Export thread

Hey guys!
As some already know, I am repairing a Murray 42" with B&S 31P777 and one of the problems is the oil plug that came with a water valve (don't laugh).
I need to know the measures of such a plug to make an appropriate one, because here it is either very expensive or it is very difficult to get original parts.
I need the following measures:
What is the external measure of the plug thread?
How many threads per inch? I believe it is 20 ... is that correct?

Wrong valve...?

More than likely a 3/8” pipe thread.

Rivets said:

More than likely a 3/8” pipe thread.

Click to expand...

Ditto,
Tractor supply sells 3/8 pipe, male thread on both ends, then a cap on one end.

There's something different ...
The hole in the housing is 9/16 = 0.563 "
The tube as quoted from 3/8 = 0.375 "
Did they widen the casing hole?


The thread of the water valve is quite different and what was sealed was the excess of teflon tape.

No
Pipe threads are named by the size of the hole that the liquid flows through
So a 3/8 pipe thread is around 9/16 outside diameter
And to make things more confusing it will be a tapered thread so it locks into itself air tight

I understand ... but I waste time or money looking for a representative ... the best thing is to do it.
But do you say that the thread is tapered (not parallel)?
This complicates a little without knowing the angle.
Do you know the standard (BSP, NPT)?

No
I use BSPT taps & dies or NPT taps & dies

Most likely it's npt. I'll use the model # and see if i can confirm...

Okay, being NPT, I already saw that the thread tooth angle is 60 ° and the taper can be 2 °.
But I also saw that every NPT / BSP female is parallel, so the male can be at standard NPT angle (1 ° 45 ' to 2 °) or parallel.
I believe that the fact that bertsmobile1 uses both NPT and BSP in "taps & dies", is due to aluminum fluff in the housing, as it will be compliant for both 55 ° (BSP) and 60 ° (NPT) teeth.
I also saw that all thread material in tubes, for the 3/8 tube, the thread has 18 wires per inch ... if confirmed, this information is enough for me to make the thread in an aluminum or bronze tube, I don't know yet .

I don't mean to sound condescending but i think you're over thinking it some....go to your hardware store. Buy a 3/8 NPT tube, male thread on both ends and buy a cap or valve to fit on one end.
Teflonsealing tape on both ends. Install it. You're done.
Or you can call Briggs And Stratton and ask them what size thread the 31p777 engine sump drain plug is.

Or look at #15, in the parts list

bertsmobile1 said:

No
I use BSPT taps & dies or NPT taps & dies

Click to expand...

They are different thread pitch.

And the Briggs is 3/8-18 NPT. If you use a 9/16 drill bit you can confirm this.

Bange said:

Okay, being NPT, I already saw that the thread tooth angle is 60 ° and the taper can be 2 °.
But I also saw that every NPT / BSP female is parallel, so the male can be at standard NPT angle (1 ° 45 ' to 2 °) or parallel.
I believe that the fact that bertsmobile1 uses both NPT and BSP in "taps & dies", is due to aluminum fluff in the housing, as it will be compliant for both 55 ° (BSP) and 60 ° (NPT) teeth.
I also saw that all thread material in tubes, for the 3/8 tube, the thread has 18 wires per inch ... if confirmed, this information is enough for me to make the thread in an aluminum or bronze tube, I don't know yet .

Click to expand...

NPT (normal pipe tapered) and NPSM (normal pipe straight male) are two different animals. Also BSPP (British Standard Parallel Pipe) and BSPT (British Standard Pipe Taper) are two more different animals.

Scrubcadet10 said:

I don't mean to sound condescending but i think you're over thinking it some....go to your hardware store. Buy a 3/8 NPT tube, male thread on both ends and buy a cap or valve to fit on one end.
Teflonsealing tape on both ends. Install it. You're done.
Or you can call Briggs And Stratton and ask them what size thread the 31p777 engine sump drain plug is.

Click to expand...

