dbanbery
Senior Member
- Joined
- Nov 11, 2008
- Messages
- 1,206
- Reaction score
- 76
- Location
- Huddersfield
- Your Mercedes
- 1995 R129 SL500
a re-occurring issue i am sure with the community of people running the M119 with twin distibutor/rotor setup i am sure.
as some may know i have had my car about 2-3 years and have only recently gotten round to doing the distributor caps.
i had a massive paranoia over a year ago when i hadnt run the car for ages, started it up, took it down the road and it ran terribly, stalled, and then wouldnt restart. this was traced back to moisture in the distributor caps which were cleaned out and bingo! no more problems.
on investigating this, i found that the set of caps were not matching. there was one bosch cap and one beru, with a bremi rotor and a bosh rotor. the beru cap was in considerably worse condition than the bosch one, but cleaned up and worked okay for another year. whenever the car had been laid up i would check them, or if i was going on a long motorway drive, let it run badly when it got warm and then it would work itself out of it eventually.
About a month or two ago i was travelling back from shrewsbury [about 100 mile journey and it started to randomly miss a little more than normal [the odd actual jerky thud under throttle]. it always missed ever so slightly when warm [slight dip in tickover], and i put that down to the EGR sensor and/or the old caps.
i took the plunge and bought a set of brand new bosch items for both the caps and the rotors, which i managed to get for a good price imported from germany. when i fitted these i did two things, one - i re-routed the igniton leads as they were a total mess, and two - accidentally refitted the old bosch cap i had on the other side of the engine and nearly threw the new one away! [facepalm] the car started and ran fine on the old cap from cold. when i realised my error i switched off and replace it with the new one. it started and ran clear on cold, and warmed up slightly, and when it started to warm up more, it started randomly missing, to the extent it would actually stall, and when it was test driven it was borderline undrivable. on the motorway it would work fine and then be terribly intermittent. we did 5 miles on the motorway on a test and then pulled off, and switched the second cap back over with the old one, and it worked fine, save for that slight miss on tickover that had returned. then a week later it started doing it again and i replaced the old one with the new one AGAIN and re routed the coil-cap leads. it now has its periods of hesitation but its markedly better than it was before.
oberservations.
all leads bar the cap-coil leads seem recent. the cap-coil leads are considerably stiffer than the others in places, due to age I imagine. you cannot buy these leads from mercedes, you have to buy the cable by the metre, the two different caps and the sleeves.
distributor caps and rotors are band new, the spark plugs are brand new and replaced the same time as the rotors. the old ones werent knackered, but they were 2 years old and i have fitted the correct F8DC4 bosch plugs now. it had new air filters also, and i have replaced the oil filter. [not the oil, the oil is a year old oil and still a good colour and 4000 miles into its life, [i may do it in the new year anyway] the distributor cap bowls were sealed to the cylinder heads when i replaced the caps to stop moisture getting in. everything was dry
there was a slight amount of metal dust when i cleaned it out a second time, which i thought to be remnants of having to dremel a groove in one of the old allen bolts on the old rotor arm on the one side. annoyingly enough the heads of the new bolts rounded really easily so they are stuck on. i think this might have interfered with the running of the car slightly.
no error messages. no smoke. it doesn't use oil at all.
i have deduced from all of this that what may cure the issue was to replace the coil leads,which seems to be a bit of a mission. the process of elimination is such that re-routing the leads, and the new rotors are the actions that have changed the running problems. the other running issues have gone - IE the slight hesitation on tickover... that u can see anyway. when she runs properly its more responsive, and sounds and runs perfectly, but when shes bad, its been awful at times.
i have a length of the mercedes cable, but am unwilling to dismantle the existing leads to replace the cable only. the other option is to buy the replacement components to make the leads, but i dont have the pliers to do it, and they are £135 from mercedes!
