Engine wouldn't start??

[jamie N]

Yesterday, I took out the cockpit decking and exposed the full engine area on my Folkboat; all very standard stuff.
I'd had an 'incident' a couple of weeks ago where I'd smelt oil whilst motoring, a very vague haziness of smoke occasionally, but nothing 'wrong'. After a couple of hours of pondering/worrying, I found the problem to be a slightly displaced oil breather cap. Not big, no significant oil loss or damage, I just carried on.
So, with the cockpit floor up, there's a thin veneer of oily shite all over the place, which took a good coat of cleaning up. At the same time, after having run the engine up to temp, I gave the engine an oil change, checked the fastenings and connections and nannied the area a bit.
OK, a degree of smugness coming into view by now, let's just check out this cleaned and serviced piece of kit for good measure.
Of course, it wouldn't start. It turned over magnificently, but never gave a hint of ever starting, ever again. We all know when our engine's are 'trying' to start. This wasn't.
The engine had run perfectly, then wouldn't start? WTF??
When I run the engine, I start it by pulling the decompresser, turning over the engine a few times on the starter, then releasing the decompression, and it starts.
When I stop the engine, I pull the decompresser, and it stops.
Whilst cleaning the engine I'd pulled the 'other' control on the engine, the fuel cutoff valve, which is the other way of stopping the engine, though I rarely use it.
What had happened was that the fuel cutoff valve had become slightly claggy, and when I pulled it, it remained in the cutoff position, as the return spring on it hadn't the strength to fully operate.
WD40, a swift jiggle, and it's now back happy. The engine started immediately, and I began to drift towards smugness again.

 

[Tranona]

You deserve your Saturday evening dram now.

 

[Wansworth]

Yesterday, I took out the cockpit decking and exposed the full engine area on my Folkboat; all very standard stuff.
I'd had an 'incident' a couple of weeks ago where I'd smelt oil whilst motoring, a very vague haziness of smoke occasionally, but nothing 'wrong'. After a couple of hours of pondering/worrying, I found the problem to be a slightly displaced oil breather cap. Not big, no significant oil loss or damage, I just carried on.
So, with the cockpit floor up, there's a thin veneer of oily shite all over the place, which took a good coat of cleaning up. At the same time, after having run the engine up to temp, I gave the engine an oil change, checked the fastenings and connections and nannied the area a bit.
OK, a degree of smugness coming into view by now, lets just check out this cleaned and serviced piece of kit for good measure.
Of course, it wouldn't start. It turned over magnificently, but never gave a hint of ever starting ever again. We all know when our engine's are 'trying' to start. This wasn't.
The engine had run perfectly, then wouldn't start? WTF??
When I run the engine, I start it by pulling the decompresser, turning over the engine a few times on the starter, then releasing the decompression, and it starts.
When I stop the engine, I pull the decompresser, and it stops.
Whilst cleaning the engine I'd pulled the 'other' control on the engine, the fuel cutoff valve, which is the other way of stopping the engine, though I rarely use it.
What had happened was that the fuel cutoff valve had become slightly claggy, and when I pulled it, it remained in the cutoff position, as the return spring on it hadn't the strength to fully operate.
WD40, a swift jiggle, and it's now back happy. The engine started immediately, and I began to drift towards smugness again.

Didn’t get the chance to hit with a hammer ,then

 

[AntarcticPilot]

Didn’t get the chance to hit with a hammer ,then

In my experience, engines work best if they fear you. There's a big hammer in.my toolkit...

 

[rogerthebodger]

If it its not broke don't fix it

 

[scottie]

using the decompression to stop the engine is a definite NO and can cause valve damage

Artic pilots big hammer will discuss it which your fingers

 

[penberth3]

When I run the engine, I start it by pulling the decompresser, turning over the engine a few times on the starter, then releasing the decompression, and it starts.
When I stop the engine, I pull the decompresser, and it stops.
Whilst cleaning the engine I'd pulled the 'other' control on the engine, the fuel cutoff valve, which is the other way of stopping the engine, though I rarely use it.

You should always use the fuel cut-off to stop the engine, not the decompressor.

 

[AntarcticPilot]

using the decompression to stop the engine is a definite NO and can cause valve damage

Artic pilots big hammer will discuss it which your fingers

There are older engines (e.g. SABB 6-8HP) that can ONLY be stopped using the decompressor. No other mechanism is fitted!

 

[jamie N]

Why should the decompressor never be used to stop the engine? And how can it cause valve damage? It can't interfere with the piston, so won't be damaged there. It is simply allowing cool air and a tickover amount of unburnt fuel to pass by it, and that won't cause damage.
Many engines of this era were recommended to stop by decompression.
All advice welcomed of course, but the engine's been stopped in this manner for quite a while now, as well as using the fuel cut off occasionally, but I can't see why it'd matter, as all one is doing is depriving it of one of the 3 things it needs to operate: air, fuel or compression.

