My Car Doesn't Run Right!

Please also see Car Won't Start!.


Cold Weather Running

Somebody wrote with a problem that grieves many VW owners - I have a '68 Beetle with a 1600cc engine fitted and a Bosch 009 distributor. I'm having trouble with it stalling when idling when the engine is cold, at traffic lights etc. It runs like a dream when hot. Can you offer any suggestions for adjustment to solve my problem?

Rob responded with a terrific treatise on the subject of cold weather running -

The most likely culprit is the automatic choke needing adjustment. With the engine stone cold (and the ignition off so the choke does not start to heat up) take the air cleaner off and look at the choke butterfly. Pull on the throttle cable once to set the choke and it should swing closed - touching at the sides of the throat. If not, loosen the three screws on the retaining ring of the choke canister (right side of carburetor) but don't remove them - the choke canister can now be rotated a few degrees to turn the choke on more - set it to JUST touch the sides of the throat. Check the operation of the choke - when the engine is completely warm the butterfly should be standing upright, or very nearly upright.

Sometimes it's a slight compromise to get it working well with a cold engine and still switch off when hot, and you might need to reset it to a little less choke as summer comes.

If the choke is okay, test the horizontal heat riser tube under the inlet manifold - after the engine has been running for a few minutes it should get quite hot (finger burning - take care!)- it might be hotter on one side than the other (that's normal) but if it's only warm one side and cold on the other then it's blocked and needs to be cleaned out - there's a procedure for that on our site. Some after-market mufflers/headers don't have the holes drilled out at the connection points either side and so the heat riser will never work in this condition - the holes need to be drilled through to the exhaust gases if this is the case. The reason they are not pre-drilled is that the headers can be used on twin carb setups too - they dont use any heat riser so the heat riser atrtachment points are not used. Something to check if you decide to buy aftermarket headers.

Is the warm air inlet for the carburetor connected (paper tube between the carburetor inlet and the right side cylinder head)? If this is missing the engine will take longer to warm up and will be harder to keep in tune - warmed inlet air helps the fuel evapourate more evenly in the carburetor and inlet manifold, and this could show up as rough running - and could be more noticable at low rpm than high rpm.

Is it timed right? The 009 distributor must be set to between 28 and 32 degrees at 3000+rpm, and let the idle timing fall where it may. Use as much of the 28-32 degrees as the engine can take without pinging/detonating. If you try to set it at the normal 7.5 used for vacuum distributors you might have a poor setting - 009s vary and MUST be set at 3000rpm first (then you can measure the idle advance and use THAT setting (usually between 5 and 10BTDC) for THAT 009 on THAT car next time to set it at idle.

Check the fuel jets. The main jet should be a 130 or 132.5 for use with a 009 distributor, and the idle jet should be a size 55 or just maybe a 60 (the Bug usually uses a size 55 but the heavier KGs and buses used a size 60 or 65 to help get the heavier body moving). So you could try one of those - it might help since you have the 009 distributor which likes to work with richer carburetor settings.

You can also try increasing the accelerator pump to maximum squirt - that might help if it's stalling as you first touch the throttle.


Jerky Running

The following question is typical - "We picked up a '74 SB for nearly nothing... The car idles fine, but when we give it gas and try to slip into first gear from idle, it does not want to go. It's as if it slips out of gear very gently as the clutch is let out. And it has died a couple of times when the clutch is let out and the accelerator pedal is pressed. Sometimes in that situation it jerks a bit, and will sputter and finally "catch" a little and go forward enough to put into second gear, where it does the same thing. It does not do this in third or fourth gears. When we try giving LOTS of gas when accelerating into first or second, it backfires and jerks, but will go a little better. It will move forward if I ride halfway between clutch out and in and the gas pedal."

Rob responded - It sounds like either a carburettor/distributor problem or a gearbox problem.

If it's going into gear, staying in gear, and changing OK, then it's probably NOT the gearbox. Popping out of gear, crunchy changes and sloppy gear stick are the most common gearbox problems.

You said that the engine idles okay but when you try to apply power it sputters and resists -- THAT sounds like a fuel or ignition problem.

