Uggh...Thermoquad carb still leaking fuel. ---> FIXED!!!

[Super Blue 72]

Ok, so before winter I rebuilt the carb as on shut down, there was gas leaking out the passenger side of the carb from the primary shaft.  It was a pretty steady drip, drip, drip on shut down. 

What got me to looking for a carb issue at all was that my oil pressure dropped and I checked the oil level and it was a quart OVER and the oil smelled like gas and the oil was thinned out.  The car was also a hard restart due to the flooding of the engine due to the gas dripping into the intake manifold.

So, back like in October last year I rebuilt the carb but didn't set the float levels as the directions I had I thought the directions were for the plastic floats and wasn't clear on setting them so I let it fly and tossed the carb on the engine and started the car.

Same problem.    Leaking from the outside of the carb, on the passenger side, from the primary shaft.


Ok, so last night I pulled off the carb after reading up on the float stuff, set the float and tried to start the car and there was a lot of gas coming out of the same area.  The floats initially were set too high at 1 1/4 inches, spec is 1 inch so I lowered the floats which entails that MORE fuel is let into the carb.  My initial thought was maybe too much fuel was going in and the floats weren't closing the needle/seat assembly but I figured I should set it to spec.


So, carb still leaking. 

I was wondering maybe the passenger side O-ring is not sealing?  Is that a possibility?  I wonder if there is a defect either on the air horn or the body so there isn't a complete seal so it dumps fuel?

Has anyone heard of doing an extra gasket in this area?  There were 3 sets of O-rings in the kit:
-squared off (I installed those.)
-rounded O-ring
-flat O-ring

I have the squared off ones in there.  When I worked on it last night I reused all the same gaskets as I had just rebuilt the carb not long ago.  I didn't run the car since last November or so.

When I read the rebuild literature, it said on reassembly the airhorn may be slightly raised due to the O-rings and should the O-rings should be compressed when putting in the 10 body bolts.

Last night (I can't remember back at the last carb rebuild.) the airhorn was not raised up at all making me think the O-rings were not sealing/compressed?

Would it be a bad idea to use both the squared off AND the flat O-ring together?    Is this why the rebuild kit has both in there?  Anyone ever try this? 

I feel like trying this as this is making me do like this: 

Thanks for any input! 

[spamtank]

Bummer. 

Are you sure the needle valve is closing? 

[Bullitt-]

Had a similar problem on a rebuild a few years ago on a very low mile carb.  Didn't think I needed to replace the needle seats just put fresh needles in(the part the float pushes against) I discovered the new needles did not match the old seats, changed out the seats & problem solved.  The way I identified the problem was to hold the carb upside down & blow through the fuel line, I should not have been able to but there was no seal.
I have known of trash holding the needle open, sometimes a shot of compressed air trough the fuel line clears this out.
There is also the possibility that the wells that are glued on the bottom of the main body are leaking but I have never observed this issue on any of the many T/Qs I've rebuilt.
I'm sure you checked that your floats are good. 
The O-rings I would not think is the issue as they are in the very bottom of the body way below the fuel level but I could be wrong, never had a problem with them. 
Your not running an electric pump are you?

[Super Blue 72]

Thanks for the replies guys! 

Ok, here's my answers.

Needle and seat:  They are closing.  I took off the air horn and turned it upside down and I could not believe how tight a seal the needle and seat assemble made, no air could pass through.  These were replaced at the time of the rebuild, both matched needle and seat assemblies as matched new pairs.  I examined the rubber on the needles and they are clean with no scoring.  I was very gentle with the needle/seat assembly on install and handling them in the air horn.

Floats: as I thought that the problem could lie there, I submerged both floats under water for 45 minutes and when I took the cover off the glass they were in, they both shot up at me so they had pretty good buoyancy.  They are brass floats.  I heard the plastic ones leak after a while, so I've heard.  I dunno.

Main Phenolic body: I examined the glued on bottom parts of the main body and the epoxy there appeared intact.

Fuel pump:  Running stock mechanical fuel pump.

Where is the shut off to relieve pressure when the needle seat assemblies close off the flow of fuel? I assume it is in the pump. 

Is it possible that relief valve is bad and it is able to push past the closed needle seat assembly? 

I'm thinking my plan of attack is this:

1) disassemble carb and fill main wells with water to see if glued portions on the bottom of the bowl are leaking or if there is a crack somewhere.  While the carb is out I may just do a skim coat of epoxy just for safety but the way the carb was leaking it'll be pretty evident if there is a leak there if I fill the main bowls with water.

