M113 V8/SLK55 hot starting niggle - advice

M113 V8/SLK55 hot starting niggle - advice

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rgv250ads

Original Poster:

434 posts

114 months

Sunday 25th September 2016
quotequote all
Hi all
ive got a 2005 SLK 55.

over the last year or so it's getting harder to start when hot. Example, fuel stop, takes a few attempts to get it going. If left for 30min+ then easier to get going.

when luke warm or cold, starts on the button.

So, anyone got a steer. I think I've read this could be the start of the demise of the crank or camshaft sensor.

Other than this niggle, battery and other things are tip top.

let me know views and thoughts!

Happy Jim

968 posts

239 months

Sunday 25th September 2016
quotequote all
I had this on my S350 (V6 petrol), it was the crankshaft sensor - cost me about £100 and 10 mins to swap - been perfect ever since.

Jim

rgv250ads

Original Poster:

434 posts

114 months

Monday 26th September 2016
quotequote all
Cheers, yep i had suspected Crank Position sensor and reading a fair bit online in last 24hrs, symptoms i've got are identical.

Euro Car Parts got a sale on from now until 30Sep2016 whereby 30% off for online order, so got a Bosch one, all in, incl euro car parts delivery driver & VAT to my door within 3 hours for £48!

Main stealer wanted £110 incl VAT for the same part just in an MBenz bag.

Crazy frown

Will fit in the coming week and hopefully that'll solve it. Thanks for replying Jim.

slk 32

1,486 posts

193 months

Tuesday 27th September 2016
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Just to concur this does sound like the crankshaft position sensor. It's the size of a Bic biro and a generic merc part which fits multiple models. Mine went on the slk 32 after approx 8 years, apparently they're made out of plastic which becomes brittle and fails after a certain amount of heat cycles.

Luckily mine failed one Sunday morning when I was pulling in to the gym and I could call upon several other powerfully built company directors to help me move it. I was just grateful it didn't happen the night before when I was 60 miles from home in the pissing rain!!

MattyB_

2,011 posts

257 months

Saturday 1st October 2016
quotequote all
rgv250ads said:
Main stealer wanted £110 incl VAT for the same part just in an MBenz bag.

Crazy frown
Tell me about it - mine gave up on the ramp at MB when it went for an MOT. I knew it was a ~£30 part and not too difficult to DIY, charged me £250 change it! FFS!

rgv250ads

Original Poster:

434 posts

114 months

Saturday 1st October 2016
quotequote all
MattyB_ said:
charged me £250 change it! FFS!
ouch!
fitting mine tomorrow, forecast looks very good. Lets hope its not too much of a knuckle scraper.


rgv250ads

Original Poster:

434 posts

114 months

Monday 3rd October 2016
quotequote all
From start to Finish took about 3 hours. If attempted again would be half that time, as spent alot of time just looking, guessing what to do, what to move out the way.

Just posting this in case this thread is searched for in the future on PH.

Sensor is located here:



behind left bank cylinder head, i thought access would be better from underneath but no chance. Only accessable from the top. It is buried deep deep. On larger engine bays might be easier, but in the SLK it's a real squeeze. Jokes aside if you have big hands, would be very difficult.
All airbox and pipework needs to be removed, and MAF sensor and pipes, plus the majority of the wiring loom behind the engine needs unclipping (cable tied to engine block via cable tie mounts, replace all cable ties when reassembling). If you can get everything out of the way per the above black and white photo, then you'll be okay.

The red lines i crudely added to the photo are to show the raised sides of the bolt location and the only socket that will fit is a 1/4" Drive deep 'slim' socket like this:


the correct size is E8 Torx. However, i found upon removal an old imperial 1/4" in size fits perfectly and snaps straight on the torx bolt like it was meant to be.

Access is incredibly awkward, if you have wobbly head drives and CV joint style bar joins, then the job will be a lot easier.

Its a D.I.Y but you need a decent tool kit and fair amount of patience. I can see why a main dealer would charge £250 Inc Fitting.

Adam.

595Heaven

2,408 posts

78 months

Saturday 8th February 2020
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rgv250ads said:
Just posting this in case this thread is searched for in the future on PH.

Sensor is located here:
beer

Perfect!

ChrisHampshire

97 posts

183 months

Saturday 8th February 2020
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Nice write-up but you haven't stated whether or not it's fixed the issue!

rgv250ads

Original Poster:

434 posts

114 months

Saturday 8th February 2020
quotequote all
It didn't fix the issue. I had the car on a CTEK charger so thought the battery was good. Turned out it was a duff battery, well it was the original 2005 oem fitted battery and it lasted until this original post period.

