yanmar b08-3 won't start

[GazCro]

If you are not skilled/confident enough to put the engine back together if you do go as far as taking the head off DON'T take it to bits. You won't find anyone to put it back together if they come to see it and its all in bits imho.

 

[TiltyShaun]

If you are not skilled/confident enough to put the engine back together if you do go as far as taking the head off DON'T take it to bits. You won't find anyone to put it back together if they come to see it and its all in bits imho.

I was thinking we are going to get a forum engine rebuild thread!!

 

[Gecko]

when you refer to the heavy breathing, what is the sign for that. Is that from the air it was pushing out when I removed the rocker cover? Should there be no air escaping like that?

The air/oil mist up the pushrod tubes was very pronounced. I needed to find a pic of the crankshaft to see if this is normal:

Back to basics:
A 4st engine fires each cylinder every two revolutions. This is easy to imagine for a cylinder, but with a twin, you have options.
There are various crank angles the second cylinder can be added. Commonly 180, 270 and 360 degrees are used.

https://motofomo.com/wp-content/uploads/2020/12/360-180-270-degree-firing-order-explained.gif.webp

Yours looks like this, so it's 180deg separation.

With one piston going up and one going down, there should be no net change to the crankcase volume and therefore you should no be seeing any significant pumping. All that mist suggests you are getting significant blowby past the piston rings (or worse).

 

[Mick-the-fitter]

If you have the tools, we can do the job, and with the wonders of modern phones, help along the way. The first step is to get the head off and assess the pistons, bores and any damage there may be!

 

[Mick-the-fitter]

The air/oil mist up the pushrod tubes was very pronounced. I needed to find a pic of the crankshaft to see if this is normal:

Back to basics:
A 4st engine fires each cylinder every two revolutions. This is easy to imagine for a cylinder, but with a twin, you have options.
There are various crank angles the second cylinder can be added. Commonly 180, 270 and 360 degrees are used.
View attachment 35697

https://motofomo.com/wp-content/uploads/2020/12/360-180-270-degree-firing-order-explained.gif.webp

Yours looks like this, so it's 180deg separation.
View attachment 35696
With one piston going up and one going down, there should be no net change to the crankcase volume and therefore you should no be seeing any significant pumping. All that mist suggests you are getting significant blowby past the piston rings (or worse).

What engine runs a 270 deg crank on a 2 cylinder? unless it’s inclined block of course.

 

[Canal Navvy]

I keep looking back to the original post, it still screams injection pump to me.

It's one of those machines that you'd never take on at a fixed price or an hourly rate but would like in the corner of the workshop to get to know . It'll likely be a case of the last straw breaking the camels back

If it did come on the market I'd be tempted for a project although I'm realistic enough to know that another member has already got an option on it

 

[Mick-the-fitter]

If you have the tools, we can do the job, and with the wonders of modern phones, help along the way. The first step is to get the head off and assess the pistons, bores and any damage there may be!

 

[Mick-the-fitter]

Sockets mainly 7mm, 10mm, 12mm, 14mm the same spanner sizes and a torque wrench up to 200 ft/lb.

 

[Canal Navvy]

I'd love to see it up and running, I look for updates before the weather forecast these days.
It's a right bugger when threads like this don't come to a conclusion.

I'm half looking for a micro to turn into a CKD machine for those horrendous access jobs but wouldn't be at all surprised if the six fingered one is thinking the same way (which is meant as a complement to Rory)

 

[Gecko]

What engine runs a 270 deg crank on a 2 cylinder? unless it’s inclined block of course.

A surprising number of bikes run a 270° crank - from Triumph to Rotax powered BMW's and most of the Japanese brands.
There are some other 'non-traditional' cranks around too like the Husqvarna Nuda 900 which runs a 45° (or 315°) and KTM do a 75° crank'

There are a number of reasons a 'non-traditional' may be used - the first is engine balance. Basically a 360° crank is just two singles stuck together and has the same vibration problems (but twice as often).
180° twins balance better, but tend to be "buzzy", particularly at certain revs.

Last, but not least, they have a distinctive note!

 

[Mick-the-fitter]

A surprising number of bikes run a 270° crank - from Triumph to Rotax powered BMW's and most of the Japanese brands.
There are some other 'non-traditional' cranks around too like the Husqvarna Nuda 900 which runs a 45° (or 315°) and KTM do a 75° crank'

There are a number of reasons a 'non-traditional' may be used - the first is engine balance. Basically a 360° crank is just two singles stuck together and has the same vibration problems (but twice as often).
180° twins balance better, but tend to be "buzzy", particularly at certain revs.

Last, but not least, they have a distinctive note!

Depending on the block shape and angle to the crank, most crankshafts with differing big end journal degrees will work with being timed correctly.

