Measure crankcase pressure

[ArranP]

Originally Posted by ArranP

Thank you for your comment, this leaves me a little uncertain as to what I should be expecting from my compression test gauge.

Video of my guage - does not hold pressure, difficult to take a reading
https://photos.app.goo.gl/VzNgSX6yL1L9M4gH6

An example of many videos from you tube - all the videos I have watched show that the guage is holding pressure, this makes the reading can be taken easily.
https://youtu.be/u-zJGv4gp54?t=251

Mechanic talks of check valve that lets pressure only go in one direction.
https://youtu.be/u-zJGv4gp54?t=274

This video talks about the check valve being inside the glow plug adapter
https://youtu.be/jzfe3NEZDLI?t=571

[ArranP]

Originally Posted by waltini

My neighbor had all sorts of problems with his engine and black smoke. At the end of an expensive week it was an exhaust hose blocked with oysters that caused all the dramas. Is that a possibility?

Thank you I will need to disconnect the mixing elbow or find a way to redirect the exhaust gas.

[skipperpete]

No uncertainty at all, the compression gauge definitely has and needs a non return valve otherwise ya never get a cumulative reading, just the one stroke and back towards zero as it leaks into the cylinder. In the first video you can see the incremental climb. The button at the gauge is the pressure release for the next test. On a mechanically injected engine if using the glowplug hole you might want to activate the engine stop or you’ll get some really high readings and kill your gauge.

[ArranP]

Originally Posted by Shaneesprit

Hi
Don’t block off breathers to measure crank case pressure, you would be altering the situation and therefore causing a crankcase pressure.
Anyway I think your chasing the wrong thing - and sorry I didn’t read the whole thread.
I read 2 issues -
1) compression test doesn’t hold a reading - simple answer is no it won’t - only reads while cranking - it’s not that sealed
2) Black Smoke ? This is fuel not oil
Oil is blue fuel is black - Air is white.
Start with Injectors for black smoke - assuming you have done the obvious things first.

What are the obvious things ? just so I'm certain I have covered them.

[ArranP]

Originally Posted by Ballsnall

That loading sounds way too high, your theory of the drive train loading the engine may be correct. How are you measuring load?

The standard load reading on the Yanmar C35 panel.

[ArranP]

Originally Posted by Ballsnall

I would highly recommend you redo the compression test with a working gauge to get an accurate indication your engine condition and especially the wet test.

I re-did the compression test with a working gauge today.

Cylinder #1 Dry 440 Wet 550/600+
Cylinder #2 Dry 340 Wet 550/600+
Cylinder #3 Dry 410 Wet 550/600+
Cylinder #4 Dry 440 Wet 550/600+

I put 550/600+ for the wet test but it was still climbing so I stopped cranking.

[ArranP]

Originally Posted by waltini

My neighbor had all sorts of problems with his engine and black smoke. At the end of an expensive week it was an exhaust hose blocked with oysters that caused all the dramas. Is that a possibility?

I removed the exhaust elbow and let the exhaust directly into the engine compartment and the water line into a bucket.

It made no difference, the max revs whilst in gear was 1900 rpm and still black smoke.

[Dirk01]

Just following. VERY interesting ;-)

[Ballsnall]

Originally Posted by ArranP

I re-did the compression test with a working gauge today.

Cylinder #1 Dry 440 Wet 550/600+
Cylinder #2 Dry 340 Wet 550/600+
Cylinder #3 Dry 410 Wet 550/600+
Cylinder #4 Dry 440 Wet 550/600+

I put 550/600+ for the wet test but it was still climbing so I stopped cranking.

Nice, you definitely have worn rings on no.2 and that will be causing some blowby and also some black exhaust from unburnt fuel but not excessively so.

Your injectors are fine, your exhaust is not blocked yet your engine is loaded excessively.

Is the issue the same in reverse as forward. Can you get to WOT in reverse? The engine load with the prop bound has me mystified.

Are you able to disconnect the prop shaft and recheck engine load, failing that I would pull the prop to eliminate it which would leave only the transmission but a faulty transmission would have been running extremely hot.

[sinnerman]

To test blow by most mechanics just unscrew the oil fill cap and let it rest on top of the oil fill opening.

They then pinch the breather line closed and see how much the cap "dances".

There is no spec to my knowledge for crankcase blow by (pressure -or- volume).

IF you block off the breather (as others have stated), the crankcase WILL pressurize, even on a new spec engine until the crankcase seals blow out or the front cover, valve cover or oil pan blows off of the engine....

my two cents

cheers

[waltini]

Thanks for the feedback on removing the exhaust pipe.

The Yanmars at my work are much larger but they hate being overfilled with oil. Seeing as you have tried just about everything and the engines have had a traumatic event can you compare dipsticks to make sure they are the same length?

[ArranP]

Originally Posted by Ballsnall

Nice, you definitely have worn rings on no.2 and that will be causing some blowby and also some black exhaust from unburnt fuel but not excessively so.

Your injectors are fine, your exhaust is not blocked yet your engine is loaded excessively.

Is the issue the same in reverse as forward. Can you get to WOT in reverse? The engine load with the prop bound has me mystified.

Are you able to disconnect the prop shaft and recheck engine load, failing that I would pull the prop to eliminate it which would leave only the transmission but a faulty transmission would have been running extremely hot.

Since replacing the damaged turbo the load at WOT has dropped from 100% to 70%.

Yesterday I did the valve clearances, the exhuast outlet on cylinder #1 was a little high at 2-3mm or more, I set them all to 0.2mm according to the manual.

I have removed the charge air cooler and air ducts to clean them, they got heavily clogged with the oil leak from the damaged turbo. Those will be re-installed in the next days to see what difference they make.

To do :
#1 Take the set of 4 injectors that are removed to be serviced, a neighbour tested them and stated " They pop at @ 260MPa I just put them at 2.6 to see if they leaked and 2 do so they all need servicing !"

#2 Replace the 2 engine mounts on the transmission side as the engine is rising and dipping every so slightly in forward and reverse with throttle, not sure if this is normal.

#3 Disconnect prop shaft from transmission and note the load.

#4 Remove head to inspect valves and pistons.

[skipperpete]

That sounds like a fairly logical sequence, trouble is if you do it all at once, you might never know which thing was the initial problem.... and you might do a lot of work for nothing if it was just the clogged intercooler. I don’t know where you can get those injectors serviced locally but there’s a good fuel injection guy over the border in Alor setar, his workshop is called “ Public fuel pump company”, worth a phone call if you can’t find a local tech. Have you considered testing the transmission for internal leaks using compressed air rather than running it in gear..... they’re easier to hear and locate in a quiet engine room. Don’t try for high air pressure, 100 psi should be enough. Do you have electronic shift controls and solenoids or simple cable and shift lever setup?
Good luck with it all

[ArranP]

Will clean and reinstall the air-cooler and ducts first to check the result of that.

Transmission is mechanical selector.

[ArranP]

I'm intrigued by the black smoke only comes over 1500rpm whilst in gear but not under 1500rpm, and no smoke all the way upto 3200 rpm in neutral.


Could this be a pressure issue that evades the compression tests as those are conducted under no load and little rpm.