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1973 450SL
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Discussion Starter #41
Couple more things:
We can't get it to go below 15 degrees timing. The crankshaft was turned to TDC. Rotor aimed towards small notch in distributor / cylinder 1 position.
I tested engine temp sensor, within limits according to OHM meter, 2400 ohms. Also tested air temp sensor (if that's the one on he air cleaner housing), also tested fine. 235 ohms

As of now, the car won't start, but sounds like it's firing a little, trying to start.
Pressing on...
 

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Discussion Starter #42
And... After calling a large number of Mercedes shops in the region, none, as in zero, thought they were able to properly tune the car. So, win or lose, I'm it.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Couple more things:
We can't get it to go below 15 degrees timing. The crankshaft was turned to TDC. Rotor aimed towards small notch in distributor / cylinder 1 position.
I tested engine temp sensor, within limits according to OHM meter, 2400 ohms. Also tested air temp sensor (if that's the one on he air cleaner housing), also tested fine. 235 ohms

As of now, the car won't start, but sounds like it's firing a little, trying to start.
Pressing on...
Not sure I understand. You have crankshaft at TDC mark on balancer, and distributor rotor pointing at mark on edge of distributor at cyl1. How about the cam lobes on cyl 1? Are they sitting up like rabbits ears when observed through oil filler cap?) If ALL of these are set that way, then engine is at close to TDC and should start, unless there are ignition or injection problems.

Given that you are set up as above and car will not start, how did you measure the 15 deg?

Now one thing, and others can shoot me down.
Spec is for engine to be at TDC at idle with vacuum. But when setting up static timing, we don't have vacuum. Manual says installation value for timing is 7deg BTDC. (this because vacuum retards the timing by about that much at idle)
So, instead of the first method which is often posted on-line, perhaps you should set the balancer at 7deg BTDC and then set the distributor so the rotor points at the mark on edge? If need be, re-insert distributor so you can do this) Lobes on #1 cyl still sitting up like rabbits ears!

I have done it both ways, but the engine always started and could be timed with light.
 

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Discussion Starter #44
Point taken, Graham. My mechanic set and played with the timing, but I didn't see him checking the cam lobes. his method is to put a finger over a spark plug hole and crank until it gets "blown" off. Meaning on compression stroke...

I'll check myself using the cam lobes means. Thanks for your patience, I'm a retired airline pilot, but a hack mechanic. ;)

Ed
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Point taken, Graham. My mechanic set and played with the timing, but I didn't see him checking the cam lobes. his method is to put a finger over a spark plug hole and crank until it gets "blown" off. Meaning on compression stroke...

I'll check myself using the cam lobes means. ;)

Ed
Sounds ok. Just another way of ensuring you are at top of compression stroke.

How about that 15deg? How was that determined?
 

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Discussion Starter #46
It has started occasionally, and that was what we saw with the timing light.
 

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Discussion Starter #47
On another note:
I've spoken with all the shops I can find in the area that purport to work in older Mercedes. None of them are interested in working on a D-Jet car. Most were sympathetic, a few offered advice such as swap in a later engine: Mercedes or GM LS...

All expressed that the D-Jet cars are very difficult to diagnose, and said it's mostly a matter of throwing parts at it. Hard to get & NLS parts at that.

I'll continue to pick away at it, but the common opinion seems to be that it's very tough to achieve optimum performance.
 

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'72 450SL, 107.044-12-000422
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That djet training manual in the egv107 and that I linked to earlier provides good tests of most of the components. If you work through all the hand-drawn T/S flow charts, you will almost certainly find the problem.

That is, if the problem is fuel-related. Have you verified good spark at all the individual plugs?


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Thanks for your patience, I'm a retired airline pilot, but a hack mechanic. ;)

Ed
As an airline mechanic who is a hack pilot, I’ll try to refrain from any wisecracks. Just know that if I slip, it’s all in good fun.


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Most dangerous thing in aviation is a pilot with a screwdriver in his flight bag.

Sorry Cush, I had to get that one in...


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Couple more things:
We can't get it to go below 15 degrees timing. The crankshaft was turned to TDC. Rotor aimed towards small notch in distributor / cylinder 1 position.
I tested engine temp sensor, within limits according to OHM meter, 2400 ohms. Also tested air temp sensor (if that's the one on he air cleaner housing), also tested fine. 235 ohms

As of now, the car won't start, but sounds like it's firing a little, trying to start.
Pressing on...
You are missing 1 more sensor/resister, and I know the car will not run or start without it. The one marked Thermo Time Switch. and How much Fuel are you working with in the tank?
 

