cold start, no decompression yanmar1500

[ziggywiggy]

What happens if you cold start without using the decompression? I did this accidentally and the motor seemed to start right up and then there was a lot of white smoke from the crank case exhaust. I'm trying to figure out if it was just because I started it wrong or something else is amiss. It also shut off when I moved to the area I was going to cut.

Thank you

 

[ziggywiggy]

As an afterthought, I realized "cold start" might not be the right term, as it's definitely not cold outside, but I've never started the tractor without using the decompressor.

 

[4get gto]

I'm just the opposite. I never use the decompression until colder weather or it seems as though my battery is low. Guess it doesn't matter either way..

 

[winston1]

The compression release does several things. It eases the pain on the starter by and easier and faster spin. It also allows oil pressure to come up without as much pressure on crankshaft journals. The fast spin also helps with the starting.

Having said all that, starting without it should not damage anything. My old 2002D always fired on the first couple of revolutions but I use compression release just to gain oil pressure before bust off.

 

[thepumpguysc]

The faster spinning, heats the cylinders so the atomized diesel fuel will ignite faster.{starting}
I've seen the other end of that spectrum also.. engine would NOT start unless it was spun up w/ the decomp. pulled..
The engine would "lug" under the pressure of the fuel being sprayed into the engine & wouldn't have the rpm's{speed} to start.
I like the idea of getting the lube oil moving before it starts also..

 

[RalphVa]

Never had a diesel engine with decompressor. In my experience, diesels tend to start with about a 1/2 turn of the crankshaft. If they have to "spin", something isn't right.

Almost the same way with fuel injected gasoline engines now.

Ralph

 

[careyo63]

Always use mine every start. 1, easier on the starter which is one of the biggest repair I had to get done since I've owned it. Besides regular maintenance since 2/08. 2, Is let the oil Pressure come up before letting go of the Decompression. This 2000 is Original as far as me or the seller could tell. He's Fredrick supplied so I pretty much knew it just looking at it. Honestly just kicking tires so to speak but I left him a check until I could get back with a trailer in a few days. Not far from putting a thousand Hrs. on it. The Original rear tires started to dry rot and crack at the Lugs. The Lugs are HUGE still to the day. So I opted to reline them which was the only other major repair to keep it functioning. I still chuckle to the day when I asked the seller were the He!! did he get it. He mumbled something besides trade in. He didn't want to disclose it..............LOL.

 

[CoyPatton]

It is my opinion that you are doing a ‘cold’ start anytime the motor is not at operating temps when you start the tractor. Others may not agree but that is my $0.02 worth.
I try to use the decompression feature every time I do a start. Mainly because I like the ideal of lubing the engine and reducing the strain on the starter. I find that by doing so the motor fires with a couple of seconds. In cold weather starts I use the thermo start function in addition to the decompress feature.
Beyond these habits that I do, I doubt you are harming anything more than the strain on the starter.
Hope this helps.

 

[ziggywiggy]

Ok, so it sounds like I didn't mess anything up. I'm going to try and start it properly this afternoon and see if I have the same white smoke/sputtering out issue. If it still happens I'll look for another problem, it's just frustrating because it ran beautifully last week when I replaced the fuel return hoses. No overheating or anything and now this, but I guess that's just how it goes :confused3:

 

[CoyPatton]

White smoke generally means moisture. This could be from lots of sources. Your profile does not mention where you live, so unsure but it could be your moisture issue is from overnight temp drops and then warmer temps during the day. I would not be concerned if the white smoke goes away as the tractor warms up.
Now if it is a gray color, it could be an unburnt fuel issue. If it starts harder than it did before or runs rougher than before, you may have issues of it sucking air through the lines you replaced recently.