Leaking Carb

Guys, Looking for some help. I rebuilt my carb on a Simplicity 3416, Briggs engine. The carb is a 326431. The rebuild went great and the tractor now runs well, the problem I now have, that I didn"t have before, is that when I shut the engine off, gas drips out of the "vent" port on the bottom of the carb housing. Not sure how this could NOT have leaked before, but it is leaking now. This is really annoying, any thoughts on why this is leaking? My 3314 with the same carb doesn"t have this problem. The only thing I can come up with is that there is a part, "Washer, Fiber Viton Seat" in the carb kit I didn"t install. I don"t know where it goes, didn"t take one out during the rebuild, could this allow the vent to leak?

Thanks

The reason carb leaking is probably being caused by a age hardned or damaged float needle seat or a worn float needle,other possible cause float level set incorrectly.

Goto link below & look at left side of drawing,the parts you're talking about go on/under float needle bushing.On older mod carbs the brass bushing threads into carb body,the vitron seat goes under bushing & washer goes under lip on top of bushing to seal bushing,on newer mod carbs brass bushing is pressed into carb body & has to be extracted with a sheetmetal screw,seat under bushing replaced & old bushing pressed back into carb body.
seat

Slight correction,should read age hardned,damaged float needle seat or dirt in seat.

Some use a rubber seat at the bottom of the hole where the needle goes if the needle is solid aluminum. If your carb uses the rubber seat, I use a drill bit just the right size and blow air thru the fuel inlet. That usually gets it out. If you have to pick it out, be gentle to not scratch edges on carb too much. To install, I push the new one back down with the flat back of a drill bit or an allen wrench.

If the needle has a black rubber tip, then it does not use that rubber seat (washer).

Also, when float is removed, shake it. If it has liquid in it, then it needs to be replaced.

I test the needle seal while the carb is off the engine. I connect the fuel line, turn carb upside down with only the bowl off, blow air in the needle area to dry it out. I inspect it for wetness. I lift float to allow gas past needle. Blow it off again and make sure it stays dry.

Thanks for the replies. I did put in new needle valves and float with the rebuild. The comment on the Viton seat is interesting. I am struggling with where this goes in the carb. I did not remove one when I tore appart the carb, but maybe it is stuck inside. On mine, the "needle valve" threads into the "jet". Does the Viton seat go in first before the needle valve?
Thanks

I was generalizing about carbs. Joe knows which carb you are working on.

"On older mod carbs the brass bushing threads into carb body,the vitron seat goes under bushing & washer goes under lip on top of bushing to seal bushing"

Remove needle bushing, remove old vitron gasket if it is still there. Install new vitron gasket, install needle bushing with washer. I don't think I have ever worked on one like this. The one's I have worked on have the bushing pressed into the carb.

Post an engine model/type number and I will try to find a break down of the carb.

Also, check to make sure the float is set right.
Briggs IPL look up

You're confuseing the needle in the main jet with the float valve needle,look at drawing of carb again,locate needle on float valve,you'll see a bushing that float needle rides in,it may thread into or be pressed into carb body,if float needle doesn't have a vitron tip,then the seat installs in/under bushing,the washer is only used if bushing threads into carb body,the arrow in pic is pointing to same.

Thanks again guys. I think I see the Float Needle Seat on the diagram, but I don't remember seeing that during my rebuild, maybe stuck up in the carb. I am going to pull the carb Monday or Tuesday and I'll look again.

For reference, my engine is a Briggs 326431 with a Welch plug. I am not certain how to change that part. I am trying to attach the diagram I have for the carb, but have had issues with this in the past. I'll try it again.

Again, thanks for the help. I'll give an update after I tear off the carb. Any additional advice will still be appriciated.

OK-I looked at your parts drawing & drawing/parts list at partstree & also looked at repair instructions in my newer briggs manual,the pic I posted was for older style flo-jet carbs,looking in newer manual it appears briggs now use's a needle/seat(134)similar to tecumseh,I which case you'll either have a brass bushing pressed into body with seat under same or a cast hole for float needle guide in carb body with seat pressed into bottom of hole as robert said.

IF you have needle/seat as shown in parts list & float needle guide is a cast hole in body,you can remove old seat useing robert's method or use a small crochet hook/dental pick to remove old seat,I bought a set of denal picks from hf to work on carbs.Use a drill bit that just slides into hole to install new seat useing SHANK end of bit to install/seat in bottom of hole.IF the new seat has a rib on one side & flat on other side,flat side faces float needle,rib seals chamfer hole at bottom,if both sides flat it makes no difference which way it installs in hole.

IF needle guide is brass & pressed into body,then it will have to be removed useing sheetmetal screw method to replace seat,if fiber washer id is larger than hole/brass bushing,disgard same as it was probably included in kit as a seal if you had a thread in bushing,as far as welch plug(128),if same ok/not damage I'd leave well enough alone,if your talking about plug(158)this style plug has to be destroyed/damaged to remove & a new plug installed.

You might want to pickup a briggs service/repair manual(pn 270962)from local dealer,briggs website or ebay,it covers all repairs to carb & rest of eng.

Joe & Robert, Thanks for all your help. Tonight I tore apart the carb again. It does appear that the needle valve seat is the problem, but I still don't quite have a solution.

I pulled the brass insert seat out with a screw as Robert suggested. The new seat that came with the rebuild kit is threaded and is to small to thread into the hole. So I took the Viton seat, which was too big for the insert, and sanded it down till it fit. I then re-assembled & put back on the tractor. The GOOD news, it doesn't leak... The BAD news is there is no gas flowing through at all now, so the tractor won't run. When I put the Viton seat in, I thought this may be a problem because it was to tight when the float is up.

So where to go now? The old needle valve looks black on the end, but it doesn't feel like rubber but maybe I will try putting it back in. I don't know if I could get a new insert style seat or not.

Do you have any additional advice. I really appriciate your help so far, I am really getting to know the interworkings now.

Thanks,
Doug