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Re-Booting a Classic: 1978 450SL Garage Find

8K views 42 replies 16 participants last post by  304065 
#1 ·
Ladies and Gentlemen,

I'm new to the Roadster board and am the new owner of a 1978 450SL with only 39,000 original miles. The car is a time machine, still has the service stickers in the door jamb, it's unmodified from new, but has been sitting for over a year and will need, by my estimate, around 100 hours of detailing to bring it up to show condition.

But before I go entering in Silver Star Preservation class, I thought I would ask a few questions around "re-booting" this car without risk of harm.

1) Draining the fuel tank. I'm planning to empty the tank to remove the old fuel and any condensed water. Is there a drain plug, or should it be siphoned out?

2) Replacing fuel filter-- I'm assuming this is gummed up from sitting, is there anything special to changing it, just a couple of banjo bolts in the axial dimension. I have a M-B original filter ready to install.

3) Motor. If it hasn't been turned over in more than a year, I think that just hitting the starter would be ill-advised. So my plan is to remove the plugs and squirt some Marvel Mystery Oil in there and turn the crank by hand. What size bolt on the crank pulley? What direction does it turn, clockwise or counterclockwise, facing the pulley?

And of course I will vacuum all those rodent droppings and seeds off the poor air cleaner.

4) I plan to change the air filter and power steering filter, change the brake fluid and bleed the brakes.

5) What about the fuel injection system? I'll be checking the hoses for any leaks or dry rot, of course the CIS system uses fuel pressure to operate. How should the cylinders be primed, do you depress the flapper to signal a larger airmass and cause the fuel distributor to go rich?

6) Electrical system all appears intact, prior owner fitted a group 48 battery which has fewer CCA than the original group 49. But we're not in zero degrees so I'm assuming that a 48 can turn the motor over when the time comes, and I will be using a 50A booster in addition.

THANKS in advance for any further advice or suggestions on bringing this car back from rest. . . any guidance appreciated from those who have BTDT.
 

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#2 ·
Congratulations on your new car. Quick answers to your first questions:

1) The drain plug is hard to access and is a 47mm offset bolt. Siphon out is an easier alternative, but you will not be able to inspect/change the filter in the bottom.

2) Replacing fuel filter-- Filter is a straight R/R if you have drained the tank. Inspect all rubber hoses carefully, including clamps and replace if necessary

3) Motor - 27 mm socket on the crankshaft, clockwise when looking at the engine from the front. But you will need to remove the fan. You can also turn over with the power steering pump pulley. Flush the fuel line at the fuel distributor side before you start the engine.

4) Do a power steering flush and use PS specified oil. There is a recent thread on this if you search, including a pictorial on flushing the system.

5) CIS – I would not prime the cylinders, but turn the key on to second position and back 2-3 times to prime the fuel pressure. You should hear the pump run a second or two each time.

Changing the engine oil is a good idea before you start the procedure of bringing it back to life. A flush of the radiator is probably smart as well. All fluids, basically

Good luck!
 
#3 · (Edited)
.

1) Draining the fuel tank. I'm planning to empty the tank to remove the old fuel and any condensed water. Is there a drain plug, or should it be siphoned out?

2) Replacing fuel filter-- I'm assuming this is gummed up from sitting, is there anything special to changing it, just a couple of banjo bolts in the axial dimension. I have a M-B original filter ready to install.
First have a couple of large gas can ready, even if you have to borrow them from neighbors. If this car is like my 83 it will have a 23 gallon gas tank. It your gauge is reading 1/4 it could still have as much as 10 gallons in the tank. Have a drain pan ready or you can do what I did and jack up the back of the car high enough to get a 5 gal bucket under there.

Remove the protective plastic shroud.

Looking at the photo of you fuel pump it appears that you have the large 14mm fuel hose coming off the bottom of the gas tank. You can loosen the clamp on the vertical line that goes into the dampener -- what look like an odd looking 90deg elbow -- and wiggle that loose. With your drain pan in place pop your loosened large gas line off of the dampener and let it drain. This 14mm line in the main line off the bottom of the tank, and it will likely need replacing. Be ready to put the gas line back on the dampener so you can drain your drain pan into a gas can and repeat the process until the tank is empty.

