1990 Mercedes 300SE (W126)

[Knugcab]

Seems like a nice example.

I would stick to yellow indicators too.

[Onne]

Thanks, I am sticking to yellow (at least for the moment)

Got myself a new rear bumper, and a front one too (not sure that'll fit though, it's a SEC chrome.
Need to sort out the leaky fuel pump too, might make it easier to start in the morning!

[khimanimohiki]

the bumpers are a royal pain to take apart, all of the special little fasteners will probably need chiseling off. I know the saloon front chrome will fit on a SEC but I'm not sure if it will work the other way round as the SEC chrome doesnt have the recess for the grill.

[Onne]

I'm not looking forward to the rusty bolts... but I'll live, at least I have some spare joiners...

[splendidmcawesome]

Hi - I've also just bought one of these, and am waiting for it to come back from its LPG conversion...it'd be interesting to compare notes!

Jobs to do on mine so far are:

New alternator - intermittent voltage fries bulbs and causes battery to boil on long runs

Replace wooden trim around gearbox (current piece cracked and painted by previous owner to cover up the crack!)

New thermostat

...and that's about it. Loving the rest of it!

[stwat]

Mar 23, 2011 17:24:54 GMT splendidmcawesome said:

Hi - I've also just bought one of these, and am waiting for it to come back from its LPG conversion...it'd be interesting to compare notes!

Jobs to do on mine so far are:

New alternator - intermittent voltage fries bulbs and causes battery to boil on long runs

Replace wooden trim around gearbox (current piece cracked and painted by previous owner to cover up the crack!)

New thermostat

...and that's about it. Loving the rest of it!

The alternator problem will simply be the voltage regulator which can be bought seporatley and is a simple bolt off bolt on job.
No need to replace the whole alternator at all.

[splendidmcawesome]

Yup, bang on - regulator now replaced and running smoothly.

Thanks!

Now, if only I could stop it stalling 50% of the time when I slow down to a halt...it's been suggested that it's the overvoltage protection relay failing to supply 12v to the idle control valve. Any other ideas welcome...

[levismerc]

Hmmm, on the 280 engines theres a biggish plastic idle speed control screw that can be given a tweak. If the 300s are bosch kjet (I think they are) then you should be able to do something similar. On the 280s it's mounted on the front of the inlet manifold area under the air filter.

Might be worth investigating?

[Little eddie]

Hmm seems like theres a few merc fans on this thread, maybe one of you knows what the problem is / was with my merc 300se.

Basically it wouldnt change up out of 1st gear so was limited in speed to around 20mph. I tried changing the gearbox filter and fluid but to no avail.

The weird thing is before this merc i also had a 1978 350se (was pictured on here some time ago at santa pod in white) and exactly the same thing happened to this as well!!!

Any ideas?

[Onne]

Just thought I'd quickly update this one, I've replaced the fuel pump over the weekend, it was on its way out and leaking.

Tip, don't do change the fuel pump with a full tank of petrol, it does run out fairly quick!

Starting on the button again now, which is lovely!

[Onne]

Another update, no picture though...
I've serviced the car, biggest challenge was to find a big enough container to collect the 7,3 litres of oil.
Tried to change the plugs, is there a trick to getting the HT leads off? I managed nr 1 and 2, but thats about it, don't really want to hoik them off in case they say snap/crack/bang

Cheers

[stwat]

7.3 litres ? Mine takes bang on 6 litres.

To get the plugs leads off the plugs use a pair of needle nose pliers on the crimped part of the metal end. Once off spray some silicon spray in to each one and they will simply pop off by hand in future.

[Onne]

I'm sure it was something along those lines oil wise... How to get to that crimped part though, isn't that almost on top of the plug?

good point about the silicon though, I'll try that.

Cheers

[stwat]

If you look at the metal part of the cap where it clips on to the plug you will see the crimped parts around the edge. Grip onto that part with the needle nose pliers and gently move from side to side while pulling and they will pop off.

Don't as I have done in the past, pull on the actual wire or it will pull out from the metal cap and a new lead will be needed.


Mercedes probably have a special tool for the job but the needle nose pliers have always worked for me.

[stwat]

Mar 28, 2011 14:51:45 GMT splendidmcawesome said:

Now, if only I could stop it stalling 50% of the time when I slow down to a halt...it's been suggested that it's the overvoltage protection relay failing to supply 12v to the idle control valve. Any other ideas welcome...

Mine has started doing this now !! Did you manage to find out what was causing it ? One specialist said it could be the crank sensor failing as it's quite common on the M103 engines in the 300's

I did take my OVP apart and solder a few dry joints but the problem is still there.

It's something I really need to get sorted out.

[Onne]

Small update, I've managed to source two corner chromes, and a rear set. Hopefully will have some time to fit them soon inbetween working on the house...

Also contemplating what oil is best to use. Just serviced her with some fresh 10W40 semi-synthetic, but the oil pressure seems somewhat lower. (for the W126 drivers amongst you just under the 1 at idle...)
Oil stays lovely and clean with the LPG though, amazing really!

[Onne]

I thought I'd better do a small update on this one, not much has happened really... Now on 170K miles, changed brake pads this weekend.

Rear tyres are wearing a bit much on the inside though, with the extra weight of the LPG tank.
I know it's more about lowering here on RR but what would be a good solution to get the back end in the air a bit more?

Photos will follow... at some point

[mirafioriman]

You could put thicker pads under the rear springs to lift it a bit. Personally I stick to Castrol GTX on the oil front. I don't think these engines need synthetic or semi-synthetic oil like newer ones do.

[Onne]

Had my first breakdown today... Backfire into the inlet (LPG)

Would it start after? Nope... But thankfully a persistent AA man found the issue

No ruined metering head or anything horrible... Just a hose that popped off :-)

All well again on the merc front, will get some replacement hoses though!

[Onne]

Just got myself some nice shiny bits to replace my cruddy and knackered fuel pipe:


To replace: