What is a "Welch plug?"

[Olias]

Okay....rookie question #5.....What is the "Welch Plug" that I hear folks referring to when talking about carb cleaning? Is it the same thing people call the "Freeze plug", which I know as the silver round concaved piece (see photo) that is found on the top of my carb. I have done one carb rebuild/cleaning already and the kit came with one of these plugs so I removed the original and as far as I can tell that area is/was completely clean/clear but I shot carb cleaner through it anyway. I'm pretty confident that all ports are now clean and clear but I understand the "idle ports" are underneath the plug and I'm having some idling problems so I want revisit this area. I just wanted to make sure I wasn't missing some other plug somewhere in the carb, hence my question. Thanks

-B-

 

[boobie]

Re: What is a "Welch plug?"

Welch plug, core plug, freeze plug, they're all the same and come in many different sizes.

 

[Olias]

Re: What is a "Welch plug?"

Ok, thanks for the verification.

-B-

 

[the machinist]

Re: What is a "Welch plug?"

In the older metal topped carbs, the factory needed a method of drilling connecting holes to other parts of the carb. These core plugs, even lead birdshot (for the smaller holes) were used to seal off one end of these holes. With the advent of the plastic topped carbs, things changed & it is done by the confiuguation of the gasket or top.

 

[lindy46]

Re: What is a "Welch plug?"

I usually run a thin wire through the holes down into the carb throat, and check the orifice where the low speed needle fits to make sure it is not chipped. Ive seen them pretty chipped up from someone tightening the needle too much.

 

[Dee Jsaan]

Re: What is a "Welch plug?"

LOL, yes a "Welch Plug" throws a lot of people. Just ask where the Zerk's are and see what kind of reaction you get. (they are the grease fittings)

When I first started working on my Ol' Scott Atwater 40 hp I found it's single Tillotson OM4A carb which had been left full of fuel and not run dry before pulling the outfit out of the water.

As I got the float bowl off it, it looked like it was full of molasses or tar. So I figured I'd have to go all through the thing. I boiled it out in carb cleaner and scrubbed it down to like new. The Welch plug was made of thin aluminum and I didn't know where I'd find another if I tore it up. Finally I found an old compass with a little piece of yellow pencil still in it. The point was sharp and fine enough to catch the edge of it and pry it out without damaging it.

I used the trick with the thin wire from a bread loaf twist tie and ran the tubes after cleaning the tar like muck out of it. I blew everything out using compressed air and was satisfied that all was venting properly. Got everything back together after cutting my old gaskets. Wound up using larger rifle shells cut and sharpened for circle die's for some of the parts.

But an old timer told me something about that Welch on top of the carb. He explained that since I had that out, I should take some non hardening Permatex and wipe it over the top of the Welch that was reinstalled back into the same position. It didn't take much of the stuff and I took an old single edge razor blade and wiped the tip of this seal even. It's never bled air or leaked fuel back out of it.

So I pass that little tip along. This is an interference fit Welch plug and after it had been installed and removed it may not have the
same characteristics. So a little sealing putty can avoid a lot of grief once it's all back together and doesn't seem to run right.

Here is the inspection hole with the Welch plug removed. Take time to get everything cleaned out as it will pay off later.

After separating the power head from the lower unit I discovered why I was able to get this motor so reasonably. In the bottom of the power
head there was a "missing" welch plug that kept the water in the cooling jacket. So it was overheating and the owner out of frustration
just bought another motor. After buying a .65 cent welch plug for that hole....I was on the water running fine. I also replaced bearings and seals on the prop shaft, water pump impeller, had the drive shaft serviced at a machine shop and otherwise took care of the lower unit
while I had it down. I only discovered that missing welch plug during routine inspection. I'm sure the guy would have crapped had he known
that a 65 cent part was all that was really necessary. But I've slowly got everything back to spec's and is all nearly OEM.

 

[Olias]

Re: What is a "Welch plug?"

Wow, fantastic information. I really appreciate the detail you went into. I'm a little concerned now about that missing welch plug you mentioned on yours. I'm wondering if my motor has one of those and if it's missing or leaking or what have you as my motor, which so far has only run for 45 sec.'s to a minute is extremely hot to the touch. Meaning, if I try to touch the lower unit I can't touch it for more than a second. I have a brand new thermostat in it and it's spitting water nicely out the pee holes so I can't figure out why it would be so hot. I have yet to pull the lower unit to check things out as this is my very 1st O.B. motor and I don't know the 1st thing about them and am afraid to tear that section apart. The only thing I've done down there is drain the gear oil and put fresh stuff in. May have to get bold and take a peek in there and make sure the impeller, and bearings, and washers etc., are ok and doing their job. Thanks again.

-B-

 

[Dee Jsaan]

Re: What is a "Welch plug?"

Glad it helped Olias.

What I'd suggest you do now if you haven't done this yet, is to get with someone you know who is experienced with outboards and get your motor on a boat or in a water barrel and let them observe it it with you. Let them tell you if they think it is too hot or what's about normal with it. Nothing beats having some experienced friends around who know their outboards.

