Diesel Bike Diary

[alexanderfoti]

It did sound like the engine had no compression on the starter in those vids.

What does the valve gear look like?

[Tetronator]

Its buried behind an cover plate on the front of the engine so I do not know yet. But what would the valve gear do to the compression?...

[alexanderfoti]

Its buried behind an cover plate on the front of the engine so I do not know yet. But what would the valve gear do to the compression?...

When I say valve gear, I mean, all the stuff to do with the valves, rather than the gear that runs it. Sorry.

[Tetronator]

Yeah I wondered why you called it that.

Anyhow, they seemed to look fine but I'll take a more detailed look at it tomorrow.

Post some pictures and such.

[alexanderfoti]

Sorry, I was using gear and stuff interchangeably.

Be interested to see, they are pretty reliable these engines.

[Tetronator]

Engine! #7
Date: 12-7-2015

As I do not have any real way of pulling the valves out and putting them back in, I had to get creative to take a look at them.








To my untrained eye, they look fine. What do you guys think?

[gilburton]

The middle pic doesn't look right. There seems to be a lot of carbon around the valve??

I know you won't have a decent chamber to do it as the head is basically flat but close the valves and pour some diesel in to every head recess with the head upside down until the diesel is covering each valve then wait an hour or two and see if any has disappeared.
If it has you have a leaky valve.

You could do the same with the pistons and if it disappears quickly you have worn or sticky rings. Obviously this will ruin your engine oil if you haven't drained it yet.

[Tetronator]

Engine! #8
Date: 12-7-2015

Well I gave it a shot, here's the results. Couldn't do the valves as I cannot lay them down flat enough.

Begin


~25min


~35min


~40min


~45min biscuit for scale.


~60min


The flywheelside is pretty much empty and the middle one is about to go as-well. Water pump side is fine.
Now there is a 500w halogen lamp shining on top of it... I'll check again in about an hour.

[gilburton]

It's not a foolproof test as some will leak past the piston ring gaps but it does seem that you have a problem on the r/hand side?
Is that the one that corresponds to the pic of the carbon on the valve or next to it??
The seal where the head gasket goes between that outside cyl. and the middle cyl. does seem a bit discoloured and it should have a clean ring around the cylinder like the others.
I think the best bet would be to get the pistons out and check them.
Does the gasket look ok at that point between the cylinders??
By the way you could check the heater plugs while the head is off. They should glow after a few seconds.

[Tetronator]

Valve pictures are from left to right.
Left being the water pump side.
Right being the flywheel side.

Its the middle cylinder with the carbonized valves.
I'll have a look at that gasket, and I'm pulling the pistons out.

[Tetronator]

Engine! #9
Date: 12-7-2015

Right, last picture of the "seep trough test".



Middle and flywheel side are gone it looks like.

Gasket area seems ok.




So, pulling the pistons out...

That means pulling the oil pan off... No problem I thought...


THESE...


F#$%&ING...


BOLTS!!!


RAGE.


Ok, which geniuses decided to use 12 pointed bolts?...


I cant pull the piston out untill I get one of those socket heads.

Meanwhile, this normal?
https://youtu.be/_cZGh7wJjcA

[UAofE]

Front-back play is normal, movement in the direction of rotation is not.
There is a lot of carbon in that engine. Cleaning the rings and lands will surely make a significant difference but you still need to check for piston scuffing and cylinder wall damage.

[Tetronator]

Engine! #10
Date: 14-7-2015

Tried to pull the crank shaft out, of course the pulley bolt is stuck, and I mean STUCK.
Went at it with pneumatic wrench at 10 bar, still wouldn't go. I even tried an cross tire iron with an 2 meter long pole on it for more torque.

https://youtu.be/i5hnybLL1E0

Idea's to get the bastard off? I've already soaked it in penetrating oil and WD-40.