Scrubby.
I thing you will find Bange is in a third world country so there is no Harbour Freight 10 minutes down the road.
This is why he is doing the work arounds.
One of the downsides of the new format is the location tags have been deleted .

bertsmobile1 said:

Scrubby.
I thing you will find Bange is in a third world country so there is no Harbour Freight 10 minutes down the road.
This is why he is doing the work arounds.
One of the downsides of the new format is the location tags have been deleted .

Click to expand...

didn't realize that

Scrubcadet10
The world here is another one of my friends ... 3/8 is not standard for ordinary people, just for industry and nobody sells a 10 or 15cm piece, only 3 or 6 meter sticks. In addition to conical threads here it is only for materials under pressure (gases or fluids), minus the public water service.
I saw the plug and it didn't look like a conical thread ... it's actually cheap there ... but what I'm thinking about is a piece of pipe so that the oil falls out of the chassis so it doesn't get dirty.

StarTech
Yes, in numbers there is a small difference that is significant when the materials are hard ... aluminum is compliant and ends up sealing, even with this small difference.
In the materials I have seen so far, the female thread allows for a tapered or parallel male ... the seal, in the case of straight, can be a little damaged and you should abuse teflon tape or put a soft metal washer (aluminum , copper), to compensate.

bertsmobile1
Bingo! This is one of my biggest problems with imported parts ... difficult to find, to have in stock, with a reasonable price ... which never happens.

Continuation...
Yesterday I researched the market and found 3 stores and only 1 accepted to sell me, a piece as said by Scrubcadet10, if it were in iron it would be quite cheap, but I prefer in aluminum or brass, I found what is called here "long nipple" , in brass, whose value is BRL 55.00 (+ -USD 11.00) and the plug for BRL 22.00 (+ - USD 4.2) ... total BRL 77.00 (+ - USD 15) ... but I didn't buy it.
Today I bought a hexagonal piece in brass 7/8 with 10cm long for BRL 40.00 (+ - USD 7.5).
I also made a test piece with the water valve that came in place of the plug, but the piece only went halfway, signaling that either the thread was obstructed or the taper of the NPT is in the housing.
Since I don't have a 3/8 thread opener, I improvised one that solved the problem.









The plan now is to make an extended plug with the purchased hexagon and other pieces of my scrap.

Hey Bange,
The drain plug is probably National Pipe Thread (NPT)
I got these sizes on line
Nominal Pipe Size 3/8"
OD .675"
Threads per inch 18
Angle between threads 60degrees
Taper 3/4"/ft
Use teflon tape or pipe dope to seal
Need some way to attach tool to tighten and loosen
If what's there now works leave it as is.

Looks similar to a bathroom faucet stem. LOL

slomo

muddy 51
Yes, friends have already passed on this information ... but I imagined that the taper (angle) was on the male thread (plug) but after placing the test plug I saw that the angle is on the female thread (engine).
But when passing the improvised tool, the NPT thread was changed to a normal thread (without an angle) ... this will facilitate my project.

Slomo
Yes, in fact it is a bathroom or kitchen faucet (I didn't know the name "faucet" ... google previously translated it as a water valve).
The kitchen faucet improvised by the previous owner, served for me to make the test plug.?‍

Evolution ...
Turned and ready parts, lacking a nitrile rubber, a soft washer and a small chain to hold the lid.

Preparation of the exagonal part.


Internal turning with the same size as the connection pipe


Detail of the internal channels for better sealing.


Turning the sealing pin to the opposite side of the pipe


Preparation of the connection pipe


Parts to be pressed
Before pressing, the brass one goes to the oven, the aluminum one goes to the freezer.


Chemical lock


Chemical lock application


Using the lathe to press

Evolution 2...

Turned and ready parts.


Connected parts.

Note: soft washer is missing and exchange EVA rubber for another nitrile.

Scrubcadet10 said:

I don't mean to sound condescending but i think you're over thinking it some....go to your hardware store. Buy a 3/8 NPT tube, male thread on both ends and buy a cap or valve to fit on one end.
Teflonsealing tape on both ends. Install it. You're done.
Or you can call Briggs And Stratton and ask them what size thread the 31p777 engine sump drain plug is.

