Cold Starting. Getting Heat Pressure Fuel

[pbknowles]

Hi all, since I hate to ask questions that have been answered already first let me begin by saying that I have carefully read all the previous cold start posts. I have carefully gone over and verified correct operation of all the related support systems, to include:
1. Visual, resistance and bench test verification of each glow plug.
2. Verification of engine compression (390 psi with a cold engine and air throttle closed).
3. Glow plug and after glow timer. I have an led wired directly to the glow plug harness to show when the glow plugs are powered.
4. I have experimented with advancing the injection pump timing slightly. I even pulled the cover off and verified that I had timed the gears correctly when I assembled the engine.
5. Verification of fuel supply, including filter bleed bolt and free of air bubbles.
6. Injectors are freshly re-nozzled by a reputable shop.
7. Valve clearance is in spec.
8. New battery, upsized positive cable and additional ground cables.
9. Finally, since my "smoke" screw had been tampered with by a previous owner, I have installed an EGT probe and adjusted the screw so that a long hard 3rd gear pull results in max egt's of anbout 1200 deg. f. and no visible smoke. This number was arrived at because the other IDI engines I own (or have owned) all maxed out at about this figue with stock pump calibration.

All of these efforts have resulted in improved cold start performance, but it is still not what I had hoped for. I can start reliably down to about 15 deg. f with no block heater. The starting technique I have found to work best is to not touch the throttle at all. Application of any throttle results in white smoke and rough running, but if I just leave it alone and let it idle naturally it comes up OK, but until it warms up a bit it will not take any throttle, instantly going into "white smoke/rough running" mode. Also, if it is really cold, the fire will simply go out and the engine stall when the afterglow circuit times out.

Now, my reference point for all of this is my old F-350 with a 6.9l. It starts down below 0 deg. f. with little drama, and you can pretty much just drive away once it is running. I can't plug the truck in when I am at work, so that is driving the "no block heater" part of this discussion. So back to the title of the post:
Am I just expecting too much from the little SD? I am having a tough time accepting this because of my experience with the 6.9 plus a MB 300td, Kubota powered skid loader and Isuzu C201 powered generator that I own. Any thoughts appreciated!
PK

[philip]

(See also: Cold Start Difficulties)

SNIP- All of these efforts have resulted in improved cold start performance, but it is still not what I had hoped for.

One of my long held wisdoms: "Unfulfilled expectation is the seed of depression"

I can start reliably down to about 15 deg. f with no block heater. The starting technique I have found to work best is to not touch the throttle at all. Application of any throttle results in white smoke and rough running, but if I just leave it alone and let it idle naturally it comes up OK, but until it warms up a bit it will not take any throttle, instantly going into "white smoke/rough running" mode. Also, if it is really cold, the fire will simply go out and the engine stall when the afterglow circuit times out.

With ambients in the mid 20's, I've observed a similar phenomenon with regard to smooth cold idle that turns rough and smokey if the engine is accelerated ... especially right after the glows turn OFF (more than 30 seconds after starting). Remember, you're dousing (quenching) the glow plug tip with chilled fuel when you accelerate which would result in unreliable ignition while the prechamber is still so chilled.



What changes have you made to the fuel to accomodate cold weather? At 15 degrees F, clouded/gelled fuel needs to be addressed.

[lacolocho]

You could get some 12v injection line heaters. People are using them a lot with biodiesel and SVO, but if you want a good clean cold start it seems like it would help quite a bit.
They're cheap, easy to install, and don't draw too many amps.
I haven't used them, but lots of people seem to find them really helpful.

Here's some for $40 on ebay: Injection Line Preheaters

[philip]

RE:Injection Line Preheaters

This is the first time I've such a product. Seems logical. Sure puts The Heat where and when it is needed. The narrative is worth reading:

"Why use injector line heaters? -SNIP- ...but, the main reason for heating the WVO is to provide good atomization at the injector and combustion in the cylinder. When the WVO is hot the combustion is much more complete. So while your WVO may be at 160-180 as it enters the injection pump, temps can drop to 120 or lower by the time it gets to the injectors, this GETS WORSE IN COLD WEATHER. I use an electric resistance heater on the injector lines just prior to the injectors. This heater applies heat directly to the injector lines and heats them to about 180 - 220f . This really makes a huge difference, smoke is much less at idle, power is improved even emissions are much lower. "



I wonder how much preheat time is required to achieve 110 degrees fuel temperature at the injector when ambients near zero degrees.

[philip]

I messaged the Seller asking about how long to get fuel in the injection line up to about 110-120 degrees when ambients temps were down there near ZERO.

Here is his reply:

"The heaters get up to 180 degrees in about a minute. This time will depend on your system voltage of course. I would just be guessing on what your preheat time would be without actually testing myself. My best guess would be about 2 minutes. Remember there is no flow untill you start so it shouldn't take too long. Thanks, Kieran"

[EvergreenSD]

This really caught my attention. I have been brainstorming ways to quickly preheat fuel on cold starts even though my engine has shown tremendous improvement since advancing the timing. This seems like just the solution I have been trying to figure out.