Here's a clip and some pictures off the pistons and Cylinders, they seem to look fine. Tougths?

https://youtu.be/pG4krt5XENI

From waterpump to flywheel.

Cylinder 1


Cylinder 2


Cylinder 3

[gilburton]

They all look reasonably ok to me. They have a few scores in the bore but nothing "nasty".
I was expecting stuck rings?
All you can do now is find the specs for the piston ring gaps and the pistons themselves when in the bore.
It's possible that they are out of limits causing lack of compression,HOWEVER, it would seem that someone has been in there recently and rebuilt the engine.
The crank seems fine so if there is no obvious wear or up/down movement on the bearings I would leave it.
I don't know the engine but even with wear on the rings/pistons you should still get reasonable compression.
That leaves the question why is there lack of compression?
As the engine has obviously been stripped before I would direct my suspicions at the cam/valve timing (assuming you are sure the valves and the head are sound).
It's possible the cam timing is out slightly causing the valves to open at the wrong time releasing any compression so check the timing marks.
Did you check the valve clearances before stripping?
The injector pump timing won't affect compression but once you are sure the engine timing is ok the pump timing can then be checked.
Once all that is done and if you haven't found any obvious problems then the only thing left is the head or the valves including the valve guides??
Most diesel engines when they have problems are usually head related!!

[Tetronator]

Engine! #11
Date: 14-7-2015

I got her loose...

https://www.youtube.com/watch?v=b4d-nuE ... e=youtu.be

All tough it took about a gallon of penetrating oil, a whole lot of propane and a 2 meter long steel pole, which is now bent, with me hanging off of it.

Once I got the cover off some things caught my attention.

The timing marks are off and however much I turned the gears they would not align. So 'dere's yer problem.


Once I was done completely disassembling the engine.


I figured I might pay some extra attention to the Injector pumps, it appears this pin is stuck. (It's called the rack pin right?)



So tomorrow I'm heading over somewhere to measure out the engine and see if it's salvageable.

[alexanderfoti]

Aha, bit odd though, whoever put it back together last must have mistimed it.

The rack pin on the pump mustnt be forced to work it free, or it will damage the internal mechanism.

[Tetronator]

Aha, bit odd though, whoever put it back together last must have mistimed it.

The rack pin on the pump mustnt be forced to work it free, or it will damage the internal mechanism.

Ehrm... How much force is too much? I managed to 'force' it to move by slightly tapping it with a spanner...

[mark_in_manchester]

Just a word of encouragement from me, and thanks! I have a mystery Daihatsu engine which has been sitting around for a year with no compression, while my bike languishes with (at best) a blown head gasket. Your thread is encouraging me to have a go at the spare engine at long last!

[Tetronator]

Engine! #12
Date: 15-7-2015

Results are in, engine is in prime condition except for the piston rings which were totally worn out!
So now I just have to replace those rings and refurbish the injector pump and injectors.

If all goes according to plan I'll have a working engine in about 2 weeks!

Just a word of encouragement from me, and thanks! I have a mystery Daihatsu engine which has been sitting around for a year with no compression, while my bike languishes with (at best) a blown head gasket. Your thread is encouraging me to have a go at the spare engine at long last!

Glad to be of help! Don't let an diesel engine sit for too long tough, it'll kill your pumps...

[alexanderfoti]

Aha, bit odd though, whoever put it back together last must have mistimed it.

The rack pin on the pump mustnt be forced to work it free, or it will damage the internal mechanism.

Ehrm... How much force is too much? I managed to 'force' it to move by slightly tapping it with a spanner...

Erm i think that may be too much

[Tetronator]

Engine! #13
Date: 19-7-2015

Engine is still in bits but I'm on the hunt for piston rings and a gasket set.
I have also left the whole injector assembly along with the pumps at a refurbisher to fix it up.

Once the gaskets and rings are here I will start reassembly.

Other things that need to be done on the engine are porting the head to get more power out of it and modify that darned oil pan.

