How long to start aD2?

Uncle Rich,
I had a 212 that started about like yours. Especially the pony holding it back.

I have noted over the years that many run decompressed with the throttle half open for ages, depending on warmth from the donkey exhaust to warm up and flooding the cylinders with unburnt fuel. I have found the best way is to run on full compression once the oil pressure is up and leave the throttle closed until the engine is ready start, they will usually start trying to fire, and then open the throttle for a clean start. Its far quicker this way because it warms up the cylinders under compression before introducing fuel.

Im with Cat Silver on this one I reckon you get a better cleaner start with less strain on everything

Paul

twice it has been mentioned that the pony can hold back the diesel from starting----is this because the pinion latches are too tight?? 😕

twice it has been mentioned that the pony can hold back the diesel from starting----is this because the pinion latches are too tight?? 😕

Yes a friends D2 5j won't take off until you disengage the clutch lever , you get thick black smoke and a slight increase in pony revs but not quite enough to throw out the latches.. seems the bigger engines will overspeed the pony if the latches are to tight !!!!!
most D2s seem to end up so the moment you give them fuel the pinion throws out before they start
and you have to hold the lever up until you start seeing black smoke or if you are doing it by the book let them crank longer , They all seem to need different amounts of warming up I have a 5 u that goes as soon as its been cranking for a couple mins even when the weather is cold another that takes ages to get warmed up , like all indirect injection diesels they need a fair amount of heat to start cleanly hence later direct starts had glow plugs... my JD 730 diesel only neads to go over compression and its away , but that is direct injection ....

At first I never noticed the pony keeping the engine from starting because I had a terrible problem with the latche s kicking out often when ever the Diesel had a strong fire on one or more cylinders. I gave each latch screw a turn and a half and then it stayed latched and I was happy, but I once accidentally dissenaged the starter clutch when it was getting close to being hot enough and the Diesel took off. So I figured that trying to drive the pony actually was keeping the Diesel held back. Since then I've learned that when I pour the fuel to it and it starts huffing good smoke, I disengage the clutch and often it goes. Maybe I have the latches too tight but as soon as the Diesel comes up to speed they do kick out. I like it better this way then frequently kicking out too soon.
I also flip the decompressor off as soon as I get the engine rolling. It makes no sense to crank it decompressed. The compression is what heats up the compression chambers to ignition temps. Pouring lots of fuel to it before it's ready only quenches the heat. I crank with no fuel until it's hot then I start trying to put fuel to it, but if it doesn't show signs of starting I back off and crank another minute or two. I'm getting better at reading when it is ready to go.
I just can't stop wondering if I need more fuel pressure as Old Magnet states during cranking. I really can't see that fuel pressure needle move much until the Diesel is running, then it goes green.

Two factors have a lot to do with starting times, especially on the D2 size engine.
1. You need adequate fuel supply and pressure. If all you needed was gravity feed you wouldn't have a transfer pump.
Injectors and pumps need to have reasonably consistent outputs so that one cylinder is not popping off different from the rest.
2. It's all about compression pressure which along with the exhaust heat transfer is the major source of heating to auto ignition temperature. Leaking valves, worn rings, worn valve guides, carboned up cylinders all contribute to starting issues.

Not unusual to see a worn out D2 pony cranking for a good 15-20 minutes before it will take off.