6.5hp old briggs leaking gas at air filter

[1RB2534]

Welcome input on this.
This mower is a very old 22" Poulan Hi Wheel push Mower (originally sold as Weedeater model) with a Briggs 6.5hp engine. It has one of those 4x5 plastic plates that holds the primer bulb and the PVC hose connector (from valves cover) and this whole plate bolts to carb.

After shutting engine off I heard a bubble noise coming from mower when I pushed it in garage. I noticed some gas leaked down on mower deck under air filter area. I pulled the air filter and it was soaked with gas.

I'm thinking the float bowl needle valve seat has worn a leak but also got to wondering if maybe something has gone bad with my engine valves causing excessive blow by coming thru PVC tube into carb area. But that wouldn't make the gas leak would it ?

Anyhow I've already ordered a rebuild carb kit since it's due one anyhow. But welcome any input on what else might be causing this.
Thanks.

 

[EngineMan]

Yes am sure we can give you answers if you post up the engine numbers.

 

[1RB2534]

Yes am sure we can give you answers if you post up the engine numbers.

This mower is close to 30 yrs old. There's no engine number on it that's readable. I have a ticket from an old trip to a local parts house that says they ordered parts for it under Briggs Engine Model 12J802, Type 3135. And the parts worked so I guess that's close enough.

The Air Cleaner Primer Base plate that I spoke of looks just like Briggs OEM 795259 part.

Anyhow I'm cleaning up the carb and have ordered the rebuild kit and the Air Cleaner Base plate which includes a new bulb since the old one looks rough. This has been probably the most dependable mower I've ever owned and I've owned a long time.

 

[EngineMan]

Primer System carb one of 498966, 498170, 497347 before giving more answers apart from give it a good clean out before fitting all the new parts and it should fine after that, if not let us know and we will take it from there.

It may also be time to check the valves....they may need a lapping...!

 

[1RB2534]

Primer System carb one of 498966, 498170, 497347 before giving more answers apart from give it a good clean out before fitting all the new parts and it should fine after that, if not let us know and we will take it from there.

It may also be time to check the valves....they may need a lapping...!

The mower is so old I've never really had (or lost) the OEM Nomenclature numbers on it. I bought decades ago at a big box store. Always had to feel my way along with part orders. I've never ordered a new carb (yet) just always rebuilt it with Briggs OEM 498260 Carb Kit. Many carbs look very close except for throttle linkage lever length. The carb on mower does have a readable number 8823 0209 stamped on backside of carb flange on engine side flange. Never found any with this number ref for sale. In one ebay pic I found it looked identical (throttle level etc) to the Briggs 8823 8257 carb.
However listings show the Briggs OEM 799868 Entire new Carb, replaces Briggs 498254, 497347, 497314, 498170 but the pics don't show the exact same linkage lever. I will rebuild it again this time.

I need a little help on the lapping thing. I've adjusted the valve lash on my JD tractor as it has adjusting nuts. But I've never got into any of my push mowers. They don't actually have adjusters do they ??

 

[EngineMan]

If the engine compression is good then leave the lapping for now, do the repair on the carb to see if that helps with the problem you have, lots of videos on youtube doing the valves if you need to do them.

 

[1RB2534]

My rebuild kit came in, I've cleaned the carb and put the new stuff in. I have two questions at this point.

1. What is the Round Tin Plate looking thing that's in the bottom of the carb (top of bowl area). It looks pressed in (?) and there's also one in the rebuild kit. I've never removed these before, is this something I should remove and check or clean behind it?

2. Also the Float Bowl attachment screw (which also looks like it feeds the high speed jets). The screw has a Tee type passage orifice. The horizontal passage is large enough to get a small pin in to clean it out. The vertical passage however is so small I cannot even get a needle through it. How do you guys clean this?

I did squirt some PBlaster in it and then blew it out with the compressor. Then I blew on it the vertical and I could feel air coming out the horizontals so I guess it's ok.

 

[Boudreaux In Eunice La.]

That round object you are talking about is a welch plug... No need to worry about that unless your carb is extremely dirty or corroded........

Yes the bowl nut is your main jet...... You can get a bread tie with the plastic taken off of it and get it thru that top hole.... Use carb spray instead of PB Blaster..... Wal Mart has carb spray for 1.75 a can.........

Take the seat out also and replace it as well.. A crochet hook works well... I snatched my wife's small one and it works perfect......

Put the new seat back in groove side down in the carb.... Flat side facing needle.....

 

[Boudreaux In Eunice La.]

Here's a video link in case you need it...........

https://youtu.be/kJfpTX2Lx0g

 

[1RB2534]

That round object you are talking about is a welch plug... No need to worry about that unless your carb is extremely dirty or corroded........

Yes the bowl nut is your main jet...... You can get a bread tie with the plastic taken off of it and get it thru that top hole.... Use carb spray instead of PB Blaster..... Wal Mart has carb spray for 1.75 a can.........

Take the seat out also and replace it as well.. A crochet hook works well... I snatched my wife's small one and it works perfect......

Put the new seat back in groove side down in the carb.... Flat side facing needle.....

Thanks! Now I know what that thing is. My carb was surprisingly clean for such an old engine so I won't bother removing it. I guess regular use tends to keep varnish residue down but the needle seat just wore out and was leaking. I surmise underneath the welch plug is just another orifice passage (?) and it's no longer needed on current carb applications?