380SL Diesel Conversion Project - Page 19

mach4 · #**271** 05-05-2012, 08:25 PM

Got back on the project a bit today - mainly got the new fan clutch and new belts installed.

All the vibration I was experiencing before is now gone.

Here's a quick :30 video of the car at idle.

It drives really nice now too.

mach4 · #**272** 05-13-2012, 07:09 PM

Druck called my attention to something I completely missed in making a swap from a gas vehicle to a diesel and that is the fuel strainer in the tank. The gas and diesel units are completely different, even though some vendors show applications for strainers the same for 107s and 123s, for example. Here's a visual of the difference.

So the obvious implication is that it would be very easy to clog up a gas strainer with diesel crud and risk fuel starvation at a most inopportune time.

So I decided to pull the strainer on the 380SL and swap in the diesel one. Wow, that was easier said than done. I looked at the strainer and found that it was not centered in the access hole, so getting any kind of a standard socket on there would be impossible. So after much thought, research and consideration, I decided to build a "spanner" type wrench to pull the strainer. On the right below is what I built.

It actually worked pretty well, in terms of fitting on the strainer nut and applying ample torque to the nut, but that strainer was completely stuck - a standard 3/8" wrench did nothing, neither did a 1/2" breaker bar and neither did an extra long 1/2" breaker bar and neither did an air gun. So there was no option but to pull the tank, which I did. Since I had it out there was no reason not to use a standard 46mm socket - which worked find with plenty of working room and direct access. Most 46mm sockets are pretty expensive, but I found this one for about $12 at the local VW shop - it so happens that the axle nut on a VW Van is 46mm.

As long as I had the tank out, I decided that I didn't want to risk having to pull the tank every time I wanted to clean/change the strainer, so I spent a bit of time with an air die grinder and opened up the hole quite a bit so the 46mm socket could be used in the future.

I decided to pull the strainer off the donor car, and, of course, that was completely stuck too, so I pulled the donor tank to get at the strainer (anyone need a good 123 diesel tank?)

Since I had everything apart, I decided to re-engineer the fuel hose setup. Rather than use the large exit line of the 380SL and a bunch of fittings, I decided to use the smaller line off the 300D. I cut off the crimp on the diesel exit line and just used the fitting with a hose and clamp.

The final installation looks like this. I'm very happy with the improvement.

I also decided to simplify things even more by eliminating the vapor tank. Diesel fuel does not produce vapors, so there is no need for this extra item. I capped both side sets of vents and then left the center vent open with a hose that rises above the top level of both the tank and the filler. This way I don't have to try to make a vented cap.

That was a project I wasn't planning on, but glad to do it now, rather than find out I had a problem along the road somewhere. Good information for anyone doing a gas to diesel swap.

ROLLGUY · #**273** 05-13-2012, 07:55 PM

Quote:

Originally Posted by mach4

Since I had everything apart, I decided to re-engineer the fuel hose setup. Rather than use the large exit line of the 380SL and a bunch of fittings, I decided to use the smaller line off the 300D. I cut off the crimp on the diesel exit line and just used the fitting with a hose and clamp.

I have done this on many cars that I needed to change the fuel lines on. It is much easier and cheaper than ordering a factory hose.

mercmad6.3 · #**274** 05-13-2012, 08:17 PM

here is something a little off topic .a 3.0 liter SL. W113.

Druk · #**275** 05-14-2012, 02:41 PM

Quote:

Originally Posted by mach4

Druk called my attention to something I completely missed in making a swap from a gas vehicle to a diesel and that is the fuel strainer in the tank. The gas and diesel units are completely different, even though some vendors show applications for strainers the same for 107s and 123s, for example. Here's a visual of the difference.

The reason behind how I discovered the tank strainers are different is because parallel to Mach4 doing his conversion I am swapping the 280 M110 engine in my 107 for a 606.962. Trying to get the rubber drop pipe out of the tank unit the complete thing came out and I saw it had 'Benzin' cast into the flange. Exploring the depths of the EPC revealed that the same strainer is fitted to a whole host of vehicles and some of them have diesel engines straight from the factory. Below is a pic of my unit. The reason it has a large nut just below the strainer is because I'm using that to tighten the unit into the tank rather than take the tank out.
I prefer to have a bolted system for the fuel pipe rather than a spigot. I don't trust spigots not to develop air leaks sometime down the line. Been there...done that.

With the encouragement I've had from Mach4 I'll start a fresh thread sometime soon to tell the story of my own conversion. Meantime this is how the car looks at present.

