I know it's better to keep the emissions stuff in place, but the truck gets about 3000 miles a year and the tube rusted off of the exhaust pipe like they all do. I'm not paying $80 for a steel tube. It's been running fine for a year with a bolt welded into the exhaust to plug it.

Removing the smog pump would be one less bearing to worry about freezing up when I need the truck to run. I've seen people talk about doing it but has anyone actually gotten the belt length for '87-'91 I6, no air conditioning, with smog pump delete? It just looks like more wrap on the alternator and a little less on the water pump. Anybody have any issues with short belt life? Am I better off just putting new bearings in the smog pump and running it as an idler pulley?

I'll just take a fishing line or floss and measure if nobody has the length.

 

In case anyone is interested for reference. The stock belt on the truck is 97 inches long. An 81 inch belt fit but it's just a little long, the tensioner is right at the end of the indicated range. An 80.5 inch belt would be better if you could find it.

 

my tube broke off @ the cat so i hacked it off at the little filter thingy near the smog pump and now i wanna get rid of it totally...any idea for a belt size for a 93 300 w/ AC??

 

Don't know for sure, since I don't have A/C... What I did was just take some wire that doesn't stretch (regular insulated wire, 16 gauge or whatever is laying around) and wrap it around the pulleys where you would want the belt to go. I tried fishing line and floss first but those both stretch too much. Leave the old belt on so you can see where the tensioner pulley sits. Then just measure the length it took to wrap and you've got a ballpark figure. Then just go to the store with a 5/8 socket and breaker bar to release the tensioner, get a belt that's close and try it. If it's too long or too short you'll see right away. After you put it on look at the tensioner. There's an indicator on the top where the pointer needs to be between the two marks on the other piece of the tensioner.

You can just gut the pump and put new bearings in it to use it as an idler too if you can't find the right length belt... I welded my hose fittings shut and threaded and plugged the holes in the back with bolts to keep the weather out... That way if this shorter belt gets thrown or something I still have the old one in the cab I can put around the pump.

 

I had to bypass a smog pump while out of town once or burn up the belt.
I took the old belt an looped around how I wanted it while a helper held back the tensioner. At the simplest point I put a fold in the belt and clamped Vise Grips on it. Checked the length by easing up on the tensioner a little-not completely. Took 3 or 4 tries but but when I took my "sample belt" to the parts store they were able to match up with one that worked on the first try.
It was six months before I got around to actually replacing that smog pump. Still got the bypass belt as a backup. This was on a different vehicle, so sorry, can't help with the exact length.

 

how did your smog bypass work? i did a smog/egr bypass on a 91 f250 i had with a 351 but sold the truck before i could really test long term effects on power, fuel economy, dependability, tuning, etc. has it changed the way your truck runs for the worse or the better? and what size bolt did u use in the head for the "keep the weather out"? thanks