Mercedes-Benz Forum banner

1 - 20 of 35 Posts

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #1
Anyone who has been following my posts describing my efforts to return a '74 450SL to good running condition probably noticed I am not exactly a lucky person. Persistent is a better descriptor.

OK, my original distributor has a shaft that is very difficult to turn, so I ordered another one off eBay. The new distributor was described as throughly tested and functional distributor. It came with no trigger points. I checked it out as soon as it arrived. I found 1) the upper lobe section firmly frozen onto its shaft, and 2) mismatched advance weight springs.

To disassemble and clean, I had to remove that little ring down insde the points lobe. It took two hours plus to get that little stinker out. I assembled a bevy of picks, little screw drivers, and little punches. Nothing worked. I began to allow a bit of anger to distract my normally good judgement. I went a bit nuts and just stated sticking a curved pick in and and jerking it out as fast as I could. Suddenly it just popped out. Two hours of my life I will never get back. Took everything apart, cleaned it thoroughly, and reassembled the whole affair. A word to the wise - keep that little felt well oiled, as it serves a purpose. Decided to take a break and cut my 12-acres of grass so I could see my horse.

Never take a seller's word that he has "tested" a piece of equipment and that it is functional. This distrutor would have passed no test I know of. The points were closed.

This has squat to do with a Mercedes, but I think some will find it interesting. My Super A tractor was refinished about three years ago. I use it to bush hog my pastures. I had coated its new fuel tank with POR15 when I refinished it as a safety measure (there was no rust). No problem for 3-yrs. The tractor would run for 15-mins and quit. An inspection revealed that the POR15 lining was disintegrating into hundreds of little particles of less than 1mm in size, plugging up the fuel line, filters, and everything in between. This had been a new tank, boiled in caustic water, rinsed in water, then MEK, and dried for days in a very hot sun before coating. I have coated numerous motorcycle tanks (none of which I currently own) with POR15, and never had a problem, but now I had a very big one. A quick net seach indicated others had the exact same problem. I won't go into any more detail, I just wanted to warn people that POR15 will break down with time. Beware, caveat emptor!

Tomorrow we start the 450SL! I hope?
 

·
Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
·
29,507 Posts
I just wanted to warn people that POR15 will break down with time. Beware, caveat emptor!

Tomorrow we start the 450SL! I hope?
Well I hope you didn't use POR 15 in THAT tank. LOL.
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #3
Well I hope you didn't use POR 15 in THAT tank. LOL.
I will never use POR15 again, and I have two full quarts in my shop.
 

·
Registered
1974 450SL (US), 2005 SLK200 (UK)
Joined
·
421 Posts
I would like to know the name of the ebay seller so I can avoid them. If described as tested and functional then it should have come with everything operational and ready to install. Thanks. Andy
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #5
I would like to know the name of the ebay seller so I can avoid them. If described as tested and functional then it should have come with everything operational and ready to install. Thanks. Andy
I might want to do business with this guy again. He did supply me with the part I needed in a very timely manner. Granted, it was seized up, and it had a mismatched spring. I was lucky. I had a spring from my old distributor to replace the odd one. It was advertised with no trigger points, so that wasn't an issue. My trigger points appear to be in good shape. He did make a fictitous claim. I am serious when I say this distributor would have passed no test as it was. If you are determined, PM me.
 

·
Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
Joined
·
10,334 Posts
I have used POR-15 or it's NAPA Canada relative DOM-16 for many things. But I could never see how it could be used inside a fuel tank. It doesn't adhere well to smooth metal. They even tell you that. On an external surface you would have to abrade the surface to give it something to grip onto. Can't see how the surface could be prepared INSIDE a fuel tank, despite they sell it for that purpose,
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #8
I used to build motorcycles, and I used old original parts, some modified, as much as I could. I welded up many a tank, and POR-15 was the tank sealer to use to plug pin holes. This is the first time I have had a problem with POR-15, but it is a serious problem because of the way it is disintegrating in such small pieces. This tank is partitioned.
 

·
Registered
'79 450SL, '04 CLK200 convertible; former A124, W210, A209.
Joined
·
1,860 Posts
I'm a big fan of POR, use it extensively, but it's defo a big nono for shiny /smooth surfaces. I tested it on many different surfaces over the years and por works great with rusty / gritty surfaces, but not so great on chrome etc. unless it's pitting.
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #10
This is not a case of the lining releasing its grip on the tank. The lining is disintegrating into tiny pieces about the size of duck weed (world's smallest flowering plant). It is not coming off in sheets. I remember the old epoxy linings that looked like folded paper in your tank, as well as some of the early polymers when emersed in ethanol based fuels. Others have had the same problem as I am having now, it seems. I am hoping methylene chloride will remove what is left of the POR-15. I run E10 in this tractor, after replacing all the fuel related gaskets which began to leak when exposed to anhydrous E10. Since the tractor spends a lot of time not running, the E10 isn't anhydrous very long. But I digress.
 

