Daihatsu diesel generator troubleshooting

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Merlyn
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Re: Daihatsu diesel generator troubleshooting

Postby Merlyn » Fri Aug 09, 2019 10:11 pm

Only the readings amigo, only the readings.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

Revolver
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Re: Daihatsu diesel generator troubleshooting

Postby Revolver » Sat Aug 10, 2019 5:11 am

Have to play with something off the engine? Hmm

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Re: Daihatsu diesel generator troubleshooting

Postby Revolver » Sat Aug 10, 2019 8:21 am

What about 36v engines Merlyn?

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Merlyn
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Re: Daihatsu diesel generator troubleshooting

Postby Merlyn » Sat Aug 10, 2019 9:13 am

Don't see many ( if any ) 36 v engines but lots of Common rail stuff circuits on 5-5volts for modules and -5 volts for oxy. sensors etc.
However you are ( intentionally or otherwise ) on the right track here mentioning voltage.
Think about other measurements in the voltage field era and see if you can apply that answer to cracking this problem.
Casting your mind back along major clue coming up.
The Wheatstone Bridge.
There, virtually told you.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Re: Daihatsu diesel generator troubleshooting

Postby Revolver » Sat Aug 10, 2019 11:07 am

I've worked with a 36v-er, and damn those batteries were heavy! (And impossible to find replacements haha)

I'll be honest, as soon as i read the way you specifically included small and 24v and 12v engines, I had a good idea where it was going. Worked with small perkins, and 2 x 36v Cats...

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Merlyn
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Re: Daihatsu diesel generator troubleshooting

Postby Merlyn » Sat Aug 10, 2019 11:25 am

Good old Frank Perkins, started out with them, R6 and P6.
Still got the workshop manuals for them.
And the old smokey Cats.
So racking the old brain then re the Wheatstone Bridge clue which I remember doing in the early sixties what's the answer to it all?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Merlyn
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Re: Daihatsu diesel generator troubleshooting

Postby Merlyn » Mon Aug 12, 2019 3:00 am

BP and Revolver,

Further clues required here methinks?

This is what your first girl friend put out to you on your first date together?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Merlyn
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Re: Daihatsu diesel generator troubleshooting

Postby Merlyn » Thu Aug 15, 2019 4:47 am

It appears to me to be somewhat of a problem here engineering wise to crack this one?
As there are more than one ways of skinning a cat ( as they say ) perhaps a different angle of attack might be the way to go.
A personal approach maybe.
So I put it to you in a different format.
Winding back the old clock for me to about 1964 here I am doing my seconds exam in my fourth year of my apprenticeship.
I am going out on a date with a girl and to impress her and show her how far advanced I am I have decided to tell her all about my career and my seconds ticket exam.
As that week we have paid great attention to the Wheatstone Bridge and all it's surrounding calculations I am full of it and reel it all off the top of my head non stop.
I can see she is well impressed so I, with my underwater grease on ( Brylcreem that is, same colour and consistency anyway ) imply what a great catch I am with all this knowledge onboard .
However she tells me that since our last date when I apparently gobbed off about the Wheatstone bridge she too has done some research on it in preparation for our date and does not believe that my name really was Merlyn Ohms ( which in order to further impress her I had told her ) and subsequently tells me later in the evening when I drop her off that she is going to do a Wheatstone Bridge on me.
So what was she going to do?
It's the same answer we seek concerning measuring cyl. compressions with no dismantling but winding back your old clock in a similar situation the answer you seek should be easily obvious now.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Merlyn
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Re: Daihatsu diesel generator troubleshooting

Postby Merlyn » Sat Aug 31, 2019 12:29 am

RESISTANCE is the word applicable here.

Everyone must have encountered it in some form or another in their lives.

So Mr Ohms and that upside down circlip symbol denoting the unit of resistance is how to measure each and every cylinder compressions accurately and very quickly with no dismantling whatsoever.

But how?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Merlyn
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Re: Daihatsu diesel generator troubleshooting

Postby Merlyn » Wed Oct 30, 2019 8:02 am

IMG_0807.JPG
Cranking amp waveform displa
So the way to measure compressions in a Diesel engine with electric start with NO dismantling whatsoever?

By measuring the resistance of the starter motor.
How to perform the test;
Disable the engines fuel injection system.
Using a Engine diagnostic Oscilloscope ( preferably a four channel one ) connect the high amp clamp to channel A.
Select the highest range and zero the clamp.
Connect the clamp to either the positive or negative battery
lead.
By looking in your waveform library you will see the correct waveform pattern for the actual engine and model you are testing for 100% correctly displayed compressions waveform.
Start the Scope. ( i.e. The Oscilloscope )
Crank the engine for around five seconds to capture the waveform displayed.
Use the Waveform Buffer, Zoom and Measurements tools in the Scope to examine/ expand etc the pattern displayed.
The orientation of the clamp relative to the wire will determine whether it has a positive or negative output.
Should the waveform be inverted then reverse the clamp orientation to correct it.
This test uses the following property of a DC starter motor to provide a convenient non envasive comparison of engine cylinder compressions.
With a fixed supply voltage the current drawn by a DC starter motor is proportional to the load on the motor, when the load increases the current drawn therefore increases.
During the engine cranking both the starter motor's load and current increase as each piston travels through its compression stroke.
Therefore, a continuous measurement of starter motor current indicates the relative degree of compression across the cylinders as they cycle through in their firing order.
Ideally of course the measured cylinder compressions and the indicated associated current draw would be equal but in reality even on a good engine there will be some slight variations displayed.
A repetitive low peak in the waveform indicates a cylinder waveform which will display that cylinder low compressions and will therefore require further investigation.
Compression related issues can cause poor running , misfires and emission related symptoms.

Typical faults causing compression losses are,
Inlet / exhaust valve problems.
Piston/bore and/or compression ring faults.
Blocked air intakes.
Blocked exhaust.
Head gasket leakages.
Turbo faults.
Cylinder bore washing .
Lube. Problems.
Cracked liners.
See the sawtooth type patterns typically displayed for a good engine waveform pattern.
Note the high initial high kick up Amps displayed, the current then falls and stabilises to form a uniformly repeating waveform pattern as the engine continues to crank.
Note the waveform troughs which indicate no repetitive anomalies.
So all you folk out there who still believe in the white metal bearing scraper, the flogging spanners and all torque settings should be F.T. its time to draw out, buy yourself a decent Scope and get on this crazy roundabout of modern, up to date engine diagnostic problem sorting.
Then you will have completed the test in full by the time your colleague is still trying to get that seized no one pencil injector out of the head!
In conclusion not having heard anything whatsoever from the originator of this post I can only conclude that by adjusting all tappets correctly that tight one or both exhaust valves have cured the problem.
Wonder if we will all be put out of our nightmare scenario and get this confirmed?
Over to you Rohanmariner.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Re: Daihatsu diesel generator troubleshooting

Postby sts07 » Wed Nov 06, 2019 8:12 am

Do you have mobile onboard lubrication oil test kit? I'm asking this question because you may check tbn value of LO and match it with last periodic LO analysis report if there is significant leakage from piston compression rings , the tbn results tend to be low. Also have you checked fuel leakage points of engine( I don't know if dk20 have one) from fuel pump or injection v/v of related cylinder. On the other hand the cylinder exh temperature is same as others, it decrease possibility of inadequate fuel supply. By the way you should write corrected compression value on performance report because of your vessel type. :twisted:


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