The symptoms I had at the time were identical in every way to the crank sensor starting to give up the ghost.

After a new battery was fitted the problem went away. I left the new crank sensor in anyway as it was over 10 years old the one it replaced, so was likely to start giving issues at some point anyway.


595Heaven

2,408 posts

78 months

Saturday 8th February 2020
quotequote all
rgv250ads said:
It didn't fix the issue. I had the car on a CTEK charger so thought the battery was good. Turned out it was a duff battery, well it was the original 2005 oem fitted battery and it lasted until this original post period.

The symptoms I had at the time were identical in every way to the crank sensor starting to give up the ghost.

After a new battery was fitted the problem went away. I left the new crank sensor in anyway as it was over 10 years old the one it replaced, so was likely to start giving issues at some point anyway.
Hmmm....

My battery has run low a couple of times, but it has given a warning about a Vario roof fault, which needed a battery disconnect for 30 minutes and charge to solve. No such message this time...

I’d agree it’s probably a good idea to replace the crank sensor anyway, but I might need to add a new battery to the shopping list!

BlimeyCharlie

902 posts

142 months

Wednesday 1st November 2023
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Symptoms I'm experiencing are;

Won't start when hot - typically a petrol stop etc. Leave it 30 mins and it might be hesitant but starts.
Car is totally fine when cold.
Has been like this a while, maybe over 1000 miles, I don't use it much and have compensated by getting petrol when car is cold and so on. Slightly mad 'solution'...was going to get it replaced at service time...

However, CEL has now come on, presume that the Crank Position Sensor has deteriorated further/about to fail.

Car did seem to run slightly lumpy at idle prior to light coming on during same journey.

Quoted under £200 for replacement from Specialist inclusive of VAT etc, further charge for hooking up to Diagnostics, though I am confident it is CPS...

Thoughts, advice appreciated. Thank you

Car is a 2005 SLK55 R171 with the M113 V8

595Heaven

2,408 posts

78 months

Wednesday 1st November 2023
quotequote all
BlimeyCharlie said:
Symptoms I'm experiencing are;

Won't start when hot - typically a petrol stop etc. Leave it 30 mins and it might be hesitant but starts.
Car is totally fine when cold.
Has been like this a while, maybe over 1000 miles, I don't use it much and have compensated by getting petrol when car is cold and so on. Slightly mad 'solution'...was going to get it replaced at service time...

However, CEL has now come on, presume that the Crank Position Sensor has deteriorated further/about to fail.

Car did seem to run slightly lumpy at idle prior to light coming on during same journey.

Quoted under £200 for replacement from Specialist inclusive of VAT etc, further charge for hooking up to Diagnostics, though I am confident it is CPS...

Thoughts, advice appreciated. Thank you

Car is a 2005 SLK55 R171 with the M113 V8
Could well be the CPS. Get yoursefl a cheap OBD reader and get the codes. I have this one and it works perfectly well https://www.amazon.co.uk/gp/product/B07RQCP5PY

It is not too difficult to replace the CPS yourself but you will swear - not much room to manouvre, and once your hand is near the CPS you can't see what you are doing. If I'd needed to change it again before I sold the car I'd be much quicker though.

I think a new Bosch one cost me about £25 and I also had to buy a Torx bit or something to fit it. There are some good 'How To' guides on SLKWorld.com

gregpot2000

233 posts

144 months

Thursday 2nd November 2023
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I am pretty certain I have this issue also, along with very occasionally cutting out at speed which has thankfully only happened in quiet situations so far!

My car is now hibernating for winter, it's a job I'm planning on doing when it comes out for spring again.

One tip I do have though, if it is the same issue as mine, is that I managed to almost completely eliminate the warm start issue by just being slower with the key, I found if I tried to start the car straight away as normal it would almost always fail, where if I turned it to the "lights on" position, then waited around 10 seconds before final turn, it was almost always ok

BlimeyCharlie

902 posts

142 months

Thursday 2nd November 2023
quotequote all
595Heaven said:
BlimeyCharlie said:
Symptoms I'm experiencing are;

Won't start when hot - typically a petrol stop etc. Leave it 30 mins and it might be hesitant but starts.
Car is totally fine when cold.
Has been like this a while, maybe over 1000 miles, I don't use it much and have compensated by getting petrol when car is cold and so on. Slightly mad 'solution'...was going to get it replaced at service time...

However, CEL has now come on, presume that the Crank Position Sensor has deteriorated further/about to fail.

Car did seem to run slightly lumpy at idle prior to light coming on during same journey.

Quoted under £200 for replacement from Specialist inclusive of VAT etc, further charge for hooking up to Diagnostics, though I am confident it is CPS...

