truck keeps cranking

[TexasNomad]

Dose any one know if he figured out the problem?

 

[blackhat620]

Dose any one know if he figured out the problem?

Bad solenoid. See post #15 above from yesterday.

 

[blackhat620]

i was told that most of the time an engine will diesel backwards and thats when most of the damage occurs.

The damage comes from the knocking, "dieseling" which is caused by excess heat, hot spots, poor engine cooling etc... The excess heat & hot spots along with the high cylinder pressures encountered when an engine diesels produces holes in the pistons, is hard on the bottom end of the motor, can cause head gaskets to fail etc. Pinging and knocking when during normal driving can cause the same heat related problems. Cast pistons are not designed to deal with much excess heat, they are relatively easy to compromise.

Generally any time you run a forced induction engine or NOx you do not want to use cast pistons, you want the added strength and heat rejection properties of forged pistons. This is do to the added cylinder pressures & heat.

 

[Mil1ion]

Engines that have extremely stretched timing chains and stripped Cam Gear are a HAZARD toward this problem as well.

 

[Alvin in AZ]

No they do Not run backwards when they diesel, ever!

Ever?
As in... -never- ever? LOL

Can you explain to me what's causing the vehicle to move in the opposite
direction from the gear it's in (1st or reverse) when they diesel sometimes?

I'm pretty dangged stupid so can you 'slpain it to me in detail, please?

Alvin in AZ (my first post, picking on blackhat420
ps- "red hot" carbon build up was causing lots of trouble in my 360FE@148K

 

[Mil1ion]

Run-on by dieseling is caused by fuel in engine igniting without spark.

Possible explanations:
a.) Running winter fuel in warm weather.
Winter formulated fuels have a higher vapor pressure, meaning that they evaporate easier. Only vaporized fuel will burn, not the liquid stuff. The cure is to run the fuel tank nearly empty and fill up fresh. The oil companies change the fuel formulation seasonally, and sometimes even monthly.

b.) Using gasoline with alcohol content.
Gasahol gasoline contains about 10% alcohol, usually methanol alcohol. The alcohol vaporizes at a much lower temperature than the rest of the fuel. The result is alcohol vapor in the combustion chamber, and the engine runs on easily. This stuff can also cause vapor lock in a carbureted engine on a hot day, or when you shut off a hot engine and then try to start it five minutes later, after heat soaking the carbs under the hood. This is a nasty problem with my MGA, with only a feed line to the carbs -- no return line. A carb with a fuel return line to the fuel tank will help ease this problem. Keeping the fuel circulating back to the tank can keep the fuel and the carb cool. Also carbs located on the same side of the engine with the exhaust manifold are especially susceptible to this problem. My solution is to stay completely away from the alcohol content fuels.

c.) Using low octane gasoline in an engine that should have high octane fuel.
High octane fuel is more resistant to both evaporation and pre-ignition. Check your owners manual (if you still have one) for the recommended octane requirement. For good measure, add one or two points to the recommended number. The method of rating fuel for octane level changed some years ago, and the numbers are now a couple of points higher to achieve the same results.

d.) Run-on valve defective or out of adjustment.
The function of this part is to completely shut off all fuel to the engine when you turn off the ignition. On a carbureted engine you may otherwise find a run-on solenoid. The function of this part is to completely shut off the air intake at the carb when you turn off the ignition. If either of these devices is out of whack, fuel/air mixture can get into the engine after shut-down, causing run-on.

e.) Hot spots in the combustion chamber.
Any carbureted engine having neither of the above mentioned devices will continue to draw in fuel/air after shut-down. Any hot spot inside the combustion chamber can ignite the fuel causing run-on. Right off hand I can think of at least three sources of hot spots.

 

[CaFordDude]

What does that post mean Alvin?

 

[Mil1ion]

Dieseling or engine run-on is a condition which can occur in spark plug gasoline powered internal combustion engines whereby the engine keeps running for a short period after being turned off, due to fuel igniting without a spark.

Dieseling is so-named because it is similar in appearance to how diesel engines operate, by firing without a spark. However the ignition source in a diesel is the compression of the gas in the cylinder, while in the dieseling phenomenon the compression ratio is not sufficient to ignite the fuel and it is a hot spot inside the cylinder that starts combustion.

An automobile engine that is dieseling will typically sputter then gradually stop rather than continue running as if the engine was not switched off at all — the latter would usually indicate an electrical fault.

Dieseling is not nearly as common as it once was because it most commonly occurs in carburetted engines. The vast majority of American, European, and Japanese vehicles manufactured after 1990 are fuel-injected-- the injectors and high-pressure fuel pump immediately cease supplying fuel to the cylinders when the ignition is switched off. If the injector is damaged or malfunctioning, a small amount of fuel can enter the chamber and be ignited, causing a sputter or two after the engine is switched off.

Ironically, dieseling (in the sense of engine run-on, and disregarding combustible gaseous mixtures via the air intake) cannot occur in diesel engines because they are controlled entirely by the rate fuel is delivered to the cylinders. The only way to shut them down is to cease fuel delivery. Whether electrically or mechanically driven, the fuel pumps and injectors are switched off to stop the engine.

Some carburetted engines have fuel pumps, but they are often low-pressure. They are typically designed only to overcome a loss of suction in the fuel line near the engine due to fuel evaporation in hot weather, to supply sufficient fuel to maintain stoichiometric combustion under heavy load with wide-open throttle, or a combination of the two. Fuel demand is low at idle and there is more than enough manifold vacuum to draw sufficient fuel for combustion even if the fuel pump is switched off.

Gasoline engines that are much smaller than the typical automotive engine are usually carburetted for economic and engineering reasons. Dieseling can occur in such engines. These engines include those installed in mopeds, scooters, small motorcycles, ATVs, and most lawn-and-garden power tools.

 

[TexasNomad]

I didn't think most gas engines had high enough compression to get the gas to ignite?

 

[Alvin in AZ]

What does that post mean Alvin?

Nuthin. :/
None of my posts ever mean anything. :/

A guy with a manual transmission can put on the brakes and put it in gear
and "kill" a dieseling gasoline engine. It's hard on stuff but so is dieseling.

Killing the motion of the vehicle (after turning off the key and coasting) by
letting out the clutch can be a little scary when they diesel and you're half
out the pickup's door. LOL BTDT one, uhhh... every, time too many.

No kidding you can have it in first gear and the dieseling sucker will start
backing up on you, then as you are trying to kill it, it'll start moving forward
again then maybe even rock back and forth.

Dang those were the good ol' days, huh?

YMMV on whether you've experienced it yourself or not I guess?

Alvin in AZ

 

[Alvin in AZ]

I didn't think most gas engines had high enough compression to get the
gas to ignite?

Yeah, when everything is "right" they need the spark plug's spark but when
things are messed up with hotter-than-red-hot fuel and oil deposits, it changes.

I remember them blaming it on 10W-40 having quite a bit more additives and
it would build the deposits up where as straight 30 weight could keep them
burned off (when all else was equal). It's mostly a temperature thing I believe,
because my factory built 360FE would do that in the summer time under certain
conditions and carburetor settings.

Alvin in AZ