·
Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
·
10,196 Posts
Usually I find the words tested on E-bay to mean it came out of a running car. How well it ran????. Also it is not uncommon for distributors to have two different size springs, a light on and a heavy one. I dont know if MB did this but GM did in the 60's.
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #12
The odd spring was too long for the weight. I think it is a spring out of a SBC distributor, which has heavier weights. It had come off its post on one end and was flopping around like a chicken. It does not the 450SL distributor.
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #13
Installed the "new" replacement distributor with the Ignitor and she started, albeit a bit rough. Changed timing and starting was a lot quicker. It won't idle as it drops below 1000rpm. Oh yea! The tach works like a charm! I'll kidnap my reclusive neighbor tomorrow and power time it at 30 degrees BTDC at 3000 rpm tomorrow.

I am going to pull all the injectors and rig them up above a large pan and crank the engine over to be certain ALL injectors are firing. I still have a problem I need to isolate. I have repaired or replaced all but the Manifold Vacuum Sensor, so it will be coming out for testing. I will also check all vacuum lines for integrity.

It was great to hear the beast running again. I need a load of non-ethanol 93 octane gas too. I really like this car. Have you ever had a girlfriend that treated you like crap, but if she called, you would be waiting on the curb for her arrival? This car is kinda like that girlfriend.
 

·
Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
Joined
·
10,334 Posts
Have you ever had a girlfriend that treated you like crap, but if she called, you would be waiting on the curb for her arrival? This car is kinda like that girlfriend.
No, but that is funny!
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #15
Started the car, stuck a 2x4 against the pedal at 3000 rpm, and timed the car. It smoothed out a bunch, but it idles at about 400-600 rpm, which isn't going to cut it. I turned the idle adjustment from stop to stop, and it had zero effect. Can someone explain to me how that idle screw adjustment works?

Time to rewire the injectors. It will be temporary at first, as I am still awaiting my boots and terminal ends from Germany (COVID-19 issue supposedly). I may get the old girl to run the way she should yet. She idled so low I couldn't believe it was still running, and I had one injector wire pulled off (after timing it at 30 degrees BTDC at 3000 rpm. Timing seems to have a drastic effect on this engine.
 

·
Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
·
10,196 Posts
Started the car, stuck a 2x4 against the pedal at 3000 rpm, and timed the car. It smoothed out a bunch, but it idles at about 400-600 rpm, which isn't going to cut it. I turned the idle adjustment from stop to stop, and it had zero effect. Can someone explain to me how that idle screw adjustment works?

Time to rewire the injectors. It will be temporary at first, as I am still awaiting my boots and terminal ends from Germany (COVID-19 issue supposedly). I may get the old girl to run the way she should yet. She idled so low I couldn't believe it was still running, and I had one injector wire pulled off (after timing it at 30 degrees BTDC at 3000 rpm. Timing seems to have a drastic effect on this engine.
I believe on the D jet the idle adjustment screw is essentially a valve that lets more air bypass the throttle plate. sounds like its clogged.
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #17
I presume turning the screw counterclockwise should increase idle speed. I'll clean it and see what happens. I'm getting pretty good at tidying up engine parts.

Thanks for the information. I need all the help I can get.
 

·
Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500se+500slAMG +250seStkW108 350sl4spdX3 500secEuro
Joined
·
22,561 Posts
I presume turning the screw counterclockwise should increase idle speed.
Correct.

Does it maybe have any affect at different timing settings?
 

·
Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
Joined
·
10,334 Posts
Follow the air lines from the intake housing. You will see that it splits so part of air flows to the aav and part to the idle valve.
If the engine is fully warmed up, the aav should be fully closed. At idle the throttle plate is closed. Only air engine gets, is through the idle valve. If the idle screw is screwed all the way in, the engine should stall.
That screw is normally 1 1/2 to 2 turns ccw. At that point, engine idles at about 700 rpm.
It could be that there is a problem with the idle mixture. Make sure the TPS you bought is installed so that it actuates the idle circuit (read the section on tps repair in stickies)
Air lines from throttle body to aav and idle valve could be blocked, I guess. But that would be unusual.
Do rpms increase if you slightly open throttle plate?
By the way, there is an idle mixture adjustment screw on ecu under pass side dash. Put in middle of its range for a start. Only adjusts idle mixture and only if tps is adjusted correctly.
Good luck!
 

·
Registered
1974 450SL 1965 Thunderbird 1927 Oldsmobile 1950 Buick 1977 Jeep CJ7J7
Joined
·
98 Posts
Discussion Starter #20
Engine rpm increases slowly as the pedal is depressed. At max pedal deflection, it might get to 3500 rpm. As mentioned, it climbs slowly regardless of speed of pedal deflection.

It is possible I goofed when installing the TPS. I don't think so, but it is possible. I can re-adjust the TPS to see if there is a change.
 
1 - 20 of 35 Posts
Top