A blocked main jet perhaps (runs on the idle jet OK but fails when you try to accelerate on to the main jet), a blocked accelerator pump (which helps spin the engine up), or maybe the advance section of the distributor has failed (is it a 009 or vacuum distributor?) and it's got no advance as you rev the engine.

If you have a timing light, this one is easy to check. Paint the timing notch with a blob of white-out so it's easy to see, put the timing light on and start the engine. Pull on the throttle arm to rev it whilst watching the notch in the timing light. With the 009 distributor it should start to move to the left (advance) smoothly as you accelerate the engine past about 1200 rpm (very fast idle). With a vacuum distributor, the timing mark should JUMP to the left as you blip the throttle.

It could be the clutch itself - slipping or not engaging properly. Are there any noises/vibration when you use the clutch?

Binding brakes could be part of the problem. Does the car roll okay if you push it (gearstick in neutral)?


A similar question "I just bought a 1974 Super Beetle... It was running perfect, then it started to lose power. (I thought fouled spark plug). I checked the back and it looked like oil was coming from the fuel pump onto the fan belt. It was very hard to start, like a real low battery (bought brand new one - wasn't that). Then it wouldn't start at all. We tried push starting, rocking it, etc. We thought the engine might have seized, but it still will turn over in reverse. We are totally at a loss as to what could be making it want to seize. There was plenty of fuel, oil. Could it have gotten overheated?"

Rob responded As it lost power was the engine still running smoothly, or was it getting a hesitation of stutter (trying to eliminate plugs and fuel here)?

So is it cranking at normal speed, or slow-cranking? If slow-cranking (with a good battery and the ignition lights still dimming as it's cranking), the starter might be on the way out.

Or not cranking but you hear a clicking as the starter solenoid moves (starter kaput - rebuild); or not clicking at all and the ignition lights stay full bright (solenoid not pulling in - starter kaput).

So you can turn the crankshaft anti-clockwise (viewed from the back) but not clockwise? That's really weird. Nothing stuck down behind the crankshaft pulley is there?

What happens when you push the car forward and try to bump start it in say 2nd gear - does the engine turn over or does it lock the back wheels when you let out the clutch and the engine stays motionless?

Not too much oil I hope. The VW crankcase uses 2.5 litres (2.2 US quarts) of oil. Overfilling can cause an excess of oil behind the pistons (since they lie on their sides just above the sump), and too much oil sloshing about there can cause problems with oil being forced out of the sump (but not usually causing overheating). I mention this because you said some oil seems to have been forced up out of the fuel pump area. Was the fuel pump replaced at all? There are several types of fuel pumps, the older type (pre-'71) have a longer push rod inside them which would make it difficult/impossible to screw down the pump properly. Any possibility a wrong pump/rod has been fitted?

The old upright rectangular fuel pump use a 108mm pushrod. The more modern squat raound style pumps use a 100mm pushrod. You can NOT mix n match the pump rod and pump - they muist have the corect length for the style of pump. Just for info, the squat round style was interoduced with the first alternators in 1983 - the fatter alternator interfered witht he old style upright pump, so it was redesigned. The squat roud style is a direct replacement (with the shorter push rod of course) for all the older unright pumps.

Regarding overheating -- nothing definite there, but a few things worth checking. The engine might turn over OK once it has fully cooled, but the cause of the overheating needs to be found. If it has been overheated, it might have suffered internal damage too.

Here are some things to check -

  • Is anything obvious (like a rag) caught in the cooling fan inlet? Occasionally the thick tarpaper sound insulation on the firewall just in front (front) of the engine can come loose and cover the fan inlet.
  • The timing may be too retarded. It's unlikely that this would cause overheating to the point of seizure, but it's possible.
  • Are the brakes binding? This feels like a loss of power. Easy to test - the car can't be pushed (gearshift in neutral and hand brake off of course :-) (Please see our Brake System Pressurization discussion.
  • Perhaps the oil on the fan belt has caused it to slip so much that the fan isn't providing adequate cooling.
  • You said it's had work done on it recently -- go back and look at the work that was done to see what has changed. If the car was running well before the work, it is most likely that something done during the work is causing the problem. For instance, was the distributor put back in the right way? (it goes only one way but can be forced 180 degrees out).
  • Was the cam shaft removed from crankcase? If it's out a cog or two that will affect both valve timing and ignition timing and could easily cause overheating.


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