$40 seems awfully expensive for what he's really trying to market, though. Correct me if I'm wrong but a length of insulated wire wrapped around the injection lines would do the same thing. A quick calculation shows that if you used enough wire to reach 1.72 ohms (I haven't yet figured out what to use or how much it would take) would put out 84 watts and draw 7 amps. I used this as a baseline to emulate the numbers the seller gave. Ideally I would like to put something like this on a time-delay switch so it stayed on for the first several minutes on a cold-start situation and then turned itself off. It seems unnecessary to run it all the time for #2 or bio-d.

BTW, I just got myself a new battery so I'm much relieved to not feel like I'm on the verge of getting stranded all the time. I got an 85-month 700CCA for about $50. The old one had no markings (which seemed strange) but was honestly only half as big and was struggling with the cold weather. I knew it was too small but it wasn't untill I saw them side by side . . .

[philip]

SNIP- $40 seems awfully expensive for what he's really trying to market, though.

Resist the temptation to deny the man the value he puts on his time to design, model, and package up the components and instructions to do the job.

SNIP- It seems unnecessary to run it all the time for #2 or bio-d.

The Seller's audience is the SVO/WVO user, not us D2 users who just what a cold drive-off aid.

BTW, I just got myself a new battery.

I have a Group 27 size battery rated: "725 CCA @ 0 degrees F" , "900 CA @ 32 degrees F". Never had it below 25 degrees. Never fails.

[zen]

$40 seems awfully expensive for what he's really trying to market, though. Correct me if I'm wrong but a length of insulated wire wrapped around the injection lines would do the same thing.

No it won't. He will be using specific high resistance cable specifically designed to heat up without melting the insulation and catching fire. It ain't cheap.

[EvergreenSD]

Right you are. It would take 228 ft of 18 AWG wire to reach the target 1.714 ohms. You can bet I will be researching resistance wire, though.[/i]

[pbknowles]

Thanks all for the replies.....Philip, I have not experimented with any fuel additives, I just buy from a high volume station near my home. We have a UPS hub nearby and they fill up there, so they go through a lot of fuel. Perhaps I will try one of the additives discussed in other recent posts. The fuel line heaters look interesting too, and would indeed need to be made of a high temperature material like nichrome or other heating element specific wire, or a fire is the sure result!

[philip]

SNIP- I can start reliably down to about 15 deg. f with no block heater. The starting technique I have found to work best is to not touch the throttle at all. Application of any throttle results in white smoke and rough running, but if I just leave it alone and let it idle naturally it comes up OK, but until it warms up a bit it will not take any throttle, instantly going into "white smoke/rough running" mode. Also, if it is really cold, the fire will simply go out and the engine stall when the afterglow circuit times out. -SNIP

Cold (below freezing) starting these little beasties is a recurring theme.

Tonight I ran across this overview on a CHEVRONwebsite:

" When a cold diesel engine is started (cold start), the heat of compression is the only energy source available to heat the gas in the combustion chamber to a temperature that will initiate the spontaneous combustion of the fuel (about 750°F [400°C]). Since the walls of the combustion chamber are initially at ambient temperature rather than operating temperature, they are a significant heat sink rather than a heat source. And since cranking speed is slower than operating speed, compression is also slower, which allows more time for the compressed air to lose heat to the chamber walls. (A glow plug provides an additional source of heat in indirect-injection diesel engines.)

A fuel that combusts more readily will require less cranking to start an engine. Thus, if other conditions are equal, a higher cetane number fuel makes starting easier. As the compression temperature is reduced by variables like lower compression pressure, lower ambient temperature, and lower coolant temperature, an engine requires an increasingly higher cetane number fuel to start easily.

Research indicates that fuels meeting the ASTM Standard Specification D 975 cetane number requirement of a minimum of 40 provide adequate cold starting performance in modern(*) diesel engines. At temperatures below freezing, starting aids may be necessary regardless of the cetane number of the fuel.

Even after the engine has started, the temperatures in the combustion chamber may still be too low to induce complete combustion of the injected fuel. The resulting unburned and partially burned fuel is exhausted as a mist of small droplets that is seen as white smoke (cold smoke). This situation normally lasts for less than a minute, but the exhaust is irritating to the eyes, and can be objectionable if a number of vehicles are started together in an enclosed space. A fuel with a higher cetane number can ameliorate the problem by shortening the time during which unburned fuel is emitted to the atmosphere. "

(*)I understand the term "modern" to suggest DI combustion chamber design. The SD engines are of the ancient IDI design.

[Nissan_Ranger]

It's getting late in the cold season now to bump this cold starting thread back to the top, but... oh well:-)

Here in eastern Ontario, January and February night time temps get down to an average of -20 F with dips to -30 F. Since I started using synthetic oil, my SD22 starts readily down to -20 without being plugged in and it has started at -30 with extra glowing and a stall or two after firing up. I left out the automatic timers when I did the Ranger conversion and use a push button to control a fender-wall mounted Ford style solenoid switch to feed the glow plugs. In the colder nights, I feed the plugs at least 30 seconds before attempting a start. If the engine stumbles and quits, I glow it for another 20 seconds before trying again. When it does start, I do NOT touch the fuel pedal but do feed the glow plugs some more until the idle is and remains smooth. Clearly, synthetic oil is the magic bullet for good cold weather starting here...

Regards,

N_R