Educate me on glow plugs

pburchett

Member
Until recently I have been running a Ford 640. It had gotten in bad shape and needs a complete restoration. So me entire 47 years of life has been with this gas tractor.

I needed a better tractor so I bought a Kubota MX5200HST. I like the tractor as far as the front end loader, 4x4, the fact that the hydraulics work, and love the hydrostatic. It uses about the same amount of fuel as the 640 so that is a plus. I dislike the fact that is is not as tough or simple as the old Ford. I also dislike the diesel catalyst, particulate filter and all the electronics. I looked for a good used tractor but the market here was ridiculous and a new tractor cost only 3000-4000 more, plus I got 0% interest. I compared New Holland, Massey Fergurson and the Kubota's and settled on the orange one.

So, with the vast knowledge on this forum I once again seek advice on the operation of a diesel along with glow plugs and turbos. I have been using the ultra low sulfur fuel with a little Diesel Kleen additive. Is there anything I should add to the coolant that is specific to diesels? As far as I can find I need to keep clean oil and let the turbo spool down and cool with the engine at idle for about 5 minutes before setting the machine off.

The glow plugs come on automatically and the indicator goes out in a few seconds. The indicator stays on longer in the cool weather, 40F is the coldest it has been since I got the tractor. The glow plug indicator comes on if the tractor is at operating temperature or not and will start with out pre heating. Should I always use the glow plugs or should I only use them when is is cool or cold? What is the correct procedure for glow plugs?
 
First step is to read the operators manual and follow it. Each piece of equipment is different, and the manufacturer will try to lead you into the best practices.

While I know this is a "non-answer", it's the best direction.

I've never heard of idling for five minutes to protect the turbo.
 
This is my opinion and experience. I always use the glow plugs even in the dead of summer. If not, you are relying completely on compression to ignite. Can get really smoky and using the plugs has no down side. I consider it akin to the position that my tractor has a cooling system but I don't uses in the winter because I don't need it.

Good clean oil is important for any engine. I personally don't use additive.
 
One of the changes that has happened with the diesel emissions standards, is the engines have a lower compression ratio than before. Engines that in previous designs never needed any starting aid at all, now have glow
plugs or grid heaters, or some utilse pilot injection. So even if it seems warm out, let the glow plugs do their cycle, and then let it rip. Turning the key on and waiting a few seconds is generally good practice
with the newer diesels anyway; gives the computer time to boot up.

As far as cooling the turbo, it is a good idea especially if you have been working the engine hard. If just putzing around moving mulch and flowers not as big a deal.
 
(quoted from post at 16:45:00 05/22/16) First step is to read the operators manual and follow it. Each piece of equipment is different, and the manufacturer will try to lead you into the best practices.

While I know this is a "non-answer", it's the best direction.

I've never heard of idling for five minutes to protect the turbo.

Just checked the manual---- 3 to 5 minute cool down period for the turbo.
 
I have a new Kubota and my glow plugs are hooked to the switch. I turn it on and wait until the light goes
out then start it. They recomended to me to let it sit and idle to make sure it gets the oil lubing everything
up> If my tractor is warm the glow plug light comes on and right off when I start it. The colder it gets
outside the longer the glow plug light stays on, but as soon as the tractor starts it goes out. If your has a
Teir 4 engine it will have 2 lights in the dash that will flash and the one tells you you need to increase the
RPMS. When you do this light goes out. The regen on mine takes about 15 mins and other than the engine sound
you don't even know it is happening. One big caution is the regin light. In bright sunshine if you wear
glasses that tint this light is had to see. The higher RPMS you run this engine the leas it will go into regin
cycle.
 
Hello pburchett,


Glow plugs are for cold weather starting. A block coolant heater would work also. If it doesn't start
readly, then you can use the glow plugs. Maintain the fuel system faithfully, and the air cleaner. With
proper oil changes, you'll get good service out of it,

Guido.
 
