380SL Diesel Conversion Project - Page 11 - PeachParts Mercedes-Benz Forum

sixto · #**151** 01-13-2012, 02:01 AM

I'm only here to see how the retitleing goes. I'll have a a 603 in a LWB 140 within minutes of you saying you got the SL retitled... K&N or not.

Sixto
87 300D

mercmad6.3 · #**152** 01-13-2012, 02:53 AM

Quote:

Originally Posted by mach4

I thought it might be helpful to just go through my thinking process vis a vis motor mounts.

When I began the project the forums were rife with stories of collapsed motor mounts. Any motor mount made of rubber is going to deteriorate and fail over time. So if the stock Mercedes mounts collapse when they deteriorate and fail and allow the engine to drop and contact the subframe or other parts, what other options might be available? I spent considerable time researching mounts and found that they all pretty much have the same failings.

So why do the 300D mounts collapse? As this image shows they are hollow. Rubber side sections support the entire weight of the engine. This is great for minimizing vibration and absorbing engine movement but upon failure you have essentially metal on metal and oftentimes the metal engine arm platform tears out... allowing stuff like this to happen - 01 Benz CLK55 AMG Busted Motor Mount - YouTube

I thought about what might be done to eliminate that kind of lifting and found this mount that provides positive containment of engine lift.

But the lack of vibration absorption material made me reject this solution. Further, the torque generated by the OM617 is probably not enough to make that a problem, witness the reality that the mounts on the donor car were completely collapsed and torn and the car was still drivable.

For about 32 seconds I considered solid motor mounts... the ultimate solution for preventing collapse, but the ultimate non-solution for drivability.

When I decided to stay as stock as possible, by going with the earlier engine support arms I likewise decided to stay with the stock MB motor mounts. So knowing that these are prone to collapse, and I had clearance issues that needed some extra support, what kind of a solution could be used to prevent that from happening?

The solution I came up with was based on solutions others have used for supporting all manner of other motor mounts - urethane.

So I filled the mounts with urethane

This compromise is almost assured prevention of collapse in exchange for some level of additional vibration, as yet to be experienced. If the vibration is too much, there are ways to soften the urethane and yet keep most of the supporting effects.

By the way, this solution was super simple in my case because I could just pour the urethane in up to the rim, but it can also be a solution for hydraulic mounts that are also prone to collapse.

On a fresh motor mount, the liquid can be drained by drilling small holes and then injecting urethane into the voids... same compromise, better support and thus more vibration.

It's not a failing. When the cars are serviced properly the mounts get changed .It's a service job to inspect them. The mounts are designed to tear and let the engine travel under the car in the event of a head on smash. most car designs still let the engine come back in the car .Not a good sight, I can assure you.

ROLLGUY · #**153** 01-13-2012, 01:04 PM

Quote:

Originally Posted by mach4

I pulled the tail cones off the donor and the original cars today. What I found was not happy news.

I sort of knew this would be the outcome based on rollguy's experience, but I just had to check.

I can confirm that the transmission tail cones are not swappable between a 380SL and a 300D.

And the parking brake gear is completely different as well.

As indicated above, it appears that the tail cone/parking gear off a 300SD will swap, but I'd like to confirm that before heading off to the junk yard to find out for sure the hard way. Any pictures or experience?

And assuming they would swap, I guess it wouldn't hurt to ask if anyone has a spare one lying around they would be willing to part with for appropriate compensation? I'm getting too old for crawling around under junk yard cars if not necessary.

Here is the photo of the tail cone from the 124 (not sure what 722..... but I think the '82 and later SD's and all 124's should have what you need).

mach4 · #**154** 01-13-2012, 02:12 PM

Quote:

Originally Posted by ROLLGUY

I think the '82 and later SD's and all 124's should have what you need.

That's what I'm thinking. I'm planning on a junkyard run tomorrow to at least check out the situation. Thanks for the picture... it's an important datapoint.

mach4 · #**155** 01-13-2012, 05:57 PM

As the major fitment issues seem to be getting resolved, I've started to begin familiarizing myself with the various systems that will need hooking up. One of the more complex, I'm finding, is the vacuum system. Keep in mind that I need to maintain the complexity at least until I get the vehicle re-titled, so removing the EGR and stuff like that has to wait.

