non running 280SL II

[dseretakis]

Hi all.  I hate to beat a dead horse but I'm still struggling to get my 71 280SL running.  You may remember the many posts under the subject: "non running 280SL".  This has been going on for about 3 years now.  I am able to devote some time to my car on and off but have really gotten nowhere.  Again this car was running and being driven as a daily driver 3 years ago when it stalled out one day on the way back from work.
To summarize the following have been done:
-replaced coil, wires, plugs, condenser, rotor, cap, points and ballast resistors.  Yes, I do have spark.
-played around with timing by turning distributor back and forth
-checked CSV and it functions well with no leaks.
-looked inside fuel tank and it is very clean
-filled tank with fuel to rule out a flower pot issue.
-replaced main fuel filter
-performed psi/flow test.  16 psi, 600cc fuel in 15 secs which is suboptimal.
-checked return line for obstruction-there is none
-checked injection pump rack and it moved freely and springs back
-checked that throttle valve is not stuck
-checked compression - 200psi across all 6 cylinders
-replaced WRD thermostat although it was probably OK anyway
-replaced electric fuel pump with new one today as per recommendation of 2 MB mechanics including Gernold at sl tech

Car will still not run! (It does the same as always which is start sometimes, then stall out after a few seconds) I've basically made no progress other than rule out a bunch of things and learn a lot about this car. 

I've contemplated having it towed out of my apartment building garage and to a shop but have not done so yet due to cost, uncertainty over whether tow truck will clear garage ceiling and now car being unregistered.

If anyone has any more light to shed on this problem I'd appreciate it very much. And if anyone is local (Georgetown, DC) and would like to help troubleshoot first hand then please don't hesitate!

Thanks, Dimitri

[johnd]

You just need to be methodical  When it is not in a mood to run, see if you get fuel.  See if you get spark then.   If comp. is good, I think you start with those 2 things, then figure out why one or the other isn't happening.  I am ruling out timing since it starts sometimes.  And I guess you need to focus on fuel since you indicate that flow is not good (can't recall the spec). I had a problem with fuel delivery from a crimped evaporative recovery hose, causing vacuum in the tank, but that should take longer than a few seconds to show up.  Still, might be worth trying to start with gas cap off.  On some old cars the wire to the dist plate can be problematic, as it has to move when the dist is advanced, and after 40 years . . . . Can't recall how these are made, but that is an example of the type of troubleshooting you need to do before buying any more parts.

Good luck.  You'll get it!

John

[Martijn]

Have you checked the ground strap between the firewall and the engine? Clean the surface of the metal on the engine and firewall with a brush and replace the strap if needed.

Martijn

[dseretakis]

I have been assuming fuel delivery should be ok since I just replaced the fuel pump but that is probably not a sound assumption.  I checked the spark plugs again after fuel pump replacement and they are fuel fouled so I honestly don't think that fuel delivery is an issue but you never know.  I will check for spark again also.

[dseretakis]

I have not but the car always cranks.  Again, you never know, so I'll check it.

Have you checked the ground strap between the firewall and the engine? Clean the surface of the metal on the engine and firewall with a brush and replace the strap if needed.

Martijn

[dseretakis]

Well, I don't know what happened but I gave it another shot. It fired right up and idled smoothly without my having to apply any throttle.  First time in 3 years. Problem is that it continues to belch out massive amounts of gray/brown smoke that will not subside for the couple of minutes I ran it.  Car is in an enclosed apartment building garage so I can't fumigate the area.  I'll try to drive it out to the back tomorrow and see if the smoke will clear.  Car is no longer registered so I'm not thrilled over this plan.

[J. Huber]

Sounds like an Italian tune-up is in order. Keep an eye out for the other smoky though.

[dseretakis]

My neighbors will be thrilled with me.  Even my girlfriend was complaining how the exhaust fumes had permeated my clothes, skin and hair.  Hahahaha.

Sounds like an Italian tune-up is in order. Keep an eye out for the other smoky though.

[al_lieffring]

It is possible from all the cranking without starting that the fuel is saturated with gasoline, pull out the dip stick and see if it is over full, smells like fuel or looks way too thin, This could be the cause of all the smoking when the car is started.

have you checked to see if the cold start solenoid on the intake is leaking fuel into the maniflod when the fuel pump is running?

 

[dseretakis]

The CSV is not leaking.  The oil however does smell of fuel and kind of always has.  I will do as you say and change the oil and see what happens.

It is possible from all the cranking without starting that the fuel is saturated with gasoline, pull out the dip stick and see if it is over full, smells like fuel or looks way too thin, This could be the cause of all the smoking when the car is started.

have you checked to see if the cold start solenoid on the intake is leaking fuel into the maniflod when the fuel pump is running?

 

[dseretakis]

Al you couldn't be more correct!  I changed the oil which seemed to be more fuel than oil.  When I remove the drain plug the oil gushed out like water - it was so thin.  I have never seen anything like that.

It is possible from all the cranking without starting that the fuel is saturated with gasoline, pull out the dip stick and see if it is over full, smells like fuel or looks way too thin, This could be the cause of all the smoking when the car is started.

have you checked to see if the cold start solenoid on the intake is leaking fuel into the maniflod when the fuel pump is running?

 

[glenn]

Years ago I had a 220SE pontoon early in my Mercedes affliction.  Pumped so much gas into the oil that it was like 2 cycle engine fuel, 50:1, gas to oil(poetic license!).  Crankcase was full.  Where in DC?

Bring it to PUB......

[dseretakis]

I'm in Georgetown on Wisconsin Ave.  You?  PUB?  What's that?

Years ago I had a 220SE pontoon early in my Mercedes affliction.  Pumped so much gas into the oil that it was like 2 cycle engine fuel, 50:1, gas to oil(poetic license!).  Crankcase was full.  Where in DC?