Click to expand...

Perfect answer. Believe it.

I totally agree ... but when the option is too far away or too expensive, there are other possible and fully acceptable options ... not for everything, of course!

You know something is good, but can it improve?
So it is...

A small modification ...
Nitrile rubber is expensive and would still have to be adapted ... but there is an almost inexhaustible and free source on the floor of car workshops.
It is an O-ring of the fuel injector nozzles.
Then...





I tried to make an aluminum washer, it didn't look good ... so I made it out of brass too.


With a good grip I don't think it would leak, but I added teflon tape as a guarantee.


I am concerned with vibration ... as the lid will not need a tightening tool, only the hand, can it loosen and leak? It will be seen during the first hours of use ...
This is for those who open engines: is it worth making a magnetic trap to retain iron filings present in the oil?

You’ve stuck more time than 99% of us here and you’re having fun. Go for it, what do you have to lose. Only thing I would question, do you think there are that many iron filings in an aluminum block engine? Aren’t most of the bearings/bushings aluminum?

Really, spending my time on the things I like is fun ... boring is not having the materials on hand and taking a while to get them, doing is another fun.
Just as there was no magnetic plug in my car, after putting it on I was amazed at what was circulating and I imagine the harm it does ...
After analyzing the oil that came out of my B&S (I don't know how long it was there), I noticed shiny particles, in fact I don't know if iron, bronze or aluminum, hence the question) that come out with the friction of some parts and I find it interesting to apply the same reasoning as for my car.
You commented something interesting ... if they are not made of iron or steel, it will not do any good ... as I have not yet discarded the oil, I will pass a magnet on it and see the result.

Scrubcadet10 said:

....go to your hardware store. Buy a 3/8 NPT tube, male thread on both ends and buy a cap or valve to fit on one end. Teflon sealing tape on both ends. Install it. You're done.

Click to expand...

Exactly. AND the short pipe extension will mean that oil drains into the pan, and not all over the mower frame.

Analyzing the oil ...
Due to the lack of knowledge of a standard procedure (which can even be centrifuging and not magnetic), I adopted a very simple one that can be seen and understood by the photos and video below, remembering only that the oil was not at the working temperature and that the debris in greater volume and size must be retained in the oil filter.

This was the initial oil collection pot.

Attaching a magnet to the bottom of the pot



Iron filings ...


Wrapping the magnet in a PVC film and immersing it in the oil.


Iron particles captured by the magnet.


It was not in my plans to replace the oil filter now, however, after the presence of iron filings was confirmed, I decided to remove the oil from its interior ... and I found another problem ... the engine thread is 3/8 inch and the filter thread is 1.5mm, sacrificing the motor thread.



Well, the evaluation was preliminary and I do not consider it conclusive, but it only served to confirm the presence of iron filings, which certainly passed through the filter, if they are harmful in size or volume, I can say nothing, but logic tells me that it is.
I will think of a way to set a trap, but this will take a lot more time.

I really wish people with little understanding of the lubrication system would refrain from posting simplistic "experiments " on the web.
All mower oil filters have a bypass valve so when the filter is clogged the oil bypasses the filter so the engine does not seize .
If you can see it then it CAN NOT PASS THROUGH THE FILTER PAPER unless the paper is damaged.
Next there are a lot of things that are ferro magnetic, like gravel dust for one.
Oil filters on mowers get changed on an hours of operation or lapsed time basis, not on a full yet basis.
And yes the oil filter thread can be NPT or Metric
However the thread cout & profiles are close enough for it not to matter.
Remember these are no formula 1 engines running at 11 tenths of their design limits
Mower engines , now that Honda have exited the market are the cheapest easiest to make lowest output engines it is possible to manufacture & sell.
They are really not much more advanced technically that they were in 1920

