Nozzel check valve

[Vintage Engine Repairs]

The bane of my existence these bloody check valves.

Anyway, I have a Tillotson HS 118A 9 carb and need a new nozzel check valve, mines leaking.

I can’t find this exact carb, the closest is for a tillotson 118B.

Would they be the same? I have this part number for the the B version of the carb:

363-518

Any advice would be much appreciated!

 

[RED-85-Z51]

The bane of my existence these bloody check valves.

Anyway, I have a Tillotson HS 118A 9 carb and need a new nozzel check valve, mines leaking.

I can’t find this exact carb, the closest is for a tillotson 118B.

Would they be the same? I have this part number for the the B version of the carb:

363-518

Any advice would be much appreciated!

The parts breakdown shows that part number specifically for the B spec but never shows the A spec in the list of carbs.

Sent from my SM-G996U using Tapatalk

 

[Vintage Engine Repairs]

The parts breakdown shows that part number specifically for the B spec but never shows the A spec in the list of carbs.

Sent from my SM-G996U using Tapatalk

Yes that’s what I found.
Just to make sure I understand, are you saying

1). Tillotson never show the A version, they only show the B version but the parts are interchangable

or

2). You can only find the parts breakdown for the B carb (which is all I can find too)

 

[Old2stroke]

Without a pic, can't be sure what that check valve looks like, but most can be repaired by replacing the rubber disc. Lots of info here on how to do it, just do a search on "repair nozzle check valve"

 

[RED-85-Z51]

Yes that’s what I found.
Just to make sure I understand, are you saying

1). Tillotson never show the A version, they only show the B version but the parts are interchangable

or

2). You can only find the parts breakdown for the B carb (which is all I can find too)

I cant find any literature about an A version from Tilly at all. They spec the B for an o56av I think it Said

Sent from my SM-G996U using Tapatalk

 

[RED-85-Z51]

Without a pic, can't be sure what that check valve looks like, but most can be repaired by replacing the rubber disc. Lots of info here on how to do it, just do a search on "repair nozzle check valve"

Its a cylinder, about as big as a couple small hearing aid batteries

Sent from my SM-G996U using Tapatalk

 

[Vintage Engine Repairs]

I took the whole thing apart, attempted to polish the ball smooth (you can see it was rough) and polished the brass seat. Tapped the retainer back on, but was still letting air through like a sieve.

I’ll take a chance and go for the one I mentioned in the original post here.

Just for reference:

 

[lone wolf]

The bane of my existence these bloody check valves.

Anyway, I have a Tillotson HS 118A 9 carb and need a new nozzel check valve, mines leaking.

I can’t find this exact carb, the closest is for a tillotson 118B.

Would they be the same? I have this part number for the the B version of the carb:

363-518

Any advice would be much appreciated!

You blowing out the carbs with high pressure air?

 

[Vintage Engine Repairs]

You blowing out the carbs with high pressure air?

Nope, never do, this is a solid ball check valve and not a diaphragm / disk anyway so I could, but it’s just worn.

 

[KASH]

Years ago when all the snow mobiles were equipped with Tilliston carbs the check valves gave us nothing but grief there was a company here in Canada that made their own replacement it was called Gosse Jet it used a glass type ball it almost looks like yours is one mind you it has been about 25 years since I saw one.Gosse jet disappered not long after the carb of choice was Mikuni .
Kash
Ps I hate those check valves with a passion a dumb idea to start with.

 

[Vintage Engine Repairs]

Years ago when all the snow mobiles were equipped with Tilliston carbs the check valves gave us nothing but grief there was a company here in Canada that made their own replacement it was called Gosse Jet it used a glass type ball it almost looks like yours is one mind you it has been about 25 years since I saw one.Gosse jet disappered not long after the carb of choice was Mikuni .
Kash
Ps I hate those check valves with a passion a dumb idea to start with.

How interesting!! Give me a screen that works off capillary action that can be cleaned with retaining clip and plug any day...

 

[Old2stroke]

Is the ball bearing close enough to a standard size so that you could just replace it instead of trying to polish it?

 

[Vintage Engine Repairs]

I’m not sure actually. I was able to get a new check valve from Stihl which was surprising!!

 

[Old2stroke]

Can I add 5 cent and educate you.
Nozzel check valve is there to prevent damage of the carb in case of engine backfire. And is only to be serviced if plugged with dirt. It is supposed to leak, that is its job. If it is not leaking, then you have problems.
Service or replacement of this valve is required extremley rarely...almost never and poloshing retaining ball and valve is a futile job.

Not really. The purpose of it is to prevent air from bleeding back through the high speed fuel jet into the low speed circuit and leaning out the mixture at idle when the throttle closes. It is supposed to provide very little restriction to fuel flow through the high speed nozzle when the saw is operating at full power and not leak any air back through it at all when the engine is at idle. The usual problem with the ones where the check valve is a tiny rubbery disc is the disc gets deformed by alcohol in the fuel and sticks open, really screwing up the idle and if they are just intermittent, it can drive you nuts. As far as I know all of these carbs have some form of nozzle check valve. Smaller saws may just have the fine capillary screen, some with a rubbery disc, some without. Any saw with a separate primer bulb will have 2 of them. The good ones have a stiff fiber disc that is very resistant to deformation. Many of us make out own rubbery disc replacement and repair them, some are easy, others are impossible. What is disturbing is they are never included in a repair kit, have to be ordered separately and cost about the same as a AM carb.

 

[Vintage Engine Repairs]

Can I add 5 cent and educate you.
Nozzel check valve is there to prevent damage of the carb in case of engine backfire. And is only to be serviced if plugged with dirt. It is supposed to leak, that is its job. If it is not leaking, then you have problems.
Service or replacement of this valve is required extremley rarely...almost never and poloshing retaining ball and valve is a futile job.

That’s not good education as it’s wrong.

The role of a check valve is 2 fold. For carburetors fitted with a purge it stops air being drawn through instead of fuel and for ones without, it’s to stop air bleeding back when the engine is idling upsetting the mixture.

They shouldn’t leak either. The only time you should get a leak through the H speed circuit is if the high speed drilling is fitted with a capillary screen and you’re pressure testing it expecting it to have a valve instead. This uses the fuel and fine mesh screen to stop the air returning to the carburetor.

Edit from Zama:

 

[OM617YOTA]

Good time for this thread to come around for me, thanks to everyone for contributing.