To replace the fuel filter I would dismount the whole assembly. There is 3 tiny nuts holding it to rubber mounts and then 2 tiny nuts for the fuel pump wires. There will also be a fuel line on one side of the filter to remove. It should come out at that point. The whole assembly will simpler to deal with on a work bench.
 
#4 · (Edited)
It is strongly recommended that you do not try to start it and distribute the garbage gas through out your fuel injection system. I would also disconnect the fuel lines under the hood from the fuel distributor after you have drained the tank and dismount the pump/filter assembly. Then with compressed air blow out the lines, both the incoming line and the return line.
 
#6 ·
When I converted my R107 to diesel I needed to drain the tank to get rid of all the gasoline. I found the easiest way to do the job was to put a length of hose on the supply line to the engine and the other end to a gas can. Then put 12v on the fuel pump and pump it dry. Make sure you don't run the pump dry.

Note: it won't work to just turn the key on as the pump will only run for a couple seconds (to prime) unless the fuel pump relay has a tach signal indicating that the engine is running.
 
#7 ·
No drain plug? Pull the main feed to the dampener cage and stand back. A year isn't really that long, if the gas smells good crank it and see if it starts. Pull a sample of gas if you like.
 
#8 ·
IMHO gas today sucks but Im old and I actually remember leaded premium lol.

The worst thing you can do is pump gas that has sediments into the fuel distributor. I would suggest first don't get in a hurry. Disconnect the fuel line at the strainer. drain the tank. look at the gas and see if it is just dirty or has particles in it. after only a year it should be ok but i dont trust 38 year old tank. I f you can get the fuel screen out and stick a light and a dental mirror up there then please do and inspect the tank. then disconnect the main fuel lines going from the fuel distributor to the accumulator / fuel filter. then spray some brake cleaner and blow the lines out. do this a few times. Bad gas will hurt you but a rusted tank with sediment will kill you. I just posted a post with pics of me doing the exact same thing because mine has set up for 6 years. change fuel filter and at least then you are trouble shooting real problems and not gremlins.
 
#9 · (Edited)
Why not siphon gas out of tank first? Thats what I did. Still had to collect what was left, so clamped hose, disconnected and ran fuel into shallow container (outboard motor tank, I think).

I agree with Daryn. Ifcar has only sat for a year, should be ok to just start it. Friends have a couple of cars here but only visit about once a year. Just run them when here and then park for another year!
 
#13 ·
Gentlemen-- THANKS for all the info, this is going to be a great experience with the support of the Board.

The provenance of this car is amazing-- original toolkit bits still present. (I think the spark plug wrench is missing, is that all?) I come from the Porsche world where these things have long since separated from their original cars and now command ridiculous four figure premiums to be reunited-- a welcome change.

I'll keep you posted of my progress, I am certain to have LOTS of questions. I need to add coolant, trans and differential fluid changes to the list as well as potentially replacing the tires-- the current ones are Pirelli P400 with a date stamp I can't determine. . . will swap those out for some Michelins as a first order of business.

Thanks again and stay tuned.
 

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#14 · (Edited)
original toolkit bits still present. (I think the spark plug wrench is missing, is that all?)
Looks like the spark plug wrench w/t-bar handle (part # 1075810067 ) and a double ended hex tool w/10mm female end and 11mm male end (part # 0005313301) are what you may be missing. Do you have 2 original MB hard/soft top locking tools? They have the tristar logo stamped into them.
 

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#15 ·
FLHRU, thank you for the info-- is there a list somewhere by year of what came in the toolkits? That would be a help to me when I search for the missing tools, if they are common to more than one series.
 
#17 · (Edited)
The re-boot continues. . . I had the car towed home on the rollback, didn't want to take a chance. Got it home, drained some fuel, fuel looked pretty good, turned the engine over a bit then hit the starter. . . started instantly and settled down into smooth idle. With it running my first order of business was a wash. . . took it to the quarter car wash to blast off about ten pounds of caked on mud from the wheel wells.

Not bad for a 38 year old car. . .


I took the opportunity to GENTLY remove the original stickers then wash the engine compartment to remove rodent droppings and associated grime. While it came out fine, to really do this right will require an engine drop. . . much later.