My level of knowledge in this equipment is very low, so some questions may seem naive, but I believe they are valid since most users are in fact ignorant and I believe that this forum exists to clarify doubts about defects, operation, exchange experiences as you and many others do so gently.
Of course, these engines are very simple, but if treated with the care and importance of a Formula 1, they should give the owner a lot more satisfaction.
I do not know, internally or for information (now I do), an original B&S filter with a bypass valve, I know that in the automotive industry there is ... but I see no problem with having an extra guarantee with a magnetic trap, like in a car.
In the event that the owner changes the filter regularly, I think that the presence of such a trap can prove the quality of the filter, show that the change must be made in less time or even that a random or manufacturing problem has occurred.
To change the filter itself, it's like the drain without the extension ... the oil runs over the chassis ... I saw a JD model with an "easy change" filter, very smart ... there is something similar for the 31P777 ?

Well ... I bought another automotive filter with the same thread as the previous one (M20), only a little bigger.
This decision was not to further spoil what was started by the previous owner.


I also opened the old filter to analyze more filings and get to know it from the inside.


I washed it with gasoline to loosen the oil and filings, then I filtered the coffee (rs) and captured the filings with the magnet.

I certainly didn't capture everything and I don't know if it's too much or too little.

In the oil filter element, not everything that shone was made of iron.


I discovered the two internal valves ...


One thing that worries me is the bypass valve spring ... it is very strong and depending on the pressure of the pump, it will not open in the event of a clog and the internal irrigation of the engine can be impaired. In cars around here, the oil pressure ranges from 20 to 70 PSI, depending on the engine, I don't know what my B&S pressure is ... would anyone know?

Bange said:

Hey guys!
As some already know, I am repairing a Murray 42" with B&S 31P777 and one of the problems is the oil plug that came with a water valve (don't laugh).
I need to know the measures of such a plug to make an appropriate one, because here it is either very expensive or it is very difficult to get original parts.
I need the following measures:
What is the external measure of the plug thread?
How many threads per inch? I believe it is 20 ... is that correct?

Wrong valve...?
View attachment 56204
View attachment 56205

Click to expand...

Not sure where you are but check This out

Virgil_c
I live a little far from the big lawn mower market (USA), where everything that is imported is very expensive or difficult to find. Things that are simple and even cheap for Americans, are complicated and expensive for Brazilians, leaving us with the creativity for various solutions.
The problem (plug) has already been solved, leaving two questions:
1 - What is the pressure of the B&S 31P777 oil pump?
2 - How and where to place a magnetic trap to capture iron filings?
These are important questions for me, but they do not prevent the machine from working and can wait a longer time.
I saw an adapter on Amazon (Briggs & Stratton 492061 Remote Oil Filter Adapter), which can solve both issues and a third one, which is the clean filter change ... but the price to get my hands more than doubles and the solution is also to make one, and this is not difficult for me.

Bange:A simple way to determine the size and threads per inch is to find or create a piece of round wood that is slightly tapered to start in the threaded hole. Screw into the threaded hole abaou a 1/2" then remove. The marks left on the wood will tell you the correct number of threads per inch. It will also tell you the minor dia. of the thread. I have seen this done with a small limb from a tree that had the bark removed with a pocket knife. It takes longer to read this than to do it. Good luck.
Sheenist

Bange said:

My level of knowledge in this equipment is very low, so some questions may seem naive, but I believe they are valid since most users are in fact ignorant and I believe that this forum exists to clarify doubts about defects, operation, exchange experiences as you and many others do so gently.
Of course, these engines are very simple, but if treated with the care and importance of a Formula 1, they should give the owner a lot more satisfaction.
I do not know, internally or for information (now I do), an original B&S filter with a bypass valve, I know that in the automotive industry there is ... but I see no problem with having an extra guarantee with a magnetic trap, like in a car.
In the event that the owner changes the filter regularly, I think that the presence of such a trap can prove the quality of the filter, show that the change must be made in less time or even that a random or manufacturing problem has occurred.
To change the filter itself, it's like the drain without the extension ... the oil runs over the chassis ... I saw a JD model with an "easy change" filter, very smart ... there is something similar for the 31P777 ?

