Jump to content

Q-Jet Fuel Leak at Filter Boss Welch Plug


EmTee
 Share

Recommended Posts

Goldie had been laid-up for about 3 weeks while I worked in a "as time allows" manner to overhaul her hydraulic brake system (new hoses and wheel cylinders).  Once I finally had everything back together and was ready to road-test it yesterday I twisted the key and cranked the engine for about 30 seconds with no sign of life.  OK, that's not really unusual if she's been sitting idle for a couple of weeks or more, so I waited a few seconds and tried again.  Still nothing...  Hmmm, not good.  So I grabbed the gas can and removed the air cleaner.  I dribbled a little gas into the primary throttle bores and tried again.  It immediately fired and then stalled.  I dribbled some more gas and it started and was running at fast idle.  As I turned back around ready to drop the air cleaner base into position i see fuel pouring out onto the manifold from the Welch plug in the fuel filter housing (ref. the picture of a similar Q-Jet below).

 

IMG_4833.JPG.14ecd6515d4cfcd6ee7b26ce590

 

I shut-off the engine and processed what just happened...  As I stared at the plug, I could see where someone had smeared epoxy over the plug, but oddly the seam where the plug meets the fuel filter boss was 90% free of any epoxy.  I filed off most of the epoxy on the plug surface in an attempt to figure out why the epoxy was there in the first place.  I removed most of the epoxy, leaving a thin layer in the recessed part of the plug (ref. above).  Not knowing how I'd go about finding a replacement plug, I figured I'd try tapping it around the circumference with my small ball peen hammer.  If that failed, plan B was going to be to add new JB Weld over the plug and the mating interface.

 

As it turned out, just tapping the plug (i.e., re-seating it into the filter housing) stopped the leak and it's still holding following about a 30-mile trip today.  Is there something more i can/should do about this?  Can I get a new Welch plug anywhere?  Any thoughts or information would be appreciated.

Link to comment
Share on other sites

A mechanic that I know uses some kind of epoxy on every plug on every Q-jet that he rebuilds. It’s a factory flaw and I’ve never heard of any other way of fixing it. Perhaps someone knows of a better fix.

  • Thanks 1
Link to comment
Share on other sites

1 hour ago, EmTee said:

Goldie had been laid-up for about 3 weeks while I worked in a "as time allows" manner to overhaul her hydraulic brake system (new hoses and wheel cylinders).  Once I finally had everything back together and was ready to road-test it yesterday I twisted the key and cranked the engine for about 30 seconds with no sign of life.  OK, that's not really unusual if she's been sitting idle for a couple of weeks or more, so I waited a few seconds and tried again.  Still nothing...  Hmmm, not good.  So I grabbed the gas can and removed the air cleaner.  I dribbled a little gas into the primary throttle bores and tried again.  It immediately fired and then stalled.  I dribbled some more gas and it started and was running at fast idle.  As I turned back around ready to drop the air cleaner base into position i see fuel pouring out onto the manifold from the Welch plug in the fuel filter housing (ref. the picture of a similar Q-Jet below).

 

IMG_4833.JPG.14ecd6515d4cfcd6ee7b26ce590

 

I shut-off the engine and processed what just happened...  As I stared at the plug, I could see where someone had smeared epoxy over the plug, but oddly the seam where the plug meets the fuel filter boss was 90% free of any epoxy.  I filed off most of the epoxy on the plug surface in an attempt to figure out why the epoxy was there in the first place.  I removed most of the epoxy, leaving a thin layer in the recessed part of the plug (ref. above).  Not knowing how I'd go about finding a replacement plug, I figured I'd try tapping it around the circumference with my small ball peen hammer.  If that failed, plan B was going to be to add new JB Weld over the plug and the mating interface.

 

As it turned out, just tapping the plug (i.e., re-seating it into the filter housing) stopped the leak and it's still holding following about a 30-mile trip today.  Is there something more i can/should do about this?  Can I get a new Welch plug anywhere?  Any thoughts or information would be appreciated.

  This was a problem on the first version `66 carbs and GM came out with a campaign which targeted Buick and Chevrolet applications to remedy the problem. I thought they had this ironed out for the `67 models? Yours is a `67 version, correct?

  The campaign is basically a bracket which secures under one of the top cover screws and physically butts up against the welch plug to prevent it from blowing out.

  I`ll see if I can find a picture of the kit.

Tom Mooney

quadrajet campaign 1.jpg

quadrajet campaign 2.jpg

Edited by 1965rivgs (see edit history)
  • Like 2
Link to comment
Share on other sites

13 minutes ago, 1965rivgs said:

Yours is a `67 version, correct?

 

Yes, but an early build '67.  Thanks for the info and pictures!  I could replicate that device when the problem reoccurs.  ;)

Link to comment
Share on other sites

1 hour ago, JZRIV said:

For now I'd apply some JB weld over the plug.

 

Yup, that's what i was thinking.  I'll clean and scuff the area around the circumference and apply epoxy.  That'll probably be enough to keep it in place (at least for now).  The thing that has me scratching my head is that a previous repair just had the epoxy on top of the plug -- virtually nothing bridging the interface between the plug and the filter casting...

Link to comment
Share on other sites

I applied some 2-part epoxy around the circumference of the plug.  I think it should be OK, but I'll keep an eye on it...  ;)

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...