I did discover that some unwanted guests had overstayed their welcome and left a big mess, in the air cleaner. This was all vacuumed out and the air filter was replaced.


The airbox lid has a bit of surface rust, but I'm leaving everything as it is for now, I want to learn what's original and what's not before I make any changes.

I went to test the climate system and unfortunately it came apart in my hand-- the Zebrano wood panel has lost a couple of its wooden tabs that hold it in place somehow. Also, the nomenclature plate that covers the switches and temperature knob was loose in its mountings. . . I need to dig out the diagram to find out how these go together-- maybe there are some clips or screws missing that would hold this in place. I didn't test whether the compressor clutch was energized with the switch, this is work for later.



First impressions: This car is AWESOME. It drives. . . like a Mercedes Benz, with effortless speed, the V-8 barely turning 2000 rpm. The steering is very light, but there's good on-center feel and I don't have to saw at the wheel to keep it in the lane-- evidence of a low mileage steering box. There is a bit of a puffing noise from the exhaust which I think could be a holed rear muffler-- I don't think this car has an original muffler, but have to see what an original looks like to know.

I'm not used to the size of the hood, this car is all hood. . . and when you nail the throttle the hood climbs skyward, have to check the shocks which could be worn after 38 years. Braking action is good with no pulling side to side, no squeaking, no drama.

This car is a keeper. . . it has more body dings than I expected, more touched up paint, but the beauty is that everything is there, and nothing has been altered or messed with over the years. . . my plan is to preserve everything as original except where safety is concerned.

Any thoughts on how the climate panel goes together? Thanks again to this forum for the experienced guidance, this is all new to me.

 

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#20 · (Edited)
Thanks gents, I am pretty sure it was mice just given the diameter of the schnorkel.

A few more questions.

1) The original Hirschmann antenna won't go down or up with the switch, and it takes brute force to manually move the mast. Are these replaceable with a modern part and you keep the mast, or are the modern replacements the same as original?



2) What is this cylindrical thing next to the Heater Servo? The Servo has been replaced, the replacement says "Universal German Auto Inc (818) 767-64XX Warranty Void if Removed."



3) Look at this ghost under the ashtray! Last five digits of the production number! (NOT the VIN of course)


4) On the rear panel, some prior owner affixed the license plate bracket with a pair of self-tapping sheet metal screws. I am surprised this panel isn't rusted away given that.



While I wouldn't put it past a dealer, this just doesn't look like something the Factory would do. On the other hand, those debossed holes with the rubber plugs DO look like typical Teutonic thoroughness. How did the rear plates mount?

This is what I have for a rear plate mount.



This part appears identical to the front plate mount. Is this a factory part? The reason I ask is when it's in the correct orientation with the mountains pointing UP, and a standard plate is screwed to it, there is not enough room for the top of the plate to clear the depression in the panel for the trunk button. Perhaps the holes were drilled in the wrong place. . . if this is the right bracket I will weld those up and drill new ones, but something tells me there's a better fix out there.

This is a fun voyage of discovery. . . and the rough initial detailing is a lot of work. . . cleaning the interior with Chemical Guys interior cleaner diluted with water turned the rinse water black with dirt. . . I will tackle the carpets shortly.
 

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#21 ·
Hmm this photo of Rowdie's suggests that the Factory plate bracket is different. . . .



One thing is for sure I have got to get EPC working again before my $75 subscription expires. Which will probably require buying Parallels desktop to run it on the Mac.
 
#22 ·
The original Hirschmann antenna won't go down or up with the switch, and it takes brute force to manually move the mast. Are these replaceable with a modern part and you keep the mast, or are the modern replacements the same as original?
New masts are available - recommend opening up the case and cleaning out the grime and hardened grease that caused your present mast to fail. PM me if you need further assistance - I have boxes of spares.
 
#23 ·
Do you hear your antenna motor running? Assume it should be the same as my late '77 model. When you turn the radio on it should run just briefly. You can then operate the antenna rocker switch to extend it further or retract it.

If you don't hear anything check for power first and ground first. As a side note, check all the old fuses and maybe replace them. At least I'd recommend doing so.

