Mercedes W114 250 Coupe - help!

[guydewdney]

If "HERMAN" doesn't exist then another accessible solution might be a toothed wheel and sensor bolted to the front of the crank'pulley

I think you misunderstood - the socket was for the equivalent of STAR (called Herman) - but had a wire to a CPS pre installed.

 

[John Jones Jr]

I've had a car (a converted BMW 2002tii) with a sensor mounted to run off the crank - it was a disaster, the bracket holding the sensor on cracked on two occasions (hello hard shoulder from overtaking lane at speed), and then a forged one was fitted which lasted a bit longer, until that one went. That car broke down some 6 times in my ownership, all bar one were caused by the mods being done badly - the one that did was the workshop forgot to re-connect the alternator to the battery after refitting the sensor! The Dutch guy who did my SM started with the same route on his experiment, had similar issues, so decided if you are going to fit a sensor, do it where the manufacturers do - the flywheel.

Personally, I'd have no issues with using a front crank mounted sensor, I even know a few people & a garage owner who have gone this route without any reported problems and it's very common & accepted practice generally. Then again it depends very much on how it's been installed/mounted - mounting brackets cracking is just poor design/installation.

 

[Charles Morgan]

Back to the car itself, popped over this morning to start moving the important trim bits. Of course, since it had been put in, a large bush had grown up blocking the garage door. So down with that.

The rear bumper and the front bumper had been put into the car itself, clearly before the model railway had been built to the side. Apart from them being very large and awkward shapes, they weigh a blinking ton. Muggins here managed to manoeuvre them out without damaging the car, Tony or himself.

The state of the car now reveals itself. Rear seats nowhere to be seen, carpets mostly missing. It turns out to be a proper manual (Tony had said it was column shift) which is a considerable improvement. Underneath is all fine, lots of tiny rust spots but nothing major on the bits of paint at the rear. The door cards are stunning - except for broken plastic top on the driver's door side bin.

Anyway, despite a lengthening part bill (of course it would be) it is immense fun sorting. Tony is a hoot and he showed me the compressor he offered to me - this is an immense commercial one he used for car painting before. I can see I'm going to need a garage annex somehow!

 

[John Jones Jr]

I can see I'm going to need a garage annex somehow!

Ah, a new thread beacons!

 

[grober]

Short /8 documentary

Enjoy!
[YOUTUBE]hUwax13Ddtw[/YOUTUBE]

 

[grober]

http://alabbasi.com/backup/Merc_114.pdf
and
http://stroke8.org/autocar280CE.html

 

[grober]

 

[grober]

Great pictorial thread on a megasquirt conversion on a slightly later JETRONIC K SYSTEM on a 280 SL M110 twin cam engine. Mercedes-Benz M110 engine - Wikipedia, the free encyclopedia

the thread
280SL "K-Jet and Ignition conversion to Megasquirt" write up - Mercedes-Benz Forum

 

[Charles Morgan]

I'd stumbled across that conversion thread - it's immensely helpful. His analysis of the post installation benefits are just spot on from my experience with the SM. Within the constraints of a 50 year old engine design you are getting 95% of what a new engine would deliver.

Again, many thanks Graeme, my W114 useful weblink directory grows ever larger, as does my awareness of the scale and costs of the task!

 

[Bellow]

Thanks Charles, this is a fantastic thread that can only improve once you commence work on the W114.
The eye opener though was your early comments on fitting Megasquirt to the SM.

His analysis of the post installation benefits are just spot on from my experience with the SM. Within the constraints of a 50 year old engine design you are getting 95% of what a new engine would deliver.

And further alluded to above.
I'd only thought of Megasquirt in terms of tuning an engine beyond its own fuel system's constraints but the opportunity to make an older car much more fuel efficient (typically the downside of an older car) is one that definitely needed further publicity. Thanks again.

 

[Druk]

the thread
280SL "K-Jet and Ignition conversion to Megasquirt" write up - Mercedes-Benz Forum

Thanks for this link Graeme. What a great read.

