Positive Displacement air pump

[PWRCATZ]

I recently drove my newly purchased Z 1700 miles across country to get it home. About 3 hours from home I have a beearing sound coming from my engine. I bought a listening device and this is what I found.

I seems like a bearing or rough noise from the positive displacement air pump equipped on some 240/260Z's. According to the net (my manual is in transit), this acts as a Anti Backfire valve, check valve, and an air pump relief valve. It is located on the drivers side opposite the Alternator.

Before I start the process of replacement, I thought someone might have some information.

1. Will my engine have problems if I go to replace this part and do not have installed. (Meaning is it driveable or not)

2. Is there a way to bypass? Problems?

3. Does the entire unit need to be replaced or can I replace a valve component?

Thanks for any help you might be able to give.

PWRCATZ

[PWRCATZ]

I know some of you are asking what a "positive displacement air pump" is and I do not want to create any confusion.

It has to do with the early air injection system. Just so everyone knows, I do not have the conventional air cleaner. I have K&N Filters on the original carbs so the hose that would be going to the air cleaner had been plugged when purchased.

This is a early 71 Z with an ATK 2.6 in it when I purchased.

Thanks

PWRCATZ

[Bambikiller240]

Originally posted by PWRCATZ

(snip)....I seems like a bearing or rough noise from the positive displacement air pump equipped on some 240/260Z's. According to the net (my manual is in transit), this acts as a Anti Backfire valve, check valve, and an air pump relief valve. It is located on the drivers side opposite the Alternator.

(snip)

1. Will my engine have problems if I go to replace this part and do not have installed. (Meaning is it driveable or not)

2. Is there a way to bypass? Problems?

3. Does the entire unit need to be replaced or can I replace a valve component?

The item you describe is the "smog" pump. Depending on where you live, it may be necessary to retain this item in order for your car to pass Emissions inspections. I do not believe that your engine will suffer if it is removed.

I believe that MSA in Los Angeles (and maybe others) can get you a rebuilt pump if your locale requires it to be retained to pass emissions inspections.

It does not "act(s) as a Anti Backfire valve, check valve, and an air pump relief valve" ; rather those separate items are located "downstream" of the pump. In other words they are mounted up near the intake manifold connected by hoses to the output of the pump, where the partially burned hydrocarbons that the pump sucks out of the engine crankcase are forced back into the exhaust manifold where they are more completely burned to minimize some components of "smog".

[PWRCATZ]

Bambikiller,

You are correct that the valves act as part of the system and are not air pump. Thanks for the feedback.

Since we are smog checked likie when I was in CA, I will just remove. Should I plug the hose to the check valve when I take it off?

Thanks again for the help,

[PWRCATZ]

Boy, doing to many things, need to watch my fingers. That should read that my state does not smog check the vehicles.

PWRCATZ

[Victor Laury]

Remove the drive belt.

diconnect and plug the hoses.

Keep everything in place and connect it all back before inspection.

How's that for a plan.

I keep all my smog equipment ..... in a box, under the shop table

[PWRCATZ]

Thanks Victor/Bambi. As always I appreciate the expert advice I get here.

PWRCATZ

[beandip]

Are you sure that you need to pass emissions ? 25 yrs. is the cutoff here in Or. :classic:

[Bambikiller240]

Not all states are the same.

There is currently a move afoot in the California State Legislature to change the current law which exempts pre-1975 cars from Smog testing/inspection requirements. (they are still required to have all original smog equipment installed, but if they don't inspect, who will ever know what you remove) They want to change the law so that cars have to be 45 years old before they become exempt from Smog inspection requirements. If they are successful, there will be a number if 240Z owners suddenly scrambling to find original smog equipment for their cars!