Jetta Choke Problems

Idling problem - choke

Symptoms: Starts willingly enough, but once warm the idle stays around 1400rpm, but goes back down after standing idling for about 10 minutes or more. Runs on when turned off.
In cold weather, choke comes on again, engine smells of fuel and runs badly around 2000 rpm. Choke completely cured by bridging choke heater thermo-switch contacts, but idle still high.

     Evidence: Choke cover stays cold, as does water pipe to it from inlet manifold. No water flow from small pipe at rear of manifold. Sucking or blowing on this pipe produces only a small amount of fluid/bubbles (don't get coolant in mouth). Thorough cleaning out of cooling system does no good.

Findings: Rubber gasket sealing water passage to manifold pre-heater has swollen and buckled to block the passage.

Water passage blocked Grommet removed +
seating cleaned
The old and the new

The removal of the manifold is not well described in Haynes. There are 6 socket-head screws, in a line (you need a new gasket, so you will see this). You must remove the plate joining the inlet and exhaust manifolds at the back (two 13mm bolts on the inlet and a rusty nut on a stud on the exhaust). You may also need to remove the warm air intake shroud at the back of the exhaust manifold (rusty nuts - originally 13mm but now maybe only 11mm). You need clearance for a 6mm hexagon driver with two short 1/4" extensions and ratchet. Tape the bits together to stop them falling off between the two manifolds. Bolt no. 4 from the left is particularly difficult to locate. There is room to remove the manifold with the carb still attached. You may find the carb nuts still have a lock-tab sticking upwards, and anyway one isn't very accessible.

Good luck!

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