‘Italian Tune’………….died after 45mins
 

1978 280CE not used for 5yrs Part II (Part I)

Italian tune……(injector cleaner & long hard run)

After many circuits of our block decided to give it a go (neighbours stared to give me strange looks)……..drove ~20 miles from home at up to 60mph………accelerating and changing well at first...........noticed slight miss after ~30mins……… on applying the gas at first………then increasing problems under load……….eventually refused to continue running when put in drive…. 500yds from home….walked home…….2hrs later started first pop and drove home without a problem

Further driving around the block…….similar problems after ~20mins

No overheating on temp gauge

Noted fuel pump ‘zinging’……..varying buzzing……..certainly noisier than I remember………like you would imagine if fuel vaporizing in pump

Thinking new pump, but quite expensive in Oz………would like to be sure before throwing parts at it……..may even consider buying a fuel pressure gauge if someone could give me advice on how/where to connect it and interpret readings

Electrical/Ignition problems also need to be considered

‘So near and yet so far’

Help please!!

Sounds like a blocked fuel filter. Causing the pump to work harder - hence the funny noise from it.

Change the fuel filter and check pump supply. Not sure of exact figures but you should get so many ml per min. If after changing the filter you don't get the required volume - change the pump.

BTW, do not work in the pits when working on the fuel line under the car. Fumes get trapped in pits. This can be dangerous.

Adam

Do check your fuel tank venting.
 

Even if your model doesn't have a USA style evaporative emissions system, it is possible (common 30 years ago or so) for cars with vented gas caps to get a clogging in the cap vent which would result in a gradual buildup (-down?) of vacuum in the fuel tank, preventing the pump from drawing any fuel and giving just the symptoms you describe. On some models you can test this quickly by driving without the fuel cap on, but some injected cars won't run properly without the cap in place. Vented caps and systems are common places for bugs to produce clogs on cars which have set unused for a while

So close David...so close. It can be any of the mentioned reasons and I can't recall details of all you've done, but a gummed up fuel filter is the easiest place to check and logical given the conditions you found when cleaning. I think I mentioned the possibility that injector cleaner can knock stuff loose only to have it deposit crud someplace else, and with the gummy conditions you first encountered; this seems a possibility. Would'nt surprise me that if you repeated your clean out sequence you'd find more crud had replaced what you first found. FYI, while my 79' 280ce was sitting for six weeks waiting for a replacement tranny, there was a heavy concentration of injector cleaner and just 1/4 tank of gas in the car. When I got the new tranny in, the car ran rougly for 20-30 miles and then smoothed out and now starts instantly nearly all the time hot or cold. I attribute it to giving the cleaner time to soak and loosen crud which blew out in the first miles. For three weeks now, I've been driving it as hard as I can get away with and it just seems to get smoother by the day. Remember, you have an engine that is known to run better/longer if it isn't babied and that 150 MPH speedometer is there for a reason.

Thatsa good attitude, Yorktown, about running these engines hammer down, long haul for several hours at least once each month. Old lady cars - they are not!!

What we gotta do is put together 'Italian tune-up' kit for Mr.Speed..... am thinkin tool box in trunk, full tank of gasoline, ultra high octane purchased at airport.... 1/2 dozen fuel filters, each at first with life expectancy of maybe 1 hour...... then kick him in the ass and get him on his way.

In terms of ignition/electrical problems..... coil and wires alone come to mind as something that can cause feeble spark. Thats an electronic ignition, so should be maintenance free.

Am also wondering what kinda shape the fuel strainer is in.

Definitely fuel filter. Car sat too long. symptoms as described are right on target here.

I would order 2nd fuel filter to have on hand if a new one eventually gets clogged again. Good idea. Especially if you consider that it may take a lot of driving to clear out the junk in the tank.

And use the car every day. At least 2 or 3 highway runs a wekk.

Deiseldog was kidding about the aircraft fuel...I think (grin), I actually asked recently and was told the stuff was just too likely to scorch the engine's innards and not recommended. Don't know for sure the truth of that, but why chance it, otherwise I'm glad my advice has supporters. Of course I'm not recommending exeeding speed limits (yah right), but after adjusting the linkage for the new tranny by trial and error, I left the shift points higher than typical. On easy acceleration the 2-3 shift happens at about 35mph and the 3-4 at about 55. Being more aggressive raises those by another 10mph. The effect is running at higher RPMs around town. Hurts city mileage some, but the car likes it. And since it is annoying to still be in third when cruising along at 50 or so, all I have to do is feather off the pedal around 45 and she'll kick up into 4th nicely.

No real surprise when you think about it, but the harder I drive it and the longer the haul, the less oil it uses too. It's only when stop and go city driving and short hauling that consumption goes up to a quart every 1000-1500 miles which seems typical/expected of this engine.

So David, take the fuel filter advice, then kick the tires and light the fires.

