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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Have gone through 4 rebuilt smog pumps and finally gutted the last one, blocked off the lines. Screwed up the hot idle pretty bad as the ECM adjusts for the lean O2 sensor reading and that adjustment really messes with the idle until the closed loop kicks out. Going to put a later model electric AIR pump on it and see how that works. Question, what is involved in removing that old pump and rerouting the belt? What belt would I need? Just in the thinking stage at this point, need to do something though.
Removing the pump and blocking the air ports in the exhaust manifold is all you have to do. Put the bolt that goes into the block back in, the lower one can stay out. I used Edelmann 120500 5/16 brass plugs. I highly recommend using lots of heat and line wrenches to remove the air tubes.
Technically there's an idler pulley that can be installed in place of the air pump. Might be useful if the belt is seeing a lot of rpm.
You can use the old belt? I'm about due for a new belt anyway so I was thinking this might be a good time to try this. Thanks for the replies! (Did see the Dayco belt number for this in the link)
I don't think so. For whatever reason I had a hard time getting the 96.8" belt on and got a 97.5" belt. It was good initially but stretched a little more than I would like. 96.8" is probably correct.
Yep, in So. Ohio about 100 miles east of you. Looks like what your picture shows is the best route for me. Not eliminating the whole deal, just the belt drive pump. Rebuilds are near $200 now and out of stock mostly. And the 1 year warranty doesn't give me a lot of hope either. Next step is to make sure the check valve is working like it should. Not sure how the electric pumps are set up for that, time for more research. I have an electric pump setup for a fourth gen that I'm hoping to use on this.
Looks like you'll need a 968K6. I deleted my smog pump using this guide when I got my car, old one had a bad bearing in it. No problems running this belt on mine, been on for 5 years now.
Getting the belt and a couple new check valves while I'm in there. Prices are kind of amazing these days. That Dayco belt was $63 at the local place that had it. Rock Auto had a really good price for both but their shipping is nuts. Went to Amazon and got the Dayco belt, two Standard Products check valves, and two new Fram air filters for about 80 bucks with taxes, free ship. Thinking I'll rig up the electric smog pump to the brake lights with a relay, that would have it running when it's most needed for drivability. I do wonder if the electric pump will do what the belt drive pump is capable of pressure-wise. We'll soon find out.
The electric LT1 pumps will make sufficient pressure to overcome the forward resistance of the check valves and deliver air.
Another option to power the pump might be to use the divert solenoid in the A.I.R. system. It is powered when the system is in open loop. Another power relay in that circuit might handle the electric pump.
Never thought about that. I'll do some research on that when I get to the wiring part. Thanks! A relay draws very little power to trigger it so that diverter circuit should handle it fine.
First stage of this figured out. The Dayco belt 968k6, now 6pk24605, or 5060968 is a perfect fit with the smog pump removed. The tensioner is about in the same position as stock. Do have to remove pump to get clearance for the new belt routing.
Got the pump mounted. I had spent a hour or so trying to get the big aluminum bracket off so I could cut off that bottom pump mount but those two inside torx head bolts just behind the rad. hose stopped that deal. Good thing actually since that cutout and bracket was a near perfect spot for the electric pump. >>>>>>Also a note here, all three check valves were shot, blow right through them in both directions. Pretty simple replace and not expensive.<<<<< I did eliminate the line down to the center of the cat.converter, after three replacement converters removing that fresh oxygen might make it live longer.
Got hose routed, now on to the wiring. The third gen wiring setup is sort of a mystery since the belt drive pump is always running, diverts here and there. Going to hook up a test light and check the operation of those two diverter circuits. Electric pump draws some current too, need a relay.
Final update on this. Got the new pump all mounted and plumbed, wired to a relay. Hooked up a couple LED test lights to the two connectors on the old diverter unit and took a drive. Couple surprises there. ECM energizes the green connector to the air diverter valve and sends air to the exh. manifolds after cold start for a couple minutes, then off and stays off. White connector then energizes the air select valve that - I think - sends air to the cat. converter. That flows all the time except when cruising at a steady highway speed. Otherwise air flow is exhausted to the silencer?
But one thing that surprised me is that the engine now runs perfect, smooth idle, no surging, fans on and off, AC compressor in and out, very good idle. I have to assume changing those check valves cured the actual problem I was having. I'm running the electric pump only on the cold startup directing air to the exh. manifolds.
But still can't believe the bad check valves was the real problem?
That is sure a big improvement with the A.I.R. and heat valve systems out of there. Need the heat up here though! I had an 85 Corvette with the same motor but the packaging was quite a bit different and that tuned port motor really looked good in that car.
Just picked up a nice 1989 with 305tpi. It still has the air pump installed (noisy) but all the air tubes are missing, the manifolds are plugged off and the cats (N10) air inlets are plugged off.
I want to remove the noisy airpump and spent a couple hours searching on this site but still have a few questions,
1. If I just remove the pump I can reroute the belt to work - Do I need a different (shorter) belt to do this? Possible part numbers, Dayco 968k9, 6pk24605, 5060968?
2. If I remove the pump per #1, and add the GM 10129569 smooth pulley it just helps stabilize the belt and really does not effect length?
3. If I remove the pump and add GM 10186167 grooved pulley, it simply replaces the smog pully and belt routing and length is the same as stock?
4. The air intakes on my cats (N10) are plugged, will no air going to the cats make them fail prematurely? Get plugged etc?
5. Does the ECM need to be revised to keep correct tune on the motor with air injection removed? How do I do this?
Go through this whole post to see what you need. Post #13 gives the belt specs if you just remove the pump. That secondary air injection in the cat. converter is not needed and might actually cause problems in the aftermarket converters. I went through 4 replacements and finally plugged this line off when I put the electric pump on and haven't had any trouble since.
Go through this whole post to see what you need. Post #13 gives the belt specs if you just remove the pump. That secondary air injection in the cat. converter is not needed and might actually cause problems in the aftermarket converters. I went through 4 replacements and finally plugged this line off when I put the electric pump on and haven't had any trouble since.
Thanks,
I removed the pump today. Everything else had already been removed and the pump was just sitting there for the belt to ride on and to make noise. Installed the 968k9 belt per the new routing and works like a charm! I may add GM 10129569 idler just to help fill the hole from the missing pump but not sure it serves any purpose? Might help stabilize the belt at high RPMs?
I confirmed through other sources that air only goes to the cats when engine is cold to help with quick heat up.
I removed the pump today. Everything else had already been removed and the pump was just sitting there for the belt to ride on and to make noise. Installed the 968k9 belt per the new routing and works like a charm! I may add GM 10129569 idler just to help fill the hole from the missing pump but not sure it serves any purpose? Might help stabilize the belt at high RPMs?
I confirmed through other sources that air only goes to the cats when engine is cold to help with quick heat up.
When I removed my air pump I went with the shorter belt, I don’t believe I had any issues at all there not being a pulley there. Having a air pump delete pulley would probably look better there though.
10-04-2022, 09:11 PM