Idling the turbo came out in some ways. Because when turbos became popular on cars and trucks. Most knew nothing about them. People would rev up the
engine. Then cut the engine off. Which would cut off the oil supply to the turbo. 60 thousand RPM with no oil makes a short life for a turbo. Five
minutes gives the turbo time to slow down. Standard practice on standby generators.
 
Also, a turbo will run quite hot if the engine is loaded. Idling results in lower exhaust gas temperatures which will allow the turbo to cool down while it spools down. Ben
 
Glow plugs make it start faster and that helps keep the EPA happy. If the tractors are as bad as the road trucks, never let it idle than you have to,the exhaust filter plugs up, and then it is off the the dealer for a cleaning.
 

My experience. For 42 years I have started 10 engines a day (a guess) I have learned to listen to the starter to tell me the condition of the battery etc. I would think some here have accumulated the same ear they can tell by the sound of the starter if it has a dead hole are low on compression...

What I learned on my BOTA. No pre-warm cycle I can tell a big difference in the sound of the starter it sounds like its working hard, It does not lite off as fast. I think at times the battery may be low hummm...

When I use the Pre-warm up cycle the starter and battery seam to be happy it lite's off much faster...

Try it for yourself I think you will be able to come to the same conclusion... On mine its manual I turn the key to the left and count to 5 then hit the starter it seams to be easier on the starter and battery.
 
Using starting fluid and glow plugs together can not only break things it can blow the head off causing great pain when metal parks strike you at high speed.
 
At operating temp or after you have ran the tractor just turn the key and forget about it. When it is 40 of lower turn the key to the first position watch the light and when it goes out crank the engine. I love the part about idling for 5 minutes. Certainly a good practice but in reality I would say 90 % of the folks just turn the tractor off. My opinion you are idling it before shut off.
 
After being worked, ALL of our turbo
tractors get idled for 10 minutes to let
everything, including the turbo cool down.
Any N/A diesels we have, we let them go 5
minutes.

Ross
 
I would think that the glow plugs are part of the emission system-they help prevent smoke at start up,and the ecm/controller keeps them on for a predetermined time for this reason.
Ivan in Mich has it right about the regen system.Mark
 
As much as things have moved forward in diesel design, some things remain the same. I say that because a lot of the small diesels have gone back to precombustion chamber style design. When CAT had larger, precombustion chamber engines years ago, they recommended energizing the glow plugs for a few seconds before starting, even on a hot day. On the colder days, of course, a longer period of preheating was required. Given that a diesel runs by compression ignition, having the combustion chamber warm is a BIG help in getting the engine started, especially when it's cold outside.

Now days the same things hold just as true as they have since the first glow plug was used to help start a diesel. The main difference is now it's electronically controlled, based upon engine temp, to help keep the emission down upon startup. In other words, a warm engine/combustion chamber will start with less smoke than a cold one.

As far as the turbo, you don't want to go from a full load immediately to a complete stop. IF your pulling hard, it's good to give the turbo time to slow down, as well as cool down a bit. In normal operation, it won't take but a minute or two for it to be OK to shut the engine off.

Talking about the turbo also, using a good oil makes a world of difference in the life of a turbo. I had a customer going through them every 8 months or so on his air compressor engines. In his case there was no way to change the fact the engines started and went immediately to around 1300 RPM, and shut down from the same speed (as opposed to 500 +/- like a most engines). I got him started using a better brand oil and we started getting more than 2 years out of them before replacement was needed.
 
Glow plugs have been around much longer than emission controls, I do agree the engines smoke a lot less when they are used.
 
Not to overthink this......

Diesel engines run on compression ignition. Air in cylinder is compressed to ignition point, then fuel is injected into the now hot cylinder. The whole principle is that as air is compressed, it gets hot. Higher compression means hotter ignition. Typical diesel compression is 16 to 1 or higher with some going as high as 22 or 23 to 1.

