1965 just cranks and cranks when hot. Won't fire up

[DeVertible]

I have a six volt 1965 convertible bug that just doesn't want to fire when the engine is hot after driving it. It is a 6 volt, newly rebuilt 1600 with a Solex H30/31 without and idle kill solenoid (no such thing available for my carburetor in 6 v.)

The optima battery cranks it at a reasonably good speed but it just won't fire. It does diesel when turning off ignition. Its a beautiful car but I can't take this thing anywhere without getting stuck as soon as I shut it off I know I'm in trouble. I can't be the only person that has experienced this so anyone with the remedy short of going to 12 volts please speak up. . . . even starting fluid doesn't work. Timing is correct. new plugs, points wires, carb rebuilt, etc and this thing runs and idles great. The funny thing is that the 40 horse 1200 that was in it previously without the optima and a different carburetor had the same FN problem. The coil and condenser come to mind but I think the condenser is new also. HELP, I love this car but she is really PSN me off.

[DrKeck]

I had the same problem and figured it out, to start, are you following the proper starting procedure when it's hot

http://www.thesamba.com/vw/archives/manuals/65bug/page16_17.jpg
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1966 Beetle
1600cc 50bhp
Daily Driver

[buguy]

Gunna have to check it for spark. I would run it and then go home. Shut it off and then check to see if the coil has power to it. Then if your getting power out of it. Then if its getting power to the dist, and power from the points....etc. A Bently manual is a great thing to have if you dont know these cars inside and out. Even when you do know them, you will still referance things in it. Many local parts stores carry them.

[txoval]

Have checked your fuel system?

Filter in tank, filter before carb, float valve

If the system builds up a vacuum, and then releases at shutoff, you could be flooding the engine.

Is your tank vented properly?

See here to: http://www.thesamba.com/vw/forum/viewtopic.php?t=620577&highlight=flooding

[61SNRF]

As mentioned hot re-starting procedure is to hold the throttle wide open as if the engine is flooded.
In warm weather with a hot engine flooding can occur on re-starts if the choke is set to a cold or "Winter" position. Is it set really tight and springs closed position on warm-to-hot re-starts? You should be able to see this at the fast idle cam stepping up.
Maybe that's why the starting fluid doesn't help?
Does the engine smell of fuel when this occurs?

If the fuel side seems to check out then it can be from weak spark from one or more causes.
Even perfectly tuned 6V cars with a little excess resistance in their wiring, terminals and ignition switch can develop a voltage drop in the coil +15 power supply circuit under cranking/high battery load conditions. Put a voltmeter on the coil +15 terminal and check the voltage there with the engine cranking. It should only be few tenths below what battery voltage is under the same cranking conditions.

Coils can often fail under high heat too. Following every standard safety precaution, take the center lead out of the cap and hold it about 1/8" to 1/4" from a good clean ground while cranking. It should produce a clean blue spark with a crisp sound. You might do an experiment first to see how "hot" it looks on a cold start to get a fair comparison. Either that, or swap in a known good one and give it a trial run.

Heat induced leaking or shorting within the condenser can cause weak spark too. Like any modern electrical part, when new if it's going to fail it will likely do so soon. Again a swap with a good one is the easiest way to rule out. That or a complete test distributor.
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-Bruce

An ounce of prevention is worth a pound of cure.

[tasb]

Check the valve clearance. When the clearance is too tight the engine will exhibit those symptoms.

Valve clearance is acceptable when the engine is cold but as it warms up the metals expand and the clearance tightens.
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Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse

[DeVertible]

Much appreciate the things to check. Fuel mixture or spark issue for sure. Let it cool for an hour and it fires immediately. Had a Bently manual and others for years - Invaluable indeed. Thanks and i will post progress and resolution otherwise the discussion does not help others.

