My salvage engines, and bench starting.

#1

Hey, all. I've joined because I have two LD28 engines that I've picked out of yards. Both are unknown condition, and one has had gas run through it recently. It was in a car with a license plate that was current thru 2008. The gas I got out of the injector return line and injectors themselves was still fresh (it's been that recent). The mileage of this Maxima was 248,000. The cam looks worn. It's egg shaped on one side of all the lobes. The other engine, I've had for many years. Plucked it in an unknown condition from a junkyard Maxi.

Q: So, how does a person test fire one of these without it in the car? The engine is complete. I got the starter, alt, torque converter and ac pump, even. I have the fuel filter housing/mount (thanks to posts here). I also have a 280ZX turbo automatic to mate to it if I could get it to slide on (it won't yet. Can't determine why it won't.)
The IP has 4 wires hanging from it. Three grouped together are: (RED, RED/yellow stripe, RED/blue stripe). There is also a RED wire that attaches to something that looks like a sensor on a diaphram at the back top of the IP. I didn't mention the WHITE or YELLOW wire that goes to the block behind the IP and injector lines.

I have a pic I can send of the IP area and wiring. Thanks,

59rollingiron · #2

When I was working on Stovebolt engines (Big ol' gasser 6-cyls GM made from '27-'61), I'd build a wooden frame, and then build up wooden posts that held onto the engine, and start it right on top of that. Not sure how safe that is, especially on a diesel, though ... If you feel like you don't need one of those diesels, I would be VERY happy to take one off your hands!

#3

Thanks. I went thru too much to get them to give them up.

I just need to know where to apply voltage to get them tested. Nobody knows how? Anyone have an engine wiring diagram they can look at for me?

#4

The only wire you must power continuously is the stop solenoid. It is located on the back of the injection pump in the same block where the high pressure fuel lines attach. This wire must have 12 VDC at all times for the engine to run.

The other wires on the IP should be the rev sensor for the EGR system and the advance solenoid for the EGR system. Leave them alone.

The glow plugs will need to be powered at 12 VDC for a few seconds immediately before cranking. Without knowing what glowplugs are installed, it is hard to say exactly how long the plugs should be powered. Start with a 4 or 5 seconds. If the engine starts rough you may increase this, but I wouldn't go over 8 or 10 seconds. The factory plugs are a reduced voltage design that can't stand 12 volts for more than a short time. It is fairly easy to fry them with manual control...

#5

Thanks. If you can view on HybridZ.org, here's the link.
I'm guessing it's the single red wire attached to the solenoid that is attached to the diaphram thing?
HybridZ pic.

#6

Pictures are great things, but I couldn't see anything over there at Hybridz. I will look for the right pics and post them. The info is here...somewhere.

#7

I think I got the skinny from the Unimog 404 LD28 Youtube video, but a confirming picture always helps an anxious person. It looks like the solitary red wire is attached to the stop solenoid. I'm about to the point of a test cranking to determine condition of the first engine.

#8

Question: do I need a fuel pump to start an LD? If so, what pressure does it require?

#9

opie wrote:Question: do I need a fuel pump to start an LD? If so, what pressure does it require?

I would so no, there is a lift pump in the injector pump that should pull fuel... ...but... ...make sure the fuel line (from fuel tank to the fuel filter to the injector pump) is primed up first and then as you try to start it, if it doesn't start for a while crack each fuel line at the injectors while it's turning over to rid each line of air.

#10

I took the fuel filter from the donor car too. Is the wire on attached to the filter and housing a water sensor or is it a heating element?

#11

I grabbed the fuel filter form the donor car. There's a wire hanging from it. Is that for a WATER IN FUEL sensor light, or is it a fuel heater?

#12

I grabbed the fuel filter form the donor car. There's a wire hanging from it. Is that for a WATER IN FUEL sensor light, or is it a fuel heater?

#13

Single wire attached to the drain at the bottom of the fuel filter is water in filter sensor.

#14

After studying on the issue for a while I decided to walk away from it.

But now I'm back and just tried starting the engine. It's in the bed of my truck but I had zero luck. No fuel was pulled into the IP at all. My goal wasn't really to start it, but just to get fuel into the system instead of the gasoline it has in it now.

I pulled the inlet line and the remaining gas came running out of the hose. The good news was it still smelled like gas and not varnish. With a gallon of diesel in a fuel can with an inline filter in the line I hooked it to the IP and then the red wire off the back of the IP to 12V. Then I bumped the starter over. The engine turned over with no trouble but I never got any fuel to enter the system.

I elevated the fuel can over the engine. I tried forcing it in with compressed air while turning the engine. I removed all 6 fuel tubes at the injectors, and still got no fuel going into the IP or through the system.

Any suggestions?

#15

[later] Read the last sentence of this post first.

The IP's internal lift pump is a vane pump. Same basic design as a power steering pump. They wear out. Running gasoline through one possibly toasted it.

I lived in Oregon for a decade, one of only two states that prohibits self-serve in fueling stations. All fuel must be pumped by an employee. I had two diesels filled with gasoline while living there.

The first one ruined the IP; it had to be rebuilt. That was a Stanadyne DB2 in a 6.2l GM. The dealer first tried to flush the fuel system and give it back to me, but it smoked like a demon (black) and I refused to accept it. They rebuild the IP and replaced all eight injectors, and that took care of that.

The second one was a VW Rabbit with an IP very similar to the one on our LD28s. The gas station's insurance company totalled the car for the damage to the IP, and I bought it back from them for $100, flushed the fuel system myself, and drove it -- briefly. It, too, smoked badly and I sold the car that way. The engine was very worn on that car, and now it needed an IP rebuild, so I sold it (with full disclosure) to a fellow in Eugene, who emailed me a year later that he was still driving it (it was a very nice Rabbit, great condition -- except the engine)!

Both those IPs rely upon internal fuel pressure developed by their lift pumps to control the timing advance, and when the internal pump is not developing enough pressure, the timing goes retarded and if it runs, it will smoke from the retarded timing. Many, many LD28s seem to suffer from insufficient timing advance due to worn internal lift pumps. You can't fix it by pushing fuel to the pump, as the internal housing pressure has to get to around 105 PSI for proper timing advance.

I had to replace a bad IP on a Toyota diesel a few years back due to a bad lift pump. It had gotten contaminated fuel in it that had water that made it to the IP, and the internal pump's housing was pitted. That IP is again very much like ours. The truck would run using an electric pusher pump to feed fuel to the IP, but it had no power and would barely idle, would not drive. Pic of that one are here; The post below that one has a very good picture of the pitted vane pump housing ring.

Summary: the IP may be toast. It may not even be good enough to test start your engine. That wouldn't surprise me.

However, every once in a while the stop solenoid fails on this style of IP. I've never seen a bad one on an LD28, but they did occasionally go bad on the real Bosch version in VWs back in the day.

I assume that you have all six injector lines disconnected? All six glow plugs out, so you can crank it over without overheating your starter? Both of those are good ideas.

Finally, unless you are certain, don't assume that the IP belt hasn't stripped out. Hardly anyone knew that there is a belt that drives the IP (and nothing else) that is supposed to be replaced every 60k miles, and I assume that many, if not most, of the LD28s in the JYs merely needed their IP belt changed. My first LD28 just wouldn't start one morning, and that was the problem.

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My salvage engines, and bench starting.

My salvage engines, and bench starting.

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