1993 big block 454 7.4 l V8 intermittent screeching belts especially when started now a loss of power

Hi yall. You

are my favorite group of people on earth. Hope I got an easy one.

I have a 1993 big block 454 that has a belt squeal that went away and now I have really sluggish acceleration and it sounds like the RPMs are really high when I’m going 50 mph. At low speeds the acceleration is fine. But at high speeds it’s sluggish loud and high-pitched almost as if it’s in limp mode. The belt used to Screech as soon as it turns on. (Tiffin Allegro Bay class A). I’m hoping you all are willing to help guys give even though it’s a motorhome. I have a screen grab from a vid at least that will tell you a lot I believe because you can see one of the v belts the one towards the bottom of the image that looks bent whipping around.

I know you guys will have some great advice with your god-like car intelligence.

The only other thing that correlates would be me having done a hard reset as in I disconnected the battery entirely for several hours and cranked it a few times draining the power and that’s when the belts didn’t squeak anymore or at least as much but it’s when I noticed the actual drive and power issues. Before the squeaking died down and I had the issues it would go away entirely for perhaps seven or eight seconds and then come back on again it was pretty regular as I would drive.

Belt noises? If you say belt(s) are new and tensioner is new then I’d wonder what was up. Loss of power? 1/2 dozen things. Coil pack. Ign module? Dying motor? Who knows from afar.

That belt drives the air pump


The air pump introduces air into the exhaust to light off the catalytic converter.

I’d check if there;s something wrong with the air pump.


Hmm, if air pump has failed, could the catalytic coverter(s) be fouled/clogged producing the sluggishness at higher speeds?

Isn’t saying Big Block 454 7.4L V8, just a bit overly redundant?

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Seems like the first thing to do is solve the belt-squeal problem. Sometimes the particular belt can be ID’d by using a spray bottle to spray a little water mist on each belt, one at a time. If the squeal goes away, problem is with that belt or something on that belt path. I have a Corolla of similar vintage. It developed an alternator belt squeal one time. I fixed it by tightening the belt a little. No automatic belt tensioner w/that car’s configuration.

In your case the belts and tension may be ok, but one of the accessories is failing and placing an add’l load on the engine. A/C compressor, P/S pump, Air pump, roughly in order of likelihood.

Any cooling system servicing lately? If so, sometimes that can knock cooling system deposits loose and cause weird noises from the water pump. Usually when that happens on my truck’s 302, the water pump is about to fail. Ask shop to check for any unusual play at water pump pulley.

The note on that belt arrangement image appears to say 1990 to 1994 A.I.R. pumps were eliminated. Hard to read. This is a 1993 so it may not have an AIR pump.

Regardless, that belt is clearly running out of the normal path indicating it is either severely loose or there is a huge load on it. I’d remove that belt and turn any of the accessories it is driving to see if they are unusually hard to turn. If something is loading it down enough to cause that amount of slack, it could easily put a significant load on the engine as well and act like a big loss of power…big motor but also big rig so it won’t take much to be noticeable loss of power.

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Thanks for everyone’s reply I was able to do the paperclip trick and jump the diagnostic connector to find out that I had codes 81 and 82. It seems to indicate that I’m in limp mode or at least that those two solenoids the A and B solenoids aren’t firing. I am going under to check the pins on the side of the transmission the resistance and all that but if there’s anything you guys can think of that this sounds like let me know. I’ve ordered a new belt too for good measure.