 

[38mess]

There are older engines (e.g. SABB 6-8HP) that can ONLY be stopped using the decompressor. No other mechanism is fitted!

My 9 hp sabb could be stopped by turning the throttle control to stop.
I loved that engine, it would push my 28ft yacht at hull speed all day, and I could get it to tick over at around 20 rpm. Splash lubrication and a simple water pump that would last forever. Bullet proof, a proper marine engine.

 

[LittleSister]

My magneto ignition 1957 AJS 500cc single motorbike had only a decompressor for stopping (and starting) the engine. Turn the engine over the magneto would spark and the engine would fire unless you operated the decompressor lever. Never had a moment's problem with valves or the valve lifter (nor magneto), while pretty much everything else on the bike required constant attention or replacement at some point (or several points!).

 

[penberth3]

Why should the decompressor never be used to stop the engine? And how can it cause valve damage? It can't interfere with the piston, so won't be damaged there. It is simply allowing cool air and a tickover amount of unburnt fuel to pass by it, and that won't cause damage.
Many engines of this era were recommended to stop by decompression.
All advice welcomed of course, but the engine's been stopped in this manner for quite a while now, as well as using the fuel cut off occasionally, but I can't see why it'd matter, as all one is doing is depriving it of one of the 3 things it needs to operate: air, fuel or compression.

The stop control cuts off the fuel and the engine stops. Using the decompressor fuel is still being injected into the cylinders. That's what causes problems.

Nobody recommends stopping by decompression if there is a stop control fitted. Don't do it!

 

[jamie N]

How can a tickover amount of fuel being injected into an 'open' cylinder, 3 or 4 extra times cause problems as the engine stops, and what are those problems?
I'm not being deliberately obtuse or confrontational, but it genuinely doesn't add up to me.
When I'm starting the engine, I'm having far more unburnt fuel passing through the engine, until it kicks in.
I will say, that in the future I'll be using the fuel cut off more often to help prevent it ever becoming 'claggy' again.

 

[scottie]

How can a tickover amount of fuel being injected into an 'open' cylinder, 3 or 4 extra times cause problems as the engine stops, and what are those problems?
I'm not being deliberately obtuse or confrontational, but it genuinely doesn't add up to me.
When I'm starting the engine, I'm having far more unburnt fuel passing through the engine, until it kicks in.
I will say, that in the future I'll be using the fuel cut off more often to help prevent it ever becoming 'claggy' again.

it’s not to do with fuel but to reduce valve damage
so no one told you before but you know now what not to do
it’s your engine your choice and your repair bills

 

[Tranona]

The two cylinder air cooled Listers in our old club launches (going back 30 years) could only be stopped with the decompressors. Fail to see how it can cause valve damage.

 

[scottie]

The two cylinder air cooled Listers in our old club launches (going back 30 years) could only be stopped with the decompressors. Fail to see how it can cause valve damage.

burnt seating

 

[penberth3]

How can a tickover amount of fuel being injected into an 'open' cylinder, 3 or 4 extra times cause problems as the engine stops, and what are those problems?
I'm not being deliberately obtuse or confrontational, but it genuinely doesn't add up to me.
When I'm starting the engine, I'm having far more unburnt fuel passing through the engine, until it kicks in.
I will say, that in the future I'll be using the fuel cut off more often to help prevent it ever becoming 'claggy' again.

You are being obtuse. Do you stop your car by stalling it in top gear?

 

[penberth3]

The two cylinder air cooled Listers in our old club launches (going back 30 years) could only be stopped with the decompressors. Fail to see how it can cause valve damage.

Are you sure about that? ISTR Listers have a stop lever on the side of the engine.

 

[jamie N]

burnt seating

The decompression valve is the exhaust valve. If the exhaust valve is passing tiny amounts of unburnt fuel, and large quantities of uncompressed air, how will that burn the seats when the usual gas passing through that valve is about 500C

You are being obtuse. Do you stop your car by stalling it in top gear?

Umhh, I can't see any similarity between overloading the engine to dynamically over stress it, and force it to a stop, and of depriving it of compression through a factory fitted device.
Can you?

 

[Refueler]

I cannot help but think that the engine turning over a few revolutions with Decomp lever - the fuel is still being injected - but now unburnt and left on pistons / up through valves into exhaust ...
But I suppose also - its not much different to cranking engine on decomp before closing to start it ??

But I still think Fuel Stop is way to go - why have it if not needed ?