"Flood Control" - 71 Super Beetle Convertible

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vwlover77
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"Flood Control" - 71 Super Beetle Convertible

Post by vwlover77 » Wed Aug 02, 2017 7:43 pm

I finally got fed up with my 34PICT-3 carb flooding after "heat soaking". I recently pulled the top off the carburetor about an hour after a long drive on a warm day and the bowl was completely empty! I'm sure some of the gas just evaporates but some also percolates through the circuits into the carb throat. Enough to make the subsequent warm restart an embarrassing fiasco of lengthy cranking while slowly flooring the gas pedal followed by sputtering idle, copious engine revving, and that lovely rich exhaust smell - sometimes even a small cloud.

My suspicion was that the engine heat just had nowhere to go. As a convertible, the only air vents are the 4 on the decklid. There's no vents under the rear window like the sedan has, so no opportunity to get cool airflow in through the decklid and out through the top of the engine compartment.

I now have a "forced air" system to get the heat out. I bought a 12v low-profile fan and 12v thermostat control from Amazon . Total investment less than $20. I cut a hole in the decklid behind the license plate to mount the fan and mounted the controller on the firewall in front of the fan shroud on the right side of the engine compartment. The fan is completely hidden by the license plate - you'd never know it was there. I put the temp sensor that came with the controller in an unused carb drilling and packed around it with aluminum foil to keep it in place and conduct carb heat to it.. I wired everything up and set the thermostat for around 110 degrees F. About 15 minutes after shutting down the car on a mid-80s day, the fan comes on and cycles on and off for the next 60 to 90 minutes until the heat is gone. The temperature never gets above around 120 degreea.

The result? The restart after a hot drive is a thing of beauty. Crank the engine for a few seconds with NO throttle needed and it fires right up to a smooth idle and is ready to go! :cheers:

Fan: (4 3/4" diameter)
Image

Controller: (Display is degrees Centigrade only)
Image

Sensor:
Image
Don

---------------------------
78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by Amskeptic » Wed Aug 02, 2017 9:20 pm

vwlover77 wrote:
Wed Aug 02, 2017 7:43 pm
I finally got fed up with my 34PICT-3 carb flooding after "heat soaking".
I now have a "forced air" system to get the heat out.
The result? The restart after a hot drive is a thing of beauty.
Wow. Really really a thing of beauty?
The float bowl was empty????? How could it do that?
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . .199,735 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by vwlover77 » Thu Aug 03, 2017 4:29 am

Is there nothing more beautiful than an air-cooled VW engine coming to life with but a mere touch of the key?

My only theory on the fuel bowl is that today's ethanol blend gasoline evaporates and percolates very easily. Heat the carb up to 180-200 degrees for a while and it escapes, apparently!
Don

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"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by Amskeptic » Fri Aug 04, 2017 8:56 am

vwlover77 wrote:
Thu Aug 03, 2017 4:29 am

My only theory on the fuel bowl is that today's ethanol blend gasoline evaporates and percolates very easily. Heat the carb up to 180-200 degrees for a while and it escapes, apparently!

So rather than flooded hard starts requiring accelerator to the floor, I have been merely refilling up the float bowl with these extended cranking events?
I need to test that.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . .199,735 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by wcfvw69 » Fri Aug 04, 2017 9:28 am

IDK, I think there's an underlying issue here that hasn't been discovered with the carb or fuel pump. I can drive any of my bone stock VW's in 95 degree temps down the freeway to do an errand. I then shut them down to go inside a store, come back 15 minutes later and they all restart very quickly. The carbs are original German Solex's that have been rebuilt with new throttle shaft bushings. The fuel pumps are restored Pierburgs with two of them being the square tops with the fuel shut off tops in them. My 69 convertible only has the two rows of vents in the lid.

As Colin stated, I don't understand where the fuel is going from the fuel bowl in such a short time frame. I've seen some some German Solex 34-3's with corrosion in the fuel bowl. They would weep fuel out that back on them from a tiny hole in the corrosion area of the fuel bowl area.

It would have been interesting for you to have installed say a Volksbitz restored German Solex 34-3 carb and see how that effected your hard start situation and if the fuel bowl stayed full after shut down and heat soak.
1970 Westfalia bus. Stock 1776 dual port type 1 engine. Restored German Solex 34-3. Restored 205Q distributor, restored to factory appearance engine.

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by Amskeptic » Sun Aug 06, 2017 7:36 pm

wcfvw69 wrote:
Fri Aug 04, 2017 9:28 am
IDK, I think there's an underlying issue here that hasn't been discovered with the carb or fuel pump. I can drive any of my bone stock VW's in 95 degree temps down the freeway to do an errand. I then shut them down to go inside a store, come back 15 minutes later and they all restart very quickly. The carbs are original German Solex's that have been rebuilt with new throttle shaft bushings. The fuel pumps are restored Pierburgs with two of them being the square tops with the fuel shut off tops in them. My 69 convertible only has the two rows of vents in the lid.