 

[grober]

I'd stumbled across that conversion thread - it's immensely helpful. His analysis of the post installation benefits are just spot on from my experience with the SM. Within the constraints of a 50 year old engine design you are getting 95% of what a new engine would deliver.

Again, many thanks Graeme, my W114 useful weblink directory grows ever larger, as does my awareness of the scale and costs of the task!

Just like the idea these early analogue systems can be tinkered with or improved to keep these old cars running. This is the definitive site for the D system ECU electronics. actual discrete electronic components hardly a chip in sight --who'd have thought. The waveform analysis is way above my head but the pictures are nice. Best to regard it as a black box I think Has some useful links too.
The ECU

 

[Charles Morgan]

My first task having collected all the trim bits is to start cleaning them. My one and only rule being First do no avoidable harm to my wallet. I'm also photographing everything I can so I know where it all fits. As parts are cleaned they will be labelled, a list drawn up of each part needing replacement, and then wrapped and boxed.

Headlights are pretty mucky.

Getting the lenses out revealed this - both sidelight and main beam reflectors on the first lens need replacing or re-silvering. Neither option cheap!

 

[Charles Morgan]

Thanks Charles, this is a fantastic thread that can only improve once you commence work on the W114.
The eye opener though was your early comments on fitting Megasquirt to the SM.



And further alluded to above.
I'd only thought of Megasquirt in terms of tuning an engine beyond its own fuel system's constraints but the opportunity to make an older car much more fuel efficient (typically the downside of an older car) is one that definitely needed further publicity. Thanks again.

My original experience with using a replacement ECU and mapping was entirely for performance gain on a BMW 2002tii that had been fitted with an Omex ECU. The guys who did it did a great job in optimising the driveability of the car, but it was only when I was exploring options for improving upon the rotten D Jet on my SM that I stumbled across the Dutch SM specialist who had been experimenting on his own car for five years or more, having got totally fed up with an ageing system that was perpetually going wrong. Being a bright guy, an engineer as much as a technician, he persuaded me of the merits on a research trip. While some minor performance gain might be possible with better injectors than the original, the reality of the performance improvement was right across the range until fully open throttle, in which case there was little.

I think by doing that work I have future proofed the car, and am no longer reliant upon elderly technology and components (plus an ever decreasing pool of experience - my Citroen indy was the mechanic at Citroen UK responsible for training UK mechanics on D Jet and he's now 68!).

 

[grober]

Despite their reputation for engineering excellence Mercedes corrosion protection like many other manufacturers back then left a lot to be desired!

 

[Charles Morgan]

Oh yes! The reflector corrosion on the back is superficial, but judging by the state of the interior someone has had a go at cleaning the silvering with a heavy hand. A gentle touch with the paint brush and the silvering is coming off like glitter - I suppose at 46 my glitter was fading somewhat too!

 

[nick mercedes]

Oh yes! The reflector corrosion on the back is superficial, but judging by the state of the interior someone has had a go at cleaning the silvering with a heavy hand. A gentle touch with the paint brush and the silvering is coming off like glitter - I suppose at 46 my glitter was fading somewhat too!

DBdepot sell the reflectors:

https://www.dbdepot.de/index.php?nav=4&lan=2&

 

[Charles Morgan]

Found some on MB classic too (for some reason DB depot's site is hanging). I think the big bowls need replacing but the small side light ones (totally useless anyway) can be done with foil tape.

 

[nick mercedes]

Found some on MB classic too (for some reason DB depot's site is hanging). I think the big bowls need replacing but the small side light ones (totally useless anyway) can be done with foil tape.

https://www.niemoeller.de/w115-en/B115-47.html

Niemoeller too, 115 bits have got rather more expensive than they use to be...

 

[grober]

A good article on the Manifold Pressure Sensor principles of operation and repair found on the Bosch jetronic D system. It would be a brave man who would take one apart but you have to marvel at the watchlike electromechanical precision mechanism all the same!
The Manifold Pressure Sensor