Smog Pump????
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Smog Pump????
Hey All,
I just aquired an 85 F150 51,000 original miles with a 302. It's pretty sweet. I went to check the oil as I just got it home and I saw a pump of sorts located where an A/C unit would be located. It's driven off a fan belt. Looks to be emissions related is this some sort of smog pump?
Also......
I've been driving it a bit with the sliding rear window open and I here a winding of sorts as well. Maybe 2000 rmp or so. Is this noise from the rear gear? Anyone know what stock gearing might be for that year?
2 - Wheel drive.
Thanks
-brian-
I just aquired an 85 F150 51,000 original miles with a 302. It's pretty sweet. I went to check the oil as I just got it home and I saw a pump of sorts located where an A/C unit would be located. It's driven off a fan belt. Looks to be emissions related is this some sort of smog pump?
Also......
I've been driving it a bit with the sliding rear window open and I here a winding of sorts as well. Maybe 2000 rmp or so. Is this noise from the rear gear? Anyone know what stock gearing might be for that year?
2 - Wheel drive.
Thanks
-brian-
Senior User
Joined: Jul 2006
Posts: 132
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From: Durham, NC
That is indeed a smog pump (aka "air pump") and is an emissions control device. Some people take it off, some leave it on. This varies on personal taste and local/state laws, combined with ones willingness to obey or disobey those laws.
If you are getting a whining sound that is based on RPM and not road speed, I would suspect the transmission not the differential.
You can figure out what rear axle ratio was installed by the factory by looking at this article:
https://www.ford-trucks.com/article/...r_Decoder.html
If you are getting a whining sound that is based on RPM and not road speed, I would suspect the transmission not the differential.
You can figure out what rear axle ratio was installed by the factory by looking at this article:
https://www.ford-trucks.com/article/...r_Decoder.html
Senior User
Joined: Jul 2006
Posts: 132
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From: Durham, NC
Forget that decoder link; it's only for newer trucks. It doesn't work on my truck. For example, I have an axle code of "15". Not even on the decoder. Transmission code is "T" but I don't think they offered an overdrive automatic in '81 (I think I have a C4 but haven't confirmed yet).
I posted a door sticker from my '81 F150 in my gallery to show the differences... I think that article needs to be clarified to show it's only for later model trucks.
I posted a door sticker from my '81 F150 in my gallery to show the differences... I think that article needs to be clarified to show it's only for later model trucks.
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Thanx Swamp Fox.
Advantages to taking the air pump off? Seems to me like this engines got to breathe!!!!!
And I guess the whining could be the trans but just maybe road noise. Although I must say it sounds mechanical. And seems to far back to be the trans. Humm.... I'll have to have a closer look.
Thanks
-brian-
Advantages to taking the air pump off? Seems to me like this engines got to breathe!!!!!
And I guess the whining could be the trans but just maybe road noise. Although I must say it sounds mechanical. And seems to far back to be the trans. Humm.... I'll have to have a closer look.
Thanks
-brian-
Senior User
Joined: Jul 2006
Posts: 132
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From: Durham, NC
The air pump puts a parasitic load on the engine as it is driven by a fan belt. Most people seem to think it doesn't hurt performance or fuel economy at all but I have yet to see any imperical evidence on either side of the argument.
As for the whining noise, last time I ignored it, I was out $1800 for a transmission in my Jetta. It would be worth tracking down, IMO.
As for the whining noise, last time I ignored it, I was out $1800 for a transmission in my Jetta. It would be worth tracking down, IMO.
Post Fiend
Joined: Jul 2004
Posts: 8,786
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From: Northern California
Originally Posted by armantanzarian
Advantages to taking the air pump off? Seems to me like this engines got to breathe!!!!!
Only advantage in taking it off is to free up some horse power. IE: The horse power being robbed from the engine to drive the pump. Make sure you plug the ends of the hoses you remove.
Disadvantages, your state may not let you register your vehicle if the pump is not on the truck in proper working condition. This varies state to state, but California is the worst offender. Be warned however, other states are starting to follow California's examples.
It's also against federal law to tamper with or remove the smog devices in all 50 states. But it is seldom inforced, in non smog controlling counties or states, and there are exemptions etc...
Senior User
Joined: Jul 2006
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From: Durham, NC
NC only does emissions tests on vehicles 1996 and newer. But they are still supposed to visually inspect to make sure that the smog pump is there, hooked up, and appears to be running (as well as other pollution control devices like the catalytic converter)
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What kind of tranny do you have, auto or stick. A manual tranny will whine when it is low on fluid, the rear axle may also whine if low on fluid. May be a carrier bearing or pinion bearing going out as well.
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The trans is an automatic, not certain which one but, the whining noise is really wierd. There is certainly "some" road noise but this is different altogether it seems with the sliding rear window closed it could be the trans but with the window open is sounds like it further back. Rear diff. but then the sound could just be bouncing around the bed. I'll have to have a closer look this weekend.
Thanks All.
-brian-
Thanks All.
-brian-
Post Fiend
Joined: Jul 2004
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From: Northern California
The sound could be traveling up or down the driveline.
There are two drain holes on each rear cab corner. The sound may be coming up from there with the window shut. Especially if the truck has the Reduced sound package.
Something to possibly consider.
Check the oil levels in the rear end. Make sure it isn't leaking. etc...
Transmission mount? U-joints?
Shocks.
bushings.
I'd check all that stuff as well while doing an inspection of the tranny.
Give it a good lube job with a grease gun as well while under the truck. Couldn't hurt.
There are two drain holes on each rear cab corner. The sound may be coming up from there with the window shut. Especially if the truck has the Reduced sound package.
Something to possibly consider.
Check the oil levels in the rear end. Make sure it isn't leaking. etc...
Transmission mount? U-joints?
Shocks.
bushings.
I'd check all that stuff as well while doing an inspection of the tranny.
Give it a good lube job with a grease gun as well while under the truck. Couldn't hurt.
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
Originally Posted by kermmydog
They started using air punps in the 70s long before Cats. An air pump injects air on the exhaust valves.
The first record that I can find for the smog pump was in the year 1975, for the 1976 California F-100s, this truck also had catalytic converters, and burned unleaded gas.
Called a Thermactor System.
Air from the pump goes to a thermactor air bypass valve. This valve vents air to atmosphere during certain conditions such as Idling or decelerating.
When air isn't being bypassed, it goes to the thermactor air diverter valve. This valve when the engine is cold, when first started in the morning diverts the air into ports in the exaust, for aid in warming the truck engine, and aid of burning unburned fuel in the exaust manifold during the choking process.
When the truck is at normal operating tempurature and the air isn't being bypassed, the air gets injected into the exaust close to one of the catalytic converters, if not injected right into the catalytic converter itself. This helps the converter in the catalyst process.
If you have more info about a air pump system without Cats, I'd love to hear and learn about it. I can't find any info for one however.
