Smog pump making a noise

[joshwilson3]

On my 89, I had cleaned the engine bay and got the smog pump wet to where it seized. So I got a good used one from a 45k mile car.

It seemed to work fine. Then later on I noticed a kind of rattle type sound. I'd call it a soft rattle or something as it didn't make a buzz sound. Just a noise. After the car had warmed up and had been parked for several minutes. Then I would hear the noise when I started the car. And the noise would go away a few minutes later. Odd.

I never could find the noise with my scope. But after listening with my ear, I believe the noise is coming from the smog pump.

Just wondering if that means the smog pump is on its way out? It just seems odd it only makes the noise for a few minutes after I start it when the engine is hot.

I guess I could go through to make sure all the bolts are torqued down. Anyone know the pulley, mounting bolts, and air tube bolts torque specs for the smog pump?

 

[boomdriver]

i can tell you that the torque is NOT much. The aluminum brackets WILL strip very easily, so go easy and use thread locker. IF you do strip one out, you have to get a bolt thats 1/2"
(so a little will stick out past the bracket hole) longer AND a nut to fit on the end once its run all the way thru the mounts. I have a couple done that way because I got too aggressive on the bolts when tightening. Some of those only have 3 turns worth of threads to bite into inside the bracket so go easy. Just go snug and use the blue locker on the threads.
A smog pump that rattles is probably a dying smog pump. The roller/impeller inside has vanes that ride against the pump walls to capture and expell air under some pressure. That rattling is a roller thats loose, or even broken and rolling around until it finds a seat and fits again. It will eventually come apart and blow the chunks into the AIR system, and valves. Sometimes they will seize but they usually break apart and self destruct inside. Its just soft aluminum inside as well as outside.
Why a used one? A rebuilt with warranty is around $50... Thats a high risk used part. If it ever got wet, it got damaged and will fail.. All it takes is a couple drops of water or wd-40 inside and they seize. They do not like liquid. Even lubricants. There are 2 reasons why air pumps die....washing or someone lubricating it.

 

[joshwilson3]

i can tell you that the torque is NOT much. The aluminum brackets WILL strip very easily, so go easy and use thread locker. IF you do strip one out, you have to get a bolt thats 1/2"
(so a little will stick out past the bracket hole) longer AND a nut to fit on the end once its run all the way thru the mounts. I have a couple done that way because I got too aggressive on the bolts when tightening. Some of those only have 3 turns worth of threads to bite into inside the bracket so go easy. Just go snug and use the blue locker on the threads.
A smog pump that rattles is probably a dying smog pump. The roller/impeller inside has vanes that ride against the pump walls to capture and expell air under some pressure. That rattling is a roller thats loose, or even broken and rolling around until it finds a seat and fits again. It will eventually come apart and blow the chunks into the AIR system, and valves. Sometimes they will seize but they usually break apart and self destruct inside. Its just soft aluminum inside as well as outside.
Why a used one? A rebuilt with warranty is around $50... Thats a high risk used part. If it ever got wet, it got damaged and will fail.. All it takes is a couple drops of water or wd-40 inside and they seize. They do not like liquid. Even lubricants. There are 2 reasons why air pumps die....washing or someone lubricating it.

I've heard problems of the rebuilt smog pumps. And got a good deal on a 45k mile OEM pump. And figured it would last a while since my OEM pump lasted to over 90K miles before I got it wet.

It just seems odd it started right after I put the frisbee back on. It was like the next time I started it, and I had thought I forgot to bolt something back on, or something was loose. But it drove fine.

I've also heard someone say the rebuilds have a different thread pitch for a couple of the bolts, and so the person had to return the pump since their bolts wouldn't work. Don't know if that was a one off, or they are all like that. But I have heard of others using the smog pumps at Autozone.

The prices on the smog pumps have gone up. At Autozone it is over $60 with a one year warrany. Over $80 at Napa with a one year warranty. And over $80 at Advance with a lifetime warranty. I just hate to spend more money on a smog pump. Just odd I guess if it really is failing, to start 4 months after I've had it bolted on.

Someone else had told me it was normal for it to make noise at start up. But that just doesn't sound right since I've never had this noise in the 3 years of owning it.

One thing though which is why I was wanting to check the bolts torque. Is it sounds like it is coming from the smog pump when I put my ear in front of the smog pump pulley. But I don't hear the noise with my scope on the smog pump. Shouldn't I also hear the noise with my scope?

 

[boomdriver]

whinning is normal ONLY on a new pump.;

I only paid $59 for mine with warranty. parts for corvettes just cost more.

 

[joshwilson3]

Haha. I think I found it!!

I pulled the hoses off the diverter. And I checked the 3 check valves by blowing into the line, then sucking on it to make sure they held vacuum. They passed.

Went into town came back. Then pulled the same lines again. I blew into them and the passenger side check valve at the manifold made a noise like or horn or something.

Put it back together. Started it up. And the smog pump was making the rattle noise. Put my scope on that check valve, and that is where it is coming from.

So I saved myself $100.

Autozone has a GP Sorensen which is aluminum in color, and Advance has the BWD that is a gold color. Got any ideas which one would be better?

