Cranking with the compression release

[dieselfuelonly]

Just a quick question for you all.

On my Yanmar when I first crank it up I like to let the oil pressure build. It takes I'm guessing about 4-7 seconds for it to build enough for the light to go off, and I have the compression release pulled during this time so there is very little load on the stater, though if I wasn't using the release it may start a little faster, but that would also put more load on the starter and start the engine without oil pressure.

Which is the better to do?

 

[BruceR]

Dennis,
I think you are better off using the compression release to start your Yanmar. Oil pressure is a good thing. Also, you are releasing any moisture from the cylinders before start-up.

Bruce

 

[mark777]

Just a quick question for you all......

Which is the better to do?

Dennis, I use mine every time...all the time. It's just better to extend the battery and starter life. More importantly, it pushes oil to the rods, mains and rocker arm assembly and prevents destructive dry starting.

"Yanmar YM1401D | 4WD for when I thought it was a good idea to drive in that mud hole | Dirt Scoop that scoops up pine needles and leaves | Bush Hog I can't get the PTO shaft together on | Tiller I hit lots of roots and rocks with | Electric sprayer I have no use for now | Carryall with useless sprayer mounted on it | ONE INCOMPETENT OPERATOR -- At least the horn works."

Why, and what's wrong with the PTO drive-line problem under your signature line? Are you using an ORC ??

Mark

 

[dieselfuelonly]

Dennis, I use mine every time...all the time. It's just better to extend the battery and starter life. More importantly, it pushes oil to the rods, mains and rocker arm assembly and prevents destructive dry starting.

"Yanmar YM1401D | 4WD for when I thought it was a good idea to drive in that mud hole | Dirt Scoop that scoops up pine needles and leaves | Bush Hog I can't get the PTO shaft together on | Tiller I hit lots of roots and rocks with | Electric sprayer I have no use for now | Carryall with useless sprayer mounted on it | ONE INCOMPETENT OPERATOR -- At least the horn works."

Why, and what's wrong with the PTO drive-line problem under your signature line? Are you using an ORC ??

Mark

THanks guys.

As for my sig its just my way of saying I am very new to this and will have to figure things out slowly . The PTO shaft for the bush hog can slide you know, to adjust the length based on where it is in the lift. I pulled it apart and had some trouble getting it back on, but I did nonetheless. There is more about what happened in my latest post in my "Started Learning To Use My Tractor Today" thread on Owning & Operating.

 

[RonMar]

Diesels are high compression. The force to compress the air in the combustion chamber is transfered down the rod to the crankshaft rod and main bearings. The only think keeping these pieces of spinning metal from contacting each other is the pressurized oil film. By cranking the engine without compression, you are allowing the oil film to build before the full loads are applied. This is a good thing and about the only way you could get any better would be to add a hand or electric pre-lube pump to pressurize the galleries and bearings before any rotation occurs. Every large marine diesel I have operated had a pre-lube pump that we were required to use untill operating oil pressure reached 30PSI.

Another good point is moisture. Water down an exhaust stack or a leaking headgasket or injector could put liquid fuel oil or water in a cylinder. Cranking on this fluid without the compression release will hydraulically lock the engine. This can blow headgaskets, crack heads and pistons, bend rods and twist crankshafts. All very expensive results that encourage the use of a compression release. Every large diesel I have operated had a blowdown procedure in it's operating instructions. This is cranking the engine with the compression released to clear the cylinders of fluid. This was required prior to starts or every few hours if the engine was in immediate standby status.

 

[arthr31]

THanks guys.

As for my sig its just my way of saying I am very new to this and will have to figure things out slowly . The PTO shaft for the bush hog can slide you know, to adjust the length based on where it is in the lift. I pulled it apart and had some trouble getting it back on, but I did nonetheless. There is more about what happened in my latest post in my "Started Learning To Use My Tractor Today" thread on Owning & Operating.

DFO, as mark777 said, use on ever startup. On all 3 of my yanmars I make it standard operating procedure. Pull compression release, let pressure and temp build, <use thermostart if required> , keep release out until read to start engine (usually a couple of revs or less), start up and adjust idle.

I hate to say this, or post like this, but follow directions from yanmar owners only (e.g exclude general posts) It is a unique setup and unless you own one, you don't know how it behaves (e.g. jinma is totally different (no feelings hurt))