So earlier today I was cruising right along on the highway in my 91 F150 5.8, everything's going smoothly, I'm enjoying the breeze with my 2/55 AC system, and then all of a sudden.....SQUEEEEEEEEEEAAAAAAAAALLLLLLL!!!!!! The loudest, non-stop squealing I've ever heard from an engine.

So I pull over (having just finished a service call for work not 15 minutes earlier, I might add), pop the hood and find that my smog pump is locked up solid, causing the wretched screaming that's now deafening an already hard-of-hearing individual such as myself.

I shut off the engine... Well, now what? ... After a few moments of staring blankly at the engine, trying to decide if I should call for a tow truck or at least a ride back to work, I get an idea.... but wait, those almost never work out! But I decide to try it anyway....

I remove the belt from the smog pump, leaving it otherwise routed normally, and slowly let off the tensioner... it seems to bottom out, but there's tension on the belt! Just barely (and by barely, I mean at least 1.5" of free play in the belt), but it's there!

I hesitantly turn the key - as expected the engine starts, and for a moment, the squeal is there, but not nearly as bad. I look at the belt to find that the smooth side is now lightly rubbing against the smog pump pulley, but everything else seems to be turning normally!

I shut the hood and cautiously pull back onto the road, hazard lights... hazarding... and very closely observe my gauges... ... voltmeter, normal.... ... temperature, holding steady... ... oil pressure... pfff! That gauge hasn't worked in a year! And besides, the oil pressure gauge doesn't run off the s-belt, dummy!

I managed to get back to work (and along the way, stop by the parts store and order the new pump as tomorrow's project ), finish my day, and drive home - all with the s-belt routed off the smog pump! The alternator, water pump, and power steering all worked just fine! I checked the belt when I got home and I'm gonna replace it anyway just to be on the safe side, but there's hardly any wear on the smooth side of the belt. It's obvious where it was rubbing against the smog pump pulley, but otherwise my truck ran "completely normal" with the belt routed that way.

I'll try to get some pictures before I take it apart tomorrow, but I just thought it was really interesting that my truck ran normally with the belt routed that way. I never would have expected enough tension on the belt to make it happen.

 

Very interesting indeed. I have to remember this & see if it works on other engines like my 5.0L

 

Yeah, I think the set up of the pulley's and it being the smog pump is the only thing that made it possible. I don't think any of the other pulley's failing would have allowed for it to work....










Like I said, I'm gonna replace the belt anyway just to be safe, but it (surprisingly so) held up very well and even though it's obvious it's been rubbing, it doesn't look damaged.

 

My A/C compresoser siezed up on me on my 92 with the 5.0. MY truck wouldn't even turn with the belt still in place, yet when I tried to bypass the compressor , the belt was way too long. I then tried to buy a shorter belt, but that deemed impossible. after trying several belts in the O'reilly's parking lot I finally gave up and drove the mile or two to my bosses house and stayed the night.
I then found out from another O'reilly's store that I could have bought a a/c bypass pully and remove the compressor all together. Which by the way is still in place after around 8 years now.

 

I don't have anything against bypassing systems you don't use, but as this truck is my DD and much of my driving is in town, I like having my stock engine, and I enjoy the (are you ready? Here comes the debate.....) fuel efficiency the AIR injection system gives me. I read posts on here all the time about guys deleting their emissions systems and then getting upset about the 8-10 miles per gallon that results from it. I've left this engine stock since I bought it (except for components that needed replacement, such as my water pump and smog pump) and in that time I've maintained 13-16 mpg (empty of course - hauling/towing is naturally less) with 180k on the odometer.

 

The AIR pump is only needed if you have a catalytic converter; it's purpose is to add fresh air to make sure excess fuel is burned continuously and doesn't build up in the catalytic converter (new motors don't have AIR injection since the ECU can better control the air fuel ratios). It doesn't help with fuel mileage like the EGR system does which most people delete at the same time. I've been running without the AIR pump for over 3 years now, but I left the EGR in place and have seen no change in MPGs.

 

Fair enough. I didn't know the exact purpose of the AIR injection system, I just knew it was emissions related. I do still have a cat though, so no reason to delete it anyway.