 

[boomdriver]

I just bought and installed a check valve from O'Rielly, but do not know which mfg that was. I know that a bad check that allows exhaust to flow back to the pump will cause noise and eventually kill the pump.
I actually have a new PCV that vibrates and makes a buzzing sound that was making me crazy till I touched it when the motor was running....

 

[joshwilson3]

I just bought and installed a check valve from O'Rielly, but do not know which mfg that was. I know that a bad check that allows exhaust to flow back to the pump will cause noise and eventually kill the pump.
I actually have a new PCV that vibrates and makes a buzzing sound that was making me crazy till I touched it when the motor was running....

I think I'm gonna get the GP Sorensen as it is aluminum colored and would probably blend in better than the gold colored one Advance sells.

I think that check valve was still working as it held vacuum when it was cool and hot. It just made a horn noise when warm and air was flowing through it.

Yeah, it sucks when that PVC likes to buzz. It doesn't do it on the Vette, but it does it on the Firebird.

I've been told to only use AC Delco for the PVC valve.

 

[boomdriver]

I like to use Delco ANYTHING...but I did not know that they offered a PCv...I will be looking for that. The buzzing has to go.

Also, don;t expect too much out of these check valves. They will pass air one way, and often block most of the air-flow from the other way...The one I replaced was rotted out inside and letting exhaust come back toward the pump. I'm pretty sure (positive actually) that is what caused my 2 month old pump to start the death rattle. Thats what warranty does...gives the owner a chance to get his story straight before returning the "defective" part so you can wipe out the exhaust soot from the pump fitting that should be clean...

 

[joshwilson3]

I like to use Delco ANYTHING...but I did not know that they offered a PCv...I will be looking for that. The buzzing has to go.

Also, don;t expect too much out of these check valves. They will pass air one way, and often block most of the air-flow from the other way...The one I replaced was rotted out inside and letting exhaust come back toward the pump. I'm pretty sure (positive actually) that is what caused my 2 month old pump to start the death rattle. Thats what warranty does...gives the owner a chance to get his story straight before returning the "defective" part so you can wipe out the exhaust soot from the pump fitting that should be clean...

The AC Delco PCV will buzz too. I've got one on my Firebird. Maybe you need to replace the grommet so it holds the PCV tighter? You can get that at the dealer as well. Just make sure to get the correct one.

 

[joshwilson3]

Holy shit. Getting that check valve on and off on the passenger side is a bitch. I got that GP Sorensen on. Then I went to bolt back down that bar for the air compressor. And it hit the check valve to where I can't bolt it down at the block.

That sensor is a little shorter and fatter than the OEM check valve.

That thing was a bitch enough that I don't feel like pulling it off and spending $30+ for one at the dealer.

I think what I will do is put a couple of washers on the stud first to help take up the gap. Cut open a thin piece of rubber vacuum hose to put around the pipe where it touches the check valve. And tighten it down. I did a test on it. And it does push the air tube stuff a little, but I don't think it would cause a problem.

If this was on the driver side, there would have been no problem.

Even though the old one held vacuum. I noticed it was very hard to blow through it compared to the new one. I wonder if that is why some have problems passing smog as the check valves are restricting air flow from the smog pump.

 

[boomdriver]

yep....

"easy" is not anywhere in the passenger side description.

neither is "accessable" or "pain-free".
Thank God plugs last a good while.....

Take a good hard look at the compressor support bar...it should have some tension on it and it might just need to be loosened at the top to allow the bottom to start properly. Without some pretension the aluminum brackets will twist with engine torque and crack. Same goes for the alternator and its support. Especially the alternator because it only has 2 mounts. The compressor has 3 or 4 but still needs the rear support to prevent twisting.

 

[joshwilson3]

What I ended up doing was swapping the driver and passenger air check valves around so I had an OEM on the passenger side. Now I don't need washers on that bar as it doesn't hit the OEM valve.

I had cut the spark plug wires last with my wrench last time I replaced that valve. And everything was fine till one day I drove into town and noticed a miss at idle. Popped the hood and saw the spark plug wire arcing. Put electrical tape on while it was at a shop. But then noticed a detonation or something when I started it. So, I've got new AC Delco plug wires ordered. And I'm gonna go ahead and replace those two spark plugs just incase they got damaged from the detonation or whatever that knock noise was when I start it. Kinda strange as I had so happened to have 91 in the tank as I usually have 87.

 

[joshwilson3]

Well, damn. I finally got around to start it up since the check valve swap out as I had to do plug wires and some other things.

And that noise is back on a warm start up. It is coming from the passenger side air check valve. The one I moved from the driver side. Before, it wasn't making any noise on the driver side.

So, I guess this means something is going on with the passenger side of the air system. But I'll probably go ahead and replace that check valve as well so I don't have that rattling noise on every warm start up. I'll probably go for the AC Delco check valve since it looks like the same as the OEM. So hopefully it is the same shape so it won't interfere with the plug wires and that metal bar like the aftermarket check valve did.

Just strange the problem is just on the passenger side with two different original check valves. The new aftermarket one I had on the passenger side didn't make any noise.