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Farm Fresh 1986 300 SL

21K views 221 replies 15 participants last post by  jndaigle 
#1 ·
I bought a 1986 300 SL in very rough shape. A tree fell on it and crushed the top. This, unfortunately, is not its biggest problem. It has been partially disassembled, but some of the parts are still with it. I'll post pictures later, but you're not going to like them; I know I don't.

The previous owner says it has been sitting for about 3 years and it was running when it was parked.

The oil is clean on the dip stick. I want to get this car to running, but I am not sure if I would ever want to get it to roadworthy condition. My plan is to start by chafing the oil, turning the engine by hand, and then inspecting and fixing the fuel system before I try to start it.

The car has an in-line 6 with fuel injection. Do people have experience resurrecting these engines after the engine has extensive periods of sitting around?
 
#2 ·
m103 is about the most bulletproof engine ever made by MB.
 
#3 ·
Welcome to the 107 forum jndaigle. I think you will be amazed at how active this forum is compared to the vintage forum. The knowledge base here will blow your mind and the best part is... everyone is willing to eagerly share what they know.

I've had the pleasure of meeting jndaigle personally a few weeks back and he is a great guy. I hope he will become a regular here.
 
#4 ·
Welcome to the 107 section jndaigle, probably the most active Benzworld forum. If you can post some pictures, the vultures and helpers will be here in minutes. Let's see this thing!

And post a few here if your w114 too.

The upgraded 107 subframe will be a good replacement for your w114 subframe too.


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#5 ·
Come to Jesus talk

Before you get started:

a. Restoring any R107 is expensive, even if you do most of the work yourself
b. You will never get your money back if you sell it
c. If you want SL like this, it is by far cheaper to buy the best example you can find and go from there.
 
#6 ·
Thanks very much for the insight.

Having brought back to life numerous (and I do mean numerous) junk motorcycles, I am sure what you are saying is absolutely true. I haven't seen figures on what people have spent on Mercedes restoration lately, but I know the costs were outrageous in the mid 1980s. More recently, one of my friends spent $US 60K on an 1965 Olds 445 convertible, and it was in pretty good shape to start with.

The car is probably just for parts. The absolute most I would ever want to do with this car is make it drivable. Maybe I would enter the "ugly car" contest or something like that.

Before you get started:

a. Restoring any R107 is expensive, even if you do most of the work yourself
b. You will never get your money back if you sell it
c. If you want SL like this, it is by far cheaper to buy the best example you can find and go from there.
 
#9 ·
Thanks for the pics. It looks like you've got a part-out on your hands. This thread is on its way to the FS sub forum I think. Lots of euro bumpers are available for sale right now. I decided to put one of my sets on my rough 280sl "on the brink" even though I bought it as a parts car. If that thing runs, and if it's just the lights that have been taken out, it might be easier to just fix it up. I would be interested in seeing more of the damage from the tree.




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#12 ·
Man that is one poor beast ! ANYTHING can be brought back to concours with enough time, money and determination. That being said, you got yourself there your basic parts car ! If you are in love with these cars, find a decent example. They are all over for 2 grand and up. Occasionally somebody gets a pretty nice car ranging from free up. Don't spend a nickle on that car. May it rest in peace :crybaby2:
 
#13 · (Edited)
Thanks for the condolences. I have already started to clean it up for burial. I do, however, want to drive it to its grave. At this point, more than anything else, I want to see if I can get the engine to purr just because I like doing that sort of thing. If I can't with fairly minimal effort, I will probably just scrap it.
 
#17 ·
Sounds like you have done a bit of research.
the 114/5 and 107 subframes are pretty close to being identical, however your 86 subframe has 4 piston callipers, and different control arms, spindles and rotors, the offset is different.
That's actually a good thing unless you want to keep 14" wheels on the 114.

M103 is damn near bulletproof. Best engine MB ever made IMO. can easily take 15psi of boost on a completely stock bottom end. head breathes very well and the SOHC and 2 valves per cyl provide massive torque advantage over the dohc engines.

