Forum for air cooled diesel engines and clones

[bmaverick]

Thanks! Gonna give FreeCAD a try one day, I took a picture of the original shim and used Scan2CAD to calibrate dimensions and vectorize, I should use FreeCAD over Abviewer for printing 1:1 DXF files from now on.
I've attached the DXF file.

Yes, with FreeCAD anyone can now open 3D and 3D files and easily share or work with them.

When you launch FreeCAD, it begins in the Workbench open splash screen mode. Just change to a workbench you like to work in. Then the software gives you all the functional menus.

If you want to make gears, you can download the FREE workbench to make gears too. I really like the sheetmetal workbench. It can make folds and bends nicely. And then flatten for the blank(s) to be cut out.

You make a really nice way of making those templates too with the ink transfer.

 

[tmash]

Is it necessary to retorque the engine head bolts at 500+ hours as the manual says? Are these engines known to leak/blow gasket?
Thanks

 

[ponytug]

@tmash Since it is an aluminum engine, I think that it is worthwhile. Aluminum expands and contracts more with temperature than steel.

All the best,

Peter

 

[tmash]

So the nut position did change after retorque, not sure if it was the factory low torque as an indication or gasket compression, this was done at 400 hours for reference.
One of the bolts took ~120 n-m to take off, the rest ~75-80 n-m. (torqued with engine oil as the manual suggests)
Torqued crisscross at 42.8 n-m with a calibrated digital adapter, one at a time. (L70/178f manual: 42-43 n-m)
The intake valve lash clearance has decreased while the exhaust increased, seems like it hasn't been torqued evenly causing a slight tilt.
Engine is a no name 178F (~$250 new in my area).
Here goes nothing for the next few hundred hours

 

[tmash]

Hi hope you're all good!
I had to remove the engine head to replace the copper gasket due to a tiny oil leak that was happening at around 200 hours (now at 430), retorquing did not reduce it, one of the head nuts was overtightened at factory and it caused a leak, the copper ring is also thinner in that area. I run the engine at 50-80% load most of the time and there is no smoke, except that at ~80%, a barely visible smoke appears now, cylinder head temp (valve area) went from 95-100c new at 50% load, to 120c, and the head temperature increases rapidly as well from cold start. It seems like there is a small pitting or molten area on the piston surface? Was that due to over fueling due to loss of compression (overheat)? Why in that specific area not inside the piston hole/cone? Tested injector at ~300 hours mark, have to retest/clean after rebuild.

The leak is much larger than I expected, it's odd that there were no large symptoms, and no load speed varied very little but stabilizes perfectly under light load. The speed does go down by ~30-50 RPM when warm.
You can also see the black spot between the valves on the head matching the piston surface damage, no starting fluid was used or additive (other than fuel stabilizer for humidity/water separation).

Couldn't find copper spray in my area, guess I have to clean the copper ring area very well with acetone prior to installing the copper o-ring.
Sidenote: The outer surface engine block and head cast quality seems to be really low, full of pitting like air bubbles on the surface:

 

[bmaverick]

Hi hope you're all good!
I had to remove the engine head to replace the copper gasket due to a tiny oil leak that was happening at around 200 hours (now at 430), retorquing did not reduce it, one of the head nuts was overtightened at factory and it caused a leak, the copper ring is also thinner in that area. I run the engine at 50-80% load most of the time and there is no smoke, except that at ~80%, a barely visible smoke appears now, cylinder head temp (valve area) went from 95-100c new at 50% load, to 120c, and the head temperature increases rapidly as well from cold start. It seems like there is a small pitting or molten area on the piston surface? Was that due to over fueling due to loss of compression (overheat)? Why in that specific area not inside the piston hole/cone? Tested injector at ~300 hours mark, have to retest/clean after rebuild.
View attachment 718583
The leak is much larger than I expected, it's odd that there were no large symptoms, and no load speed varied very little but stabilizes perfectly under light load. The speed does go down by ~30-50 RPM when warm.
You can also see the black spot between the valves on the head matching the piston surface damage, no starting fluid was used or additive (other than fuel stabilizer for humidity/water separation).
View attachment 718585

Couldn't find copper spray in my area, guess I have to clean the copper ring area very well with acetone prior to installing the copper o-ring.
Sidenote: The outer surface engine block and head cast quality seems to be really low, full of pitting like air bubbles on the surface:
View attachment 718593

With so much carbon build up, it would be wise to use some SeaFoam cleaner for the top end of the engine.

