Hey Yall, long time no see but glad to be back. My 75' 450sl has come a long way. Has a new recored radiator, new waterpump belts and hoses. I did the valve cover gaskets on it, had the brake master cyclinder repalced. Rotors all resurfaced. My problem is most of my vaccume lines are very brittle and brake ohh soo easily. Soo i know i have vacumme leaks, but the car has developed a major take off problem. It sat for a long while before i had the WP done, and i pulled the smog pump out and bought early manifolds to replace my catalysts underhood. But never got to replacing the manifolds.. After i had the pump done after it sat it was never the same. Now you have to reach a much higher rpm to make the car take off from a dead stop. When as before, this car would creep and go forward on its own as soon as i out it in drive. Now it labors to shift and take off. Aside from obvious vaccume leaks which i have attempted to patch and fix.. Is my transmission on its way out? All from sitting? Is this common? It only has 117000 miles on it. And i had the trans serviced a while back and had the mount replaced. And everything was good. Im just looking at a real loss with my car, and i dread everytime driving it now as it struggles to take off. I dont want to throw money at it. I'd honestly like to fix it and sell the car at this point. Willing to do the work myself as well.
With vacuum leaks the engine will not run like it is supposed to.
Also, the transmission has a modulator on it that works off a vacuum line.
No vacuum no work correctly.
Search on here for vacuum diagrams. I swear I'm going to have to find that post and bookmark it so I can post the link as I mention it so much lol. Find the vacuum diagram for your year and get all new lines and ends. They are really pretty inexpensive. Most of the lines are bulk line you cut to length including the ends (rubber hose you cut to make a connection end). Just a few of the ends are specialized.
Thanks Hillingdoner, i'll hunt down the vacuum diagram for my car here on benzworld. I tryed your link and it was absent there, no worries lol. Im all for it, i believe you 100 percent on the vacuum. Everything on this car had a vac line running too it And 40 some years later it mostly perished. Soo now i guess im going to learn to be a vacumme expert. Do you have a parts house you have used previously to purchase the bulk hose and fittings i need? I stay updating my work on this. And will start tonight after work, thanks again!
There are several places where vacuum systems are covered in the manuals:
- One is Section 14 of the engine manual. That has the crazy complicated emission control, EGR, air pump, advance/retard system that the 75 model had. They are in the paper manual, but I could not find them on the MBUSA Startek link. Might find them on the W116 site though.
- Second is in the Climate Control manual. Section 83, I believe.
- Another would be in Central locking system. Section 80 of Chassis manual, Volume 2.
Hard to provide links from paper manual Maybe someone has the CD sections in pdf form? I may have them somewhere?? Will look.
Given that you have changed the air injection system, you are probably on your own there. Just makes sure all need tubing connections from throttle body are connected to something or plugged.
At the rear of the engine air intake manifold, there is a vacuum connection. It branches with part heading down and eventually to transmission vacuum modulator. Sometimes a short rubber tube connected to a metal line. (I don't see that branch on vacuum diagrams that I have) That connection may be disconnected or broken. If you don't see it, look again - it is kind of hidden. The upper branch of the intake take-off goes to the climate control and door locking systems. If line to transmission is intact, you might try just plugging that upper branch for a test and see if you get any improvement in transmission shifting.
In my instance I ordered all my lines and ends from OE Discount. You can get the same sort of thing from AutohausAZ as well. Pelican parts too. Others out there.
In my instance I printed the vacuum diagram and also printed off the EPC pages. Then went to the car and marked down lengths and what each end and hose was. Added up the estimated lengths with a fudge factor and then ordered. Most of the line and ends are bulk. Just cut to length, cut the hose end for connecting and you are set. Also, a lot of the line is replaced by a generic opaque type line rather than the one with colour coding. Shame, but there you go.
No kits available for this sort of thing. You just have to calculate up what you need and order. As I said, most of the ends are just bulk hose that is cut to make the end, but there are some special curved, sized and multi junction ends.
I don't seem to have Section 14 for anything except my 72. However, if you choose a 75 450SE/SEL in this W116 link, the engine vacuum systems in Section 14 are likely same as for 107. http://handbook.w116.org/matrix6.htm
Is it just me or are the service manuals online covering less and less. Thought sure I saw vacuum diagrams in there once upon a time. Not sure if this will help, but snapped this picture for you. This is out of my paper manual. Shows to be 1975 both fed and California
If you look at the diagram I just posted you can see then what you need to work around with the emission stuff removed. Apart from sealing the engine side port on any that are no longer connected to emission items the biggest issue is that you have a line that goes to your dizzy you certainly need to deal with and ensure that the dizzy is getting vacuum so your advance/retard works.
