Throttle Body Care


There are 3 points of wear on the throttle body:

  1. the pair of bearings that guides the shaft of the throttle activating cam
  2. the bearings for the throttle butterfly pins
  3. the working side (vertical face) of the throttle activating cam.

Proper maintenance is to put, once a month, a drop or two of oil – I use Gunk spray motorcycle chain oil on the bearings and a wipe of grease on the side of the cam.

The rear section of the butterfly housing will gradually accumulate a coat­ing of blow by, which enters at the vacuum nipple from the breather hose. Remove the air filter; put a brick on the accelerator pedal to hold the butterfly valve in full-throttle position; and spray the inside of the butterfly housing with carb spray. The first tine you do this, it will be necessary to work the deposits with a stiff toothbrush and then carefully work them out with a heavy-duty kitchen towel. There are sharp edges in­side the housing; doubtless, small slivers will be cut off the toothbrush. Be sure to remove all slivers with your paper towel to prevent their be­ing sucked into the induction tract. Spraying the inside of the throttle housing – the butterfly in full throttle position – once a month thereafter should keep it clear of blow by.

Each time you clean the inside of the throttle housing, allow the carb cleaner to dissipate. Then put two drops of oil at the joint of the lower butterfly bearing and, after removing the cap at the top of the throttle body, on the upper bearing. Replace the cap and tighten its two screws. Remove the brick. Work the full range of the accelerator pedal 5 to 10 times. Then reinstall the air cleaner.

Do not use WD-40 to lubricate the 2 pair of bearings. Although it will provide protection against bearing wear, WD-40 attracts dust, which snafus the idle-—it drops and remains down, or it hunts. The dust may also con­tribute to Co variation. The Kugelfischer pump has its own peculiarities at idle; don’t add to them.