Go Bottom3 CYL COMPRESSION RELEASE
 | Southerner
Join Date: Jul 2003 Posts: 11 laurens,SC 
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2002-11-21 45244
I have a 3 cyl. Yanmar 3000 with compression release. Does any one know the proper way to use this feature? Although I am a heavy truck diesel mechanic, I've not had the opertunity to use one before. As it has gotten cooler here the tractor has gotten harder to start. I have attemted to use the release, but don't think I'm using it correctly, as I get lots of black smoke and the tractor doesn't start right off. Thanks
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2002-11-21 45246
The way I've heard using them is: With the throttle off and the release on, crank the engine. With little compression there is less load and the starter will turn fast. The engine can be cranked until some oil pressure builds up. Then, decompression lever is released and the throttle is increased. The starter will slow; a few cycles of high compression will heat the charges and it should fire right up as throttle is added. The benefits are some pre-lubing, less drain on the battery and wear and tear on the starter.
A diesel shouldn't really run let alone start when the compression is released. If it does run perhaps a cable is out of adjustment and releasing very little compression. An engine shouldn't be run with the compression released, not only because it doesn't run very well, but also because the exhaust valves, which are held open may burn. Sometimes decompression is used to kill a diesel, but diesels are properly shut down using a kill switch that shuts off the fuel. Using the kill switch shuts down an engine without oil under pressure in injectors that later leak into the cylinders. Decompression also is handy for positioning a diesel engine while performing timing and valve clearance adjustments.
I don't have decompression on my 1710 but I couldn't do without it on my chainsaw.
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| TractorBoy
Join Date: Jul 2003 Posts: 4 Ohio
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2002-11-21 45248
On my 2820 during cold weather starting by turning the key to the left till the little red light that is attached to the glow plug goes out. That preheats the fuel in the cylinder. Move the throtlle control to mid point, pull out the decompression knob and crank the engine till it starts. Once the engine fires, push the decompression knob back in, and allow the engine to run at half throttle till warmed up. Then get to work. ....
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| Southerner
Join Date: Jul 2003 Posts: 11 laurens,SC
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2002-11-22 45269
Thanks guys, the info helps a little. I'll have to play arond with it a little. I do not have glow plugs on my 3000.I'll try spinning the engine without compression, then adding some to build some heat, stop add fuel and retry. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-11-22 45275
I imagine that Yanmars have direct injection engines, which is why they wouldn't have glow plugs. Many direct injection engines have various types intake manifold heaters, so there's a good chance that the engine can be pre-heated. When I first bought my tractor, which does have glow plugs, I bought a can of starter fluid as well. Fortunately I read not to use the stuff here. Ether doesn't mix with diesels very well, and doesn't mix with diesel pre-heaters at all. ....
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2002-11-22 45277
Many years ago an old friend of the family tipped me off to a fantastic, safe, starting fluid for diesel engines.
WD-40.
It seems this stuff was developed by the military during WWII (thus the military acronim, Water Displacing formula # 40, "WD-40") and in true SNAFU (Situation Normal, All F*#$%ed Up) fashion, they were woefully short of all sorts of items, but swimming in this new WD-40 stuff, so they started using it for anything. Since all the ether available was required as aenesthetic, they had to find something else for starting fluid. Since WD-40 is basically VERY light oil it was a natural, and since it has a flash point and volatility very similar to diesel it is very safe for the engine also.
Give it a try, and as always, best of luck. ....
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 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2002-11-22 45280
Another little known fact: one of the primary ingredients in WD 40 is fish grease, not oil, grease. If you are fishing with bait it is a great odor enhancer. When fishing salt water for silver salmon it can make the difference between getting skunked and getting a boatload. ....
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| ruffpa
Join Date: Jul 2003 Posts: 3 iowa
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2002-11-22 45281
on older JD 2cyl diesels they had a compression release. On my 830 jd (diesel) the instructions for startingthe tractor is; start the pony engine(or if you have the electric starter just go to the next step), pull the decompression lever, engage the pony motor clutch (or push the starter button), once the oil pressure has risen and the engine is turning over well you release the decompression lever and the engine will start. The reason for the pony is in extreemly cold weather you can engage the pony motor with the decompression lever, and lock themin place, the water pump on the pony pumps warm water to the big engine warming it, when the engine is warm you can start the engine. I have started my tractor at 25 to 30 below zero in a unheated shed, just by letting the pony run for 20 minutes or so. the pony is a lot more maintence than the electric starter option but the ability to start the tractor in cold weather, (works great when you need to go and push snow.
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-11-23 45301
I've heard of the use of WD-40 as starting fluid before. An idea just came to mind. I never thought if the use is with or without air filter in place. I suspect that dry filters are best left dry.
For that matter, I understand that most ether starter fluids for gas engines now contain lubricants that are supposed to compensate for the ether removing oil on cylinder walls. I don't know if that stuff leaves a residual on air cleaner elements as well. Something like that might explain why my Honda generator is much harder to start in the cold than I think it should be. I guess another explanation might be that my generator exercising every month or so might not be adequate to keep the carb clean and I should be using gasoline stabilizer.
WD-40 for fishing sounds interesting and it's probably easier on monofilament than DEET. The only exotic use of WD-40 I've made is as wasp killer. My 70-year + neighbour sent me up a ladder to clear wasps out of his old big-dish satellite receiver. With considerable doubts and visions of 1000's of PO'd wasps swarming around me on top a ladder I did my duty. The stuff worked very well even if removal of the nest didn't improve the TV reception.
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