Most likely, you will need to replace the mast. Check the EPC for the correct number. My guess is, as cushjbc says, you also have a lot of dirt and probably corrosion inside the housing. The drain may also be plugged. Not that difficult to remove the antenna assembly and check everything out. A common issue is the small tension wheel in the bottom corner of the antenna. They freeze/corrode up. In my instance the antenna was full of fine dirt and the drain tube was plugged. Easy to fix with a bit of wire through the tube. Cleaned out the antenna and found the wheel was totally frozen solid. No amount of soaking would break it loose and when I did think I was starting to get it broken free what actually was happening is the centre pin was spinning in the bracket hole in stead of the wheel (bearing) spinning on the pin.

Anyway, long story getting longer, could not get any of the "repair" places I found online to confirm they could sell me just this part so I improvised with a $2 (from memory) bearing off of eBay. Works a treat.
 
#25 ·
The reboot continues...changed power steering filter and fluid, used a Hengst filter which looked a little different from the original but fit perfectly. Original just an element between plates, the Hengst a complete assembly.
 

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#26 · (Edited)
Changed oil and filter to Mahle and Mobil 1 10W-30. I used the vacuum evacuator method to see how well it worked, there were still few hundred cc of oil when I dropped the plug. I still love the evacuator though for ease of disposal of the oil oil.

Plenty of sludge in the filter housing, which still had original paint.

The filter has internal gaskets that hold it to the bolt, the big hole went at the top, small one around the bolt.

New copper crush washer on the plug. The Hazet oil wrench works perfectly for this job, just the right amount of bend to clear the pan. I love intelligent tools!
 

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#27 · (Edited)
The reboot goes on...took the valve covers off to check out the chains, not bad on the starboard side. Except the valve cover gasket broke, so I ordered new gaskets then will do the port side. That is where I would expect to find broken bits from age.

Timing looked pretty good, I'll check the other side as well.

Tensioner is original, I will pull it off and see if I can compress it by hand, if there is any doubt I will replace it (with the M-B original!) for peace of mind.
 

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#28 · (Edited)
Did the valve cover gaskets today-- the originals were brittle and shattered when I took them off. No sludge in the covers and the cam wear pattern looked good.

I also took the opportunity to change out the plastic spraybar supports, a simple, fun job. The old ones slide off and the new ones slide on, and it's impossible to mount the spray bar in the wrong orientation due to the notches on the tube and in the end pieces.

There was some smoke! Caused by a few oil drips on the exhaust manifold, but this stopped in a minute or two.

On the port side cover it was necessary to remove two fuel lines from the fuel distributor with a 17mm flare wrench. One is held down by an M6 screw with a 10mm head, same tool as the cover came off with so its easy. Also removed the brake booster vacuum hose with a 19mm flare wrench. Easy.

No broken chain ramps, good! Will change them out this winter.

Next project: Unwired Tools ACCII upgrade!

http://www.benzworld.org/forums/r-c107-sl-slc-class/2683001-1978-450sl-unwired-tools-accii-kit.html
 

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#30 ·
Changed the rear shocks and diff fluid "while I was in there."


Rear shock removal was straightforward as outlined here. With the car on its wheels, I removed the hardtop, chrome trim (two small flat head Phillips screws and two m6 10mm atf screws, then three small oval head trim screws in the panel. On the drivers side the crank for the top has to come off, this is just a metal clip on the back of the handle, then the trim slides off, and the handle comes off.

With the trim off the upper mounts are evident. My car was original and had jam nuts- Bilstein supplies DIN 985 nylocks with the admonition to only use them once ! These are simple to remove, then with the car jacked and properly supported, the m10 screws for the bottom of the shock come out with a 17mm socket. I torqued these to 25nm per Bilstein. It's easy enough to get them through the holes up top, I didn't have to remove the rubber covers in the oval holes to poke the piston rods through.

Up top I used a GM double d socket (Amazon) to hold the rod while a 17mm open end turned the nut until there were no more threads. Put the trim back and test drive, the road feel was materially improved. The Bilsteins on there were original with 1977 date codes!

I used the Bilstein supplied hardware which was a flat disc and a rubber donut on each side. They also supplied new M10s for the bottom- some unknown headmark, but my original KAMAX were corroded so I went with new unknown vs. the best but rusted.
 

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