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1975 450sl
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Discussion Starter #1
I am in the process of transplanting M117 5.5 from a 1987 560SEC into my 1975 450sl that already has a 4 speed manual from a Euro 350SE. I plan to retain the manual by modifying the aluminum intermediate plate from the 450sl and then add Megasquirt using D-Jet intake manifold, fuel rail and exhaust manifold from the original car. Currently I am removing all of the accessories from the 560 engine and at the moment I am stuck because of three seized manifold allen head bolts.
The plan is to refresh the engine with new crank and valve seals as well as new timing chain/guides and then adapt the intermediate plate and D-Jet manifold prior to putting it into the car.
I know there are those who advocate originality and will suggest I should just keep the old engine. However, I have now owned this car for the past 18 years and I am tired of D-Jetronic expense, performance and service. These cars are not worth much even when in good condition and if I can put a better engine(which btw I got a great deal on) and a modern EFI to be able to keep the car as my daily driver, I think it is worth the trouble. Anybody done anything similar? Any constructive advice will be greatly appreciated.
 

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450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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No arguments on the swap or the value of the US 1975 450sl. Other than having manual climate controls and a dual-row timing chain, it is darn near the bottom of the pecking order due to lower power D-Jet (than earlier years), bigger bumpers, cats on the exhaust manifolds.

Speaking of exhaust manifolds, the passenger side 560se* exhaust manifold my guy no be a problem, but I think at east the driver side is going to need a 107 exhaust manifold. I’m not sure, but think the 5.6 has bigger valves and ports. So you may want to hunt down the exhaust manifold(s) you will probably need.

I am very interested in this adaptation of the 4.5 flange to make it work with a 5.6. I’m afraid that you will end up with the shafts improperly aligned or perhaps not having a long enough thought input shaft, meanwhile keeping the oddball spline clutch disk that you will need to get re-lined because replacements are hens teeth. Along with Jason Birch, we have 4 of these transmission setups, and planned to only put them on 4.5, euro 4.5, and 450slc 5.0 motors, not alloy-era motors with the smaller ring gear, starting with the 3.8, 500sl, 500slc ~1980 year. I’m pretty confident the 5.6 and even m119 use the same. Heck, why not go for the extra ~100hp an m119 might get you. Those are pretty cheap too, and the early ones are no more complex than a 5.6.

I would be ecstatic to learn the 5.6 works with the 3.5 4-speed trans, because we would then be bolting it to m119 motors. ;-)
 

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1975 450sl
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Discussion Starter #3
As far as the exhaust manifolds, I hope to use those from 450 and match/port them as I already have the rest of the exhaust system set. I wouldn't mind M119 but I got this 100K 560SEC engine for a few hundred $ including most of the accessories which I plan to sell to offset the cost of the whole project. Unlike 560 M119 doesn't have 2 threaded holes for the attachment of the intermediate plate. I will compare the fit of the adapter plate to the original as I purchased a 1973 450sl parts car and will pull that engine out to use as a reference(I am still using the 1975 as a daily driver). Yes, the ring gear is much bigger on the iron M117 but I think it will clear.
I know it is not a bolt on swap but neither was automatic to manual conversion. which I did in my driveway a year ago. It also required modification to drive shaft, pedals, hydraulic lines, shift rods, vacuum system, transmission mount, etc. In other words, I am ready for the challenge. There was a post a while ago about the same 350SL to 560SL swap using modified 350SL flange but the owner never posted the end result. If I remember correctly he managed to mount the transmission but was struggling with crank position sensor and poor running.
 

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450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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1975 450sl
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Discussion Starter #7 (Edited)
560 transplant 1 engine.jpg

Starter gear comparison.jpg
The first photo is my new 560 engine in the process of removal of the unnecessary accessories and cleaning.
The second shows difference in starter gear diameter with my old auto transmission gear on the bottom. To the side is old auto bellhousing I will use as a mock up.
 

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1975 450sl
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Discussion Starter #8
Here is my 1975 during the transmission swap last spring. I was quite happy with the result although it took a while to work out the kinks. My biggest frustration was with clutch not engaging fully and subsequently crunching into 1st and 2nd gears. This I attributed to either not using the proper fluid or not bleeding the system properly. Solving this problem took at least a month and many fluid changes and bleeding sessions. As it turned out, it was the wrong slave cylinder that was causing the problem. Apparently, these are specific to 8 cylinder transmission and have a longer shaft although the rest of the cylinder is the same. That is why no matter how well I bled the system, it would never fully engage. Foolishly, I threw away the original slave cylinder, as it was beyond repair, and when the new one arrived I had nothing to compare it with. In addition, when I ordered the new one, it stated that it should fit a 3.5 4speed application. So, the takeaway of this experience is to keep the old part until you are sure you have a right replacement.
 

