380SL Diesel Conversion Project - Page 16 - PeachParts Mercedes-Benz Forum

chasinthesun · #**226** 03-04-2012, 05:55 PM

I see a scissored powered hardtop in the near future for the SLD ,your talents are top notch.If you video the first drive for us MB diesel nuts and then post it on youtube your SL will be fondley admired as a piece of art for yrs to come.

mach4 · #**227** 03-04-2012, 09:34 PM

Some days you make a lot of progress, other days are just dead ends. For example, I thought it would be a simple task to get some heater hose and hook up the other side of the engine and then turn my attention to mounting the overflow tank, etc., but just nothing worked. At the end of the day though I had the problem solved and just need a smaller diameter hose to finish the hook up.

Here's a couple of pictures from yesterday...

The drivers side heater hose transition. Snakes perfectly around the oil filter housing.

And here's the glow plug connector mounted.

Here are the kinds of challenges that I'm having with the vacuum system, although this is the switchover valve for the boost pressure aneroid, so it's pressure, not vacuum. Got some new rubber line to repair this and other issues.

mach4 · #**228** 03-05-2012, 09:17 PM

Just about finished up the cooling system stuff today. Here's the hardline I borrowed from the 300D and modified for my purposes. It comes off the aux water pump and goes to the front of the engine by the thermostat housing.

Made a bracket for the stock overflow tank and got it mounted.

Back on the ground for the time being...

mach4 · #**229** 03-09-2012, 12:32 AM

I'm definitely in the final phases of tying up loose ends and putting things back together.

Got the center link and damper mounted, the sway bar hooked up, horns mounted and transmission cooler lines hooked up. Got the speedometer pickup mounted and the gap set to 1mm.

Got the rest of the electrical done. First needed to hook up my manual shutoff. Quite some time ago, I picked up a vacuum solenoid at the junk yard to use for this purpose. I now understand that I should really use a switchover valve. Using a simple 2-port solenoid, the vacuum won't dissipate when I release the switch, meaning that the engine will not be able to be restarted. The interim solution is to poke a pinhole in the plastic vacuum line and then rig up some kind of a simple filter so it won't clog. It's mounted on the drivers side with all the other vacuum junk.

Next I needed to hook up the oil pressure sender and the engine temperature sender to the car's wiring harness. These were buried deep in the SL's wiring harness, so I stripped everything back to get at the wires. This was for two purposes: first, the old, stiff, brittle plastic harness material took up too much space and wouldn't stow very well. Here's the harness separated and ready to be wound up and stowed. (I haven't done anything irreversible yet - everything is still present and labelled should the need to go back the original configuration ever come up)

Here's the excess wiring from the old engine wrapped and tucked behind the anti-lock controller.

Also got the starter cable and solenoid wire installed. (Bumped the engine with the key to verify it worked - it did)

Also drilled out the restrictor plate in the fuel filler. I guess this means it's officially a diesel fueled car. Surprisingly this was a plastic part so didn't have to worry about metal shavings in the fuel tank. (Now just got to figure out how to remove the rest of the "unleaded gasoline only" label and replace it with a "diesel fuel only" label. ) Hopefully I've got enough room for a diesel nozzle and won't have to take out the remaining bracket.

Also got the exhaust system reinstalled and the header pipe support bracket fabricated. (pictures tomorrow when the paint dries)

In the cosmetic department, got the front plastic grill inserts re-mounted along with the air dam.

I'm down to just a handful of other items standing in the way of adding filters and fluids and going for a first start.

Called the BAR today (Bureau of Automotive Repair) which is the agency that needs to inspect the vehicle to make sure I've done every thing proper vis a vis the smog equipment and other requirements for a gas-to-diesel swap, and determined the process for scheduling the inspection.

Once she comes down off the cribs this time, it should be the last... for awhile.

ROLLGUY · #**230** 03-09-2012, 12:52 AM

I hope you get it road worthy by April 7. We are planning another cruise, and would love to have you (and your car) join us:
Planning M.B.E.G So. Cal Coastal Cruise- April 7 or 21?

cho · #**231** 03-09-2012, 09:09 AM

nice work mate,

one question, do you plan to swap filter in gasoline tank,as I have left
mine but some people told me that I probably should replace that one with diesel one also?

hope to see that ex gasser on the road soon

cheers

.

mach4 · #**232** 03-09-2012, 10:58 AM

Quote:

Originally Posted by cho

...do you plan to swap filter in gasoline tank,as I have left mine but some people told me that I probably should replace that one with diesel one also?

I believe that the tank filter (strainer) is the same for both the 107 and the 123. I don't plan to replace the strainer at this point. When I emptied the tank of gasoline, I used the fuel pump to pump it out and there was great flow all the way to the end so I don't believe the strainer is clogged. I've heard that diesel in a used gasoline tank can loosen a bunch of crud, so I'll just let the existing strainer take the brunt of that and then install a new strainer as required.

cho · #**233** 03-09-2012, 12:20 PM

Quote:

Originally Posted by mach4

I believe that the tank filter (strainer) is the same for both the 107 and the 123.

did not know that one... after check 111 470 06 86 fits all w108-w201,thanks

Quote:

Originally Posted by mach4

...so I'll just let the existing strainer take the brunt of that and then install a new strainer as required.

well...I'm way off with that schedule I guess mine has to come off like...NOW

.

mach4 · #**234** 03-09-2012, 01:32 PM

Here's a quick picture of the front exhaust support bracket.

