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Old 08-11-2013, 02:18   #1
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Decompressing before Starting Engine?

with my old tractor i used to engage the starter with the decompression lever for a bit when starting the engine if cold. the reason being was that it would build a little oil pressure and apply a bit of pre-lube to promote less wear before the engine burst into life with compression.

my bukh 20 has levers but i don't bother using them. is there any reason to not apply the same logic to a marine diesel as i did with my old tractor?
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Old 08-11-2013, 06:16   #2
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Re: decompressing before starting engine?

I've only ever used the decompression lever if the batteries are really weak and I need to spin the engine up to speed to get it started and we use it after the engine has sat all winter to bleed out the fuel system and get it to start more easily.

As far as your wear and tear concerns I think that if it really had any benefit to do what you are saying the manufacturer would state for you to do so.
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Old 08-11-2013, 07:15   #3
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I use mine all the time when I have not started for awhile. For me builds oil psi and seems to start easer.
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Old 08-11-2013, 09:24   #4
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Re: Decompressing before Starting Engine?

No reason at all not to, it's sort of a poor man's pre-lube system, it is kinder on the engine. You will be pumping fuel into the cylinders that won't be burned off until there is compression, but unless you get silly with it and spin the engine for a long time it should make no difference. I think it's kinder on the starter, flywheel and starter solenoid too.
For those that take the approach of if it was better the manufacturer would recommend it, I offer this thought. If a manufacturer recommended this procedure, all the other manufacturers sales reps would use it to show how much better product they had because theirs didn't require anything more than turning the key.
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Old 08-11-2013, 09:40   #5
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Re: Decompressing before Starting Engine?

On the bigger engines, we roll them over like that and then close the valves on each cylinder as the engine starts. I would use it on my engine if so equipped, just when as stated before I have not started the engine for several months. I do the same without the decompression, as long as my battery will take the load, I roll my engine over several times before starting.
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Old 08-11-2013, 15:22   #6
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Re: Decompressing before Starting Engine?

pretty much same question here...

Using Valve Lifter To Help Starter...?
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Old 11-11-2013, 05:06   #7
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Re: Decompressing before Starting Engine?

thanks for the replys guys.. some helpful info there
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Old 11-11-2013, 05:40   #8
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Re: Decompressing before Starting Engine?

I would say that the fuel kill should be pulled otherwise you are injecting fuel that is not being burnt and would only wash the oil off cylinder walls
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