[sbrumby]

Don't be thrown buy the timing marks not lining up, last year I did my JCB engine same thing in principal. The crankshaft pulley has half the teeth of the injector pump which is the same as the camshaft pulley, they all meet at the intermediate cog in the middle this is not 2 to 1 or 1 to 1, it just has to bridge the distances between the cogs. From memory my JCB took 33 revolutions to line the marks up. If the head is off when you rebuild don't bother to turn until they match just point them to the centre and then line up the intermediate cog.

[Tetronator]

It did not matter how many times I turned the gear assembly, they would not line up.

I've got an shop manual which states how to do this.

Install the idle gear, aligning the marks (6) on the gears.
Refer to the illustration.

The engine is completely disassembled at the moment, so yeah the head is off.

Thanks for the hint.

[alexanderfoti]

I installed a new 88 degree thermostat, suspected the old one was sticking in random positions as I could never understand the temperature gauge.

[Tetronator]

Engine! #14
Date: 4-8-2015

Engine is back together!



All-tough It wont run until it´s in the bike due to the fact that I need too calculate proper airbox/filter size and build it. The same goes for the exhaust.

If anyone has advice on the matter, I'm still treeing to figure out the whole Helmholtz resonator thing, I get the theory but the calculations eludes me.

I've also been on the hunt for a donor motorcycle and managed to get a gearbox in advance so I could start adapter plate and clutch construction.

[alexanderfoti]

resonance frequency isn't much of an issue on bikes, I find.

In a car, its a pain as your surrounded by the metal shell vibrating!

Are you not going to test run it before you put it in the bike

[Tetronator]

I'm talking about air resonance. Maybe the term ram air makes more sense to you, it's the acoustic resonance frequency between the inlet valve closing/opening and the air reverberating in the airbox. If you time this correctly you can stand to gain 10 to 15% more air-charge.

More Air + diesel burning = good

A natural acoustic charging if you will.

http://www.calsci.com/motorcycleinfo/Airboxes.html

[alexanderfoti]

I'm talking about air resonance. Maybe the term ram air makes more sense to you, it's the acoustic resonance frequency between the inlet valve closing/opening and the air reverberating in the airbox. If you time this correctly you can stand to gain 10 to 15% more air-charge.

More Air + diesel burning = good

A natural acoustic charging if you will.

http://www.calsci.com/motorcycleinfo/Airboxes.html

Ahh, I thought you where referring to dampening the exhaust resonance. Cant help you with that one, its over my head:)

[Tetronator]

I'm talking about air resonance. Maybe the term ram air makes more sense to you, it's the acoustic resonance frequency between the inlet valve closing/opening and the air reverberating in the airbox. If you time this correctly you can stand to gain 10 to 15% more air-charge.

More Air + diesel burning = good

A natural acoustic charging if you will.

http://www.calsci.com/motorcycleinfo/Airboxes.html

Ahh, I thought you where referring to dampening the exhaust resonance. Cant help you with that one, its over my head:)

No problem mate, exhaust dampening is also not something I worry about. At least the sound level part, legally if I get a pre-70's motorbike I'm allowed to produce 102 dB .

[BertTrack]

Um from the top of my head. The speed of sound in air, is also the speed at which the pressure moves. Relative to temperature and air pressure. (keep that in mind)

Thinking in text here. (a loud)
So at 3000rpm you have 2000 low pressure dips, traveling at given sound speed through the tube, gives 33hz, the speed of sound is: (assume 343.2m/s) so your peaks/dips in pressure travel with 343,2/33 distance through the pipe, 10.4 meters between each peak umm? Doesn't look right.

But asume i'm right above, (which i doubt, it's been too long) the volume of air moved through the engine per second in relation to the diameter of the inlet will give the air speed. And you want the peak/dip to be double the frequency basically.

I lost myself... will think more about this. Maybe find my old papers from school on this subject.