2) take a straight edge and check for warping of the phenolic body/base plate.

3) double up the O-rings in the body and see if it raises up the air horn too much or if ok then check for compressibility of both O-rings if it doesn't look too high with double O-rings.

I guess I'm leary of the O-rings.   

We'll see once I get a chance to take it apart again...

Thanks guys!

[Super Blue 72]

I found some interesting links to leaking TQs.

This one suspect the glued area and how ethanol is attacking the glue.  They think that replacing the TQ with another type of carb is the cure.

http://www.dodgecharger.com/forum/index.php?topic=63067.0

Going to read this.  They mention about the O-rings in this link.  Good pics here too.

http://www.offroadexchange.com/tquad.htm

[Bullitt-]

One other issue I just thought of I had many years ago.. Someone gave me a T/Q which I rebuilt & could not get to run right, very rich. I don't know that it was leaking fuel but what I found was the tab on the floats had been bent in. It took me looking at another carb to realize this. The proper place to bend/adjust the float is right behind the floaty part. Someone had bent or smashed these down & I reasoned that they were acting as being set much higher. Once I made the tabs like the others then re-adjusted the float height she ran fine.

Here's a pic of correct floats

[Bullitt-]

I found some interesting links to leaking TQs.

This one suspect the glued area and how ethanol is attacking the glue.  They think that replacing the TQ with another type of carb is the cure.

http://www.dodgecharger.com/forum/index.php?topic=63067.0

Going to read this.  They mention about the O-rings in this link.  Good pics here too.

http://www.offroadexchange.com/tquad.htm

I'm staying away from ethanol   

[Super Blue 72]

Thanks Bullitt, much appreciated. I did bent on the arm itself, not the little tang, although that was my initial inclination. 

Yeah, ethanol is a BAD thing!!!! 

Weird, I thought you are supposed to measure the float level at the highest point of the float?  It looks like you are measuring at the end.

I cannot remember what my floats look like but I think they look a little different.  I don't remember that little step.  I think mine looked more rectangular than yours.


When I was thinking out the issues, as far as the floats go, if I am thinking of the float levels with the carb right side up as it sits on the engine, I would have thought that I should lower the floats if there is a flooding issue, making the assumption that the floats are not closing the needle/seat assemblies.  BUT- after I did the adjustment, it actually raised the level of the floats so as to let more fuel in the fuel bowls.

It could be my imagination but it did look like the carb was leaning worse than before.  I better reexamine the float adjustment!

I think I have to take a step back and use some logic looking at this carb and not be so afraid of it and just dig in to what I think might work.  After reading some other links I'm  going to do all the things I mentioned before.

Thanks! 

[Bullitt-]

Well if you give up send it to me & I'll see what I can do for it.  I have a few spare parts carbs.

[cudabob496]

My 1972 service manual says possible causes for leaking fuel:

Cracked body
Faulty body gaskets
High float level
Worn needle valve and seat
Excessive fuel pump pressure

[Super Blue 72]

Well if you give up send it to me & I'll see what I can do for it.  I have a few spare parts carbs.

Thanks for the kind offer, Bullitt.  Much appreciated.  It's nice weather out so I might try to yank off the carb before going to work.  Thanks again! 


Hi cudabob, thanks for the info!    I'll look into all those things.

Interesting with the excessive fuel pressure idea.  I was wondering that, that's why I was wondering where the shut off for the pressure is in the pump.


When I take it apart I'll take pics of the air horn and the float levels.  Maybe I'm setting the float level wrong. 


Thanks guys! 

[Super Blue 72]

Yanked the carb off the engine before the wife got home, whew!  Working on car=doghouse! 

  I'll see if I can take it apart in the basement when everyone goes to sleep...   

[cudabob496]

Yanked the carb off the engine before the wife got home, whew!  Working on car=doghouse! 

  I'll see if I can take it apart in the basement when everyone goes to sleep... 

Wife #1, Car #2, or life painful!

[spamtank]

Yanked the carb off the engine before the wife got home, whew!  Working on car=doghouse! 

  I'll see if I can take it apart in the basement when everyone goes to sleep... 

You know, gas is like perfume.  If it doesn't match the wife's scent, you got some spalinin to do....   

[cudabob496]

I've heard of guys rebuilding their engines in the living room.
Of course, they were not married!