handcranking and decompression levers

[drawp]

Explain please

Moving the throttle trips the cold start button on the fuel injector pump. So you need to set the throttle first.

 

[VicS]

Moving the throttle trips the cold start button on the fuel injector pump. So you need to set the throttle first.

Thats interesting. We usually press the button in first, often well before starting.

I'd always assumed that the button tripped when the engine started.

It's not made clear in the owners manual.

 

[paulieraw]

Cranking

Hand Cranking a cold engine can be hard work, if your engine is old it may have an oil injector for starting when cold. otheriwse start on starter then try it on hand when warm. Or use a blowlamp to warm the cylinders or fuel lines (dont over do that though)

Get a good spin with plenty of throttle and drop the commressor lever, it will either go or it wont, its a bit like lighting a fire with two sticks if your doing it to get warm, by the time you succeed you dont need a fire.

 

[mcframe]

If you have the facility, it is well worth practicing hand starting in case you need it one day. If you are doing it for the first time I would recommend doing it when the engine is warm, when it should start fairly readily.

Aye.

I've not yet done my ritual "once a season" hand-crank test, but will remember to do so next time out.

I'm reminded of trying to teach SWMBO to start the tender o/b:
"Just pull slowly for the first bit, then give it good constant-pull yank, but remember to stop at the end - it's *just* like starting a lawnmower or kick-starting a bike - feel for the TDC resistance, then keep it spinning smoothly 'til it fires"
"But I've never started a lawnmower or bike!"
"Err...."

Maybe it's a ManThing

 

[elton]

A lot of folks forget the cold start button that Searush mentioned. It should start quite easily from cold if that's pressed and the throttle's in the right position. The starting handle is a nightmare. I did myself an inguinal hernia trying to turn my MD2B over with it, just to see if I could

 

[Mistroma]

My old Bukh DV20 only failed to start once in 23 years. No response from starter motor but it was fine afterwards and never failed again.

My wife held de-comp lever back and I cranked like mad and when she let the lever go. Voila.... the engine stopped absolutely dead with no chance of getting past TDC on either cylinder.

Back to the drawing board and plan B implemented:

1) Disconnect the de-comp levers (joined by a metal bar with clevis pins)
2) Tie one lever back to a post on cyl. head using a slip knot
3) Repeat for second lever
4) Hold one piece of string in my mouth and crank as fast as possible
5) Turn head at critical point and yank knot loose
6) Engine kicks in on one cyl. and I snatch string off second de-comp to fire up other cylinder

Not ideal but it did work as I could just manage to start a single cylinder engine but not a 2 cylinder version.

Unfortunately, I've only ever seen 2 sep. de-comp levers on a BukhDV20. Perhaps it isn't a common way of mounting the levers.

 

[Rob_Webb]

Plenty of good advice here which I won't repeat - other than to say I've found a cold engine impossible to hand start but a warm one just about do-able.

Anyway, alternative (less exhausting) approach is to find a fast ferry - ideally 20-ish kts - ask them for a tow and when you're up to full speed engage gear and voila!

Just take care slipping the tow line and coming back down off the plane.

 

[aquaplane]

Thats interesting. We usually press the button in first, often well before starting.

I'd always assumed that the button tripped when the engine started.

It's not made clear in the owners manual.

My cold start button won't latch in unless there is quite a lot of throttle on, more than fast tickover. The button pops out as the throttle is eased back to tickover after she fires.

I have hand started mine, I did it from warm first then from cold, it's not easy and certainly needs a cup of something after a couple of goes as Searush says.

I had to use the decrompression levers for the first start this season, the batteries weren't as enthusiastic as they could have been, I don't usually need to though.

 

[prv]

Unfortunately, I've only ever seen 2 sep. de-comp levers on a BukhDV20. Perhaps it isn't a common way of mounting the levers.

They're separate on my 2GM20.

Pete

 

[fireball]

I don't know that engine - but others have given advice on that..

We have a club boat with (iirc) a Lister engine in it - twin cylinder - no electrics just hand crank.

It is quite easy to get the engine spinning with decomp levers open - then flick one lever followed smartly by the other - very rarely does it fail to fire.
Whilst you can do it with two ppl it's not impossible with one - start cranking with two hands and once you've got a little bit of speed you can take one hand off to operate the levers.

What I would say is: Make sure you wrap your THUMB around the handle in the SAME DIRECTION as your FINGERS .. so if you do fail to fire and the handle slips back it comes out of your hand and doesn't break your thumb!

 

[CreakyDecks]

I used to have a car that needed decompression to start in the winter. I used to have to take a spark plug out before it would fire up!

 

[seumask]

My bukh dv24 can be started from cold. 1 decompression lever for both cylinders, piece of string to foot holding it down. Apply cranking by hand for around 20 to 30 second to get the max speed, lift foot to release string, and it usually fires. If it doesnt, try again, throttle at idle (it's not close to cranking position). I think its one of those higher pressure injector engines, but I'm not sure, and that may make it easier.

 

[ianat182]

The alternative method I used when stuck in Newtown Creek some years ago with a dead Dynastart and MD1B.
A friend towed me to the entrance and we set sail, me in the engine compartment; released the decompression lever and pressed the cold start button in, then put the engine in gear, which started the propellor to rotate as we reached 4knots,the cruising chute hoisted and set. it took less than 100yards for the engine to rotate helped by cranking the flywheel and dropping the decompression lever to start; after a mile we cut the engine and continued under sail to Calshot, she started again easily by the same method and got us safely home. The old engine has now been replaced by a new VP2010a that is an excellent and quieter unit.

ianat182

 

[prv]

I think its one of those higher pressure injector engines, but I'm not sure, and that may make it easier.

Being a Bukh, the monster flywheel and convenient starting-handle position probably help too.

Pete

 

[Bilgediver]

Thats interesting. We usually press the button in first, often well before starting.

I'd always assumed that the button tripped when the engine started.

It's not made clear in the owners manual.

Two things will trip out the cold start.

1...Engine firing p and governor cutting in.

2...Bringing the throttle back to idle before starting the engine.(Usually the throttle has to be set at least to the click position say about 1/2 speed to set the cold start.)

 

[VicS]

Two things will trip out the cold start.

1...Engine firing p and governor cutting in.

2...Bringing the throttle back to idle before starting the engine.(Usually the throttle has to be set at least to the click position say about 1/2 speed to set the cold start.)

We normally pushed the button first of all.
If we checked the oil level etc we quite often pushed the button in while "in the engine room" on the basis that sooner or later we would be starting it.
The single lever engine control would probably have been in reverse.

We would then have moved the lever to neutral, pressed the gear disengage button and moved the lever to at least half throttle.

Then switched on and cranked the engine, returning the throttle to idle once running.

 

[stuhaynes]

I once tried hand starting my coventry CDB. It's 4 cylinder 30 HP 2.3 litre diesel built in 1950 (or earlier). I had my son with me, big lad, very fit, no chance. No chance at all. The original handbook makes it sound very simple. Perhaps blokes were all Geoff Capes types then. Between myself and my son we never got beyond TDC!

I used to be able to easily manage a Morris !000, but then, that was a petrol pussy cat! Change you battery and save yourself a hernia or worse....

 

[Searush]

Diesel compression ratios are such that if anyone can turn the engine past TDC without decompressors then your engine is probably fooked.