Click to expand...

The red circle is the location of the drain plug. Also, synthetic oil is over kill and wasted money in my opinion. Low oil casuess damage but in 50 years i HAVE ONLY SEEN 1 engine damaged from poor oil changes and that was caused by oil port pluggage.

B&S has lawn mower engines today that do not recommend oil changes over the life of the engine. I agree, as long as the level is maintained.

reported

reported

VRR.DYNDNS>BIZ said:

B&S has lawn mower engines today that do not recommend oil changes over the life of the engine. I agree, as long as the level is maintained.

Click to expand...

Well, I find it strange that an internal combustion engine manufacturer does not recommend changing the oil, as it deteriorates, loses its lubricating characteristics, whether due to mileage, downtime or hours of use.
As for gearboxes, without contact with fuel and the outside environment, it is more than logical.
As for the level, regardless of the combustion engine or gearbox, it must always be inspected and topped up during its useful life...because if the volume is insufficient, lubrication is impaired and the engine's useful life is reduced.

Bange said:

Well, I find it strange that an internal combustion engine manufacturer does not recommend changing the oil, as it deteriorates, loses its lubricating characteristics, whether due to mileage, downtime or hours of use.
As for gearboxes, without contact with fuel and the outside environment, it is more than logical.
As for the level, regardless of the combustion engine or gearbox, it must always be inspected and topped up during its useful life...because if the volume is insufficient, lubrication is impaired and the engine's useful life is reduced.

Click to expand...

Simple
They did a Vox Pop and found out that most home owners hate doing oil changes, so they eliminated it
Back in the days when a mower could last 50 years if maintained properly, maintenance was important.
Now days when 2 years is considered a reasonable service life and by 5 years they are worn out or in Cal no longer EPA compliant why bother to change the oil.

People conflate car & truck engines with mower engines
They only similarity is the parts have the same names
IF your car needed an oil change every 50 to 100 hours you would be doing it almost weekly
Most mowers will happily fun for several years on the original oil without mush in the way of adverse effects
Unlike pressure fed lubrications systems, full splash does not allow contaminants that can cause excessive wear into the journals because there is not the space for them to get in.
This is why the old side valve engines would run with treacle in the sump.

And yes they would run better but mower engines are very low stress engines
My 125 cc 2 stroke premix motorcycle has 14 Hp and will push me along at 60 mph on the flat all day long running at 6000 rpm
My 250 cc 4 stroke full splash 1927 motorcycle will do the same running at it's top speed of 4,500 rpm
Yet my 500cc mower engine stuggles to cut the grass

Do as scrubcadet10 says.

Get a 3/8 NPT pipe nipple 4 inches long, galvanized or black iron, a 3/8 pipe CAP and a roll of teflon tape 1/2 or 3/4 inch wide. Put 3 layers of teflon tape on the pipe threads (wrapped opposite direction from the way the threads turn into the block) Take a pair of pliers or channel locks and gently snug the pipe nipple into the ALUMINUM BLOCK. If you tighten the pipe nipple too tight YOU WILL CRACK THE ALUMINUM BLOCK because it's a taper threaded pipe and block and wedges or expands the aluminum as it gets tighter. Then install 3 layers of teflon on the pipe nipple and install the cap. The 4 inch long nipple will allow you to drain/change the oil into a catch pan by removing the cap instead of letting the oil spill onto the mower frame.

As they say you are over thunking.

The issue has now been resolved... see #16 onwards...DIY...

Reported
But perhaps we should allow all of the idiots who wan to kill themselves self medicating with methotrexate ( which is highly toxic ) fill themselves as the world would be better off without them

From what I see in the pic, it looks like a special fine thread. Take the unit that screws into the threaded hole to your local friendly machinist and he will measure the male thread and tell you what it is. It is NOT water pipe threads, I can guarantee you.
Sheenist