Juki DDL-8700 Oil Pump System Clogged

[friquant]

How to unclog the oil system on this cloned Juki DDL-8700? 

This is the first pumped sewing machine I've worked on. Machine has been sitting for about five years. Actual model number is FEIT DCL-8500N.

Pump

The oil pump appears intact. At low speed (200 rpm) it appeared to not pump at all, so I disconnected the vertical output pipe at the top and kept increasing the speed until around 1700rpm oil started spewing out the top of the vertical pipe. So there's at least oil now on the upper hook bevel gears.

 

Splash Test

But there's another tube that feeds the hook, and I'm not seeing any evidence of oil near the hook yet. In this video the man does a splash test with a paper towel to check how much oil is reaching the hook: 

https://www.youtube.com/watch?v=hQCUZs1-vUY&t=163s

 

Here is my paper towel, still dry:

 

Valves

I have opened the valve that regulates oil to the hook:

and also opened the valve that regulates the oil to the needle bar crank assembly:

but still not seeing any on the hook or on the needle bar crank assembly.

Tthe user manual says that when machine is new or anytime after it's been sitting idle for a long while to run the machine at 3000rpm for a period of 10 minutes. So far I've run the head unit a couple minutes at 2400rpm (checked with tach). I want to see evidence of oil flowing before I run it enough that it really needs oil, if you catch my 22.

 

Filter?

Earlier in this same video the man cleans out the filter in the pipe behind the hook: 

https://www.youtube.com/watch?v=hQCUZs1-vUY&t=59s

so perhaps that will be my next move. As for the needle bar crank, I'm not sure sure what to disassemble to clear the way.

Water

Worth noting perhaps that I did find evidence of water in this machine. The oil pan drain plug is rusted in place and I did not manage to free it. Not even with mild application of a kitchen torch, a few hours soaking in diesel, and an impact driver. 🤷‍♀️ Also the old oil looked milky. And in part of the presser bar I found a couple drops of water concealed within some drops of oil. But I don't really expect water in the past to clog the oil pathways

Manual

I'm using this as a manual: https://www.juki.co.jp/industrial_j/download_j/manual_j/ddl8700/menu/ddl8700/pdf/instruction_eg.pdf

 

 

[friquant]

18 hours ago, friquant said:

Earlier in this same video the man cleans out the filter in the pipe behind the hook: 

https://www.youtube.com/watch?v=hQCUZs1-vUY&t=59s

so perhaps that will be my next move.

Removed the hook

This brass screw was screwed into the end of the hook shaft. The near end has a tiny hole in it, like a carburetor jet. The far end is not brass...rather looks more like fiberglass. Perhaps it is porous?

 

After washing the brass screw in soap and water, I tried blowing through it. Nothing seemed to come out.

[friquant]

The "fiberglass" piece was removable. I pulled it out carefully. The jet was clogged, but shoving a sewing pin through it cleared the hole. In this photo we have:

(left) Oil jet
(middle) The clog. (silicone-like texture)
(right) The "fiberglass" piece. (filter?)

 

Am hoping that after reassembly (without the silicone-like clog) that it will weep a few oily tears for the hook.

[friquant]

Where should I expect to see oil coming out at the left end of the main shaft? What does it feed oil to...the needle bar crank rod? Or the thread take-up crank shaft assembly?

I expect there are some pieces that are to be oiled manually...just not sure which ones.

This diagram shows the relevant pieces. Supposedly you rotate part #32  180 degrees to go from "minimum oil" to "maximum oil". 

 

 

Diagram is from page 3 of this juki ddl-8700 parst list: https://www.juki.co.jp/industrial_j/download_j/manual_j/ddl8700/menu/ddl8700/pdf/partslist.pdf

 

 

 

[friquant]

2 hours ago, friquant said:

Where should I expect to see oil coming out at the left end of the main shaft? What does it feed oil to...the needle bar crank rod? Or the thread take-up crank shaft assembly?

Found some reference to what this should oil in the user manual.