As Colin stated, I don't understand where the fuel is going from the fuel bowl in such a short time frame. I've seen some some German Solex 34-3's with corrosion in the fuel bowl. They would weep fuel out that back on them from a tiny hole in the corrosion area of the fuel bowl area.

It would have been interesting for you to have installed say a Volksbitz restored German Solex 34-3 carb and see how that effected your hard start situation and if the fuel bowl stayed full after shut down and heat soak.

I tested the theory of "no fuel in the bowl". Oh no no no, I damn close to flooded it. It has been starting very well in the 100* + heat, however there is some additional cranking as written about in the owner's manual.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . .199,735 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by wcfvw69 » Mon Aug 07, 2017 11:33 am

Amskeptic wrote:
Sun Aug 06, 2017 7:36 pm
wcfvw69 wrote:
Fri Aug 04, 2017 9:28 am
IDK, I think there's an underlying issue here that hasn't been discovered with the carb or fuel pump. I can drive any of my bone stock VW's in 95 degree temps down the freeway to do an errand. I then shut them down to go inside a store, come back 15 minutes later and they all restart very quickly. The carbs are original German Solex's that have been rebuilt with new throttle shaft bushings. The fuel pumps are restored Pierburgs with two of them being the square tops with the fuel shut off tops in them. My 69 convertible only has the two rows of vents in the lid.

As Colin stated, I don't understand where the fuel is going from the fuel bowl in such a short time frame. I've seen some some German Solex 34-3's with corrosion in the fuel bowl. They would weep fuel out that back on them from a tiny hole in the corrosion area of the fuel bowl area.

It would have been interesting for you to have installed say a Volksbitz restored German Solex 34-3 carb and see how that effected your hard start situation and if the fuel bowl stayed full after shut down and heat soak.

I tested the theory of "no fuel in the bowl". Oh no no no, I damn close to flooded it. It has been starting very well in the 100* + heat, however there is some additional cranking as written about in the owner's manual.
Colin
When I restart my VW's with warm engines, like you I'm sure, I have the pedal to the floor. I honestly don't feel it takes more than an extra crank of two for the engines to fire up. My gut tells me there is another culprit here if he has a empty fuel bowl after x amount of minutes since shut down.
1970 Westfalia bus. Stock 1776 dual port type 1 engine. Restored German Solex 34-3. Restored 205Q distributor, restored to factory appearance engine.

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by Amskeptic » Tue Aug 08, 2017 9:07 pm

wcfvw69 wrote:
Mon Aug 07, 2017 11:33 am
Amskeptic wrote:
Sun Aug 06, 2017 7:36 pm
wcfvw69 wrote:
Fri Aug 04, 2017 9:28 am
IDK, I think there's an underlying issue here that hasn't been discovered with the carb or fuel pump. I can drive any of my bone stock VW's in 95 degree temps down the freeway to do an errand. I then shut them down to go inside a store, come back 15 minutes later and they all restart very quickly. The carbs are original German Solex's that have been rebuilt with new throttle shaft bushings. The fuel pumps are restored Pierburgs with two of them being the square tops with the fuel shut off tops in them. My 69 convertible only has the two rows of vents in the lid.

As Colin stated, I don't understand where the fuel is going from the fuel bowl in such a short time frame. I've seen some some German Solex 34-3's with corrosion in the fuel bowl. They would weep fuel out that back on them from a tiny hole in the corrosion area of the fuel bowl area.

It would have been interesting for you to have installed say a Volksbitz restored German Solex 34-3 carb and see how that effected your hard start situation and if the fuel bowl stayed full after shut down and heat soak.

I tested the theory of "no fuel in the bowl". Oh no no no, I damn close to flooded it. It has been starting very well in the 100* + heat, however there is some additional cranking as written about in the owner's manual.
Colin
When I restart my VW's with warm engines, like you I'm sure, I have the pedal to the floor. I honestly don't feel it takes more than an extra crank of two for the engines to fire up. My gut tells me there is another culprit here if he has a empty fuel bowl after x amount of minutes since shut down.

