Leaking Throttle Shaft.

[exister99]

A couple of years ago I replaced the original carburetor on my '84 GL with one I got at a junk yard and rebuilt. I was pretty happy with the results and the thing ran like a champ for the last two years. The original carb was still working when I removed it but was coated with a grimy film from leaking fuel mixing with dirt and gunk.

 

Then a few weeks ago my junkyard carb lost one of the screws on its choke linkage and the electric choke heater plate worked its way loose from the rivets. The engine was idling ridiculously rich before I pinpointed the problem and shut the whole works down.

 

This past weekend I decided to do a complete rebuild of the original carb. I took it all apart Satruday and soaked the big parts in degreaser overnight. Then on Sunday I carefuly and tediously put the whole thing back together. While I was reassembling I noticed that the throttle shafts were a little loose due to some clearance that had been worn between them and the throttle body.

 

When I was done rebuilding I put the carb back in and correctly reconnected everything. I noticed the lower tube on the vacuum switching valve was broken. This is the tube that comes from the thermo switch that is supposed to open when the engine warms up. Once this happens the vacuum switching valve opens up and vents the carburetor's bowl, I think?

 

Anyhow, multiple attempts at starting up the Soob were unsuccessful. I took a peek at the sight hole on the side of the bowl and the fuel level is just above the center mark, which seems fine considering the car is not running.

 

After my multiple attempts at starting I noticed fuel leaking from around the loose throttle shafts. So my question is, can loose throttle shafts be to blame for my engine not starting? The engine started just before the rebuild so I doubt it is a spark problem as I haven't messed with any of the electrical stuff. Has anyone else here had an engine that would not start due to loose throttle shafts.

 

My current theory is that when I soaked the throttle body in degreaser I cleaned out whatever gunk was stuck in that bit of clearance between the throttle shafts and the throttle body and created a great big air/fuel leak. Since the throttle shafts are below the venturis the engine is probably sucking air around the loose throttle shafts and not sucking enough fuel through the venturis, which then makes it unable to start.

 

Alternative theory number 1 is that the broken vacuum switching valve is to blame, but my understanding of those vacuum lines is that they usually impact idleing and running conditions, but shouldn't really cause a no start condition.

 

Alternative theory number 2 is that the rich running melted my catalytic converter, which is now clogging my exhaust. The whole business was running when I shut it off to remove the carb though, so I don't see how the condition of the catalytic converter could have changed since then.

 

So, my main question is: have you ever had a car the would not start because of leaky throttle shafts? Any comments or answers to my other theories are also appreciated.

[jacobs]

My previous experience with other brands of carburetors on American manufactured vehicles is when you have gasoline leaking out of the throttle shafts you have way too much fuel. This can be caused by over choking, too high fuel level in the carburetor or sticking/leaking needle valve. The bottom line is your engine is flooded!

[exister99]

Thanks for the input.

 

I adjusted the float according the rebuild specs and the needle valve assembly is new. The choke is also adjusted exactly where it should be.

 

My previous experience with other brands of carburetors on American manufactured vehicles is when you have gasoline leaking out of the throttle shafts you have way too much fuel. This can be caused by over choking, too high fuel level in the carburetor or sticking/leaking needle valve. The bottom line is your engine is flooded!

[jacobs]

You might check your float. I can't remember if the Subaru float is brass or plastic but if they are plastic, they can become saturated with fuel thus raising the fuel level in the bowl. I've never seen a brass float leak but it is possible.

[exister99]

When I did the rebuild the old plastic float was pretty discolored so I put in a cleaner looking one from another junkyard carb. I would not be surprised if it is leaky. Another thing I noticed was fuel on the top of the throttle body at the same height as the lip of the bowl. There is that little jet you can see if you look down the secondary barrel and there was fuel all over there. I doubt that is normal as the only place fuel is supposed to come out is down in the venturi assembly, right?

 

I think I will go to Napa and order a brass float, part number CRB2498, and install that.

 

You might check your float. I can't remember if the Subaru float is brass or plastic but if they are plastic, they can become saturated with fuel thus raising the fuel level in the bowl. I've never seen a brass float leak but it is possible.

[jacobs]

When I did the rebuild the old plastic float was pretty discolored so I put in a cleaner looking one from another junkyard carb. I would not be surprised if it is leaky. Another thing I noticed was fuel on the top of the throttle body at the same height as the lip of the bowl. There is that little jet you can see if you look down the secondary barrel and there was fuel all over there. I doubt that is normal as the only place fuel is supposed to come out is down in the venturi assembly, right?

