260E - Any suggestions - Alarm and Lumpy running

[Daniel T]

Hi All,
I'm very chuffed with my new aquisition- a D reg 260E Auto with 50K on the clock, but I'd appreciate any previous experience anyone has had with alarm problems- it has armed itself, and no matter which key I use on which door, to unlock or lock the car, every time I unlock it, off it goes. My neighbours are about to kill me.

The other concern is lumpy running at tick over, warm or cold. The tick over is set at 500-700 RPM, which seems a bit low?

 

[Anonymous]

260E - Any suggestions

I think this is the M103 engine?  If so I have the same problem with my 1986 300SL also the M103 engine.  Problem gets worse at idle in drive due to slight drop in RPM.  I have decide its an injection problem and shall have the injectors professionally cleaned.  Hope this helps

 

[Daniel T]

260E - Any suggestions

Hi Barrie,

The rough idle problem was solved by replacing my air mass intake seal, which had split, and the garage "adjusting the regulating System" whatever that means- it took 0.9 units of labour whatever it was! I assume it was idle mixture/ emissions etc. My fuel consumption is fine at 28mpg.

Solving it has brought into focus a more tricky problem though- warm starting. I have to crank the engine for 20-30 seconds before it catches, but it only happens the engine is warm, not hot or stone cold. The car has a history of it, having had the fuel pump replaced, the dist. cap/ rotor and sparks/leads  being checked, replaced where necessary, and the injector nozzles remove/install/replaced as necessary (before I owned it) Redex injector cleaner hasn't actually made that much difference, and next is checking the ingition timing and playing aroung with the trimming plug.

All fun and games!

Dan- 52K '86 260E

 

[RobNelson]

260E - Any suggestions

My 260E (1988, 142K miles) has to be cranked for 20 to 30 seconds when COLD, but is fine when warm/hot.
All the HT leads, dist cap etc etc have been replaced to no avail....

Provided it starts I just live with it!!!

Rob.

 

[G4VSQ]

260E - Any suggestions

Hi Daniel,

It's very welcome to hear from another 260E owner. I have a Smoke Silver "F" reg 260E with 150, 000 miles on the clock. I have spent large sums of money on the car in the last 6 weeks getting it into good order.

My car also has a lumpy tickover, but this was much improved by (firstly) replacing the engine mountings, as they had collapsed, and so the engine was jumping about a bit! This gave the impression of things being far worser than they were. My car also needed a new distributor cap (at huge expense-over £50!) as well. It's still a bit shuddery, but from what I read all over the MB sites both here and in the US, this is common "feature" and unless there's something actually faulty, as in your case, you just have to live with it.

My car is OK to start both hot and cold and in between. The thing to remember is that you should NOT press down on the accelerator pedal when hot or cold, initially anyway. If the car doesn't start after 4 seconds of cranking when hot, then the owner's manual I have advises you to press the pedal all the way to the floor until the car fires. Also, if the coolant temperature is high, then you CAN gradually press down on the accelerator whilst cranking. I must admit the 260E is so different to all the other generally rubbish cars I owned before (mostly Nissans, which started at the first turn of the key) that the amount of effort needed to start it is rather worrying at first. After a bit, you get used to it!

The idle speed sounds correct-my manuals list it as 650rpm.

The 260E is a really nice car. I love mine. There are a few things to watch out for:

1) Viscous coupling for the fan failing. Mine has done this. It's a good system in theory but seems to be less than perfect in practice. The symptoms are that the car is fine when moving but if you get stuck in stop-start traffic for some time it gets HOT-and the fan doesn't increase speed when it should do. I was forced to turn on the heater in my car when caught like this to dump the excess heat and on a VERY hot day. Phew!

2) Juddery brakes. It's a big car and the discs warp and wear quite fast. The feel of the brakes can be changed for the worst if nasty cheap pads and discs are used. Mine felt hard and inefficient-with new genuine pads and discs it's superb.

3) Oil leaks. There's usually one from the front of the engine. Don't worry about it (unless it gets REALLY bad!)
The car will probably use a bit of oil-this is OK, according to Mercedes it can use 1.5L in 1000 kms and will still be fine!

4) Head gasket failure. Apparently, some of the head gaskets on the early 260E's weren't up to normal quality standards and could fail.

5) As could valve guides on early cars. A lot of these were replaced under warranty. But not all (and the valve stem oil seals harden as the car ages, and it can then start smoking). Common fault.

At just 50k, your car is a real find, I hope it has some sort of service history. If not, then try to get all the work done on it, like changing differential oil, ATF fluid and filter, oil and filter to give it a fighting chance.

I do sincerely hope you like your 260E as much as I do mine. All the best!