If you're contemplating a 'swap', then do not scrap the 107. You will need the wiring harness in tact, a copy of both models electrical schematics, so you can simply swap in the fuse panel wiring correctly and you will net yourself a pretty 'straightforward' swap. the CIS-E is pretty damn reliable on the m103.
If you have the trans lockout switch in the console of your 107 (little switch on the lower left side) then you will need to pay attention to the trans wiring harness as well. Other than that, it will (more or less) bolt in. keep the prop shaft, diff, axles, rear trailing arms, swaybar etc.... it all has potential for a huge handling upgrade to a 114.
cool thing about 114/107/116/126 is that a huge number of parts are interchangeable between models. The best part about all of this is that you have a really good 6 cyl M103, 4 speed auto, quite possibly the 107 has an LSD also, and the trailing arms are anti-dive. Massive improvement.
in fact it's not too different from swapping late 107 into early 107. the parts in the 114 are very much similar in spec, and in most cases the same as early 107. My 72 350SLC (you guys didn't get the 3.5 107's) is pretty much a 'known' swap for a lot of euro compact guys.

the 3.5 is a very tight fit in the 114 bay though, and a larger 4.5 /5.0/5.6 is almost impossible to fit without firewall / trans tunnel mods.

but the 6 - haha way smaller than the m110. big improvement in reliability and fuel economy. more power & torque, easier to maintain....

If I had a 114 that would be my engine of choice for a conversion. the M104 is nice sure, but maintenance on an m104 is roughy twice that of an m103 when it comes to bits n pieces and costs etc.

All I can say is lucky you. you have a donor car which is exactly what you need to do a proper swap. Since the tree fell on it, I wouldn't bother rescuing it, I'd be getting that m103 running and swapping the lot over.
You have everything at your disposal. Make sure you think about including the ABS as well. it is not a huge undertaking, but does require more brake lines and it also means you do need to do the diff swap. Not impossible, just pull the subframes and you will see how simple.
 
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#18 ·
Cool Post

Now this is what I call a cool post! Thank you so much for taking the effort. I very much appreciate the encouragement.

I haven't really done that much research, just miscellaneous reading. When I first started thinking about getting my 280 on the road, I talked with Fonzi quite a bit and we had some discussion on the 114 forum about swaps.

Now I can hardly wait to get going! I'll proceed with caution, though, since I don't actually know what I really have yet. All I have done so far is clean it as best I could. But it sounds like there is a real possibility I could wind up with a really cool 280 C, which is what I want.

About the brakes, about all I know about ABS brakes is how they work. I don't know swat about working on the system. But, I am comfortable learning almost anything, like in this line:

https://www.khanacademy.org/youcanlearnanything?video=main

I had a 1987 300E; loved it. I sold it to a friend in January 2002 with about 215 K miles. He drove it until 2011.
 
#22 ·
I'd say get yourself a $500 SL 107, with a blown engine or so, and transfer the engine, trans, drivetrain and euro bumpers over. Not much R107's with a M103 in the US, but from experience I can tell you they're great!

If you're hooking up with Dan and Fonzi, you're definately in good company as far as passion for these old Benzes goes.....

Good luck, hope you get it running. :thumbsup:
 
#25 ·
I think the 114 conversion is way cooler and represents better and more efficient use of funds.

We all own 107's..... do we really want to prescribe this poor guy to the conundrum of owning another rustbucket? He's already got a 114 !!!!

Try and save him some money at least !!!!

I agree with John though..... 717.432 5 speed is your friend behind a 3.0 m103. ohhhh yeah.

the 114 compacts are awesome cars. particularly the coupes.
 
#27 ·
Not a lot of difference Fonz - it's pretty much sohc vs dohc, then the other ugly gap-filling MB did with the electronics on the first m104.980 CIS-E cars.
However, when they went to 3.2 and HFM, quite a few mech updates occurred, yet the basic bottom end is still all m103 based.

It's arguable that the m104 reintroduced the word unreliable into the MB owner vocabulary, as the initial m104's had soft head gasket issues and timing cover seal leaks and a few other annoying nasties, but on the whole, a huge performance upgrade occurred with DOHC and variocam infancy. Still, the m103's reputation is undamaged. Ridiculously easy to work on, (unless you have the 2.6 shoved into the 201 engine bay, that's a bit of a pain in the arse to work on, let me tell you) Hardly anything really gives trouble.... belt tensioner and maybe the odd alternator bearing / brushes and possibly the water pump.... but let's face it, what other MB doesn't need those replaced once in a lifetime...
While I still have my 300 coupe, I loved my 201 2.6 to bits. Dead reliable, awesome fuel economy (yes, my missus used to get 9L/100 in commuter traffic - amazing for an 87 model - the 2012 megane still only returns this or slightly worse... so something to be said for that)
smooth power delivery, albeit slightly high in the rpm band, and just plain nice to drive.

Yeah the m104 has all of that plus low end torque and an awesome high rpm snarl, but it comes with a fragility clause.
I love the MB inline 6's, as much as the legendary m117 v8, but there is something to be said about the character of the m103. It's like the cockroach you just can't kill.... despite exhausting all your efforts....