.

mercmad6.3 · #**276** 05-14-2012, 06:05 PM

Wow,thats a tight fit with the hoist!! If all else fails you have the tandem.

Druk · #**277** 05-15-2012, 02:43 AM

Ha ha. I wondered if anyone would comment on that. It's an all ally top folder that goes in the back of the S211 in one piece. There's actually more space than the pic shows, maybe a couple of feet spare.

mach4 · #**278** 05-20-2012, 10:59 PM

Well I've got my fuel strainer issues taken care of and the tank back in the car along with the revised fuel line configuration (thanks Druk). No leaks.

I've taken the car out on the freeway and put probably 120 miles on her in the past couple of days. I think it runs pretty well, but with a total of 20 minutes of Mercedes time prior to starting the project, I had nothing to compare it to.

Today rolfing, a very experienced Mercedes enthusiast on this forum, came by and took a look at the project and confirmed that it indeed runs well - nice to have my impressions confirmed. (He's already started his 450SL diesel swap... I guess the idea of a diesel sports car is contagious.)

I've got a really bad upper ball joint on the drivers side so I won't be taking it out much until that's done... and I don't plan on digging into that until I get the state inspection for retitling as a diesel completed (I will, however, take my chances and drive it over to the inspection station)

Got my tach calibration problem solved. When I put the new tach module into the cluster I just used the faceplate from the 380SL and it was woefully inaccurate. So as a test, I did a temporary tape job of the 300D faceplate over the top of the 380SL faceplate (the mounting tabs don't align). It's perfect. So next time I pull the cluster to add another ground (I've got the old jumping gauges when the turn signals are on problem) I'll make it permanent with some epoxy to glue the faceplates together- pictures to come. The clock doesn't work either, so I'll get the caps and solder them in - hopefully that's all it is.

I believe that I can now safely say that from a vibration standpoint, the urethane-filled motor/transmission mounts, the speedometer mod and the urethane-filled subframe mounts are a success. I have vibration at idle but that's almost assuredly injectors since it goes away with just 50 additional rpm.

For anyone that wants to prevent their new cheap motor mounts from collapsing and presumably give years of troublefree service, this is a recommended solution.

Time to start planning phase II - A/C, engine cosmetics, injectors, timing chain, turbo tuning, gauges, seats, stereo, and so forth.

Special thanks to everyone on the forum that provided encouragement, solutions, advice, options and feedback that were very instrumental in a successful project.

It's been fun!

mach4 · #**279** 06-16-2012, 08:08 PM

In post 267 I documented my progress on a new air filter and today I got the housing finished. The piece I picked up at the junk yard was smaller on one end than the other and would potentially create an unwanted restriction. So I finally got a chance to get down to the hangar and turn the piece on the lathe to take out the restriction.

When I got back I "welded" up the piece using AlumaWeld. It's the first time I used this kind of material and I'm pretty pleased with the results. This material is more like a solder or brazing process, but it should be just fine for this application. Here's the piece ready for install.

For those that are following this thread relative to the process of getting the vehicle re-titled as a diesel and therefore legal and exempt from smog, I've got my appointment on the 25th with the BAR referee and hopefully there will be no problems. Stand by.... Update: The BAR cancelled the inspection because their smog machine was down: rescheduled for July 3.

I've also got a web site that is almost ready to launch that treats this project almost like a how-to. As soon as I settle on a suitable domain and get the site transferred. I'll announce it here. A few domain possibilities are 380SLD.com, 380SL-Diesel.com, SLDiesel.com, 107Diesel.com or Diesel107.com Coming soon...

mach4 · #**280** 06-17-2012, 12:28 AM

The project web site 380SL Diesel Swap Project is now live at SLDiesel.com.

The content is essentially that of this thread, but organized more as a "howto" than as a build log. Feedback and suggestions are welcome.

DeliveryValve · #**281** 06-17-2012, 01:10 AM

Nice website.

From a quick look through, you mentioned the "1978-9 300D W115" There is no such car. The correction is a 1975-76 300D w115, with a European 1974 240D 3.0 w115.

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t walgamuth · #**282** 06-17-2012, 07:32 AM

Great job! It is clear that you have worked through this project and come up with excellent solutions to all the big and little problems that you have come up against.

Congratulations!

bkc · #**283** 06-17-2012, 09:24 AM

Spectacular! Really gives me a lot of encouragement and inspiration for my planned conversion.

(Bought an R129 with engine problems, planning to keep it stumbling through the summer to enjoy having a convertible, then convert it to diesel in the Fall with the OM602 out of my wrecked W124.)

Thanks for such detailed info and references! I hope my R129/OM602 project goes as smoothly!