Throttle Body Bores and Butterfly Valves Cleaning

Rook

Joined: 03/28/09

Posts: 20579

Throttle Body Bores and Butterfly Valves Cleaning
12/27/11 7:26 PM

Throttle Body Bores and Butterfly Valves Cleaning

The throttle body bores accumulate a small amount of carbon engine deposits. My bores were not all that dirty after almost 30,000 miles but if the throttle bodies are coming out anyway, it may be worth while to clean them up.

The ZX-14 Service Manual recommends a high flashpoint solvent be used as a cleaning agent. I used 5 parts of gasoline with 4 parts Sea Foam fuel additive. The dirt was not very hard to remove so pure gasoline probably would have worked just as well with zero risk of damage to metal surfaces. Avoid cleaning fluids that leave a residue (pure gasoline is a good choice again).

Use absorbent, nonabrasive and lint free cleaning pads. Microfiber cloth is probably ideal. Quilted cotton pads pads for washing skin work fine. It is pretty hard to find anything that does not leave a trace of fuzz behind but try to avoid using any pads or fabric that will leave behind a lot of fibers. I used my bare finger to wipe the last bits of fibers from the bores.

Be careful not to let dirt or dust accumulate inside of the bores while they are removed and open to the outside atmosphere. I kept thin sheets of plastic over the top and bottom of the bores as dust covers. The dust covers were secured with rubber bands around the outside of the bores (see INTAKE DUCTS REMOVAL, step 3) and removed only to clean inside of the bores.

Clean the last fibers away in the brightest light possible. A flashlight that can be held right inside the bores works well for night time work. There will be some fibers which are totally invisible in normal artificial light but become obvious in bright sunlight

After all is washed out and wiped to perfection, you may still see a few fibers inside the bores. Clean it away as much as possible. Don’t bother too much about it if you think there may be some tiny fiber specs that floated in to the bores. I see dust fibers and oil in the first photos of flies removal that I took 4 years ago. That was before the throttle bodies were ever removed and the first time the airbox bulkhead doors were removed.

If your 14 still has the secondary flies in, you cannot open them by hand to clean them. You will need to hold open the primary butterfly valves and clean behind them from the the bottom of the bores. I imagine there would be a soot ring to clean off at the secondary flies as well as the primaries(see the 4th picture in step 1 below).

Do First:
Remove Throttle Body Assembly, steps 1-9

Tools:
high flashpoint solvent (pure gasoline or gasoline and Sea Foam fuel additive)
flashlight
high flashpoint solvent
cotton pads
thin sheets of plastic
rubber bands

1. Remove the dust covers from the bottoms of one bores.

Use a cotton pad saturated with a high flashpoint solvent to wipe the throttle body bores and butterfly valves. Clean from the bottom with the throttle body assembly inverted, as shown below.

Open the valves by hand being careful maintain a sure grip on the spring lever. Close the valves softly. It is best to open the valves to full open in order to clean both sides of the bore and throttle plate. I would not hold the valves wide open for any longer than is necessary. My concern was that the throttle spring might loosen up from being held at maximum open positions.

I took care to avoid touching the injectors with anything. The holes are so tiny that I did not want to risk rubbing any fibers into them. Each of my injectors has a brown stain at the center but I would probably remove the Injectors from the throttle bodies if I wanted to clean or unclog them. I also avoided rubbing over the three small holes in the wall of the lower half of the bores.

I found a very slight sooty film over the entire surface inside of the bores and on the plates. There was a definite ring of carbon soot in the bores. It is easily viewed by opening the butterfly valves and inspecting the wall of the bore where the valve adjoins it. It was not hard to remove but it was is a bit tricky to reach.

2. The throttle body bores should be cleaned from the top, also. As you can see, in my throttle bodies, the secondary flies shaft is in the bore but the plates are not.