Thank you guys soo much for the knowledge and assistance here. Work was rough today and i got home late but still, pulled my air cleaner and did some tracing and sorting. I found one vac line was completely disconnected and i was unable to find where it had connected. It was the blue striped line as marked in my diagram. As you will see in my pics, all my lines as soon as they split ontop have been jimmyed back together or reconnected all using the same color vac hose. Yikes! They are still color coordinated from where they all start. Soo i made a diagram of each color and where and how they connect and start from the bell looking vaccume servo things. In the inner fender next to where my cruise control actuator used to live. You can also see where i capped the connection from behind the smog pump, and i noticed there was vac line that was capped coming directly from another servo down there by the smog pump. Im not sure what this servo does but i know, it used to be directly fed from the smog pump which is now capped, and it has more vaccume connecting to uptop that is also capped. Soo the servo is all capped off, and i have a blue striped vac line that isnt capped or connected at all!Horrible! Now i need to study the diagrams you guys shared and isolate each vacumme line and how it was originally connected and to what exactly. I also found a tee vac fitting up by the throttle body that somebody burned and capped coming from what looks to be a sensor. Soo heres some pics of all that. Im done for tonight but my goal is map out myself where each line goes, get all new lines and re color code them with electrical tape. Tonight i study Thanks soo much again guys
And then i looked at the picture Hillingdoner posted for me and now i can understand where all this air is going!
Soo the smog pump actually does serve a purpose for injection and mabey i should of left it there. This car continues to mind boggle. I have lots to learn here
A number of people have disconnected the smog pumps etc. You just have to run and plug your vacuum lines accordingly to ensure the rest of the engine (advance comes to mind) runs correctly. With vacuum leaks then those items that are run by vacuum are not going to see the correct vacuum potentially and as such not work correctly.
Myself, when I redid mine I had to fix a lot of rigged vacuum that a previous owner did. Air pump on the car was not working and it had some hose issues on the check valve. Guess the owner did not want to spend the money to fix who knows. When I put it back together I redid the air pump system as well so that it is working as it should be. Air pump was the same pump used on GM truck and camaro so pretty inexpensive. Anyway, to each his own and what is required where you live.
If you do decide to take the emission items out of the system the thing that I would suggest is buying vacuum plugs to plug off all the open ports you will end up with. More an issue of keeping dirt out of them for the most part. Thinks like the thermal vacuum valves (two prong things on the intake), transducer etc. That way, later on if you decide to get everything working again you hopefully don't have a bunch of stuff you now need to buy because it is full of gunk from being open.
PS glad that picture worked. If you click on it you can expand it to whatever max size it will come up on the page. Couple of double clicks should do it. Also I'd suggest printing off a few copies so you can use one as a map and others as areas to make notes on items you need etc.
Interesting, I had planned to remove all the emissions stuff as i live in california, 75' being the last qualifying year as being no smog required. Now i am thinking, if i do use my early no cat manifolds they have no egr valve, i would have to delete the egr and use the vacumme running to the egr accordingly. Unless i can make the air injection system work rite without the EGR and smog pump, i now would rather leave everything intact and make sure i have no further leaks. Regardless, my lines need the replacing soo i am still going to use your diagram and take my time making sure all is connected correct and no leaks. If i can get the car to run right with no smog pump but still have all other associated items with there proper vacumm i will be happy. Either that or the pump goes back . On a side note i must ask, what is the procedure for removal/installation of exhaust manifolds? I dont think i can get to the lower bolts without the motor out! or at least raised lol Thanks Hillingdoner
Air injection not going to work without the air pump to provide the air.
You are going to have to look at the schematics for what you have taken off and find what vacuum lines are run to it and what they attach to. If a particular line is the only one attached to a port on the engine then you can cap that port off. If other things are running to the port that you need to run then you are going to have to change the connection so that they will still have vacuum as needed and the deleted item is out of the system.
Diagram I posted should be a decent guide. As I said, to each their own. I just repaired everything and got it operational again. I do understand your not liking the cats where they are on yours though.
On the exhaust, I've not had to pull my manifolds. Here should be the relevant section in the service manual.
Hopefully this helps.
If you look back through this post I posted the link to the service manual site for you. Just click your year under the model and go from there. Bit strange to navigate, but works and has most things.
If clearance is tight on the bolts it may be that your engine mounts have collapsed some.
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