Throttle Plate Corrosion/Gasket

[secondchance]

Like so many LT5s my 94 had developed corrosion around the edge of plate on the throttle body side. This necessitated scraping off of bubbling area and refinishing. In my opinion, even if this area is re-powder coated, galvanic corrosion if not stopped will result in bubbling just the same. However, some LT5s seem to be immune from this phenomenon perhaps due to low mileage.

Last time I had a brief discussion with Marc Haibeck when I met him at Carlisle. In his opinion this corrosion was due to plate gasket being made of paper would soak with coolant eventually allowing galvanic corrosion and suggested only way to stop this would be to bypass coolant.

In my case, I prefer not to bypass the coolant in order to keep it looking stock and also because I drive the car even during the winter months. Therefore, I elected to come up with a solution to deal with this corrosion issue.

Then about 3 weeks ago during a get together with the WAZOO guys I had a chance to discuss this issue with a nuclear engineer and a chemical engineer. Interestingly the chemical engineer was one on the guys who was employed by GM back in the early 70s to develop catalytic converter.

After a few minutes we concluded that the coolant was acting as the electrolyte, quite obviously, either and or both the plate (possibly an aluminum alloy with other metal) and steel bolts holding the plate was the anode and throttle body was the cathode where ions from the anode was being deposited.

Then, if I can isolate the plate and bolts from the coolant, the electrolyte, this corrosion can be contained.

Best way to achieve this would be to come up with non paper gasket material and allow the gasket to span the entire opening so that the plate would not come in contact with the coolant at all.

Then I turned to water proof membrane sales rep and he suggested "Hyproof GL". This product, manufactured by Hyload, was developed as a roofing membrane for structures where fumes from oil, gasoline, jet fuel, glycol and other chemicals were of concern. Also, manufacturer claim that it can be used in environment below 375 degres farenheit.

I finally got hold of sample sheets of this product and will have it installed in my car sometime this week. Only problem is that I will not know if I am right for at least another 60-70,000 miles.