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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #1 ·
I recently picked up my first MBZ, a 1973 450SLC. It's a complete, running and driving California car. It had some obvious issues: it had been repainted at some point and the clearcoat has failed on the horizontal surfaces. The roof has some surface rust and the hood has some odd damage along the back edge. It also has a few pinholes where it has rusted through. There are a few rust spots at the bottom of the back window and above one of the rear trim pieces. It was originally olive green, but was painted a close, but slightly darker color green. Interior is dirty but in decent shape overall. Dash is of course cracked.
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Central locks were not working and the trunk opener seemed to have a mind of its own. Sometimes it wants to open, other times it doesn't. The driver's window is stuck down but I can hear the motor running. Suspect a bad window regulator. The rear passenger window only goes down part of the way.
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On the test drive, it seemed to drive okay, shifted fine, but the idle was quite high at around 1500 RPM. I went ahead and pulled the trigger on the deal.

On the drive home, it was smooth on the freeway, but a hot drive (hot air blowing out, I chalk this up to not having any idea what the various levers do at the time). Air conditioning was not working. Got it home and parked it. Made some space in the garage the next day and got it parked inside (this was especially important considering that I can't close the window).

I should also mention that I bought this car as a project car to work on with my son, who is currently just 13 but is really into cars. He was a little unsure about it at first, but he thinks it's pretty cool now.
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #2 ·
First order of business was to start cleaning it. The sides of the car still have intact clearcoat and clean up nicely. The roof is a lost cause. The interior has almost 50 years of dirt and general grossness that is taking a lot of elbow grease to remove. There is a little bit of surface rust on various chrome pieces. Most of this cleans up without too much trouble. The center console needs some paint/dye touch up, which we will be doing soon.
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Next up was figuring out the driver's window situation. We pulled the door card and almost immediately spotted the regulator spring sitting in the bottom of the door. We unbolt the window, the regulator and the motor and with a few choice words, eventually figure out how to get the regulator out of the door frame. The part where the end of the spring sits is broken off. I search the bottom of the door and find it. Unlike most of the pictures I've seen online, this doesn't have a bent up tab. It's more like a piece of pot metal that just snapped off. I decide it's not worth the trouble to try to fix it and order one off ebay.
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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #4 ·
I would be concerned about the rust over and under the rear window. Could lead to an unpleasant surprise when you remove the moldings.
Very likely. It'll be a while before I can start working on the rust repairs. There are definitely more areas that I've found since the first look at the car. At the very least it's going to need a passenger side floor pan.
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #5 ·
Next I set out to sort out the fast idle problem. Figuring this was probably due to a vacuum leak, I decided to go through the vacuum system and look for leaks there. No surprise, I found quite a few issues. The line to the vacuum reservoir under the fender was mostly missing. The vacuum advance line was disconnected from the throttle body, leaving that wide open to suck in air. A few of the hard lines were very brittle and crumbled upon inspection. These have all now been replaced. Everything under the hood is vacuum tight now. However, it seems that the vacuum reservoir has a major leak. I couldn't get the gauge to move at all using a hand pump. So that line is capped off for now. All the heat and AC control lines are holding vacuum and seem to be working properly. I also finally figured out what the blue lines are for. There is one on each side of the car. These are apparently for the seat back locking mechanism. The passenger side holds vacuum, the driver's is wide open. I'm hoping I just find a disconnected hose under the seat. I haven't spent much time on the central locking yet, especially since I don't have a functional reservoir. Testing with a vacuum pump, it seems that the fuel door and trunk actuators are working properly, but perhaps not the passenger door. More to come with the central locking in the near future.

After finding and capping all the vacuum leaks that led back to the engine, lo and behold the fast idle problem has resolved entirely.
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #6 ·
While I was inspecting the vacuum lines, I noticed something shiny under the air cleaner. I pulled it off and spotted a profusely leaking fuel injector hose. I literally had a pool of gasoline sitting on top of the intake manifold. Ugh. Not good.
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Thankfully I was able to get proper high pressure fuel line and clamps from my local parts store. Some of the injectors had just a piece of hose, clamped at the top and the bottom. Others had a couple of different styles of crimped metal holding the hoses on. Thankfully this is all covered in the manual, so they weren't too difficult to deal with. A couple of hours of work to change everything out, and I now have all new fuel lines under the hood and no leaks.
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1987 300SL
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You've been busy @bproosow (y)
Welcome to the world of Mercedes Benz. You'll find lots of frustrating issues, MB build their cars a bit differently
Looks like you don't mind wrenching and have a fair handle on things, and you and your son have some fun in front of you
Keeps us updated on how it's going. And lots of smart MB people here, find a problem you're bound to find an answer on this forum
 