Still, some people do manage to kill even an m103. and the only thing that really kills them is bad bad bad maintenance - or putting it bluntly, no maintenance.

I've seen an m103 with almost all of the cam lobes ground flat, a valvecover full of sludge and a big end knock that makes a jackhammer sound quiet and it was still running.... just not real well.

certainly can't do that in an m104 or m117 and live to tell the tale....
 
#31 ·
let me post some pics. Then you can think about whether it is worth your while. I'll use an m110 in a 107 engine bay for comparison. Note the subframes are the same in 114/5 & 107, so the pictures of the measurements to the subframe mount from the firewall should be enough to tell you....
Vehicle Engine Car Auto part Fuel line


Auto part


Auto part Pipe Fuel line Metal Scrap


Yellow Material property Metal Plant Tape measure


Engine Auto part Fuel line Vehicle Car




Auto part Tire Bumper Automotive wheel system Automotive tire


Auto part Fuel line
 
#33 · (Edited)
let me post some pics. Then you can think about whether it is worth your while. I'll use an m110 in a 107 engine bay for comparison. Note the subframes are the same in 114/5 & 107, so the pictures of the measurements to the subframe mount from the firewall should be enough to tell you....

It is interesting to note that the front of the m110 seems tighter in my 107s than the v8s do. That makes sense with six cylinders front to back vs four. But it makes me wonder, with four fewer inches front to back in the w114, how did they fit the m110?

The m110 in a 107 does feel really nice with all that space on the sides.

"Oh my", does the 6cyl m130 in a w114 feel nice, like a tiny engine in a massive engine bay. You can get to everything. 6 spark plugs can be changed in about 10 minutes or less. So I haven't exactly felt like the w114 engine bay is tiny. But seeing that measurement, how the heck does the m110 fit in a w114?




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#38 ·
in response to fonzi's question pertaining to the V8 versus I6 engine lengths, "4 cylinders stacked versus 6 cylinders", the MB V8 are actually a little longer than the I6. On the I6, the alt, p/s pump, etc are bolted to the side of the motor, and doesn't add any appreciable length to the motor.

On the V8, added to the length of the 4 cylinders, there is the timing chain and cover, the water pump, and the engine accessories. Also, the V8 radiator fan is normally bigger than a 6.

I have the old 2.3L straight six in my 1967 230, so I was looking at upgrading to a 3.5 or 4.5 V8 sometime ago. I was very surprised and disappointed to find out that the V8 were longer than the sixes by about an inch or two.
 
#39 ·
lift points?

The '86 300SL is in the lift area. Since there is sheet metal below the jacking points, it is not all that obvious so far where I need to place the lifts to raise the car.

Would someone please tell me how to identify the lift points?

Thanks much!
 
#40 ·
I go for the rocker panels just below the jack holes. The frame rails further inside are a good spot too. In the rear. The differential is a known good jack point, but on a lift, I guess you might go for the rear control arms, but honestly I'm not sure, maybe the subframe mounts?


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#41 · (Edited)
You are correct, Fonzi. Since you were unsure, I searched some more on the net. In the MBCA there is a post that explains that under the jack points it is reinforced for lifting. They suggest putting something under there like a thick rag or a piece of wood with a slot cut out. Looks right to me, and the author of the post also seemed quite confident.
 
#45 ·
Engine turns over but antifreeze coming out somewhere

Because the engine was so dirty, I decided to try to turn it over with a socket and ratchet. To do that, I had to get the shroud out of the way. The only way I could see how to do that was to remove the fan, so I did that.

With the plugs out, the engine seems to turn over very easily. But, the instant I turned the crank, as in a few degrees, coolant started leaking out; strangest thing I've ever seen

I spent a really large amount of time trying to determine exactly where the coolant is coming from. So far as I can tell, everything I can see is perfectly dry above the bottom level of the water pump, but just below that the coolant is pooling and dripping. It is possibly the water pump, but I cannot be sure. It does not look like it is coming out of the block, it looks like the source is a little away from the block. The pump does not seem wobbly.

Any ideas on this. I am thinking I have to pull the water pump to investigate.
 
#46 · (Edited)
'86 300 SL water pump and other parts needed

It seems the water pump almost surely is shot. So, now before I try to crank this car, I am going to replace the water pump, hoses, and other things at the front of the engine.

My current plan is to take the radiator out to get more room and then get on with the rest of it. At this point the fan is off. I have a couple of questions:

(1) Do I need any special tools to do this job?

(2) Is there a how to on this particular job that applies to this particular car? I did find a how to but it is for an early 300 SL, or is an '86 an early model?

Thanks for any help offered.
 
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