No leaks from the piston rings? No oil working into the top end of the engine?

 

[tmash]

With so much carbon build up, it would be wise to use some SeaFoam cleaner for the top end of the engine.

No leaks from the piston rings? No oil working into the top end of the engine?

Will do if I find one in where I live. I left a bit of engine oil on the piston wall for ~5 hours which is probably not enough but it didn't seep. The valve seats are full of carbon build up, no seal at all, the copper head gasket/o-ring is 1.2mm! New and commonly used is around 0.4mm, I've never seen 1mm+ listed anywhere. The injector nozzle gasket

black piece is broken in half didn't find any of the bits inside seems like it was installed at factory broken? The black sleeve seems to be a loose fit (on the nozzle and head mount) and made of carbon. I'm guessing the copper washers were the gasket/seal the whole time?
I'm not sure if it's worth a rebuild yet, getting a spare engine to replace for now. I'll have to fully check and disassemble the head area on the new engine before running it. :/ Removing the alternator is painful with these. Does Yanmar still sell new genuine L70? There are no regulations for emissions in where I live.

Ref. nozzle gasket:

Edit: "Heat insulating gasket"

 

[ponytug]

Those are special copper gaskets, and yes, they have an odd thickness that isn't common, at least here. The thickness is important for both sealing and diesel injection quality, so try to get whatever is specified for your engine. The broken injection seat probably explains all the carbon at such a low number of hours.

Good luck!

All the best,

Peter

 

[tmash]

Bad news, I filled the tank (external 200L) with new diesel 3 days ago while rebuilding for best performance, the new squeaky clean gasket blew few hours later after the build was done from all the edges, loss of power and the engine muffler paint turned bright grey after ~3 hours, it ran perfect no smoke on full load first 30-45 minutes, head temp was back at 90c compared to 120c before gasoline entered the fuel line, it had old diesel remains the first hour. The fuel delivery station called and told me that they mixed diesel and gasoline in their tank of around 50% and they're going to replace it tomorrow.... probably much much more by the smell. The engine sounded very soft when I returned to find what happened. The fuel in the tank is bluish, bottom green. It was green moments after filling.
There are no words to describe how pissed I am right now... The piston surface is now semi cooked with white layer, no longer flat.
I live in Lebanon, although I shouldn't be surprised about quality due to fuel shortages I never expected mixing to happen, it did smell odd but I thought it was because it's new.. Either way this is the last straw and I'll leave this country; I'm very happy I didn't dump $8K on that Perkins genny.

Edit: Thanks for the help Peter and bmaverick.

 

[ponytug]

Bad news, I filled the tank (external 200L) with new diesel 3 days ago while rebuilding for best performance, the new squeaky clean gasket blew few hours later after the build was done from all the edges, loss of power and the engine muffler paint turned bright grey after ~3 hours, it ran perfect no smoke on full load first 30-45 minutes, head temp was back at 90c compared to 120c before gasoline entered the fuel line, it had old diesel remains the first hour. The fuel delivery station called and told me that they mixed diesel and gasoline in their tank of around 50% and they're going to replace it tomorrow.... probably much much more by the smell. The engine sounded very soft when I returned to find what happened. The fuel in the tank is bluish, bottom green.
There are no words to describe how pissed I am right now... The piston surface is now semi cooked with white layer, no longer flat.
I live in Lebanon, although I shouldn't be surprised about quality due to fuel shortages I never expected mixing to happen, it did smell odd but I thought it was because it's new.. Either way this is the last straw and I'll leave this country; I'm very happy I didn't dump $8K on that Perkins genny.

Thanks for the help Peter and bmaverick.

I'm sorry on all those items. I would never have thought to expect the fuel company not to deliver pure fuel, and yet something similar happened at work a long time ago when a new employee "forgot" to follow the protocols, and didn't clean the dispenser hose between solvents. It was only caught after some of us noticed that the solvent smelled very different, but not something we would normally have tried to smell.

Good luck on everything!

All the best,

Peter