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Thoughts on flushing a K&T 3H U horizontal

parkerstudio

Plastic
Joined
Oct 3, 2021
I’ve been thinking about how to flush my 3H. As most of us know already, the old manuals suggest flushing it out with kerosine. That’s frowned upon now as being too risky. I agree with that. It’s one thing to flush it with K1 in a huge, open, war factory, where guys with fire extinguishers could take care of things safely were things to go south. It’s another thing for that to happen in my garage.
Lubricant suppliers now offer specialty flushing oils to use. These are probably pricey, and might me difficult for me to obtain. What I am thinking of using, instead, is inexpensive, detergent, automotive, motor oil.
We are warned not to use it as the normal lubricant in these machines. I think that’s because the detergents in the oil keep the dirt in suspension. That dirt is removed in modern cars by way of their high tech oil filters. My 3H doesn’t have one of those. Instead, it depends upon the dirt dropping out of suspension into a sump. The sump is drained out during flushing. So, detergent oil shouldn’t be used normally.
When flushing, however, the idea is to get as much residual dirt as possible into suspension in the flushing medium (the kerosine) then drain that medium away, along with the suspended dirt. Sounds like detergent oil would be an excellent flushing medium.
Does anybody out there have any counter considerations?
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
I'm not scared to use kerosene or mineral spirits on principle of fire or fumes. With a drain plug hole you could simply screw in a hose, or even a hose with a ball valve somewhere in line. Then drain into a bucket you put a lid on. If its pumping on to way surfaces, yeah you want to keep it cleaned up as you go.

What does worry me is disturbing certain contaminates that are laying harmless on the bottom and won't move with regular oil. Where kero or mineral spirits might wash it loose right into bearings. That sort of contaminants you need a tear down to clean right.

I would say don't flush. Change your oil. And then change again after a few months of use.

If I was determined to flush, I might use something a little thinner than machine and motor oils to maybe get passed clogged arteries, like ATF. Better lube than kero, but thinner than most machine oils. And ATF has decent cleaning properties for an oil/lube.
 

Brandenberger

Cast Iron
Joined
Sep 19, 2017
I'm not scared to use kerosene or mineral spirits on principle of fire or fumes. With a drain plug hole you could simply screw in a hose, or even a hose with a ball valve somewhere in line. Then drain into a bucket you put a lid on. If its pumping on to way surfaces, yeah you want to keep it cleaned up as you go.

What does worry me is disturbing certain contaminates that are laying harmless on the bottom and won't move with regular oil. Where kero or mineral spirits might wash it loose right into bearings. That sort of contaminants you need a tear down to clean right.

I would say don't flush. Change your oil. And then change again after a few months of use.

If I was determined to flush, I might use something a little thinner than machine and motor oils to maybe get passed clogged arteries, like ATF. Better lube than kero, but thinner than most machine oils. And ATF has decent cleaning properties for an oil/lube.


For what it’s worth I am just finishing up a k&t 205sa cleanup. To fix an oil leak I pulled the speed gearbox, which gave me the opportunity to thoroughly clean out the column sediment. As was said above, I found a lot of sludge in the bottom that a previous flush with kero didn’t even really move. The oil pickup strainer for the gearpump is well positioned to allow a fairly deep layer of sludge to live undisturbed.

Similarly I took the front of the knee off to allow removal of the saddle and associated pieces. Again the bottom of the knee had some thick sludge. I washed it out because I had the access to do so without pumping it through all those oil lines and manifolds.

So just beware as is said above, there’s probably a lot of muck in there and you may not want to get it into suspension enough to flow through the lubrication pump and gears and pour over the bearings.

A nice clean sump in the column:

4CF9445C-06FF-4B98-B871-D8AB5B470288.jpg
 

m-lud

Stainless
Joined
Sep 4, 2016
Location
Missouri
I'm not familiar with this k&T but be careful what you do. There are often trays or Troff's that catch oil splash or from gears and guide oil directly to bearings.
Be careful about wiping them out not to flush grit down any drain holes that feed oil directly too bearings.
I'm with the change filter if present, and the oil twice within short intervals. It would be so easy to stir up grit in the wrong place.
That sediment gets locked down pretty tight and shouldn't move with regular oil changes.
 
Machines in that era used oil that did NOT suspend particles in the oil like ATF or motor oils. I have used diesel and Jet-A as a sub for kero in several machines with no issue. As mentioned above unless there is a real concern with the oil drained just refill with the proper oil and call it a day.

Cleaning the sump on the other hand, get some diesel or mineral sprits, that is a horrible job!

Steve
 

yblow

Plastic
Joined
Dec 26, 2020
Isnt there an oil pump that pumps the oil thru a filter before it goes to the drivetrain? Wouldnt the filter assembly catch the garbage?

I used kerosene to flush mine with no problems but my mill came from a local university with a pile of maintenance records.
 

ramsay1

Stainless
Joined
Aug 19, 2003
Location
port allen, louisiana usa
I think I flushed my knee and column sumps on my 2hl with varsol many years ago.. I know there was moisture in knee because the oil was milky.. The coolant sump, I flushed well with a water hose and some super clean as there were dinosaur carcasses in it from soluble residue... Once the coolant sump was clean, it poured in cutting oil and it has it to this very day....After flushing with varsal, I put fresh oil in the knee and column, ran for awhile, then drained and put fresh oil in again.. I use to get Exxon Nuto free as we had drums of it at work so that is what is still in the machine....Does kerosene have a low flash point? I never used it for cleaning, always used varsol (mineral spirits)... Cheers from Louisiana... Ramsay 1:)
 

MyLilMule

Cast Iron
Joined
Jan 5, 2021
Location
Ohio, USA
I have about 4 gallons of K-1 sitting in the sump of my 2HL as I write this. I'll be pumping it out something this weekend or maybe next weekend, Give it some time to soak.
 








 
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