so what do people suggest? the only other thing is replacement of the engine wiring loom, which could be expensive. this is a 1995 car, so some of the wires could be brittle. is the special set of pliers actually special? or can i buy a set of typical pliers for £20 instead of £135?
as some may know i have had my car about 2-3 years and have only recently gotten round to doing the distributor caps.
i had a massive paranoia over a year ago when i hadnt run the car for ages, started it up, took it down the road and it ran terribly, stalled, and then wouldnt restart. this was traced back to moisture in the distributor caps which were cleaned out and bingo! no more problems.
on investigating this, i found that the set of caps were not matching. there was one bosch cap and one beru, with a bremi rotor and a bosh rotor. the beru cap was in considerably worse condition than the bosch one, but cleaned up and worked okay for another year. whenever the car had been laid up i would check them, or if i was going on a long motorway drive, let it run badly when it got warm and then it would work itself out of it eventually.
About a month or two ago i was travelling back from shrewsbury [about 100 mile journey and it started to randomly miss a little more than normal [the odd actual jerky thud under throttle]. it always missed ever so slightly when warm [slight dip in tickover], and i put that down to the EGR sensor and/or the old caps.
i took the plunge and bought a set of brand new bosch items for both the caps and the rotors, which i managed to get for a good price imported from germany. when i fitted these i did two things, one - i re-routed the igniton leads as they were a total mess, and two - accidentally refitted the old bosch cap i had on the other side of the engine and nearly threw the new one away! [facepalm] the car started and ran fine on the old cap from cold. when i realised my error i switched off and replace it with the new one. it started and ran clear on cold, and warmed up slightly, and when it started to warm up more, it started randomly missing, to the extent it would actually stall, and when it was test driven it was borderline undrivable. on the motorway it would work fine and then be terribly intermittent. we did 5 miles on the motorway on a test and then pulled off, and switched the second cap back over with the old one, and it worked fine, save for that slight miss on tickover that had returned. then a week later it started doing it again and i replaced the old one with the new one AGAIN and re routed the coil-cap leads. it now has its periods of hesitation but its markedly better than it was before.
oberservations.
all leads bar the cap-coil leads seem recent. the cap-coil leads are considerably stiffer than the others in places, due to age I imagine. you cannot buy these leads from mercedes, you have to buy the cable by the metre, the two different caps and the sleeves.
distributor caps and rotors are band new, the spark plugs are brand new and replaced the same time as the rotors. the old ones werent knackered, but they were 2 years old and i have fitted the correct F8DC4 bosch plugs now. it had new air filters also, and i have replaced the oil filter. [not the oil, the oil is a year old oil and still a good colour and 4000 miles into its life, [i may do it in the new year anyway] the distributor cap bowls were sealed to the cylinder heads when i replaced the caps to stop moisture getting in. everything was dry
there was a slight amount of metal dust when i cleaned it out a second time, which i thought to be remnants of having to dremel a groove in one of the old allen bolts on the old rotor arm on the one side. annoyingly enough the heads of the new bolts rounded really easily so they are stuck on. i think this might have interfered with the running of the car slightly.
no error messages. no smoke. it doesn't use oil at all.
i have deduced from all of this that what may cure the issue was to replace the coil leads,which seems to be a bit of a mission. the process of elimination is such that re-routing the leads, and the new rotors are the actions that have changed the running problems. the other running issues have gone - IE the slight hesitation on tickover... that u can see anyway. when she runs properly its more responsive, and sounds and runs perfectly, but when shes bad, its been awful at times.
i have a length of the mercedes cable, but am unwilling to dismantle the existing leads to replace the cable only. the other option is to buy the replacement components to make the leads, but i dont have the pliers to do it, and they are £135 from mercedes!
so what do people suggest? the only other thing is replacement of the engine wiring loom, which could be expensive. this is a 1995 car, so some of the wires could be brittle. is the special set of pliers actually special? or can i buy a set of typical pliers for £20 instead of £135?