Bring it to PUB......

[knockmacool]

PUB?  What's that?

Pagoda University Blacklick- the whole world knows that 

[dseretakis]

Shame on me!  I should have known that.  Yes, I have always wanted to go to that.  Wouldn't want to go alone with this car though.  Maybe some of us departing from same location could leave together in case of a breakdown.  I have driven my 73 220D with 800,000 miles cross country and back with no breakdowns but I'm not so sure that I trust my pagoda on a long journey.   

PUB?  What's that?

Pagoda University Blacklick- the whole world knows that 

[ja17]

Hello,

Yes sounds like a very rich running situation. Try to get it out of the garage. Sitting still trying to idle is probably wetting down your spark plugs. removal of a shim from under the WRD could help lean the mixture. Make sure the linkage is correct first, and the WRD is not stuck.

[dseretakis]

I wish I could.  The car has again decided to not idle.  Same problem it exhibited before replacing fuel pump.  This car is driving me crazy.  I think I'll check the fuel volume at the return line again.

Hello,

Yes sounds like a very rich running situation. Try to get it out of the garage. Sitting still trying to idle is probably wetting down your spark plugs. removal of a shim from under the WRD could help lean the mixture. Make sure the linkage is correct first, and the WRD is not stuck.

[ja17]

Hello,
Probably fuel fouled spark plugs again. Read your spark plugs. If they are wet or sooty black they may not be firing. Go to one heat range hotter for now. Do not use resistor spark plugs.

An extra set of new spark plugs is a cheap test.  If it runs great for a short time after replacing them, then you will just need to find what is fouling them. It sounds like you are running very rich.

I hope you have the correct ignition parts together. I read your earlier threads and see most of it you have replaced.

[dseretakis]

Joe, the plugs were fouled yesterday, some more with fuel and some just carboned up.  I cleaned them as best I could but there was still some soot that would not come off.  It still did not run afterwards.  I took your advice and bought a set of hotter plugs today -  NGK BP5ES to replace the NGK BP6ES on the car.  I'm going to meet up with another local forum member today who will try to help me get this car right.  I'll keep you posted.
Dimitri

[dseretakis]

I replaced the plugs with new NGK BP5ES and the car fired right up. Then set timing by ear and now the car runs pretty well.  It still needs some fine tuning.  Will check timing with timing light.  Re-checked compression with another gauge and now got 160, down from 200.  This makes more sense.  All this was done with the assistance of another forum member who kindly volunteered his Saturday afternoon.

[joao210]

How could you have 200psi compression? New these cars were 120 or 135   I have never heard of a gas car with over 150psi  Do you have a diesel? Also just having good compression doesnt necessarily mean you have good oil ring  the oil ring doesnt affect the compression but does affect the spark plug fouling

[dseretakis]

You can have higher than normal compression if the head was milled down too thin during a rebuild.  I turns out that the first compression gauge that I was usuing was defective.  The second one read from 155-160 psi on all 6 cylinders.  True that I could be getting some oil fouling on the plugs. They did however smell of gas but you never know with a car sitting for 3 years if the cylinder bores rusted a little.

How could you have 200psi compression? New these cars were 120 or 135   I have never heard of a gas car with over 150psi  Do you have a diesel? Also just having good compression doesnt necessarily mean you have good oil ring  the oil ring doesnt affect the compression but does affect the spark plug fouling

[Longtooth]

Getting back to the source of the problem in the 1st place, Demetri, now that you know you were fouling the plugs and a hotter new --- read NEW --- plug works to let it fire up and stay running, you need to find out why you're running to rich.  As I recall from a year or so ago, the car ran like a top and then suddenly stopped working.  Sounds like something to do with air/fuel mixture... too little air or too much fuel.  The smoking issue indicates incomplete combustion... oxygen starved or way to rich.... one way or the other.  The originial symptom (worked, then suddenly stopped working) doesn't indicate that spark plugs were the problem, but something that caused them to quickly begin to foul up. 

I've been running Bosch Silver WR9LS plugs for the last 6 years.  Of course, when I'm out and about I drive all out --- lengthy periods at 80+ mph, or high rpm's at lower speeds most of the time.  I've had no problem with them even after a week-end of stop/go or when I commuted in stop/go traffic.  I change them out maybe once every 18 - 24 months or so for no good reason, but just because it sounds like about the right time ... never sooner.

Bosch Silver Spark Plug

Silver Sport Plug, 14mm Thread Size, 19mm (3/4") Reach, 13/16" (20.8mm) Hex Size, Gasket Seat, Interference Suppression Resistor, Fine Wire Silver Enhanced Center Electrode, Removable Terminal Nut, .027" (0.7mm) Gap, Heat Range 9

Bosch Silver spark plugs are specifically engineered to improve your performance, whether sport-driving and racing conditions or power sport application. These fine wire performance plugs are specifically engineered for colder racing applications, particularly those that run at full throttle (racing, water ski, and towing) and not for traditional automotive use (stop and go traffic) as they would quickly foul out. At the heart of these plugs is the silver enhanced center electrode that conducts electricity better than copper or nickel. These plugs are specifically engineered for high performance, not long life. As silver has a lower melting point than nickel, these plugs will need to be replaced more often depending on your application. For many racing applications this is not an issue as many racers are already replacing plugs after each race or even every run.
 

[graphic66]

The biggest difference in how my car ran was when I put in non resistor plugs NGK BP5ES gapped at .034. My fully stock  66' did not like resistor plugs at all. It really changed everything, from starting, idling and power. Just my experience. I had tried a couple of different resistor plugs as non resistor are sometimes not easy to find.