Hola. First time long time.

So I just picked up a 1987 w124 300E. It’s been sitting for a few years due to a misfire. Older woman owned it and her husband just got her a W212 diesel instead of dealing with it. Body is immaculate and engine looks clean for its age and mileage so I picked it up for 800 bucks and towed it home. Pulled the plugs and got a new battery. I went ahead and ordered a new filter and a new coil. Doing an oil change and getting new plugs. I figure I also need to drain the fuel before starting. Anyway. A few questions.

The hose going from the top of the air filter to the valve cover looks sort of rough but even though it looks like it should be some kind of pcv setup I don’t see a valve. Is this kosher? Also it looks like there is supposed to be a hose coming off of that hose (pics below) and there a wire that seems to be hanging loose below it. Any idea what that is?

Plugs look rich which points to potential ignition problem.

My plan is to change oil and put fresh plugs and a new battery and coil in. Change the fuel filter and try to start it. Then run some injector cleaner through it and see if that helps. If not I’ll check fuel pressure and potentially replace pumps. Then check and refurbish or replace injectors.

Not familiar with these cars. I have a vintage Porsche and an old Land Cruiser so I know my way around engines. Please let me know anything else to check.

Thanks!

There is no pcv valve.

The vacuum line from the fuel pressure regulator is supposed to go into that black hose.

Clean the buildup on the inside of the distributor cap. You will need a hard tool like a screwdriver to scrape it off.

Inspect the orange "insulating disc" behind the ignition rotor.

The proper non-resistor plugs are no longer made. I run new old stock plugs in my m103. You can still find them on ebay.

The ignition wires are supposed to have 1k ohm resistance. 2k if you measure from the cap. Coil wire has no resistance.

Injectors aren't serviceable.

There are tests to check your fuel pump/filter/accumulator.

Kyngfish, recommend replacing the fuel filter before attempting to start the engine. It appears those NGK spark plugs are resistor type. That engine engine requires non-resistor spark plugs, as mentioned by christuna. If you have the Owner's Manual check what spark plugs it specifies. If not available, try Bosch H9DC, gapped per the Owner's Manual specification and torqued to 11 ft/lbs. Use a very light coat of Never Seize on the threads.

It would be a good idea to replace the distributor cap and rotor with Bosch brand

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Fred Hoelzle

Yep. Already ordered a fuel filter.

Any ideas on that wire? Also where is the fuel pressure regulator so I can find that vacuum like? Or is what I think is a wire the vestige of that vac line?

Thanks again.

When is a wire a vacuum line?

Lol. Give me a break. It looks like the wire that goes to some kind of sensor to me but it’s very short and hard to get a good look at. If I pull off the air filter and etc I can find out what it is. Just was hoping someone would see it and recognize it for what it was.

But yea. I know my way around an engine. You can take that or leave it. Just looking for some info on here. Appreciate the help I’ve gotten so far. Thanks.

Good choice for a car. The 300E will be smooth once you figure out the misfire. Like some have mentioned, make sure the ignition system is overhauled.
As to the fuel, empty the tank and replace the fuel filter. Do a fuel pressure test once you fill it back up and start the engine.
Vacuum test at the manifold as well.
Plugs: get non-resistor if you can find them. Single point, don't get those fancy ones, they don't really work on this car.

The hard plastic vacuum hose from the fuel regulator goes into the breather hose that goes to the top of the air cleaner.

The 300E M103 is a great car that likes it ignition system in top notch order. If the ignition system isn't in good shape it will let you know.


Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Yes to all those who said "Non-resistor plugs" and "Ignition system in top notch condition".

Correct plugs are available from MB, Beru, NGK.

As for other ignition components, I've now got 100% MB at no small cost. But I intend this to be my last car as I'm now 69.

Failing MB, Bosch or Beru are second best. Nothing else, in my opinion.

I have in stock a Bosch and a Beru cap. And an MB one. All new. The MB one simply looks and feels better.

RayH

Kyngfish, the plastic line from the fuel regulator to the breather hose is meant to direct gas to the valve cover if the fuel regulator diaphragm ever fails. Better that gas goes there rather than start a fire in the engine compartment. For safety sake, replace the plastic line if it is missing or damaged.

__________________
Fred Hoelzle

All my misfire problems have been the plug wires going bad or arcing somewhere

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

Double check to make sure that the wires are properly installed.
Also, make sure the rotor is functioning properly. I had a 300TE where that part sheered off.

Afaik that only affects the 1990 and newer m103's. His is an 87

Unless he had an engine swap.

Just updating the thread. So over the weekend I pulled out the wires, cap and rotor, fuel filter, oil filter. The wires tested fine, and the rubber felt good, so I put them back on, replaced the plugs with the Denso non resistor type. Put in a new cap and rotor, new rotor gasket, and got a new rotor cover. Drained the old gas and sort of checked for any oxidation, put in a new battery and cranked her, after 4 years sitting. It took a minute for the fuel system to pressurize, but eventually she started and…

She runs totally fine. Engine runs smooth, picks up fine, no real noise, just.. really stupendous for a car with 240k miles - but I’m also not that surprised.

Still waiting for a new ignition coil which I’ll probably replace just because.

I took her up and down the street and noticed that the shifting felt weird, so I checked the ATF and it was low. So I topped it off. Shifts fine.

I put new wheels and tires on it.

Next I’ll go ahead and do an ATF flush and filter change, run some Techron through the system and change the oil again. Also a wash, clay bar, polish and wax are on the docket for the weekend.

Things of note:

1. If ATF was low, then it means there’s a leak somewhere - maybe? I’ll have to keep an eye on it, but the fluid looked clean so I wouldn’t put it past it being something the lady I bought it from had serviced and the mechanic who last serviced it to have messed it up. Given that he couldn’t seem to fix the misfire. Also the fuel filter was pretty new so I suspect there had been some fixing going on before she parked it.
2. I was getting some smoke from the exhaust manifold near the rear of the engine and under the car, it seems to have faded away, wonder if something was just burning off from sitting.
3. AC / Heater blower isn’t blowing, looks like it’s that strip fuse below the fuse box, need to find it somewhere and replace.
4. Telescoping steering wheel isn’t telescoping.
5. Driver’s seat feels like ****.
6. Need Euro headlights, the little headlight wipers dont really work anyway.
7. Need a new grille. Probably will get the URO one.

Before pic: (woof those aftermarket wheels)



After:

#1: When checking the ATF level make sure that the engine is hot, running, and that you're on flat ground.

#2: The smoke might have been caused by spilled ATF. The transmission fill is right over the manifold and even a single drop will create smoke.

#3 and #4: To start diagnosing these items you will need a wiring diagram:
http://www.w124performance.com/service/w124CD1/Program/ETM/ETM.pdf

#6: A cheap alternative to genuine euro headlights is to find 1994-1995 W124 headlights. Despite rounded hood the headlights were still square. I've actually seen them installed on pre-93 w124's and they don't look that bad but once you get closer you can see the slightly curved glass.

#7: Find a good used original one. They're cheap, will fit perfectly and won't rust

It looks lifted. How many "burrs" or "bumps" do the spring pads have front and back?