Changed fuel filter after initial flush of fuel distributor with high concentration of injector cleaner.......so on second filter since getting it restarted

New filter may still have clogged up quickly........but at 40 Aussie dollars each I will check delivery rate cold and when playing up first.....any other tests to pin-point fuel filter as culprit ?

Fuel strainer in tank also sounds worth checking.......tank full at present just to make things difficult !

Will try removing fuel cap when starts to play up to see if 'big suck in' & any improvement........not sure how my tank is set up, but probably similar to 1978 California models

My wife has suggesting adding a cell phone and Autoclub Card to the Tune-up Kit....no faith !!

Keep the ideas coming please....I appreciate everyone's input

I still really don't know the truth in that. I seem to have been the one to bring that discussion up the last time, and I've been asking several other people about that. The issue was about my car, a 1970 280SEL running AVGAS 100LL. As far as the lead oxide scratching up the engine, logic would tend to disagree. A 1970 Mercedes would have been designed to run on leaded fuel because, quite simply, unleaded wasn't available in that era. Also, it seems to me that steel is a lot harder than lead oxide since lead oxide only has a hardness of 2.5 to 3. Furthermore, aircraft engines run for a minimum of 2000 hours between FAA mandated overhauls, and the mechanicals are hardly worn out. You should also consider that 2000 hours is quite a bit of flying in a small airplane. If an aircraft engine, that is made out of both steel and aluminum can run of leaded fuel, than why can't a 33 year old car?

Yes, lead would tend to build up on the spark plugs, but by no means should anyone run pure AVGAS because its lead content is much higher than auto fuel ever was. I only run about a 10 to 20% mixture in my car, and I get a much smoother running engine over 94 octane unleaded.

Also, AVGAS is not 100 octane, it is 110 octane. Ask a general avaition mechanic about that one. You will also find that AVGAS is stored in much cleaner tanks and operators are much more concerned with the purity than your auto gas retailer is.

Until I find some scientific backing to the assertion that AVGAS is bad for an engine, I'm going to keep using it. After all, Textron Lycoming, Continental, and Pratt & Whitney can't be wrong?

Still not there
 

Checked for vacuum build up in tank first.....cap came off without a 'big suck' and still ran poorly with cap off......so probably not the problem.......I had this in my boat a few years back (OMC Sterndrive) and it took the 'Marine Mechanics' quite a long time to find it and do a simple fix

Changed fuel filter..........unfortunately also no help.........thickish 'caramel milk' from input side of filter....so needed changing even though < 100miles

That leaves 240DieselDog's suggestion of the fuel strainer............with last drive noted tends to cut out on corners........making me think of the gunk in the bottom of the tank slopping around on corners and building up on the screen.......clearing after stopping for a while would also be easily explainable

My first job when trying to get this car going was to empty the tank........by undoing the connection to the pump and flushed it through with a few extra gallons.......I understand gunk could remain in the bottom of the tank and the strainer would not be cleaned doing this.........but removing the tank looked like a big job

Have looked at the fuel line from the tank to the pump........noted the much larger nut which I presume holds the strainer

I would appreciate some advice on undoing these connections to the tank.....the big nut looks like a challenge........can the strainer be removed this way for cleaning?

G'day Mate!
 

Many have been there before. Do a search on "fuel AND strainer" and you will find a lot of ideas.

I believe that the arrangement is basically the same as a 114, and here is how I tackled it:

http://www.peachparts.com/shopforum/vintage-mercedes-forum/14401-diy-removing-fuel-tank-drain-plug.html

Not a fun job - good luck.

G'day Chuck
 

Read most of the 'strainer' posts

Managed to visualise the description of your 'tool' with the 'back to front' plug sockets -amazing -worth a picture in the archives!!!

Checked my plug sockets........19mm & 22mm heads and my six sided 5/8 plug socket is a useable fit with my 1/2" extension

Unfortunately doesn't look like I need the 22mm allen socket after the fun of putting it together.........looks more like I will need ~45mm tube type socket......the 19mm fuel line connection looks impossible on my w123....no room unless I remove accumulators etc.

May just try the compressed air to confirm the diagnosis...what do you think ?

I have been reading about CIS to attack the funky idle on my 380. I think you should get it to crap out and then be prepared to quickly check fuel delivery. You check this off the return hose and the spec is one liter in 30 seconds. Personally, I would have a helper jumper the relay for 10 seconds and measure that quantity against the spec.

If flow is in spec, you can stop worrying about the fittings and move on to the fuel distributor or injectors.

Supply better than 1 litre / 30secs cold...........variable flow when playing up....below spec...................filter change no help so that leaves the pump or strainer screen as I figure it

Pump is relatively new, but could have been under a lot of strain with pumping the crud and poor input

Have decided to go the compressed air way..........I realise it may only be a temp fix, but may give me the answer

Probably should have started this project with pulling the tank and having it cleaned........may still have to go down that road....any advice ?

Agree. I think you will end up cleaning the tank or at least the strainer, though. We will keep our fingers crossed on the pump.

Good luck!