the Years electrolyte levels will drop within the battery along with the battery efficiency so 'Maintenance free' is a moot subject as you can take off the labels on the top of any AGM battery to access, with a little brute force and ignorance, the removable tops of the individual cells, top-up with De-ionised water as you would any flooded battery, De-ionised is better than Distilled, thereby improving the battery condition and extend life beyond manufacturers recommendations!
That's if you want your SS to start operating faster than it is doing! some wouldn't bother!

I remember the common maintenance schedule we preformed when I was in my teens with battery top ups, though back then we used normal water. New Zealand has soft water....Hmmm maybe contributing to the regular top ups?? I have never bothered checking 'top up free' batteries for many many years now, maybe I should get back into the habit of carrying out better maintenance on my cars instead of the easy bits like oil and filters.
Certainly brings food for thought though with EV these days if their batteries give off these gases....?

My son has borrowed my S212 for the week as his W213 has a flat and what was the first thing I said to him don’t use Stop/Start - the engine killer IMO

When I worked in the panelshop at Audi/VW we had a contract with a few other makes and know the BMW of 1981 had this engine cut out system if you were sitting in traffic, fuel saving ploy, or marketing skills to sell more of their cars? Never really understood this as with Gazwould reply post, engine start ups are the most demanding and engine destroying moments of a cars history (cutting out, no pun intended, running out of oil or water!) We were told this as a young teen and therefore we would leave our cars running if we went into the shops or visited friends for a short period of time. Oil technology has come a long way since the 60,70 and 80's and I tend to only use Mobil 1, Valvoline VR and Castrol Magatec in my cars now.

View attachment 72875 View attachment 72876

Totally agree with this statement Gaz, so I am not too bothered that the S/S is only working when all is good. I have never had a car with this system before so a novelty at the moment, though feels strange when you do stoop in traffic and it stops.....You think WTF

 

[Jim2]

I remember the common maintenance schedule we preformed when I was in my teens with battery top ups, though back then we used normal water. New Zealand has soft water....Hmmm maybe contributing to the regular top ups?? I have never bothered checking 'top up free' batteries for many many years now, maybe I should get back into the habit of carrying out better maintenance on my cars instead of the easy bits like oil and filters.
Certainly brings food for thought though with EV these days if their batteries give off these gases....?


When I worked in the panelshop at Audi/VW we had a contract with a few other makes and know the BMW of 1981 had this engine cut out system if you were sitting in traffic, fuel saving ploy, or marketing skills to sell more of their cars? Never really understood this as with Gazwould reply post, engine start ups are the most demanding and engine destroying moments of a cars history (cutting out, no pun intended, running out of oil or water!) We were told this as a young teen and therefore we would leave our cars running if we went into the shops or visited friends for a short period of time. Oil technology has come a long way since the 60,70 and 80's and I tend to only use Mobil 1, Valvoline VR and Castrol Magatec in my cars now.



Totally agree with this statement Gaz, so I am not too bothered that the S/S is only working when all is good. I have never had a car with this system before so a novelty at the moment, though feels strange when you do stoop in traffic and it stops.....You think WTF

I heartedly agree with you and Gaz. I've warned all of the Family to switch off SS, or be it on your own heads.

 

[Srdl]

On our 14 plate SLK 250 cdi it has the stop/start function which my wife has noticed doesn't work if the heater fan is running and sometimes when the car if first used.
Is this normal for one of these to work like this, seems a little odd to me and I would have thought it should work all the time and only if the button is switched off should it not operate.
Any one have the same issue?

Water ingress, perhaps

 

[KennyN]

RE - S/S.

Much has been written about the potential wear / damage issues of a S/S system and i do understand the principles that could cause these problems , but i dont think i have personally heard of anyone's engine or starter motor failing due to the S/S system being used , bearing in mind S/S has been commonplace on cars for around a decade or so.

For the record i always switch it off whenever the car is started as i find it intrusive during my daily commute , not because of any damage it may cause.

Just my 2p worth.

K

 

[LostKiwi]

5he main components subject to increased wear are engine bearings and timing chain.
I do wonder how many of the timing chain issues we are are at least in part due to start stop

Incidentally petrol engines can restart without using the starter motor. The ECU monitors the position of the crank and if the crank stops 8n an acceptable place it injects some fuel into the cylinder then sends a spark to ignite it.

 

[Jim2]

5he main components subject to increased wear are engine bearings and timing chain.
I do wonder how many of the timing chain issues we are are at least in part due to start stop

Incidentally petrol engines can restart without using the starter motor. The ECU monitors the position of the crank and if the crank stops 8n an acceptable place it injects some fuel into the cylinder then sends a spark to ignite it.

Yes, but regardless of the method used to start it, you still have the situation where the engine is stopped 100%, and then when it rotates to start, means taking up any "slack" in either the timing belt or chain. I'm not a fan of it, being convinced that starters, ring gears etc. have a "life" which is shortened each time the engine is started.

 

[LostKiwi]

Yes, but regardless of the method used to start it, you still have the situation where the engine is stopped 100%, and then when it rotates to start, means taking up any "slack" in either the timing belt or chain. I'm not a fan of it, being convinced that starters, ring gears etc. have a "life" which is shortened each time the engine is started.

Believe me I'm no fan either. I only posted about petrol engines not needing to use the starter as a piece of useful information.

 

[Jim2]

Believe me I'm no fan either. I only posted about petrol engines not needing to use the starter as a piece of useful information.

Yes, and I've heard of the alternator being used as a starter too but I've no confirmation of that.

 

[EmilysDad]

Yes, and I've heard of the alternator being used as a starter too but I've no confirmation of that.

The mhd 451 Smart has that set up. The belt is apparently like a bow string though which puts strain on tensioner points .... I believe MB have made 3 mods to it over the years.

 

[00slk]

Water ingress, perhaps

SLK, not SL!!!!!

 

[FiveAlive]

Yes, and I've heard of the alternator being used as a starter too but I've no confirmation of that.

The petrol W169 has that set-up. Works very smoothly, I think, and not at all intrusive.

Recently the starter motor packed up whilst we were over 2 hours from home. The breakdown guy (Green Flag) simply tow-started us rather than get us transported back so I then had to drive home without stalling - amazing how much concentration was needed for something that I would normally not even think about! Anyway, the stop/start still worked fine even with the starter motor dead, although I turned it off after realising that it was enabled because I didn't want to tempt fate. We got the starter motor replaced a few days later - it transpired that the aluminium housing at the end holding the pinion bearing had cracked into pieces, which was rather more of a catastrophic failure than I'd expected.

As for all the talk of increased wear with stop/start, I'm in two minds. Sitting at idle isn't good for the engine or the environment, and restarting a hot engine is nowhere near as strenuous as starting a cold one as everything is at operating tolerances and the oil is still in the right places. I'd like to think that manufacturers studied potential issues before introducing stop/start and beefed up any components that needed it, but I just can't bring myself to trust the modern Mercedes management to have sanctioned that.

 

[Jim2]

The petrol W169 has that set-up. Works very smoothly, I think, and not at all intrusive.

Recently the starter motor packed up whilst we were over 2 hours from home. The breakdown guy (Green Flag) simply tow-started us rather than get us transported back so I then had to drive home without stalling - amazing how much concentration was needed for something that I would normally not even think about! Anyway, the stop/start still worked fine even with the starter motor dead, although I turned it off after realising that it was enabled because I didn't want to tempt fate. We got the starter motor replaced a few days later - it transpired that the aluminium housing at the end holding the pinion bearing had cracked into pieces, which was rather more of a catastrophic failure than I'd expected.

As for all the talk of increased wear with stop/start, I'm in two minds. Sitting at idle isn't good for the engine or the environment, and restarting a hot engine is nowhere near as strenuous as starting a cold one as everything is at operating tolerances and the oil is still in the right places. I'd like to think that manufacturers studied potential issues before introducing stop/start and beefed up any components that needed it, but I just can't bring myself to trust the modern Mercedes management to have sanctioned that.

Well as I would definitely fit the description of "old timer" mechanic, I'll stick to old style thinking that all moving parts have a life, and problems occur when that term is reached.So maybe all of these factors were taken into account in the design stage..but recent vehicle design flaws do not imbue me with an over abundance of confidence, especially when it's
the accountants having a say

 

[LostKiwi]

SLK, not SL!!!!!

Junior sized pool then!