use a rubber mallet
not a metal hammer (if possible)
hit the medium section of the body close to the floats
Zenith Carbs Massive Flooding
- Thread starter Vintage56
- Start date
use a rubber mallet
not a metal hammer (if possible)
hit the medium section of the body close to the floats
Vintage56
Active Member
OK, got it. So I take it then that the top of the carb needs to come off to trim the gasket?
Vintage56
Active Member
Vintage56
Active Member
Hello All....I am happy to report that the car is running like its old self again. No flooding. I loosened all of the top screws on each carb and tapped the middle of the carb by the float area with a rubber mallet and then went to start her up. She turned over immediately, ran and didn't flood! Thanks all...
Now, I am in need of a diagram or photo on how to set the idle mixture and idle speed. Appreciate it if that diagram showing the location of each screw could be posted.
Thanks again...Great forum!!
Now, I am in need of a diagram or photo on how to set the idle mixture and idle speed. Appreciate it if that diagram showing the location of each screw could be posted.
Thanks again...Great forum!!
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This would bother me - not knowing if it is fixed and won't happen again. Being such a critical/dangerous occurence, I would pull the covers and inspect the floats and needle valves. My $.02
Vintage56
Active Member
Thanks @Stevehose for your advice and suggestions. I plan to do that today.
Vintage56
Active Member
Before I start opening up the top of a carb I've never worked on, I plan to do this with the carbs still on the engine.
Will I need:
1. a new set of gaskets on hand to put it back together?
2. to just remove 7-8 screws release the top of the carb or will something else need to be disconnected?
3. to worry about anything dropping from the top cover when I get the top separated? (ie, will anything be free-floating and potentially drop out of the top cover)?
When it is all checked out and ready to be put back together, will any pieces (ie, the float, etc) need to be positioned in some manner to get the top to meet the middle section of the carb body?
Thanks for any guidance. I'd rather be prepared for what to expect than be surprised by what I didn't.
Will I need:
1. a new set of gaskets on hand to put it back together?
2. to just remove 7-8 screws release the top of the carb or will something else need to be disconnected?
3. to worry about anything dropping from the top cover when I get the top separated? (ie, will anything be free-floating and potentially drop out of the top cover)?
When it is all checked out and ready to be put back together, will any pieces (ie, the float, etc) need to be positioned in some manner to get the top to meet the middle section of the carb body?
Thanks for any guidance. I'd rather be prepared for what to expect than be surprised by what I didn't.
Based on the amount of dirt you found in the carb throats and bodies and the serious nature if the fuel leak happened again, I'd take this opportunity to remove, disassemble, clean and rebuild the carbs or have them rebuilt.
Should also replace the fuel filter and perhaps pull the sender , check the screen and take a peek in the gas tank to check for rust and debris
Vintage56
Active Member
Thanks Dick. I did these items today. All appeared to have no issues.
Are there also inlet filters into each Zenith carb and are these filters renewable or replaced?
Are there also inlet filters into each Zenith carb and are these filters renewable or replaced?
No inlet filters but the advice on new filter and sender/tank inspection is good.
Vintage56
Active Member
jmackro
Well-Known Member
You have gotten good advice in this thread. It's is probably one of two things: a stuck float/valve or a bad fuel line (split line or leaking connection) , but more investigation will be needed at your end to pinpoint the source of the leak; people who have never laid hands on your car can't narrow it down any further.
The hammer is a nice diagnostic tool, but it won't fix anything. E.g., if tapping a carb stops the leak, it may start leaking again tomorrow or next week because the debris will still be in there.
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Vintage56
Active Member
I understand. More work to do.
Thanks for all of the wonderful input, advice and feedback.
Sal
I'll add my own two bits to your story.
Trying to run down a poor running issue, I took my Zeniths apart, cleaned them, and installed new gaskets. The car ran well during the next few months but I didn't drive it much because I was packing and then moving to Texas. After arrival, I'd start it up every once in a while to keep things circulating and one time I smelled a lot of gas. I hopped out and found a large flow of gas coming from the air cleaner pouring onto the ground, while the engine continued to idle. I shut it off quickly and did some research here where I got some of the same answers as in the posts above. For me, it was the float hanging up on the carb gasket in one carb.
You'd think it would have happened right after the rebuild, but no, it probably happened after the bowls dried out from sitting and the float edge seam fell below the level of the gasket, combined with the slight sideways and backward slope of my driveway.
Varnish and dirt can be cleaned with a spray can of carb cleaner in situ, but that's not very thorough or efficient. I opted for taking the carbs out and apart. I cleaned the parts in a bath of Simple Green solution rather than a dip can of carb cleaner like I'd used in the past. It worked fine, just don't leave the parts in overnight, it will discolor them a bit.