 

[sandbags89]

I was thinking we are going to get a forum engine rebuild thread!!

its still a possibility Shaun

The air/oil mist up the pushrod tubes was very pronounced. I needed to find a pic of the crankshaft to see if this is normal:

Back to basics:
A 4st engine fires each cylinder every two revolutions. This is easy to imagine for a cylinder, but with a twin, you have options.
There are various crank angles the second cylinder can be added. Commonly 180, 270 and 360 degrees are used.

View attachment 35697

https://motofomo.com/wp-content/uploads/2020/12/360-180-270-degree-firing-order-explained.gif.webp

Yours looks like this, so it's 180deg separation.
View attachment 35696
With one piston going up and one going down, there should be no net change to the crankcase volume and therefore you should no be seeing any significant pumping. All that mist suggests you are getting significant blowby past the piston rings (or worse).

ok i think i get what your saying. So worn rings may be letting the combustion escape. What could be the "or worse"?

If you have the tools, we can do the job, and with the wonders of modern phones, help along the way. The first step is to get the head off and assess the pistons, bores and any damage there may be!

i love your optimism Mick! yes, im up for that.

I keep looking back to the original post, it still screams injection pump to me.

It's one of those machines that you'd never take on at a fixed price or an hourly rate but would like in the corner of the workshop to get to know . It'll likely be a case of the last straw breaking the camels back

If it did come on the market I'd be tempted for a project although I'm realistic enough to know that another member has already got an option on it

haha noted.

regarding the injector pump, its definitely pumping it out, fuels getting about and the spray on the injectors looks good... are you thinking its pumping weaker than it should be?

Sockets mainly 7mm, 10mm, 12mm, 14mm the same spanner sizes and a torque wrench up to 200 ft/lb.

yep looks like stuff i have. I do have a torque wrench, will have to check what the max is on it.

I'd love to see it up and running, I look for updates before the weather forecast these days.
It's a right bugger when threads like this don't come to a conclusion.

I'm half looking for a micro to turn into a CKD machine for those horrendous access jobs but wouldn't be at all surprised if the six fingered one is thinking the same way (which is meant as a complement to Rory)

i feel like there are a few people as invested into this project as i am I am hoping one day i will be uploading a vid of her firing up to give us all a victory.

 

[Mick-the-fitter]

When are we getting started? If injectors atomise the fuel we have something to work on, and also there is enough exhaust smoke to tell me it’s unburnt diesel! So it’s not getting enough compression to make enough heat.

Do you have source for Yanmar parts when we need them?

 

[Quattromike]

If it's getting air and fuel at the right time the only thing a diesel needs is compression

 

[sandbags89]

When are we getting started? If injectors atomise the fuel we have something to work on, and also there is enough exhaust smoke to tell me it’s unburnt diesel! So it’s not getting enough compression to make enough heat.

not sure, i might try start on it tomorrow. Back to work from tues so will have to be next week if i dont manage tomorrow. Will get my tools together and a salvage sheet or something to cover it with once i open it up. Save me having to lift the seat cover on and off again

Do you have source for Yanmar parts when we need them?

not yet, I have to make a few calls to find a reliable source. There are lists of "Yanmar dealers" online, but when you call up half of them don't have a clue or need 4 days to check and call you back.

 

[V8Druid]

when you refer to the heavy breathing, what is the sign for that. Is that from the air it was pushing out when I removed the rocker cover? Should there be no air escaping like that?

most engines 'breathe' ... with pistons going up and down in the crank case a certain degree of air movement and light pressure can build and is normally vented via the crank case breather system, often re-circulated into the engine itself ... the amount of breathing yours is demonstrating would suggest that the pressures in the crank case are much higher than normal, possibly contributed to, by compression in the combustion chambers escaping into the crank case, either past the piston rings or a split/crack in a piston (or even a hole in a piston) stuck/bent/damaged/burnt valves won't allow much compression to escape into the engine casings, other than past the stem seals, but I'd expect to hear a chuffing sound if it was a valve fault, preventing compression.

 

[V8Druid]

Sockets mainly 7mm, 10mm, 12mm, 14mm the same spanner sizes and a torque wrench up to 200 ft/lb.

no 17 or 19? ..... toy motor

 

[Gecko]

Depending on the block shape and angle to the crank, most crankshafts with differing big end journal degrees will work with being timed correctly.

True - regardless of separation angle, you can get anything to start and run, but that doesn't mean you can balance it. Balance shafts are a common workaround, but at the penalty of weight and complexity.

 

[Rob65]

no 17 or 19? ..... toy motor

If it’s like it bigger brother (The TNE 68 I’m currently doing battle with) he will need 17mm for the injector pipes and I think 19mm on the crank pulley bolt to turn the engine over.

 

[Tacitus]

Anyone wanting to do work on an engine will need a set of spanners and sockets in imperial and metric as a bare minimum.
Oh and don't forget a shifter and pipe wrench