From what I read in your post, The water coming out at the rear vent "pee hole" if it is a steady stream is a good sign. Mine wasn't doing that when I got it, owing to that welch plug being missing. So my motor got hot quickly as the water wasn't being contained in the water jacket as it was supposed to. That "pee hole" serves to vent the water jacket so that there is no air pocket trapped in the
cooling system that would allow part of the motor to not be cooled. That is an important sign. As a kid, Dad always had me sitting behind him in his old boat and part of my crew duty was to keep an eye on that little stream of water and make sure it was always
there and if not let him know immediately.

As for pulling the motor, commonly called the power head, off the lower unit or "out drive" , on my old Scott Atwater the water pumps (mine has 2) are at the top of the drive shaft. But this will allow you to inspect the bottom of your motor and look down into the out drive. If you want to work on the out drive it is much easier to do this now. Likewise with the motor.

The outboard I have and yours too most likely vents the engine exhaust into the out drive where it does double duty like an exhaust pipe. Water is poured from the motor into this from the engine cooling system at the same time and is ducted out just behind your prop. The out drive is also moving through the water your boat is in and that helps to cool the engine too. But still your engine is going to get hot just like a water cooled car engine. There just isn't a Radiator and fan on it as the cooling system uses water from the lake or river and returns the heated water back to that source. So your cooling will largely depend on the ambient temperature of the water
you are boating on and the ratio of oil to fuel, and to some extent the mixture setting you use will ultimately effect the temperature your motor runs at.

So don't worry too much until you can get with some experienced friends who have their own boats and operate them frequently. They
may offer to take you out and show you how their motor runs and you can see for yourself how hot it gets in normal operation.

This youtube video would give you an idea of what a good running motor would sound and behave like at different speeds of operation.

And a 45 hp Scott on a fiber glass runabout. This is about like my own boat. Yes the motor gets hot during operation, so expect that. If it gets too hot and won't run properly, then it's time to pull it to the bank and check things out.

1961 Sears Elgin - YouTube

That's why Dad had me keeping an eye on that pee hole vent at the back of the engine. He knew if it was flowing a steady stream that the water pump was delivering water into the cooling system.

.

 

[Olias]

Re: What is a "Welch plug?"

Once again just a plethora of info. shared in your last post. My hat is off to you with many thanks. It's folks like you and others that are willing to share in so much detail even though you've shared the same thing a hundred times that make this forum so great. Thanks friend.

-B-

 

[Dee Jsaan]

Re: What is a "Welch plug?"

Glad it helped Olias.

What I'd suggest you do now if you haven't done this yet, is to get with someone you know who is experienced with outboards and get your motor on a boat or in a water barrel and let them observe it it with you. Let them tell you if they think it is too hot or what's about normal with it. Nothing beats having some experienced friends around who know their outboards.

From what I read in your post, The water coming out at the rear vent "pee hole" if it is a steady stream is a good sign. Mine wasn't doing that when I got it, owing to that welch plug being missing. So my motor got hot quickly as the water wasn't being contained in the water jacket as it was supposed to. That "pee hole" serves to vent the water jacket so that there is no air pocket trapped in the
cooling system that would allow part of the motor to not be cooled. That is an important sign. As a kid, Dad always had me sitting behind him in his old boat and part of my crew duty was to keep an eye on that little stream of water and make sure it was always
there and if not let him know immediately.

As for pulling the motor, commonly called the power head, off the lower unit or "out drive" , on my old Scott Atwater the water pumps (mine has 2) are at the top of the drive shaft. But this will allow you to inspect the bottom of your motor and look down into the out drive. If you want to work on the out drive it is much easier to do this now. Likewise with the motor.

The outboard I have and yours too most likely vents the engine exhaust into the out drive where it does double duty like an exhaust pipe. Water is poured from the motor into this from the engine cooling system at the same time and is ducted out just behind your prop. The out drive is also moving through the water your boat is in and that helps to cool the engine too. But still your engine is going to get hot just like a water cooled car engine. There just isn't a Radiator and fan on it as the cooling system uses water from the lake or river and returns the heated water back to that source. So your cooling will largely depend on the ambient temperature of the water
you are boating on and the ratio of oil to fuel, and to some extent the mixture setting you use will ultimately effect the temperature your motor runs at.

So don't worry too much until you can get with some experienced friends who have their own boats and operate them frequently. They
may offer to take you out and show you how their motor runs and you can see for yourself how hot it gets in normal operation.

Here's a 45 hp Scott on a fiber glass runabout. My O/B is earlier than this one. This boat is similar to mine. Yes the motor gets hot during operation, so expect that. If it gets too hot and won't run properly, then it's time to get it to the shore and check things out.

1961 Sears Elgin - YouTube

That's why Dad had me keeping an eye on that pee hole vent at the back of the engine. He knew that if it was flowing a steady stream then the motor was cooling properly. When the motor is shut down the hole will drain the water cooling jacket.

See if this simple training course is helpful for you. It may be just the ticket for getting up to speed with a first out board.

http://www.spc.int/coastfish/sections/training/fts_pdf/statutory/outboard_lg_en.pdf

Good luck !
.