Are yall sitting down?? Something POSITIVE about my 300E!!
 

After sitting disassembled for 16 months, I reassembled my engine. I had the head reworked with all new valve guides. All new seals in the head and block. New timing chain and guides.
Well the car burned gas like crazy. I replaced the plunger seal in the fuel distributor. No improvement. Next came fuel pressure regulator. Then all new injectors. Still 10-12 miles a gallon. After 4 tries at rebuilding the fuel distributor I learned that rebuilding one of these is best left to experts.
I bought a used fuel distributor from a local tech that knew the engine it came from. In other words he knew it was good.
Still no improvement. So, look to the exhaust. I figure I have nothing to lose by punching out the catalytic convertor to see if there was a restriction. If there was a restriction then it would be apparent. If there wasn't then it's just another needlessly replaced part.
Well, all indications point to a gagged cat. I have driven the car about 500 miles and the gas mileage is back up to 22 mpg combination city/highway. No black soot on the garage floor. Smooth running on the open road at 200 less RPM @ 60mph than it used to run. Oil consumption used to be 1 quart/400 miles. Too early to tell exactly what it will be but the dipstick level hasn't budged in 500 miles.
The temperature here in the swamp dropped to 45 F this morning. Opened the sunroof and set the climate thumbwheel to 22 C. The 17 mile open road trip to work was one of the most pleasurable I have ever had. This old Benz drives pretty dang good !!

Roger that Cap'n.

I as well had a very "spirited" early morning run down 400, this morning, before traffic, in my W124, sunroof open,and it was great.
Glad to hear something good out of your car lately.

Q

I enjoyed the same kind of run up Hwy 41 this morning around 6 am in my 300D:).
Way to go Cap'n. How bout coming over to WR in it sometime and let me check it out.

Good news!
Who would've guessed the cat?
High fuel consumption=Cat Hmmm.
Did not know that one.
Too bad you invested so much in the fuel system first.
How frustrating.

I don't think I wasted any money. My theory is that a chain of events began with the fuel distributor sitting for a year and a half with old gas in it. That led to bad flow patterns in the injectors. Several months of super rich exhaust effectively killed a converter that was already coated with burned motor oil. Freestyler went through this same scenario with his car.
Moral of the story? Old/dirty gas and fuel distributors don't mix!

I guess I was lucky...
 

...to get away with my problem with just the fuel distributor.

The ever deteriorating fuel mileage before the swap was at its worst at 5km/litre.

Now it's back to 9+km/litre.

Fuel mileage before the FD started going bad was around 10 to 11km/litre!

So I'll be working on the car to achieve that target!

Cheers y'all.:)

Hey Cap'n,,,, I liked your other avatar better.:D

just out of idle curosity and not the fact that my exaust system is off the car as I pulled the transmissiom and that we have no emission check where we live how did you rod it out. Car is a 86 Euro model 500SE. It also has a pre cat with the O2 sensor in front of the pre cat, I presume that the cats were added to bring it up to DOT rules. I have already replaced the rusty center muffler with straight pipes.

William Rogers........

I'm very glad to hear you and your 300E have become best friends again.
As you said, i went through the same circus and i vaguely remember occations where i most of all felt like torching the darn car and walk away..
I'm glad i didn't. :)

Freestyler

That blue and yellow bikini top had summer written all over it and ain't appropriate now. But I could use the Fall version!!;)

That's winter wear in Texas at least until February!

Congrats Cap'n!

I can't believe you finally got it figured out.

Did you install an aftermarket cat or one from the dealer?

Actually I'm still using the original pipes in the "test mode configuration". My testing should be complete in 6-8 years. At that time I will decide which 'cat' I need to replace the original with!!;)

Great!!!
 

How great it is when a Merc finally runs like a Merc, Congrats!!! I too just figured out the problem with my Merc it was the idle Control valve, 2 days ago I must have sat in the car for 20 mins and just listened to it humm, after just installing the New (used) ICV. This Forum is really just great!! if it wasn't for it, I probarbly would still be riding in one of the best looking and worst running 126's, but now I guess I can say the same for both!!!

God Bless!!!!

Very funny. lol.

That wouldn't work here in So. Cal.

The Air Quality Management Disctrict folks would be all over you.

With the pipes in "test mode configuration", is the exhaust note the same?

Does it affect the functioning of the O2 sensor in any way?

Shoot, if you don't need a cat where you live, then why even have one? All it does is restrict exhaust and lower hp...

Combined city / highway mpg of 22 mpg is pretty good. I'm actually averaging just under 22 mpg in my mixed driving.