[txoval]

Another thread to read:

http://www.thesamba.com/vw/forum/viewtopic.php?t=566347&highlight=flooding

[DrKeck]

One thing that has worked perfectly for me is: I have a '66 with a 1600 in Texas and it's so hot here that it did the same thing. I ended up running deck standoff in the summer to let the hot air get out when it's parked out in the sun. Now it starts every time like it should. I might take them off in the winter or try and find a vert deck lid but I also think it looks cool so I might keep them on. If all else fails u might give that a shot and see if it works.
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1966 Beetle
1600cc 50bhp
Daily Driver

[Eric&Barb]

Agree flooding could be the problem. Fuel pump putting out too much pressure, carb float cracked or too heavy, shut off valve faulty or loose, crack in carb, and even if really hot the fuel between the pump and carb can expand so much that it pushes open the shut off valve and drips down the carb throat. Fixed this last cause by adding second gasket so valve is moved down slightly and in turn pushes the float that much more deeper into the fuel, which pushes up against the valve so it5 does not open so easily.

A good indicator of any of the above is to remove air cleaner after running it hot and look down carb throat for fuel dripping. If you tried to start it is there a really strong fuel smell at the tail pipes?

If accelerator nozzle is partly plugged up it can cause hot start problem.

Have had electrical problem cause same. When engine is hot the compression is higher so starter sucks up more electrical flow, and the coil voltage can drop below the point that it will work. Clean all electrical connections and grease them up to keep future corrosion away for as long as possible. Have you soldered up the internal connections in the fuse box?

If using early bell shaped headlight switch have you done same as above to it?

Clean both ends of both battery cables, apply dielectric grease and get rid of any that are showing signs of wear or have those junk bolt on the cable battery cable clamps. WW has best and closest to stock battery cables with brass not lead clamps swedged onto the cables for a gas tight connection.

Clean/grease both ends of the transaxle to body ground cable as above, if it is even there.

Pull starter and inspect. Are all the brushes there and longer than the cages they sit in, if not replace. Check the FRONT starter bushing inside the starter if that is worn out it can still turn over great, but cause hot start problem. Inspect bushing in transaxle or just replace if you are using a supported standard starter. While you have the starter out sand clean the starter and transaxle surfaces where they seat together and grease up for good ground contact.
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In Stereo, Where Available!

[Johnous]

[Eric&Barb]

Forgot to mention to get a multimeter. Post what you find the battery is voltage wise when charged up. Have seen NOS regulator only put out 6.2 volts when should have been 7.2 volts. Battery will not charge up fully when regulator does not get to high enough voltage output...

Check voltage at each wiring connection to see if there is a voltage drop. Should be less than 1/10 volt and have seen as much as 2 volt drop due to loose/corroded connections.
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In Stereo, Where Available!

[Zylinderkopf]

Make sure that the fuel lines are not resting on the manifold. That will cause vapor lock! Since your bug starts without problem when cold I think vapor lock is the likely cause of your troubles.
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1963 Beetle
1966 Beetle 1300
1970 Karmann Ghia Coupe
1971 Super Beetle
1974 Thing


"A lot of people never use their initiative because no one told them to."

[DeVertible]

I got plenty of great suggestions and things to try. Away from home for a few days. When I get back will start applying them. Vapor lock, lean condition, low voltage at coil and poor charging regulator are all possible will check back with results after the weekend. Thx again Samba and members.

[DeVertible]

Here is the tempermental beast.

[DeVertible]

Here is the tempermental beast.

[DeVertible]

Here is the tempermental beast.

[DeVertible]

I got plenty of great suggestions and things to try. Away from home for a few days. When I get back will start applying them. Vapor lock, lean condition, low voltage at coil and poor charging regulator are all possible will check back with results after the weekend. Thx again Samba and members.

[Cusser]

[slalombuggy]

First thing I would check is valve adjustment. It does exactly what you are describing. ignition parts will cool down faster so if it is taking an hour I would look for a mechanical issue first Then I would check the fuel and ignition. IF the charging system was at fault you wouldn't be able to crank it over forever as a hot starter requires way more amps to turn over than a cool one.

brad