I have done a engine swap, and now I have a '78 300SD engine vs a gas one.
I have done all the rewiring of the car.
questions:
1- how is the diesel "pumped"? (electrical like the gas pump? or mechanically?)
2- I see on the "control box" that there is one connector that powers up the 5 glow plugs, coolant sensor and temp (from the back of my head thinking) ---
the other connector pin seems to only need the #6 red thick cable to constant power, the thin red one to switched power, ground? is this correct?
my car does not have on the gauge panel temp light, etc... I may just use the blue/white wire for the glow plug warning light (install remote location)
3- Since my car was not diesel, I don't have a diesel shut down button/switch....any parts/advice....hard to find a shut-off button..or not looking in right places.
I'm not a diesel guy, but I've read a lot of diesel related posts...
The diesel is injected under high pressure by the pump that's attached to the engine, and to which all of the injectors are attached. The fuel that this pump uses is sent to the pump from an electrical "lift pump" back at the tank. It's not the same pump as would have worked on your car when it had a gas motor. There's a return line that sends unused diesel fuel back to the tank. (What's sent to the front is far more than the car can use - circulating it back to the tank keeps it from getting too hot under the hood).
The glow plug system involves a huge relay. I don't know if the relay switches ground, or the 12v+.
As for the glow plug light. I'll bet you can find a used cluster online from a diesel car. You can substitute the speedo from your car, plus the tach if so equipped. I know that diesel cars have a different system for the tachometer, since diesels don't have spark-based ignition to track engine revs from. There's an adapter that is part of the instrument cluster that is part of this system. Regardless, you'll find the proper cluster with the glowplug lamp in the right location. Likely it's a blank spot on your gas-powered chassis. If you can swap the engine - you can probably figure out how to get the glowplug lamp circuit to work.
As for the shutoff - the diesel cars use a different ignition switch. Vacuum hoses flow from the vacuum reservoir to the switch and from the switch to the shutoff valve under the hood. When you turn the key to off, vacuum flows to the valve and stops the motor.
You may be able to buy a diesel ignition switch and swap your key cylinder in.
Not to take thunder away from this forum, but there's a diesel-specific section over at peachparts.com - those guys are very knowledgeable.
I missed that you were creating a one-off diesel '72 MB. I thought you were working on a 116 chassis car, not a 108 (I think).
Most of what I said is true, except for the cluster question.
I've seen a few old MB diesels, and the way one worked was there was a knob on the dash. You put the key in the ignition and turned it to "run". Then you pulled out on the knob until the glow plug light came on. Once the light went off, then you pulled further to crank the motor. I don't know whether you pushed the knob in after that, or it remained out and was pushed in to stop the engine.
I'm pretty sure the chassis you're working with was available with a diesel motor in Europe. There are TONS of resources over there for "old timer" parts. You might be able to source some used components to get your car accurate, in terms of the start/stop/glowplug light setup. The Google Translate tool works pretty good against eBay.de - the German eBay site.
Good luck. Far as I'm concerned, if you're pulling a small-block chevy out of an MB and replacing it with a genuine MB motor, you've got my vote.
so there is another "pump" or THE pump is supposed to be located at the tank and is operated electrically and not mechanical? any one know if this is it? (see attachment)
also, I wired up the glow plug relay and got a small dash light to put in the dash and wired it up. seems to work fine and is located in one of the unused holes. (will post pics in the cardomain website--have to find an amber colored one)--it lights up and after a few, it shuts off...so it must be working correctly.
I will check on how hard/easy it is to change the ignition switch housing so I can have the vacuum shut-off valve holes available...I was looking for an easier route.
NEXT QUESTION:
Will I need the Speed Control Sensor? I mean, is it necessary to have the car running or is it just so I can check the rpm on the car? apparently it senses TDC...just clarification.
The pump that's attached directly to the engine is the high-pressure injector pump. It's mechanically driven by the engine itself. (The individual injector lines attach to the pump).
I'm pretty sure there's a "lift" pump that provides fuel to the injector pump and handles recirculation of the fuel back to the tank for cooling. I've looked in the EPC catalog for such an item for a W116-chassis car (which is what a 78 300SD is, chassis-wise) and can't find it. However, again, I'm not a "diesel guy" and the EPC is a real rabbit warren at times.
It may be the pump is up by the engine, or possibly engine driven just like an old mechanical fuel pump from the days of the carburetor.
I did a little asking around on other forums, and the first reply I got was the impression that the lift pump was part of the injection pump on the older 617 diesel motors.
If that is the case, all you need to do is clean the tank really well - probably a good idea to remove the lower fitting and get at the filter screen...
I can send you a picture of the hoses and items that are used at the tank-end of the fuel system - just replicate what they used on a W116 chassis car (which is where the engine you've got came from), and you should be golden.
I would appreciate that. after I gutted the car, I sold it to someone that wanted the seats (easy way for me to get rid of the body)...if I would have waited I would have some misc things that didnt seem important at the time.
Here's what I got from EPC. It's very easy - just a set of hoses - one to feed fuel to the pump, and one to return the fuel back to the tank.
item 118 is called a "breather"
item 40 is the filter screen and screws into the bottom of the tank
item 572 is a a fuel hose - looks like with a special end that screws into the screen.
item 758 is a fuel filter.
The rest of the parts are generic hoses and clamps. You'll probably need a special end at the pump for the fuel feed - called a banjo fitting.
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