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1974 Euro model 350SLC 4 speed manual
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Fellow SLC owner here. The door switches are both electric and vacuum switches. When you open the door the valve opens dumping the vacuum for the seat back locks so you can push the seat back forward. The little black push buttons on the lower rear interior panels do the same thing. So surprise! You have even more vacuum lines to look for!
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #9 ·
Fellow SLC owner here. The door switches are both electric and vacuum switches. When you open the door the valve opens dumping the vacuum for the seat back locks so you can push the seat back forward. The little black push buttons on the lower rear interior panels do the same thing. So surprise! You have even more vacuum lines to look for!
LOL. I found those buttons last night. :) I'll probably poke around tonight to see if I can figure out what's going on with the driver's side. I also still need to troubleshoot the central locking some more while I have the door apart.
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #10 ·
A couple of updates on the vacuum leak work:

First, I started tracking down the leak on the driver's side seatback latch. I did either find a broken line or broke it while checking it. This was the blue line coming from the door sill to the seat. I pulled the door sill off and ran a new hose down to the seat. I checked it and it was holding vacuum and I could see the latches move when I applied vacuum. I checked everything from the tee back and it was all good. I still was getting nothing from the line going back up to the engine bay though. I traced the line up into the kick panel, pulled everything apart, couldn't find any issues. Wiggling the line from the engine side, I could see it move inside. Pulling on the door sill side, nothing, so I figured it was broken somewhere in there. Nope. Just me being an idiot. Remember that door switch @Whitewater Dave? Yeah, it turns out that if you're testing with the door open, the switch is open and dumping the vacuum. Duh. I knew that too. Just forgot about it in the moment. Realizing that, I checked everything again with the switch closed and boom, everything is working perfectly. Both seats latch when the car is running and unlatch with either the door or the backseat button.
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Next, I decided to pull the vacuum reservoir from under the fender. I knew this was not holding any vacuum. I was hoping that I might just spot something obvious and attempt to repair it. After taking it out, I cleaned all the dirt off of it and gave it a once over. I didn't see anything at first, so I decided to blow into the tube and see if I can figure out where the air is coming out. That worked. I was able to spot a tiny crack adjacent to where the bracket bolts go through. It was small but it had gone through to both sides. I was thinking I would try epoxying it, but it was so small, I decided to just try super glue first. I applied the glue to both sides, used the vacuum pump just a little to pull the glue into the cracks, add a little more glue for good measure. I went back and checked it a couple hours later, and boom! Not only pulling vacuum, but holding it steady. Back in it goes. I'm thrilled that this was such an easy fix, as I was about to order a used one off eBay. That should be the last major issue in the vacuum system, or it should've been anyways. Evidently the check valve I got from NAPA decided to break in half after just one day of sitting under the hood doing nothing. So hopefully that means I'm one check valve away from a fully functioning vacuum system.
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1974 450slc 1972 280se 4.5
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Just got the vacuum locks working. doing a diff swap back to the OG gear ratio this week .
coming attractions
Window track guides remounting
rear window adjusting
jalousie window removal and restoration
alternator only charges 12.7 at idle
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #13 ·
Just got the vacuum locks working. doing a diff swap back to the OG gear ratio this week .
coming attractions
Window track guides remounting
rear window adjusting
jalousie window removal and restoration
alternator only charges 12.7 at idle
I'm definitely curious about the rear windows. My passenger side only goes down a few inches before it jams up.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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While I was inspecting the vacuum lines, I noticed something shiny under the air cleaner. I pulled it off and spotted a profusely leaking fuel injector hose. I literally had a pool of gasoline sitting on top of the intake manifold. Ugh. Not good.

Thankfully I was able to get proper high pressure fuel line and clamps from my local parts store.
Nice looking car for a project car!

You probably know that your 73 SLC has Djetronic (Djet) fuel injection. There is a section in EGv107 (stickies) with several threads on various issues. Also a wealth of info scattered here on the Djet and other general issues that a search may bring up. If you have any questions, please ask. Many here can be helpful.

Re your leaking fuel hose. Did a parts store really have proper high pressure fuel line and clamps for this car? Very few do. The fuel line is 7.5mm ID. I forget OD, but maybe 13mm? Matching clamps are available and the originals also fit. Some owners including me, tried 5/16" from parts stores and soon had it leak. (oversize and soft liner). Operating pressure on Djet is actually low for a fuel injected car (just 30psig). However, fuel line rating is still up around 200psig, I think. This is the hose some have bought.

Hope you and your son have fun with the SLC!
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #15 ·
Nice looking car for a project car!

You probably know that your 73 SLC has Djetronic (Djet) fuel injection. There is a section in EGv107 (stickies) with several threads on various issues. Also a wealth of info scattered here on the Djet and other general issues that a search may bring up. If you have any questions, please ask. Many here can be helpful.

Re your leaking fuel hose. Did a parts store really have proper high pressure fuel line and clamps for this car? Very few do. The fuel line is 7.5mm ID. I forget OD, but maybe 13mm? Matching clamps are available and the originals also fit. Some owners including me, tried 5/16" from parts stores and soon had it leak. (oversize and soft liner). Operating pressure on Djet is actually low for a fuel injected car (just 30psig). However, fuel line rating is still up around 200psig, I think. This is the hose some have bought.

Hope you and your son have fun with the SLC!
Thanks for the information. I know for sure it was fuel injection hose and fuel injection clamps. The hose was like $7/foot (roughly 10x the cost of regular fuel hose). I actually worked in auto parts for many years and I would say that most places should carry this hose, but many of the employees aren't knowledgeable enough to know that it's different. If you ended up getting regular fuel hose, you would definitely run into problems. What I got was 5/16" if I'm not mistaken, which was the closest size to the fuel injector inlet. It comes in three sizes-- it was the middle size. The fuel injection clamps likewise come in 3 sizes. These are different than regular worm-style hose clamps. They have a much smaller clamping range than regular hose clamps, hence the three sizes to match the hose. Hopefully these will not leak any time in the future, but if they do, I'll just have to redo it with the metric hose.
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #16 ·
I went to the local dealer (Rocklin, CA) yesterday and ordered a replacement key since the only one I have is falling apart and is literally being held together with zip ties. The parts guy was able to pull a Vehicle Master Inquiry (VMI) for me.

Here's what I found out:

Production Date: 11/29/1972
Retail Date: 1/22/1973
Paint: 862 (Pine Green Metallic)
Upholstery: 265 (leather mushroom (from 06.08.1970)) or (leather cream beige / mushroom / quartz)
Selling Dealer: 05606

It also listed the option codes but there wasn't anything there that I didn't already know about.

Thanks to some detective work by @EasternOregonMBees, we were able to figure out that the original selling dealer was Stahl Motors in Monterey, CA. This is especially cool for me because I lived there for a couple years. The boy and I are actually heading down there tonight to catch the tail end of car week. I know there are at least three 300SL Gullwings on auction this weekend.

Although the car seems to have spent its entire life in California, it did not have the original plates. I think in '73 it would've had the blue plates. Those are not available, but CA does offer the 60's Tribute license plates (black with yellow lettering). I pulled the trigger on these and also got them personalized (first time for everything I suppose). Was able to get "73 SLC". I think that will be a nice addition to the car.
 

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1973 450SLC | Pine Green Metallic | 107K miles | VIN 591
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Discussion Starter · #18 ·
I'm impressed. You work fast.

Keep the radio. Those pen-stripe Beckers are so cool.
Thanks! We’ve accomplished quite a bit in just a week of ownership. More updates are coming.

We are indeed keeping the Becker. It still works, as does the power antenna. We just got a little Bluetooth adapter and we’re semi-modem with our tunes.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Great! My blue plate solutions is to order just regular ca. plates and then have some made in blue and yellow with the same numbers.
In Ontario, Canada, you would get a ticket for using non-issued plates! Even for putting color tinted plastic covers over them!

Reason presumably is so that photo-radar, police and automatic toll roads can read them reliably.

Despite that, a year or two ago, they issued a new design of plates that turned out to have a similar problem!

The Ontario government will stop distributing the newly redesigned licence plates after issues with their visibility came to light last week.

As of March 5, Service Ontario centres will only be issuing the previous used white-embossed plates, until the new ones are fixed.
 
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