Help please...my 1994 c280 is failing to start after a run..always ok when cold..go to the shops...dead!..iKnow when its not going to start because the fuel pump cannot be heard and other clicks from relays are not heard.I dont think its the fuel pump/relay as its fine once running.of couse if i remove the relay it will start but die.this is not the symtom..it is completley dead..leave it alone and it will eventually start..very embarrasing at busy fuel station.....took half an hour to get started.I unplugged the rearmost black box in the engine bay and this gave the same symtom.(gulp).are the e.c.u,s known for trouble? any ideas please.a wiring diagram would help.
c280 intermittant starting trouble
- Thread starter jeff.egan
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Common and east repair....its likely that your OVP relay...Over Voltage Protection relay is on its way out.
Cost about £45 and takes 10 minutes to replace.
Do a search for OVP and you're likely to get loads of posts.
Cost about £45 and takes 10 minutes to replace.
Do a search for OVP and you're likely to get loads of posts.
teky
Senior Member
my question is "why is it always the ovp" i know its a cause for concern due to poor quality item ( which i think its time for Mb to address ) but we must look to whats in front or before the ovp like the alternator, the ovp is there to protect voltage flash which save the ECU/computer "which last a life time" or should, i personally would be looking for corroded wires/bad earth/ground
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Thanks for the advice. Is the the OVP the tall silver relay with the fuse on top? cos i took the fuse out and the ABS warning light came on.errr??? then i took all of the relays out of the box next to the fuse box..it still started...so i would appreciate a point in the direction of the OVP.perhaps there,s big writing on it that says,"OYE,THIS IS THE OVP YOU PLONKA"....when iv,e found it i,ll post the result,,thanks,.
Teky,
9 times out of 10, the OVP is normally the culprit behind rough running, stalling on the m104 engine.
The original OVP's were manufactured with a design flaw in them and over time the internal soldering starts to break down and cause intermitent faults.
If people still have a car running with the original OVP relay, it will fail...its just a case of when.
With this in mind, it's always advisable to change the OVP and if problems persist to them start to look at other causes for the problem.
In terms of location Jeff, its up infront of your ECU's and is a silver relay about 3" high with a fuse in the top....dead easy to replace.
9 times out of 10, the OVP is normally the culprit behind rough running, stalling on the m104 engine.
The original OVP's were manufactured with a design flaw in them and over time the internal soldering starts to break down and cause intermitent faults.
If people still have a car running with the original OVP relay, it will fail...its just a case of when.
With this in mind, it's always advisable to change the OVP and if problems persist to them start to look at other causes for the problem.
In terms of location Jeff, its up infront of your ECU's and is a silver relay about 3" high with a fuse in the top....dead easy to replace.
- Thread Starter
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- #7
Mjtray,Thanks for the info and advise.I managed to track an OVP down and have just fitted it.The car starts ok (about 20 times without a fault).So,its just a matter of time to tell if the cure is good.
While on the subject,it may be worth noting that the original OVP was a Siemens with a merc part number:000540 52 45.The replacement was made in Hungary,is slightly shorter,and carries a merc part no:000540 67 45.so i guess its a different make..The parts people said that the part no i gave was a good one but they did not stock it.
I also noticed that the date of manufacture was13/02/04.so perhaps in their wisdom,Mercedes have changed the supplier.oh well ,here,s hoping.
While on the subject,it may be worth noting that the original OVP was a Siemens with a merc part number:000540 52 45.The replacement was made in Hungary,is slightly shorter,and carries a merc part no:000540 67 45.so i guess its a different make..The parts people said that the part no i gave was a good one but they did not stock it.
I also noticed that the date of manufacture was13/02/04.so perhaps in their wisdom,Mercedes have changed the supplier.oh well ,here,s hoping.
Myros
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ovp relay
For my money, it was definitely the OVP. Thanks MJTray, I managed a nice spot of leave on the continent courtesy of your advice. Not one single stranding since I replaced it. My replacement is also Hungarian in origin and seems to be doing the trick. I would have been waiting for the next untimely failure if you hadn't helped. I have to say MB weren't fantastic about volunteering the design-fault nature of the OVP themselves, and left me none the wiser until I discovered this forum.
For my money, it was definitely the OVP. Thanks MJTray, I managed a nice spot of leave on the continent courtesy of your advice. Not one single stranding since I replaced it. My replacement is also Hungarian in origin and seems to be doing the trick. I would have been waiting for the next untimely failure if you hadn't helped. I have to say MB weren't fantastic about volunteering the design-fault nature of the OVP themselves, and left me none the wiser until I discovered this forum.
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- #10
Well,three days into the replacement OVP,many starts and no failures.
looks as though this little monster has been put to bed...HOWEVER,another awkward little monster i have to cure is that of Kickdown. If i use the kickdown,say to overtake,the gearbox seems to change down to 2nd,even at around 60 mph.which under normal use, in E mode,is a little over the top. It will change down to 3rd manually which is a lot less stressful on the engine.Could this be another relay problem or something out of adjustment???? or is it likely to be something horrible like a sticking govenor or worse. Your comments please.
looks as though this little monster has been put to bed...HOWEVER,another awkward little monster i have to cure is that of Kickdown. If i use the kickdown,say to overtake,the gearbox seems to change down to 2nd,even at around 60 mph.which under normal use, in E mode,is a little over the top. It will change down to 3rd manually which is a lot less stressful on the engine.Could this be another relay problem or something out of adjustment???? or is it likely to be something horrible like a sticking govenor or worse. Your comments please.
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