Since your car has shown that it can create a gas flood once, it won't be safe to drive until you at least take the top off the carb and put in new, trimmed gaskets.
Ian
Trying to run down a poor running issue, I took my Zeniths apart, cleaned them, and installed new gaskets. The car ran well during the next few months but I didn't drive it much because I was packing and then moving to Texas. After arrival, I'd start it up every once in a while to keep things circulating and one time I smelled a lot of gas. I hopped out and found a large flow of gas coming from the air cleaner pouring onto the ground, while the engine continued to idle. I shut it off quickly and did some research here where I got some of the same answers as in the posts above. For me, it was the float hanging up on the carb gasket in one carb.
You'd think it would have happened right after the rebuild, but no, it probably happened after the bowls dried out from sitting and the float edge seam fell below the level of the gasket, combined with the slight sideways and backward slope of my driveway.
Varnish and dirt can be cleaned with a spray can of carb cleaner in situ, but that's not very thorough or efficient. I opted for taking the carbs out and apart. I cleaned the parts in a bath of Simple Green solution rather than a dip can of carb cleaner like I'd used in the past. It worked fine, just don't leave the parts in overnight, it will discolor them a bit.
Since your car has shown that it can create a gas flood once, it won't be safe to drive until you at least take the top off the carb and put in new, trimmed gaskets.
Ian
Vintage56
Active Member
Thanks @mulberryworks for your insights. I think we are on the same page. Either the float was hung up due to debris that resettled into a new home or a few passage ways where air is provided and were clogged or both. I think the car sitting or being used sparingly is the real issue. The question on my mind besides the obvious float symptoms is to try to learn about the flows of gas and air in and through the carbs (I am completely new to Zeniths). I believe some of those pathways of air from outside at the top of the carbs may be partially blocked. But it's just a theory. I tried to get to each one with a dip of carb cleaner, sewing needles, and q-tips. I removed the 2 jets at the top of each carb and soaked them in carb cleaner. At least 2 were clogged. I kept asking myself: where is all this soot coming from???
In the past, I have seen flooding happen with Holly and Weber carbs. In my experience, in more than a few instances, it was a clogged PVC valve that an overnight bath in gasoline and/or carb cleaner cured. I assume there is NO PCV VALVE on a 1971 3.0CS engine. Please confirm. (FYI......This is a EURO version of the 3.0cs so I am not sure it has much if any emission controls that the USA delivered cars had. But I could be wrong about this as I am new to BMW's of this era).
But I also thought, is there a possible emission control subsystem that may be clogged that would cause such a massive flood? A vent, a valve? Keep in mind the engine was still running and responded by increasing idle speed when the accelerator was depressed. So, I am thinking perhaps wrongly that the issue is a parallel system of gas/air flow that is blocked or narrowed. This subsystem dumped gas in massive quantity. It also seemed to worsen as the engine heat increased. That's when I noticed the problem and dripping gasoline everywhere. THE CAR WAS STILL RUNNING. I have never seen that before.....
i would like to insist in the fact that more than the debris inside the reservoir of the float, it is more relevant the gasket that protrudes on both sides of the float.
you have to check the gaskets and trim them so they can rest flat to the walls of the reservoir avoiding the chance of the float get stuck on them
here you are the two critical points of the gasket, make sure that you trim the excess...
Vintage56
Active Member
Thank you @deQuincey for the advice and the photos! Photos always help. I will do this next.
So therefore:
1. There is no PVC Valve on an E9 Euro engine from 1971? Correct?
2. There are no emission control pieces, hoses, recirculating subsystems that could cause such a condition?
3. There are no other vents for air to enter the carbs from the outside that I should pay attention to in addition to the 4 jets exposed to atmosphere?
Thanks to everyone for their wonderful advice and suggestions.
So therefore:
1. There is no PVC Valve on an E9 Euro engine from 1971? Correct?
2. There are no emission control pieces, hoses, recirculating subsystems that could cause such a condition?
3. There are no other vents for air to enter the carbs from the outside that I should pay attention to in addition to the 4 jets exposed to atmosphere?
Thanks to everyone for their wonderful advice and suggestions.
1. No
2. No
3. There is a small hole on the top of the carbs used to vent the idle mixture screw, even if this is plugged I seriously doubt it would cause your issue but check it anyway.
2. No
3. There is a small hole on the top of the carbs used to vent the idle mixture screw, even if this is plugged I seriously doubt it would cause your issue but check it anyway.