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jdemaris
11-24-2004 05:51:00
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Re: JD 300 loader wont start in reply to Rob Perrier, 11-23-2004 19:39:53
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I'm not sure I fully understand what you have done already. By the way, assuming you are in Australia, where does the term "Oz" come from? With your tractor, if fuel comes out of the injectors at, or near at, the correct time, and there is ample compression, it will fire. If compression is too low to create ignition, it should at least smoke. If you still have the head off, leave an injector hooked to a line, crank the engine, and observe when the injector fires. That particular cylinder should be near, or at, top-dead-center on the compression stroke. There isn't much gray area here . . . if the fuel comes out the injector, and the fuel is good, and it's coming out at the right time, and in proper quantity, and there is compression exceeding 350 PSI, it WILL fire. If, by chance all is okay except for low compression, try using some ether (starter fluid) and see if it at least smokes. Again, I'm not sure what you've already done. You had stated that no fuel was coming from the old injectors. Then, you replaced all three? It would be rare for an engine to have all its injectors blocked unless it had not been run in a very long time. The injector pump has to generate enough pressure to pass through an injector, which exceeds 2000 PSI. Once the pressure is reached, the check valve in the injector cracks open, and a spray of fuel escapes - hopefully a spray of atomized fuel. I've pulled out worn out injectors that just dribbled, but the engine still fired and ran. That is usually the reason for changing them - but they do get plugged at times. An engine with all its injectors plugged could result in injector pump damage (theoretically - I've never come across this situation). That particular engine is prone to breaking top piston rings. If the head is still off, take a close look and see if the top rings are still intact. Look close down the sides of the pistons, and also look for a clean carbon lines on the cylinder walls where the pistons reach the end of their travel (highest position). When the top rings shatter, the carbon line will be lower and not so well defined. Usually, with no top rings at all, the engine will still run - and be fairly smooth once hot, but otherwise - will start awful - perhaps only with ether - and will smoke like crazy when first started. Checking static, i.e. "initial" timing is no big deal - and that's all that counts to get it started. There is a bolt with a timing pin on the end of it where the engine bolts in. It is fastened to an inspection window that allows you to see the flywheel. You remove the bolt (3/4" wrench as I recall), reverse the bolt - thus sticking the pin in the hole, and gently rotate the engine by HAND (don't use the starter), while pushing in on the pin - until it slides into a hole that exists in the flywheel. THAT puts the engine on TDC (top dead center) for number one cylinder. Remember, the engine is a four-stroke-Otto cycle design so you can be 180 degrees off; i.e. a 50/50 chance of being right or wrong. You need to be sure when the pin goes in, the number 1 cylinder is on the compression stroke - and NOT the exhaust stroke. It's easy to tell, just look at the position of the valves - or - if the head is off - look down the pushrod holes and observe the position of the valve lifters. That point is when the injector pump is supposed to fire a fuel charge through the injector to that cylinder. The injector pump itself also has a pin in it for timing if its a CB pump. A JDB pump has a timing window instead with scribe lines.
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