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Discussion Starter #52
That's installed. Any idea on testing it?
Tank was emptied, flushed a bit and has probably four gallons in it.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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That's installed. Any idea on testing it?
Tank was emptied, flushed a bit and has probably four gallons in it.
Testing thermo-time switch is covered in the manual (along with all the other sensors) - Section 07.4

I can see a cold engine not starting if the T-T switch or it's relay are faulty in a way that causes cold start valve not to open. You would not get that extra squirt of fuel when starting up a cold engine (<35C coolant). You can get same effect by squirting some fuel into the intake.

As I understand it, when you operate the starter, power goes to a relay that provides power to the C-S valve. The ground wire from the relay passes through the T-T switch. If temperature is below 35C, it connects to ground. If above 35C, it doesn't connect to ground and C-S valve does not squirt!

If somehow the T-T switch failed closed, then fuel would be squirted through CS valve at every start regardless of coolant temperature and engine could get flooded after several start attempts.
 

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MB, thanx for the tech. info on that.
All I know is (on both a '73 &or a'74) if you pull that connection while the car is running it will die, and will not restart until it is plugged back in.
I also question the amount of fuel in tank, is it 4 gal. now or when we started a week ago- get that fuel level up and over 1/3 of a tank. 4 gal. on a 23+ gal. tank is like pissing on a forest fire.
Speaking of that, we been good so far this year down here but if they start choking us out like they did in '17 & '18 I will not stay down here, my plan is to go live in my sisters basement in Portland, but I can change that to Snohomish but we don't want no big fires anymore. So let's find a remote solution to his car issues.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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MB, thanx for the tech. info on that.
All I know is (on both a '73 &or a'74) if you pull that connection while the car is running it will die, and will not restart until it is plugged back in.
The C-S valve wiring is, I think, independent of anything else. Unplugging it should give an open circuit to ground so C-S valve should not do anything. I will have to try pulling that plug tomorrow and see if I get the same results :) Pulling the #2 temperature wire alongside the T-T switch could very well stop engine. I will try both :)
 

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I got another Question. Only asking because you have already said that the fuel feeds were reversed. Are you sure the plug wires are in the right order. Front cylinder on passenger side is #1 then going straight back to the firewall are 2,3 & 4 respectively, drivers side front is #5 then 6, 7, 8 to firewall. Not being insulting just going over the basics. We all overlook the obvious from time to time.
 

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I got another Question. Only asking because you have already said that the fuel feeds were reversed. Are you sure the plug wires are in the right order. Front cylinder on passenger side is #1 then going straight back to the firewall are 2,3 & 4 respectively, drivers side front is #5 then 6, 7, 8 to firewall. Not being insulting just going over the basics. We all overlook the obvious from time to time.
Trog,
Valid question!
Once, early on, I had been working on my car and had the cap and wires off. Afterwards it would barely run. Much worse than before I started. I decided to drive it to a local Indy. He had one look, reversed a few wires and she ran just fine!

Embarrassing - YES.

I marked the cap with the numbers in proper firing order as well as put tags on the wires. (Not the same as domestic engines? Ford V-8, e.g.13726548)

Injector leads could I imagine also be accidentally reversed.

My spare distributor/cap (rotated for Cush :) )
2643602




2643603
 

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The diagram immediately above raises a question because the #1 lead on the distributor is normally about where #4 is on that diagram - not pointed at cylinder #1. There is a metal locating tang mounted to the distributor body that fits in a notch on the inside of the mounting surface on the distributor cap. If that is mounted correctly, and the distributor is inserted correctly, the #1 cylinder lead, the index on the distributor body and the rotor (at TDC) will be at approximately 1 o'clock as you look down on it facing the engine bay. Those three references will be oriented on a line toward cylinder #8.
 

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The diagram immediately above raises a question because the #1 lead on the distributor is normally about where #4 is on that diagram - not pointed at cylinder #1. There is a metal locating tang mounted to the distributor body that fits in a notch on the inside of the mounting surface on the distributor cap. If that is mounted correctly, and the distributor is inserted correctly, the #1 cylinder lead, the index on the distributor body and the rotor (at TDC) will be at approximately 1 o'clock as you look down on it facing the engine bay. Those three references will be oriented on a line toward cylinder #8.
FIXED!

You are right Brad, the #1 connection is usually at about 1 o'clock. That was the only diagram I could find quickly and it might be a bit misleading. But it does show the relative connections. I actually found the diagram on this forum! Blame Reno4u and Rowdie :) Maybe some M117s have distributor in slightly different position?

 
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