And installed

As I mentioned previously, I needed to allow a way for my vacuum shutdown line to bleed off vacuum so I could restart. I initially just tried to poke a hole in the the line but it worked for a bit, but then the plastic started going back to the original configuration and shut off the bleed down. So I ended up using a hot needle to poke just the tiniest of holes in the plastic line. This provides essentially the same level of peak vacuum (12" with one quick pull of the MightyVac) and then a leak-down to 0" in about 2 seconds.

Then to prevent the orifice from clogging up, I rolled about 1" square shop paper towel around the orifice to serve as a vacuum filter and put a piece of shrink wrap over the top to protect it from water etc., shrinking only the very end to keep it in place.

mach4 · #**235** 03-10-2012, 07:20 PM

Loaded the fluids today and got the engine started. Not without a couple of challenges. Had trouble getting the fuel primed - turned out the hose clamp on the pre-filter was loose and it was sucking air. Also had a terrible transmission leak, that turned out to be a loose cooler line.

My biggest concern, however, was that I had no oil pressure. I'm using the 380's cluster and the sender from the 300. I assumed they were the same and it turns out they are. I just failed to hook up the cluster before starting. After hooking that up I show oil pressure just fine.

Once the engine started, it wouldn't turn off. I had to use the old block of wood over the turbo intake trick. I've got some vacuum issues which is why the manual shutoff isn't working consistently. And I think there might be an adjustment problem with the emergency shutoff because if you lift up on the rod that goes to the IP it will shutoff.

Can't drive it yet as the brakes need bleeding. I had to take them off when I removed the subframe during that early phase of the project. Built a pressure bleeder so that should be relatively easy to bleed the brakes.

So my big issues at this point are vacuum and tach. The tach kind of works - at least the needle moves, but it is backwards; at idle it's pegged at 6k and then rev it up and it goes to zero. It's not linear so I don't think it's reversed wires. It's probable that the SL and the 300D use different tach's in their clusters and I'll have to see if I can swap them out. It would make sense since the 380 takes its signal from the ignition and the 300D takes it's from the EGR computer with the source being a VR sensor that reads the flywheel teeth. I was hoping that the engineers would design the systems so that they would use the same tach gauge regardless the signal source - we'll just have to see.

I might have a fuel gauge issue too. When I drained the gas out of the SL it read below empty and the fuel light was on. After I put in 5 gallons of diesel it is reading about 3/4.

Idle is a little rough but revving it up smooths things out. I don't have the coolant in yet, so I'm only running about a minute at a time. After it warms up, we'll see what we've got. Very preliminary indication - I think my motor mounts are going to be ok. By the way, I only drove the donor 15 miles, and that was the first time I had ever driven a Mercedes, so I have no idea how it should feel or the condition of all the goodies - glow plugs, injectors, compression, timing, valve adjustment, etc. Sorting out all that stuff comes after I get the thing retitled as a diesel and am legal to drive it.

Still got quite a ways to go, but making good progress.

mercmad6.3 · #**236** 03-10-2012, 08:06 PM

Thr tacho on a diesel is basically the same part but uses and amplifier on the X11 plug (diagnostic point) . The gasoline engines send a signal from the ignition to the tacho via a ground signal from the coil.
You need to get the amplifier from the donor car and disconnect the ignition works from the X11 plug . Put the amplifier in place and see if it works better.
In your pic,it's the black thing with the screw cap.

mach4 · #**237** 03-10-2012, 08:39 PM

Quote:

Originally Posted by mercmad6.3

Thr tacho on a diesel is basically the same part but uses and amplifier on the X11 plug (diagnostic point) . The gasoline engines send a signal from the ignition to the tacho via a ground signal from the coil.
You need to get the amplifier from the donor car and disconnect the ignition works from the X11 plug . Put the amplifier in place and see if it works better.

That's true on the earlier 300D's, however on the 85 Cali the tach signal comes off the EGR controller. Here's the diagram

Pin 25 on the EGR pigtail goes to the tach.

Here's another diagram from the electrical schematic.

The problem is I can't find anywhere that shows what is on the other pin.

Based on info I saw in other threads, I've got 12v positive on the other pin. I wonder if I really need a ground for the 300D Cali? That might explain the behavior.

mercmad6.3 · #**238** 03-10-2012, 09:35 PM

Yes, i see that. The EGR signal is the same as you get from the amplifier and goes to W on the tacho for the 1985 and later cars. Now i understand your problem. if you look at a 300D tach (post 85) it has three pins + - and W . The SL has only two pins TD and + ,not counting the 12vlt feed for the clock. the instruments are grounded through the instrument cluster frame. From what i have seen,the 300D tacho wont physically fit in the cluster but i am sure a bit of surgery to case will make it fit.
The earlier tachos use the same engine speed sensor as the EGR cars ,simply a cable running to the pickup on the crank. On yours it's on the rear of the engine ?.

mach4 · #**239** 03-10-2012, 09:55 PM

Quote:

Originally Posted by mercmad6.3

The earlier tachos use the same engine speed sensor as the EGR cars ,simply a cable running to the pickup on the crank. On yours it's on the rear of the engine ?.

Yes, it's on the drivers side of the intermediate plate between the engine block and the transmission. Here's a picture.

mach4 · #**240** 03-10-2012, 10:07 PM

Part of what led me to believe that the tachs were the same, was a cluster I snagged out of a 300SD with a mechanical speedo. This was back before I adapted the variable reluctor speed sensor from the 380SL transmission to be able to keep the electronic speedometer of the 380. This cluster has the same two pin tach connector as the 380. Here's a picture of the 300SD's cluster: