1970 Noisy AIR Pump

[J W.]

The other day the AIR pump on my 1970 LT-1 starting making noise out of the blue on start up, kind of screeching. The noise goes away after driving a bit. Externally, everything checks out okay, nothing loose, belt is snug. A search of the archives did not turn up any threads on this topic (?). Have others had this problem? How to fix it?

[Mark E.]

Re: 1970 Noisy AIR Pump

A slipping belt is the most likely cause of a screeching noise. This could happen even though the belt is s****** if the pump is hard to turn.

[Mark E.]

Re: 1970 Noisy AIR Pump

A slipping belt is the most likely cause of a screeching noise. This could happen even though the belt is s****** if the pump is hard to turn.

I don't know why the system starred out the S word above. Replace with "tight." Hope that word is okay.

[Joe L.]

Re: 1970 Noisy AIR Pump

The other day the AIR pump on my 1970 LT-1 starting making noise out of the blue on start up, kind of screeching. The noise goes away after driving a bit. Externally, everything checks out okay, nothing loose, belt is snug. A search of the archives did not turn up any threads on this topic (?). Have others had this problem? How to fix it?

Michael------


I expect that your pump needs a rebuild. However, first remove the belt and turn the pump by hand. It should turn relatively easily. If it does not, the bearings or vanes are bad. It may squeak a little or make other "cluck-like"sounds but that is normal.

Next, inspect your check valves. First, remove them from the trees. Blow in them from the hose nipple side and the threaded side. You should be able to easily blow through them from the hose side. But, you should not be able to get ANY air through on the threaded side. If you can, then exhaust gas has backflowed through the check valve and into the diverter valve and pump. In that case, most likely both will be trashed.