Can someone point me to where I might find #80, the Control Unit? And if possible a picture and maybe even a wiring diagram?

I've been able to find most of the other components and have begun mentally thinking about how to mount and hook up and route the various lines and wires.

mach4 · #**156** 01-13-2012, 08:45 PM

Quote:

Originally Posted by mach4

...and maybe even a wiring diagram?

Found the wiring diagram

charmalu · #**157** 01-13-2012, 09:36 PM

#80 resides behind the kick panel on the pass side, to the right of their feet.

The 84 and 85 300D and 300SD have this.

Charlie

mach4 · #**158** 01-13-2012, 09:46 PM

Quote:

Originally Posted by charmalu

#80 resides behind the kick panel on the pass side, to the right of their feet.

Yup, found it right where you said. That's a big box - I was hoping for something more the size of a pack of cigarettes. I wonder if there's going to be room behind the 380's kick panel to mount....

sixto · #**159** 01-13-2012, 11:40 PM

Doesn't the 107 have room somewhere for a D-Jet ECU from the early days? Those things are far from small.

Sixto
87 300D

mach4 · #**160** 01-14-2012, 12:32 AM

Quote:

Originally Posted by sixto

Doesn't the 107 have room somewhere for a D-Jet ECU from the early days? Those things are far from small.

It appears that the 380SL has the KE-Jetronic system and there is a controller allegedly under the floorboards on the passenger side somewhere. I'll have to start tearing into it and see what I can find.

charmalu · #**161** 01-14-2012, 01:03 AM

Iam thinking if you are using the 300D 85 engine, and you install the "control unit #80", then the tach will work. you also have to use the pick up sensor that picks up the signal from the flywheel.

Maybe that won`t work with the SL gauges, and the 123 tach probably won`t fit into the cluster anyway. just a thought.

Charlie

mach4 · #**162** 01-15-2012, 12:21 AM

Quote:

Originally Posted by charmalu

Iam thinking if you are using the 300D 85 engine, and you install the "control unit #80", then the tach will work.

That's my understanding too. From what I can tell, all tachs appear to be the same, just a simple analog gauge. They can be driven by a tach amplifier, an ECU or other controller with pickups coming from a number of sources as well - but in the end it's just a voltage change that drives the gauge. There are quite a few threads on that topic. I guess we'll find out for sure soon enough.

In the wiring diagram (a) pin 25 goes to the tach.

For a bit, it looked like I could just grab a section of the wiring harness with all the sensors of the ECU and pull it through intact, but alas, no such luck. So the plan now is to cut the ECU plug and manually splice in the wiring for the respective components. There are really only 4 (plus the overvoltage relay and the trimming plug, and they are right next to the ECU and can probably be left intact) And two of those are one wire only. The trick is going to be to find an equivalent place to tap in for power analogous to circuits 15 and 30 on the 300D.

vstech · #**163** 01-15-2012, 10:03 AM

Quote:

Originally Posted by mach4

And the parking brake gear is completely different as well.

As indicated above, it appears that the tail cone/parking gear off a 300SD will swap, but I'd like to confirm that before heading off to the junk yard to find out for sure the hard way. Any pictures or experience?

And assuming they would swap, I guess it wouldn't hurt to ask if anyone has a spare one lying around they would be willing to part with for appropriate compensation? I'm getting too old for crawling around under junk yard cars if not necessary.

I have a few junk trans from SD's sitting on my shop floor... tell me what you need.

Graplr · #**164** 01-15-2012, 10:32 AM

I believe 84 was the first year the tach received its pickup signal from the flywheel at the trans and not the front of the engine as the previous years are. You may already know that and I can't recall from the 11 pages which tranny you are using.

mach4 · #**165** 01-15-2012, 06:27 PM

Got the exhaust system done today.

I needed to make a segment that would transition from the down tube in the front to the back section of the stock dual tube exhaust in the SL. I used two flare fittings and welded in a bend I got off a down tube section from a 300SD. (The right side looks like I welded in an extra 1/2 inch segment, but I actually used a short segment of 2.5" tube to form a sleeve and welded both ends of the sleeve)

I still need to fab up the front hangar that attaches to the transmission, but I'll need to get some material.