 

I think I will go to Napa and order a brass float, part number CRB2498, and install that.

 

Yes, you are correct in that the only place fuel is supposed to exit is from the venturi. When you have the option, always use a brass float. It's easy to tell if a brass float is ok - not as easy for a plastic float. The only way to check a plastic float is to compare weights to a known good one.

[exister99]

Just out of curiosity, what is the correct way to check a brass float for leaks and why does that technique not work on a plastic float?

 

I think I will go ahead and get two of the brass floats and use them to retrofit my fleet of backup carbs.

 

Yes, you are correct in that the only place fuel is supposed to exit is from the venturi. When you have the option, always use a brass float. It's easy to tell if a brass float is ok - not as easy for a plastic float. The only way to check a plastic float is to compare weights to a known good one.

[jacobs]

Just out of curiosity, what is the correct way to check a brass float for leaks and why does that technique not work on a plastic float?

 

You can shake a brass float and tell if there's fuel in it. A plastic float is just foam and when the small voids fill with fuel, because there's so many little voids, it doesn't slosh around. The brass float has just one big void inside.

[Subarian]

Yeah, the only way to know if a plastic float is bad is to weigh it. Back in the old days we used to put our Quadrajet plastic floats in the over for a couple of hours to dry them out, but it tends to stink up the house and it's only a temporary fix.

 

Brass floats almost never leak. About the only way to get them to leak is to mishandle them when they're out of the car.

 

I agree that you shouldn't be seeing any fuel leaking around the throttle plate shafts. If they're loose, you might have some idle problems, but there definitely shouldn't be any fuel.

 

One other piece of free advice: If you've been trying for a long time to start this car, check to see if your oil smells like gas. I had a problem with an engine starting after a rebuild (it was a leaking carb), and when I finally got it running, it ran for about 100 miles before I spun a bearing.

[jacobs]

Yeah, the only way to know if a plastic float is bad is to weigh it. Back in the old days we used to put our Quadrajet plastic floats in the over for a couple of hours to dry them out, but it tends to stink up the house and it's only a temporary fix.

QUOTE]

This is out of place in a Subaru forum BUT it's easy to tell if a Quadrajet float is bad - set the float (right side up) on a flat surface. If it falls over from the weight of the arm, it's ok. If it doesn't fall over it's bad.

[exister99]

Thanks for the free advice Subarian. I checked the oil after the rich running condition and it looked good. Once I get this carb situation straightened out I will check it again and make sure it is still good and thick and doesn't smell of fuel. I'll probably top it off with some 20W50 too for good measure.

 

I haven't actually run the engine yet with this flooding carb, and I won't try to start it anymore until I get the carb swapped out. Hopefully, letting it sit these couple of days will allow any fuel in the intake manifold and cylinders to evaporate.

 

Yeah, the only way to know if a plastic float is bad is to weigh it. Back in the old days we used to put our Quadrajet plastic floats in the over for a couple of hours to dry them out, but it tends to stink up the house and it's only a temporary fix.

 

Brass floats almost never leak. About the only way to get them to leak is to mishandle them when they're out of the car.

 

I agree that you shouldn't be seeing any fuel leaking around the throttle plate shafts. If they're loose, you might have some idle problems, but there definitely shouldn't be any fuel.

 

One other piece of free advice: If you've been trying for a long time to start this car, check to see if your oil smells like gas. I had a problem with an engine starting after a rebuild (it was a leaking carb), and when I finally got it running, it ran for about 100 miles before I spun a bearing.

[Subarian]

Experience is a hard teacher. Of course, getting my son to understand that is another topic...

 

That happened to me in an Olds 455 conversion I did in a car I built. The saddest part was that I did it in the middle of winter, and I had no garage, so I built the engine in my kitchen. It was a sad day.

 

Good luck to you.

[exister99]

Yeah, good times. I once had a VW engine on a stand next to my bed in a studio apartment. I was kind enough to lay down a piece of plywood and a plastic sheet to spare the carpet.

 

Olds 455 huh? I had one of those monstrosities when I was 17. Drove it 'til the transmission went bad. That was when I discovered that you can limp a shot auto tranny to the junkyard by starting in D1 and shifting it like a manual.

 

Experience is a hard teacher. Of course, getting my son to understand that is another topic...

 

That happened to me in an Olds 455 conversion I did in a car I built. The saddest part was that I did it in the middle of winter, and I had no garage, so I built the engine in my kitchen. It was a sad day.

 

Good luck to you.

