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85 500SEC (Euro), 87 560SEC (now sold)
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1,787 Posts
I'm surprised at off the line puny. But it moves well on the highway?

Have to agree about the seats. The ones in my SE in particular, are just amazing. You can literally just jump out of the car after a long journey. So spacious but supportive.

The creaking can absolutely ruin the car! Hate it, but an easy fix.
It absolutely moves on the highway. I had no problems at all with that, which is surprising when you consider how large the car it. It's clearly designed to be at it best on the highway. Absolutely no complaints whatsoever.
 

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1987 & 1991 C126
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5,740 Posts
The only driveability issues I’ve had with my C126s have been intermittent hard start cold, misfiring at idle, and stumbling at times on acceleration.

In 2004 this was some corroded/loose spark plug suppressors found when I replaced the plugs & wires. Easy Peasy!

In 2017, my newly acquired 500SEC started having intermittent idle misfires and I found loose corroded plug suppressors. I changed out the plugs and for reason or other just swapped the plug wire ends one car to another. Both cars ran fine!

Until yesterday 2021, my 560 started the intermittent idling misfire and stumbled on acceleration at times

De ja vu all over again!

Yep I found some corroded and loosely attatched plug ends… again.

Today I learned to screw the connector onto the plug as I was pushing it home… sounds nuts yes, but in two cases, for whatever reason, the connector clicked down onto the plugs another quarter inch!

The car starts and once again starts & runs smoothly! Yay!

A simple fix.

It’s in the drive for it’s outside damp cold start tomorrow morning. I bet its

M
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On both, that’s dielectric grease from the last time & I might have been more careful really.
Won’t happen again.
 

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85 500SEL
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201 Posts
She’s out of the garage. Started washing her the last couple of days, seems to be a dust magnet in the morning. Not ready to daily drive yet, still have to get the fuel tank resealed. I have a new pump to put on, waiting for the accumulator and new fuel filter.
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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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5,303 Posts

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Registered
1990 Mercedes-Benz 300SE (W126) In Astral Silver with Dark Blue Leather Interior
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117 Posts
The only driveability issues I’ve had with my C126s have been intermittent hard start cold, misfiring at idle, and stumbling at times on acceleration.

In 2004 this was some corroded/loose spark plug suppressors found when I replaced the plugs & wires. Easy Peasy!

In 2017, my newly acquired 500SEC started having intermittent idle misfires and I found loose corroded plug suppressors. I changed out the plugs and for reason or other just swapped the plug wire ends one car to another. Both cars ran fine!

Until yesterday 2021, my 560 started the intermittent idling misfire and stumbled on acceleration at times

De ja vu all over again!

Yep I found some corroded and loosely attatched plug ends… again.

Today I learned to screw the connector onto the plug as I was pushing it home… sounds nuts yes, but in two cases, for whatever reason, the connector clicked down onto the plugs another quarter inch!

The car starts and once again starts & runs smoothly! Yay!

A simple fix.

It’s in the drive for it’s outside damp cold start tomorrow morning. I bet its

M
View attachment 2716800 View attachment 2716801


On both, that’s dielectric grease from the last time & I might have been more careful really.
Won’t happen again.
Dielectric grease is one of the best tips for ease of installation & removal of M/B HT Leads on both the distributor & the plug ends.
I reckon a good 25% of the "Misfire" issues posted about w126's on this forum could be solved by new leads... All it takes is trying to pull a boot off a plug from a little high up ONCE & the lead becomes disconnected between the boot & the cable subsequently causing intermittent misfire. Usually they'll seem fine while under load because the RPM's are fast enough to not notice the miss & the current from the coil is firing strong enough to jump the break in the line but becomes very noticeable at idle or at low RPM's.
First thing I do with every M/B I've owned is all new: HT Leads (with dialectic on both ends), Plugs, Coil, Distributor & Rotor Button. They invariably run substantially better for it.
 

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1985 MB 500sel (Euro)
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846 Posts
I appreciate all the good tips that are on the W126 forum like the above and usually print them out (like this one) or make notes of the names of recommended products (like the water pumps on today's Time for a new water pump thread. Thanks all, or as my new Swedish mechanic would say "Tak."
"
 
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Moderator
1987 & 1991 C126
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5,740 Posts
Dielectric grease is one of the best tips for ease of installation & removal of M/B HT Leads on both the distributor & the plug ends.
I reckon a good 25% of the "Misfire" issues posted about w126's on this forum could be solved by new leads... All it takes is trying to pull a boot off a plug from a little high up ONCE & the lead becomes disconnected between the boot & the cable subsequently causing intermittent misfire. Usually they'll seem fine while under load because the RPM's are fast enough to not notice the miss & the current from the coil is firing strong enough to jump the break in the line but becomes very noticeable at idle or at low RPM's.
First thing I do with every M/B I've owned is all new: HT Leads (with dialectic on both ends), Plugs, Coil, Distributor & Rotor Button. They invariably run substantially better for it.
You are SO right there!

That is the very first thing I did to the all new to me 560 that spring.

Yesterday, I was waxing on about turning the connectors to the right as I pushed them into place.

Well today, I can tell everyone dielectric grease, a little, on the rubber sleeve inside the MB plug connector makes ALL the difference!

Literally night & day as to results generated.

Over & Out!

MBL
 

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Registered
1990 Mercedes-Benz 300SE (W126) In Astral Silver with Dark Blue Leather Interior
Joined
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117 Posts
You are SO right there!

That is the very first thing I did to the all new to me 560 that spring.

Yesterday, I was waxing on about turning the connectors to the right as I pushed them into place.

Well today, I can tell everyone dielectric grease, a little, on the rubber sleeve inside the MB plug connector makes ALL the difference!

Literally night & day as to results generated.

Over & Out!

MBL
....and right you were about the "twist" that makes the difference.
Both getting leads on and off but there's nothing more reassuring than hearing/feeling that "click" after the twist that ensures the lead is securely connected to the plug.
I think it's very easy to think "well it's very high voltage, surely if there's 1mm gap it won't make much difference" but Mercedes tuned these machines to the enth degree, working under the assumption of all components being properly installed. So you add a gap at the plug to a torn boot on the distributor end & an EHA that's contacts are "glazed" in petrol film... Of course she ain't gonna be running too well!!
 
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