My test engine compartment fuel filter did indeed *empty itself* during heat soak after a 100* Sacramento run. But the car started with the hot engine - accelerator floored.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . .199,735 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by vwlover77 » Sun Aug 13, 2017 7:39 pm

My carb was professionally rebuilt and had the bushings replaced a few years back. The car always started fine hot after 15 minutes. It's after an hour or more that it was having trouble. Maybe the empty bowl was a fluke..... In any case, the increased ventilation after shutdown has really helped.
Don

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"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by Amskeptic » Mon Aug 14, 2017 8:39 am

vwlover77 wrote:
Sun Aug 13, 2017 7:39 pm
My carb was professionally rebuilt and had the bushings replaced a few years back. The car always started fine hot after 15 minutes. It's after an hour or more that it was having trouble. Maybe the empty bowl was a fluke..... In any case, the increased ventilation after shutdown has really helped.
Well that is an interesting new tidbit of information. Always fine after fifteen minutes, but difficult after an hour? That sounds like a pool of gasoline down the intake, cooled down liquid pooled up at closed intake valves. Did the carb "boil" the fuel out of the carburetor, or did it just leak into the manifold?
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . .199,735 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by sgkent » Mon Aug 14, 2017 1:50 pm

it sounds like the heat soak is excessive. Are all the shroud seals in place? If it is a dog house cooler, is the air dump thru the firewall tin? How about the heat exchangers - all the hoses in place? Thermostat and flaps in place? is the vent on the tank functioning properly where the tank cannot build up pressure and push fuel into the carb as it expands? Tailpipe9s) in place where it(they) cannot add excessive heat to the surrounding metal?
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Machine Work/Shop Recommendations: http://kentcomputer.com/77VW/machinework.pdf

Pointers on rebuilding an engine: http://kentcomputer.com/77VW/rebuilding_a_vw_engine.pdf

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by vwlover77 » Tue Aug 15, 2017 11:56 am

All shroud seals are in place, all tin is in place for the doghouse cooler, heat exchangers are all hooked up and working properly, thermostat and flaps are in place, and the tank vent system is complete and stock (hose connected to nipple on back of air cleaner). Stock muffler and tailpipes are in place.

I too believe the fuel is either boiling or leaking into the intake manifold. How can I tell which? I've mentioned in previous posts that I've seen the throttle plate wet with fuel after a hot soak. I think at least some of the gas pools at the polyurethane boot connections between the manifold and the intake runners. It does not leak through or around them, but enough gas permeates them that rubbing a finger across them results in a finger that smells of gasoline. Even brand new boots do this.

Since I have a temperature read out now, I could disconnect the electric fan and plot time versus temperature after a hot run.
Don

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71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by sgkent » Tue Aug 15, 2017 7:24 pm

Other things thing that come to mind:

The manifold heat works by allowing small pressure waves of exhaust to pulse side to side as each bank fires. If you had a restriction in one side of the exhaust compared to the other then the exhaust would freely flow from the higher pressure side to the lower pressure side - super heating the manifold and then allowing a lot of heat soak.

Another culprit (common due to the age of 1971 components) can be the pre-heat thermostat in the air cleaner. If it fails on a 1971 it will often do so in the closed position and that will draw constant hot air from the engine and super heat the carb. Watch out for the spring if you play with it. It can bite. I think BusDaddy on the Samba had a fix for the thermostats when they fail to get more mileage from them. Some late Volvos use a similar arrangement, I don't know if it will fit or not.

WWest photo

Image


If that is what it is this is the only one I could find - quite rare, Don't know the seller and he doesn't say what he wants for it. Do your research first. https://www.thesamba.com/vw/classifieds ... id=2066245
Thank You -

Merlin The Wrench

Machine Work/Shop Recommendations: http://kentcomputer.com/77VW/machinework.pdf

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by bus71 » Wed Aug 16, 2017 9:01 am

I had a problem as sgkent described with the wax pellet thermastat on my 71 bus air cleaner. It no longer opens fully in warm/hot weather. Played with it a bit but couldn't get it right. I block the stove pipe and disconnect hose when it gets warm out. Reconnect for winter. I would give this a try just as a test. There is a test procedure in bently for this. I used hair dryer and meat thermometer to test mine. I think the spec was 90* full open. In 73 the bug used a vacuum control in the air cleaner for this. Don't know if this could be adapted or maybe use later air cleaner. Good luck!

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Re: "Flood Control" - 71 Super Beetle Convertible

Post by sgkent » Wed Aug 16, 2017 9:32 am

bus71 wrote:
Wed Aug 16, 2017 9:01 am
I had a problem as sgkent described with the wax pellet thermastat on my 71 bus air cleaner. It no longer opens fully in warm/hot weather. Played with it a bit but couldn't get it right. I block the stove pipe and disconnect hose when it gets warm out. Reconnect for winter. I would give this a try just as a test. There is a test procedure in bently for this. I used hair dryer and meat thermometer to test mine. I think the spec was 90* full open. In 73 the bug used a vacuum control in the air cleaner for this. Don't know if this could be adapted or maybe use later air cleaner. Good luck!
BusDaddy (Mark) has a fix for the ones that no longer fully open. The thread is on the samba but If you contact him he can explain how he fixes them when they loose a little oooomph.
Thank You -

Merlin The Wrench

Machine Work/Shop Recommendations: http://kentcomputer.com/77VW/machinework.pdf

Pointers on rebuilding an engine: http://kentcomputer.com/77VW/rebuilding_a_vw_engine.pdf

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