[jacobs]

Experience is a hard teacher. Of course, getting my son to understand that is another topic...

 

That happened to me in an Olds 455 conversion I did in a car I built. The saddest part was that I did it in the middle of winter, and I had no garage, so I built the engine in my kitchen. It was a sad day.

 

Good luck to you.

 

Why? Is it still in the kitchen?

[Subarian]

Huh? It was originally built in the kitchen, then rebuilt in the kitchen. It was (past tense) a sad day. It was a really fun day when it finally got back in.

[jacobs]

I once built a small block Chevy shortblock in the livingroom of a 2nd floor apartment - boy was that fun getting it out of there. I can't imagine moving a 455 without a hoist!

[paulpicard]

Getting back to the thread, when I rebuilt my Hitachi (84 wagon) I plugged one of the two vents on top of the carb in ignorance. Turned out to be some kind of (1) auxiliary bowl vent, or (2) an air bleed. What ever, plugging it caused big-time flooding, and once flooded, wouldn't start for days. There are actually 2 vent-type tubes and they both have very small orifices (.020" I think) The hoses connected to them each led to a vacuum-controlled round black thingy which contained the orifices and opened or closed according to vacuum or lack of. I vented both to atmosphere with a brass plug drilled to .040 in each hose. Solved the rich problem but now have a lean stumble except at full throttle. I still don't know which vent needs to be controlled which way,, and I lost one of the black plastic thingies anyway. Oh, by the way, a dishwasher is great for cleaning engine parts - did my Suzuki 850 that way. (Of course, there were no women living in the house at the time)

[exister99]

Funny you should mention that. While installing the carburetor I snapped off the lower vacuum tube from the round vacuum switching valve that vents the carburetor bowl. I managed to find the part number for the broken valve: 461057000. The cheapest I could find it was at 1stsubaru.com for $126.72. Seems like a lot for a little plastic doohickey.

 

Since this part seems to be critical for proper carburetor operation can I get some suggestions for repairing or replacing it cheaply? Seems like a pretty simple switch with only 2 tubes going into it. Is there a cheaper, newer valve that can be used? Is there a reliable way to reattach to the snapped tube?

 

Thanks for any input.

 

 

Getting back to the thread, when I rebuilt my Hitachi (84 wagon) I plugged one of the two vents on top of the carb in ignorance. Turned out to be some kind of (1) auxiliary bowl vent, or (2) an air bleed. What ever, plugging it caused big-time flooding, and once flooded, wouldn't start for days. There are actually 2 vent-type tubes and they both have very small orifices (.020" I think) The hoses connected to them each led to a vacuum-controlled round black thingy which contained the orifices and opened or closed according to vacuum or lack of. I vented both to atmosphere with a brass plug drilled to .040 in each hose. Solved the rich problem but now have a lean stumble except at full throttle. I still don't know which vent needs to be controlled which way,, and I lost one of the black plastic thingies anyway. Oh, by the way, a dishwasher is great for cleaning engine parts - did my Suzuki 850 that way. (Of course, there were no women living in the house at the time)

[exister99]

I know you are all just dying for an update.

 

I resolved the loose choke plate issue on the previous carburetor by replacing the screw that had fallen off the shaft and resecuring the electric choke pulloff using 2 #8 bolts in place of the rivets.

 

I got this carb back on the wagon and tried to start it with no success. I pulled the spark plugs and not only were they all wet, but they were also covered in black gunk from the rich running condition. I brushed them all off with a tooth brush and blew them dry with my compressor. Put them back in. Tried to start, and it almost coughed to life before going back to nothing. Any suggestions on getting the plugs squeaky clean?

 

I pulled the plugs again and the plugs from cylinders 1 and 3 were dry, but the ones from cylinders 2 and 4 were soaked. I shone a light into cylinders 2 and 4 and could see standing liquid fuel, so I threaded a rubber tube into each cylinder and blasted it out with compressed air. Cylinders 2 and 4 visibly erupted with liquid fuel, but not much came out of 1 and 3.

 

My plan is to leave the spark plug holes open for a couple of days to let the cylinders dry out. Anybody know of a better way to dry this thing out? I have been down for a month now so if you all know of anything else I should be considering let me know. My theory is that the plugs got all fouled up when the choke originally broke and started running rich. After that all of my attempts to start the engine led to a vicious cycle of dumping more and more fuel into the cylinders, which just increased the flooding. Does this theory make sense?

 

Oh, and I will defenitely be swapping the oil out as soon as I get this whole flooding mess sorted out.

 

Thanks...