For Delica L300 with 4D56
This installation will greatly increase the ease of starting the diesel engine in cold temperatures. It will allow you to add more heat into the cylinders by keeping the glow plugs on after the initial cycle. There are two systems that came on these vans over the years.
The quick start system (Dual Voltage System) first hits the glow plugs 12 volts for a few seconds to heat the cylinder, and then switches over to 6 volts to smooth idle before disengaging. Glow plugs used in this system are 6V, which is why the system only applies 12V for a short period of time. Applying 12V to a 6V glow plug for too long can cause plug damage.
The later models generally have the single stage 12V system (Single Voltage System) which hits the plugs with 12V for around 30s before disengaging. These glow plugs are 12V. The single voltage system also has a glow plug light on the dash, where the quick start system does not.
This modification will add a bypass switch to the 12 volt glow plug relay in either system to manually control it.
We will also cover how to convert the Dual Voltage System over to a Single Voltage System. This can be beneficial as the OEM dual voltage glow plugs are discontinued and the single voltage system is more robust.
READ THE “DIRECTIONS FOR USE” AT THE BOTTOM OF THIS PAGE.
Tools & Parts:
- Momentary Switch (like this one)
- Philips Screwdriver
- 10mm Socket
- 12mm Socket
- Wire Strippers
- Soldering Iron and Solder
- ~18 Gauge Wire
- Solderless Connectors/Quick Splices
- Zip Ties
Instructions:
1. Remove the drivers seat by unscrewing the 4 12mm bolts that secure the seat rails.
2. Unscrew the wing bolt to open the access hatch located under the drivers seat.
3. Remove the cross-over air duct by unscrewing the 10mm bolt on the left of the space and wiggling it loose. this will allow more access to the relay.
4. As mentioned above, there are two different glow plug configurations that came in the L300, a two stage dual voltage system and a single stage single voltage system. If dual voltage system, the two glow plug relays are under this hatch , above the airbox. The relay on the right is for the 12V system (left is the 6V system). The middle wire is the activation signal wire. Attach a quick splice on this wire as shown below.
Alternate later model configuration single voltage configurations only have one relay, shown below (left relay is 12V for single stage system).
5. Run connective wiring from this quick splice to the dash. This can be done by removing the edge trim and lifting the carpet as shown below.
- Secure the wire with zip ties accordingly to prevent the possibility with a short circuit to the frame.
6. Find a location of you choice to mount the momentary switch and wire one contact to a +12V source and the other contact to the wire running to the glow plug relay. The glow plug relay supply can be used as the +12V source. The switch will always be live regardless of ignition if wired this way. This can be done by soldering or with solderless connectors. The wiring diagram. The wiring diagram is shown below,
Note: I found the steering column was a good and accessible location to drill a hole and mount the switch as shown below. See Step 1 of the Turbo Timer Install for steering column removal instructions.
Converting The Early Dual Voltage System to Single Voltage:
The primary reason to convert the old dual voltage system to the newer single stage version is mostly cost and parts availability. The dual stage system uses 6V glow plugs. These are usually signified by their green tops. These glow plugs seem to no longer be in production and aftermarket versions are known to fail and function poorly. These 6V plugs are also expensive if you can even source them, usually it’s going to be upwards of $100 each, so that’s $400 to replace 4 of your plugs.
The single voltage system is much simpler and more robust. Plugs are less likely to blow out and have a longer life. This is because the dual voltage system hits the 6V plugs with 11V, almost double their intended voltage in order to add heat fast. The single stage system is not as fast, but also not as failure prone. The single voltage 12V plugs are also much cheaper. You can get a good set for $50, and that’s for all 4 plugs. I’ll let you do the math. The Hyundai D4BF (4D56 Copy) uses 12V plugs and they are a great drop in replacement, PN: 3671042021 or 3671042020.
There are two ways to go about this conversion. This first is to piggy back the existing system. Here the original 11V relay will be reused. Disconnect and insulate the 6V relay signal wire (green circle) and do the same for the 12V relay signal wire (blue lines, the smaller wire, not the power supply line, sorry bad picture). Then run your bypass wire straight into the 11V relay.
Here is a schematic of the OEM 11V relay. There is an inline resistor that drops the voltage from 12V to 11V:
The second method is to discard all of the original relays and send full 12V straight to the new glow plugs. This is basically the same process as wiring up a set of aftermarket fog lamps. You will want to purchase a high current relay that can handle the power. Thankfully there is no shortage of universal glow plug relays on the market. They can be had for as little as $20. Something like this:
Once you have your relay mounted, simply wire it up per the schematic below (make sure to use appropriate gauge wire for the supply lines if you choose to replace the OEM wire, no smaller than 10Ga):
And now you have a manual switch that sends the full 12V to your glow plugs without the risk of overheating and damaging them.
Directions for Use:
Essential Delica Cold Start Procedure:
Starting the 4D56 Delica can take some finesse when temperatures drop below 20F. Healthy batteries and a functioning glow plug system are a must have. These old diesels will not start like a modern gas car in low temps. This procedure outlines the tricks and process to give your rig what it needs in order to fire up in the winter months.
1. Lock the throttle knob at ~75%, lock it at %100 if it is really cold.
Later model vans did not come with a throttle lock, but the injection pump has a thermo-mechanical mechanism to increase idle when cold. I have found this does not work that well when it is really cold. So simply holding down the accelerator pedal helps on cold mornings.
2. Insert and turn the key to the “on” position, but do not start. A relay under the drivers seat will click on and activate the glow plugs for ~5 seconds (longer for single voltage systems).
- Single voltage systems also have a glow plug lamp on the dash.
- If you have a voltage gauge, voltage will drop from ~11-12V down to ~9-10V, dependent on battery health and temperature.
- If there is no voltage drop, then there is a problem with the controller, relay or the plugs themselves.
3. Once you hear the relay click off and the voltage returns to ~11-12V then turn the key to the start position and hold it to start cranking. Keep cranking for at least a few seconds.
4. If the engine is still struggling to start, remove the key and repeat Steps 2&3. If this does still not work, then use the glow plug bypass switch outlined in the next step.
5. Once the original glow plug timer expires (Step 3.) wait ~4 seconds and manually trigger the glow plug using the bypass switch.
FOR DUAL VOLTAGE SYSTEMS HOLD THIS SWITCH DOWN FOR NO MORE THAN 4 SECONDS AT A TIME, WAITING 4 SECONDS BETWEEN EACH BYPASS. HOLDING DOWN THE BYPASS FOR TOO LONG CAN BLOW OUT THE PLUGS.
For the single stage 12V system the risk of blowing out plugs is not a concern.
- Holding the glow plugs on with a dual voltage system for too long can cause them to blow out.
- This should pump some extra heat into the cylinder and help the starting process.
6. Once you think you have added enough heat, start cranking (keep the accelerator pedal pressed down if you don’t have the throttle lock). Cranking for up to 20 seconds when it is really cold is normal. Every Stroke adds heat to the engine via compression. You may also need to keep the starter spinning until the engine truly finds idle. Do not crank for more than 30s. wait between long cranking cycles to let the starter cool down.
7. Let the car warm up and reduce the throttle knob appropriately.
8. Let the car run for at least 20 minutes after starting to re-charge batteries, as this process consumes large amounts of the battery power.