Glow plugs are one of many devices used to help heat up the combustion chamber for cold engine starting. There are also grid heaters, intake manifold heaters, and other less direct methods of helping to get a cold engine started like block heaters and oil heaters.

Glow plugs operate on the principle of heating the inside of the combustion area to aid in reaching the required temperature to ignite the fuel. Glow plugs are normally only used with INDIRECT INJECTION. This is because they are used in conjunction with a pre-combustion chamber. Fuel is injected into the pre-combustion chamber and the hot glow plug along with the compressed air charge ignite the fuel.

With direct injection, there is usually a higher compression ratio used that requires less preheating.

Using starting fluids with glow plugs is a dangerous combination. Starting fluids will ignite explosively, and will generate much more pressure than normal compression and combustion. That higher pressure can result in something yielding to the pressure. The weakest link in the combustion chamber is the glow plug. When they fail, they can be turned into projectiles that have velocity and energy similar to a high powered rifle. Thus the warnings about not using starting fluids with glow plugs.

Glow plugs can also be used in the intake manifold of some engines as an intake air pre-heater. These are particularly dangerous if starting fluid is used. Manifolds are not able to withstand the pressure of rapidly expanding gases from combustion.

Normal usage of glow plugs is to preheat the combustion air for quicker ignition of the fuel. This is usually accomplished with a timer. When you turn on the ignition switch, the glow plugs are timed to heat for a time to help in starting. The timer can be keyed into the ambient temperature to determine the length of time that they will be heating. Most automotive applications will have an indicator light to tell you when the glow plugs are active, and how long to wait to engage the starter. A bad glow plug or two will make an engine difficult to start.
 


PET PEEVE!!!!!!!!

most misunderstood....

only after WORKING HARD... do you need the cool down.

In plowing or working under HEAVY load... RARELY will i just turn it off where it sits... I raise the plow... throttle down and drive back to the barn. As I never leave equipment in the field.. NEVER... so.. as I ease back to the barn, near air, water and electricity and fuel, the engine and turbo have ALREADY cooled down.

NEVER leave it in the field... why.. because,, if it rains, the tractor is stuck for a week and I need it sooner. Due to thorns every where in already in my tires, I might come back and find a flat.. EVEN if for lunch or a quick break. And in some cases the tire bead will be broke... So now I have a major problem. SOme of the equipment requres removing an axle or drive shaft to remove the rim.....
Fuel, Oil, water, air and grease.. I always check the tractor each morning for fuel, fluids, air, and grease equipment... all of which is makes it last longer and prevents breakdowns. I am quickly able to make in quick adjustments, and repairs then. I can catch a lot of minor problems and fix them then. AND some druggy has NOT stolen my battery or tires off the tractor and equipment left out of sight. I have had carburetors, batterys, and tires stolen of tractors.

So,, unless your remote working, its very very rare to just shut down a tractor right in the middle of the field.. And if I do get an emergency call, I can idle down, take the call and by the time I have hung up, the temps have dropped from peak to normal. egts are down to 600 or below.. no longer at 1300 degrees... all in a few minutes of NORMAL driving back to the parking space or barn..

So many people misunderstand the idle down sequence and leave their engines running and annoying every one around them. Most city slickers never pull a load to even get to high egt or peak oil temps... even by the time you exit the expressway, your egr and oil temps are already down below peak. Especially on a EMPTY truck or lightly worked tractor.

Again,, most understood what "under heavy load" cool down means...

Drives me crazy when all the beer c00lboys pull in to the convenience store or filling station and leave their "Coolboy Cadillac" running, no mufflers, and jacked up tires looking like a "pregnant rollerskate". They all say "well the book says....."

Only thing good about coolboy cadillacs is that they sell them every two years so I can buy their almost new HD diesel trucks really cheap, and bring them back to factory. I pull all the crap off them, and make a profit selling it on craigslist. I even dump the 1000 buck ranch bumpers off of them and go back to stock bumpers. 400 lbs off the frontend and more load capacity for me to haul with.
 

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