Thoughts, advice appreciated. Thank you

Car is a 2005 SLK55 R171 with the M113 V8
Could well be the CPS. Get yoursefl a cheap OBD reader and get the codes. I have this one and it works perfectly well https://www.amazon.co.uk/gp/product/B07RQCP5PY

It is not too difficult to replace the CPS yourself but you will swear - not much room to manouvre, and once your hand is near the CPS you can't see what you are doing. If I'd needed to change it again before I sold the car I'd be much quicker though.

I think a new Bosch one cost me about £25 and I also had to buy a Torx bit or something to fit it. There are some good 'How To' guides on SLKWorld.com
Thanks for info about OBD reader and DIY approach - much appreciated.

I think that having looked at this job there is a recurring theme of small hands being required, things in the way, swearing etc. I will be outside and don't have the time at present when I am home.

My thoughts are pay to get it replaced, it is a common fault. If it isn't that then I'll either pay extra to get it scanned or more likely get an OBD as you've mentioned here. £75 is a bit too much for a scan but £20 for an OBD if it still shows a fault is better.



BlimeyCharlie

902 posts

142 months

Thursday 2nd November 2023
quotequote all
gregpot2000 said:
I am pretty certain I have this issue also, along with very occasionally cutting out at speed which has thankfully only happened in quiet situations so far!

My car is now hibernating for winter, it's a job I'm planning on doing when it comes out for spring again.

One tip I do have though, if it is the same issue as mine, is that I managed to almost completely eliminate the warm start issue by just being slower with the key, I found if I tried to start the car straight away as normal it would almost always fail, where if I turned it to the "lights on" position, then waited around 10 seconds before final turn, it was almost always ok
Very interesting stuff - thank you.

I think I've just took the 'safe' route which is never even try to start it when hot, which obviously limits journeys - hedge-based 'comfort break' must be somewhere safe to leave engine running for example!

Since the amber 'Engine Management Light' (EML) came on earlier this week I just decided it needs doing asap.
Did/has your EML come on? My car has never cut out though.

Originally started playing up about a year/1000 miles ago.

Thanks again for info.

samoht

5,698 posts

146 months

Thursday 2nd November 2023
quotequote all

When my M113 CPS started failing it did show the EML, yes.

The other thing was I'd arrive somewhere and either be sat with the engine idling for a few secs or be parking up and it would cut out and refuse to restart until cool.

Had the CPS replaced and zero issues since.

BlimeyCharlie

902 posts

142 months

Thursday 2nd November 2023
quotequote all
samoht said:
When my M113 CPS started failing it did show the EML, yes.

The other thing was I'd arrive somewhere and either be sat with the engine idling for a few secs or be parking up and it would cut out and refuse to restart until cool.

Had the CPS replaced and zero issues since.
Thanks, sounds like hopefully I'll be at a solution soon.

Mr M

1,272 posts

202 months

Saturday 4th November 2023
quotequote all
[quote=gregpot2000]I am pretty certain I have this issue also, along with very occasionally cutting out at speed which has thankfully only happened in quiet situations so far!

I had the cutting out at speed issue too and that was after a CPS replacement. Flooring the accelerator seemed to get it going again. Not a nice feeling at 50mph on a heavy front ended car and thankfully it didn't happen at higher speeds. I've not had the problem since I moved house and the car resides in a dry garage. Previously I had no garage and had to keep it under a cover, which deterioated after a couple of years. Still don't know the cause of it though but I also recall there was a suggestion it could be an issue with the accelerator pedal communication.

Edited by Mr M on Saturday 4th November 10:17


Edited by Mr M on Saturday 4th November 10:18

BlimeyCharlie

902 posts

142 months

Tuesday 7th November 2023
quotequote all
Thanks for all recent replies.

Recent development;

Last summer battery was dead when I'd cleaned the car and had doors open etc etc.
Charged it up, all ok.

Then 6 weeks ago wouldn't start after being left for 10 days.
Charged up, knowing battery probably on last legs.

Last night wouldn't start after sitting for 7 days. Jumped it, as needed to move it. No 'Engine Management Light' (EML) on but car didn't get up to temp.

Bought and fitted new battery this afternoon.

Ran car for 40 minutes, up to temp. No starting issues whatsoever. Tried starting 5 or 6 times. Starts fine, no problem. Left car for 5 mins, starts fine. No EML.

Will take it for a proper run tomorrow, see how it is and report back here.

The battery in the car since I've owned it was the wrong capacity -it was a Bosch S4 007 and should be an 096.
Replaced today with correct capacity battery. Time will tell if I've cured what is/was CPS issue.