Why do some diesels require glow plugs and others don't?

[whistlepig]

Maybe I am being a bonehead here. I hope not. So we go to the tractor showroom and I look at a 1964 MF135 diesel. The dealer tells me it will start, sitting outside, in -10 degree weather with out glow plugs. We then look at a 2006 Kubota. The dealer tells me the Kubota will not start, with out warming up the glow plugs, sitting in a garage while it's 90 degrees outside.

 

[knightrider955]

My Long doesnt have glowplugs and it starts fine.

 

[ModMech]

Maybe I am being a bonehead here. I hope not. So we go to the tractor showroom and I look at a 1964 MF135 diesel. The dealer tells me it will start, sitting outside, in -10 degree weather with out glow plugs. We then look at a 2006 Kubota. The dealer tells me the Kubota will not start, with out warming up the glow plugs, sitting in a garage while it's 90 degrees outside.

The MF uses a Direct Injection (DI) system and the Kubota an InDirect Injection (IDI or pre-cup) system. You NEED GPs with any IDI (pre-cup) engine for cold starts, you just simply cannot get enough heat into the pre-cup chamber from the cylinder during cranking on a cold engine.

There are very specific and distinct advantages and dis-advantages to both engine types (DI/IDI), which a manufacturer chooses is a factor of many variables, one of which is cost. You can't buy a MF for what you can buy a similar Kubota for.

 

[dcyrilc]

Maybe I am being a bonehead here. I hope not. So we go to the tractor showroom and I look at a 1964 MF135 diesel. The dealer tells me it will start, sitting outside, in -10 degree weather with out glow plugs. We then look at a 2006 Kubota. The dealer tells me the Kubota will not start, with out warming up the glow plugs, sitting in a garage while it's 90 degrees outside.

I know which one I'd buy and it ain't orange.:laughing:

I have always been fond of the little MF tractors. 'Course, I like the big ones too.

 

[Ken]

Used a crank to start the cat engines with a pony starter then when it was warm use the engine to start the diesel engine. This was the 8800 and 13,000 engines on 60 and 100 kw generators. Then when had to start the international engines shift to gas engine and hope it would start after it was running shift to diesel and hope it would continue running before could load the generator. if the gas side would not start in cold weather while cranking dump 1/2 cup of gas into air intake.then immediate shift to diesel usually would run. this was better than having to explain why the 2nd louies didn't have warm coffee in the mornings. also used to have water heaters in hose to keep the engine warm . but with no electricity this was usless as well. Nothing like a hot battery and glow plugs to start the new diesels. loss of 30/ 40 sec. to start. try 1/2 hour in "0"deg. weather.
ken

 

[kenstrac]

My Long doesnt have glowplugs and it starts fine.

The Long's came with thermo-start it also had another cold start valve on the injector pump.
But neither of those were operational on my 445 and it started just fine in freezing weather.

 

[TripleR]

Maybe I am being a bonehead here. I hope not. So we go to the tractor showroom and I look at a 1964 MF135 diesel. The dealer tells me it will start, sitting outside, in -10 degree weather with out glow plugs. We then look at a 2006 Kubota. The dealer tells me the Kubota will not start, with out warming up the glow plugs, sitting in a garage while it's 90 degrees outside.

On my Kubotas in warm weather I just turn the keys to start.

 

[knightrider955]

The Long's came with thermo-start it also had another cold start valve on the injector pump.
But neither of those were operational on my 445 and it started just fine in freezing weather.

My Long does have a thermo-start but it hasnt worked since Ive owned it. I usually crank it about 10 seconds in sub freezing temps and it fires right up. Ive yet to meet a Long owner whos thermo-start works. Most Longs were direct fuel injected which was way ahead of their time.

 

[SPYDERLK]

Maybe I am being a bonehead here. I hope not. So we go to the tractor showroom and I look at a 1964 MF135 diesel. The dealer tells me it will start, sitting outside, in -10 degree weather with out glow plugs. We then look at a 2006 Kubota. The dealer tells me the Kubota will not start, with out warming up the glow plugs, sitting in a garage while it's 90 degrees outside.

90 degrees is an exaggeration isnt it? :confused2: Our BX starts to need it somewhere around 40 ... altho I havent checked it closely.
larry

 

[art]

I've found it quite interesting to read all the comments here. Following the tractors and engines for most of my life and working with gas as well as diesels.

I've worked with pony motors to start diesel engines as well as starting on gas to warm up before getting diesel fuel to start. There are some brands that I haven't had a lot of exposure with but not to many. I haven't missed to many tractor or lawn mower engines gas or diesel! I do live in an area that it gets cold in, we have seen below -20 for weeks in a row so we know what different engines start like in the cold as well as the warmth.

I've found that some start well in the cold and some don't start well even before getting to the freezing mark or until the block heater is plugged in no matter what when cold.

I like the different designs of the engines because then you might not have bench marks to know what is good. Speaking of good what is good for you, might not even start here in January or February.

Sometimes there are exceptions or reasons as there is only one that is that way! Might just be pump timing or might be more. This might include lack of compression!! We get quite technical in our diesels even setting valve protrusions when doing valve jobs to maintain factory specs on compression for our customers.

To get a diesel to run you need heat, this is caused from compressing the fuel, might it not be easier to heat a smaller area such as a pre-cup vs the whole cylinder?

There are reasons as to why things are built in the way they are, from the cost, it is more expensive to use glow plugs and have pre-cup injectors over a direct injection head.
I've also found it hard to find an engine start better in cold weather then an indirect injection system with glow plugs or one with a preheat heat system. Some might still start but you might have DEC pulling into your yard from the air polution created! This we often do for customers that perfer some of the other brands that we know have issues!

I've seen a lot of tractors that farmers park during the winter because they DON'T start in the winter when the temps go below freezing! I've also seen them switch brands because of it in a size where they need to start in cold weather.

With winter coming I know what tractors we can start for customers with out a cord going to them and I know which ones I won't. Thats for both new and used!!!!

I've seen a lot of love in this post for what people have as well as a bit of exaggeration and lack of knowledge from good comparisons.