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450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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Jason Birch had a similar issue with a pitted slave cylinder. I believe he filled it with Epoxy and honed it out. Then when testing it, I think he accidentally shot it across the shop to possibly never be found again. Maybe it was found when he moved shops. He definitely described to me the difference in rod lengths.


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1975 450sl
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Discussion Starter #10
I think I have a photo somewhere of the two slaves together and will post it as soon as I find it. It was so frustrating, I even thought that the problem was transmission synchros and that it will end up costing me more then it was worth to finish the project as the whole thing would now have to be rebuilt, not to mention trying to find someone to do it.
BTW, I forgot to mention another reason I wouldn't attempt mating a G76 transmission to M119. You can probably solve the engineering hurdles of attaching it to M119. Not easy or cheap, but doable. The limiting factor is the transmission itself and the fact that it was never used on anything over 200hp and 231ft/lb(M116 3.5). I doubt that it could handle the power of a M119. I am even worried how it will handle 250-260hp and who knows how much torque I think my 5.5 will generate once I have all of the mods done.
 

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1975 450sl
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Discussion Starter #11
I managed to put some time into the engine disassembly today. Unfortunately, one of the stubborn intake manifold bolts broke so now I am soaking it in PB to hopefully remove it without drilling. I forgot to take a photo of the valley before cleaning it but you can imagine by the dirt on the manifold how it looked underneath it. There was 5mm layer of dirt, oil and broken plastic all caked up. It took me an hour to get it look as it does on the second photo.
 

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560SL 1986 244k miles astral grey / black
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Interesting swab Ivan, will keep you busy for a while :))

Would you mind taking a few pictures from the 560 manifold please? Particularly were the "8 donuts" are located and the underside. I am experiencing a vacuum leak somewhere down there and I am keen to know were I am getting myself into replacing those donuts. How much time did it take you? Any other tips & tricks?

Many thanks!!
 

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1975 450sl
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Discussion Starter #13
As requested, here are some photos of the upper to lower manifold seal area. The access is a pain but I don't think replacing them is hard. The hard part is getting the manifold off and making sure you don't break anything in the process. That makes it a two day job for a home mechanic and that is if you have all of the gaskets and seals ready to go and no other complications as in my case(broken bolt). I am by no means a 560 CIS expert, as this is my first one, but I think those seals are usually not the prime suspect when it comes to air leaks. My 1975 has it's original ones and I have no leaks. My first and waaay easier target would be various hoses and then the large rubber intake boot sitting on top of the manifold. You see it in the third photo. This one got torn during removal. They are reasonably cheap and easy to replace once the fuel lines and wiring is disconnected.
 

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560SL 1986 244k miles astral grey / black
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As requested, here some photos of the upper to lower manifold seal area.
Thank you very much!!

My first and waaay easier target would be various hoses and then the large rubber intake boot sitting on top of the manifold.
You are absolutely right, but I already have replaced the AFM booth + all hoses connected to the throttle body. During a smoke test and with a little camera I can see the smoke coming from deeper in the manifold, that's why I am suspecting one of the donuts.

Thanks again for the photo's!
 

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1975 450sl
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Discussion Starter #17
I did some cleaning of the vent runners which were completely clogged. The first two photos are after I cleaned all of the gunk that made it impossible for anything to pass through. This might be the reason there was so much pressure in the valve cover areas and subsequent leaking from the gaskets that in turn caused the engine to be covered in solidified oil. This, as we all know is a very common area of leaks for all M117s. I can't see how these passages can be cleaned without taking off the intake manifold and mechanically scrapping the gunk. Does anyone have any ideas how to prevent this from happening in the future other than possibly more frequent oil changes?
Next, I turned my attention to inspecting chain guides, and while I didn't see any chunks missing, they were nice and brown and therefore ready to be replaced. The question I have, for those with experience, is weather I should replace them with new plastic ones or will the metal ones from my spare 1973 iron block M117 fit. They are in good condition and from the research I did those usually last for the life of the engine vs. plastic guides on the later models.
 

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Discussion Starter #19
Good tip about the vent runners, thx!

If the rails are exactly the same size, why not. The bearing pins are different between the iron and alloy block, so keep the ones of your alloy.
Thanks for the info Bauk18. I did not know about this difference in length. When I start tearing into the 1973 450 engine, I will compare and post the findings. It seems silly that MB would chose to save a few pennies(pfennings) on such an important part when they switched to all plastic guides. It seems so out of character for a company with reputation for over engineering and reliability.
 

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Discussion Starter #20
Unfortunately my satisfaction over a job well done after cleaning vent passages in the head was short lived. Upon further analysis, I realized I will need to completely block them as they are supplied by the air pump which I removed and will not be using on my application( attached is photo of inlet through which air is forced into the engine). Leaving them clogged would have been fine as I don't have any emissions add-ons. Does anyone have any suggestion what to use to fill the gaps? I thought of using gasket making silicone material. I will also be blocking that air pump inlet with a rubber cap.
 

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