The belt driving my smog air pump broke this weekend on a camping trip. The vehicle is a 1982 class C motorhome with E-350 dually rig, 460 with a Carter carb. I think the air pump locked up, then the drive pulley ate through the belt. I had a replacement belt, but since I would've had to remove another belt or two I just got back on the road and did another 150 miles. The air pump is almost impossible to turn, so I think something's seized up inside. I figured the diverter valve would keep the exhaust gases out of the pump.

Looking up the cost of a new smog pump, it runs about $80. Should I even bother, since I'm in Wyoming and we don't do emission checks? If I did the replacement, should I replace the valve too? The rig has about 82,000 miles on it, and I think this is the original equipment.

 

Survey sez: fuggetaboutit!

Engine compartment is much cleaner w/o all of the air piping in there as well.

 

Being somewhat lazy, I wasn't planning on taking anything out until I needed to. That is, as long as I won't get exhaust fumes back up the hoses.

I am assuming the thermactor is something like a sliding vane pump rather than a centrifugal fan - therefore it acts somewhat like a check valve too. True?

 

Yes, correct. And I want to say that there is at least one check valve built into the system, but I would have to look at the factory manuals to verify that.

 

Thanks for the replies, redmond. Since I might be upgrading to a more modern motorhome in a few months (hope I get $$ bonus instead of a jelly-of-the-month-club subscription), I don't want to start tearing out smog equipment that a new owner might need. Since my van's engine doghouse isn't hermetically sealed by any stretch of the imagination, I just don't want to have exhaust fumes sneak back up the hoses.

I found a schematic that shows a Ford thermactor pump as a 3 vane sliding pump, but also found a few references to a centrifugal air pump design too.