Here is the story. I bought this 1990 300SE for parts that I want to swap into my 300SD and later part the rest of the car out. It has hail damage, some sort of car accident on the passenger rear quarter panel, the paint is terrible and the front end is shot to hades. Since I will eventually sell the engine and possibly transmission, I would like to get the engine to start and run better. It will eventually start cold on its own but I have to crank it several times and way too long. The PO used starter fluid to get it going quicker and that seems to work. Once started, it runs rough until it warms up. While driving the car, I noticed that it is very low on power. It barely wants to get out of its own way even if you have the accelerator to the floor.

Since I don't want to put any money into this car, I am asking if there is an adjustment or something simple I can do to get this engine to start and run better for the sake of selling it. I believe the engine is good because I don't hear any knocking or tapping, etc and it idles like a sewing machine once it gets warm and runs for a while. The fluids look good as well.

Thanks for any suggestions.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Try a bottle of redline to start, then an Italian tune up. New plugs would help a lot too. Anything else and you are going to spend a hundred or two.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

The guy said he ran regular unleaded fuel in it. I put 4 gallons of premium in it on an almost empty tank to make it the ride home.

I can't do much Italian work on it because I can't drive the car past 45MPH or the front end starts to shimmy uncontrollably. I had a hard time just driving it home on the back roads at 35-40MPH. I could rev the engine in neutral but that may not be good for it.

I suppose additives can't hurt. Maybe I can clean the spark plugs. Can I get away with cheapie copper tips or do they need Iridium if I change them out? It does miss at cold idle and I can feel the engine shake. It gets better the warmer it gets.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Plain old copper core plugs, non-resistor if you can find them.

I found these. What is the correct gap?




Champion® Copper Plus - Spark Plug
Part Number: 401
Line: CHP

2 year limited warranty
UPC: 37551000401
Plug Type: RS12YC
Hex Size: 5/8"
Reach: 0.689
Seat: Tapered
Spark Plug Tip Material: Copper Cored Nickel
Spark Plug Type: Copper Plus Automotive
Thread Diameter (mm): 14
Gap: .032
OE Type

Detailed Description

Hex Size:5/8"
Reach:0.689
Seat:Tapered
Spark Plug Tip Material:Copper Cored Nickel
Spark Plug Type:Copper Plus Automotive
Thread Diameter (mm):14

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Check the Owner's Manual for the proper spark plugs and gap. If per chance you don't have an Owner's Manual order one from your local MB dealer.

__________________
Fred Hoelzle

Normally that would be the first place I look but the car did not come with an owner's manual. I'm not going to buy one since this is a parts car and will be parted out soon. Perhaps I can find the specs online.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Gap at 032 I believe

You likely have clogged injectors coupled with no tune up in years. Drop the gear selector in 2 or 3 and let it rip after you put a bottle of redline in it.

Nothing else works. Only the redline fuel additive. It can be bought on amazon.

__________________
Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

eaton:

The spark plug which you have in this thread (401/RS12YC) is incorrect for that engine:

1) It is the wrong reach, .689 vs .750 required

2) It has the wrong seat, tapered vs flat/gasketed required