78 300d 617 NA replaced by 617 turbo--questions - PeachParts Mercedes-Benz Forum

ridgerunner · #1 12-19-2012, 06:42 PM

I've got a 78 300d, NA 617 and I'm installing a 83 300d turbo charged engine into it. I've ran into a issue with the throttle linkage. On the car, there is a cross shaft that the foot throttle lever attaches to on firewall. On the right side of engine, the rod/linkage goes forward from cross shaft to a bracket under intake manifold where another rod attaches and runs up to crank on top of valve cover, then to IP.
Well with the 83 617 engine the throttle hooks up entirely different.
The bracket on firewall that accepts the horizontal shaft on the turbo engine isn't there. I know someone on this forym has did this modification before. I'm capable of fabricating something, or mounting the needed bracket on firewall.
Any and all info is appreciated.

kerry · #2 12-19-2012, 06:52 PM

What transmission are you using, the 78? If it's like my 77, it had a rod that went down thru the intake manifold to control the shifting on the transmission. I don't believe any turbo engines had such a rod for controlling the transmission. So I think you're going to have to factor transmission control into the equation.

KAdams4458 · #3 12-19-2012, 07:05 PM

Pretty simple if you have access to a donor car. You need the pedal rod and the firewall bracket, and the two firewall linkages. The bracket is secured with several spot welds that you will need to drill out in order to remove it, and everything else just unbolts.

I played out a simple template on the firewall of the donor car using masking tape before removing the bracket from the donor which allowed me to orient the bracket on the older car, as well as the hole for the later pedal rod. Things like the opening for the heater core pipes and firewall seams are identical and make for good reference points. One the tape template was made up, I just peeled it off the donor firewall and stuck it to the recipient firewall before drilling and cutting the required holes. I tacked the bracket in place with a MIG welder, and smeared seam sealer on to replicate the factory installation.

With both motors out of each car, the entire process took me about half an hour.

Phillytwotank · #4 12-19-2012, 07:16 PM

i don't know from experience but i have thought about this very scenario in anticipation of an eventual swap in my own '78...

barring the transmission control issue. why not just use the exact same linkage set-up from the '78?

Phillytwotank · #5 12-19-2012, 07:40 PM

Quote:

Originally Posted by Phillytwotank

i don't know from experience but i have thought about this very scenario in anticipation of an eventual swap in my own '78... barring the transmission control issue. why not just use the exact same linkage set-up from the '78?

Nevermind that question. Moments after i hit submit the answer came to me.

because the manifolds on the turbo side won't allow for the linkage to pass through like it did on the '78.

ridgerunner · #6 12-19-2012, 07:24 PM

Kerry, I'm using the tranny bolted up to the 83, so the kickdown rod is no longer used. It will be vacuum.

sleepstar · #7 12-19-2012, 07:25 PM

the 722.120 transmission installed on the turbo 116s used a rod to control the transmission, but it goes up and over the top of the valve cover in the same general area as a bowden cable would

ridgerunner · #8 12-19-2012, 07:28 PM

K.C.Adams; sounds like what I had in mind, except that I hadn't thought of drilling spot welds off donor.
When you spot welded the bracket in place; do you know whats on the other side of firewall at location you were mounting it?
I thought of drilling and using screws/nuts instead of tacking with welder.
THE BAD; I just dropped in the turbo engine today, figuring I would deal with the bracket after everything else is completed.
Hope I didn't mess up!
Thanks.

KAdams4458 · #9 12-19-2012, 07:44 PM

Quote:

Originally Posted by ridgerunner

K.C.Adams; sounds like what I had in mind, except that I hadn't thought of drilling spot welds off donor.
When you spot welded the bracket in place; do you know whats on the other side of firewall at location you were mounting it?
I thought of drilling and using screws/nuts instead of tacking with welder.
THE BAD; I just dropped in the turbo engine today, figuring I would deal with the bracket after everything else is completed.
Hope I didn't mess up!
Thanks.

Well, that will add a level of difficulty, but it shouldn't be impossible. A little more contortion will be required.

What's on the other side of the firewall? Sound deadening, mostly. I welded it in with short bursts and managed not to set anything on fire. I did have a fire extinguisher handy and the gauge cluster out for accessibility, just in case. You could just as easily screw it down, or maybe use blind rivets. Another option might even be to secure it with panel bond adhesive.

ridgerunner · #10 12-19-2012, 07:32 PM

Phillytwotank:the NA engine linkage setup will not work on the turbo engine. On the right side of engine there is a bellcrank that mounts under intake/exhaust manifold, and a rod comes up through a gap between cylinders intake/exhaust and meets at top of valve cover, then over toward IP. On the turbo engine there isn't the gap to pass the rod up and through.
Jim

ridgerunner · #11 12-19-2012, 07:51 PM

Ok, sounds good. I was thinking either screws/nuts or rivets. Wasn't sure if heater core was on other side or if anything.
I appreciate all the info. Now I've got to find a donor or if someone has a parts car.

KAdams4458 · #12 12-19-2012, 09:40 PM

Quote:

Originally Posted by ridgerunner

Ok, sounds good. I was thinking either screws/nuts or rivets. Wasn't sure if heater core was on other side or if anything.
I appreciate all the info. Now I've got to find a donor or if someone has a parts car.

Just be careful of how far you let the drill bit penetrate. A bit stop would be ideal.

ridgerunner · #13 12-19-2012, 10:18 PM

Yep, ok. Got a drill stop. I've got to get to the PNP to see if I can come up with a donor.
I appreciate all the info.
Wonder if I put a post in classified if someone would have a donor car to drill one off of? The closest PNP is an hour from me.

charmalu · #14 12-19-2012, 11:36 PM

Before running off to the PNP for the part, bring up their web site and see if they have a 82 - 85 300D. think that is the only years that used that bracket.

The ball mount or pivot may be used on the 300SD also, don`t know for sure. the mount will be different as the W126 300SD has the false FW in front of the main FW and it is mounted to the false one.

Just looked in the parts catalog (This site) and one is not listed for the SD.

there is one for the 300D. lists for $54.25

Product Information: 123-300-13-40-M22

Printable View

Charlie

BillGrissom · #15 12-19-2012, 11:37 PM

Can only add a tid-bit since I haven't seen your 78 setup. I did take the "throttle ball" thing on the firewall off a 70's Benz (over-under headlights) for my 85 W123, and it fit perfectly. My rubber part was split. The 70's car was missing the engine so don't know if a diesel, and can't say if the throttle ball bracket was in exactly the same place as in my car, but appeared so.