Serpentine Belt Problems

[Opie Knievel]

I'm having another problem with my '88 GMC K1500. A lot of you guys remember it. I've got an entire thread dedicated to the many problems it's given me in the last couple of years. After replacing all of the gaskets on the engine and all of the steering components except for the box recently, I thought it was ready for the road. I should have known better. Every time I spend a few hundred bucks on this truck, something else screws up.

Yesterday I heard a loud squealing noise from under the hood. I popped the hood and could instantly tell that the AC compressor pulley was the source of the noise. At the time I had to make a short trip, I didn't have anything else to drive and I couldn't just not go. So I made the trip and headed back home. Right as I was getting ready to pull into my driveway the belt came off. At least it didn't leave me stranded miles from home this time. I popped the hood and gave it a look. The belt had a thin sliver cut off all the way around it and that had wrapped itself around the base of the fan. The rest of the belt was wadded up in the pulleys.

I got an AC bypass pulley to replace the compressor that didn't have AC lines running to it anyways and I don't really care if I have AC in the truck. After putting the new pulley on I put a new belt on and fired it up to see if that fixed the problem. It didn't. The truck doesn't idle until it's warmed up. I turned the key, it started and idled for a few seconds and then died like it always does. I took a look at the belt right after that and I could see that it was already walking off the back of the crank pulley. The side closest to the engine.

Now I'm puzzled. I don't get why it's trying to throw the belt again. The pulleys seem to be in line and turning freely. Does anyone have any ideas? The truck has a 350 with the old steel bracket serpentine setup on it.

 

[pontiacgp]

are all the pulleys lined up?....I have that system on my GP and no issues with the belt

 

[fleming442]

It sound like your bypass idler isn't in line with the drive. I'd look at that first since it's the last changed. It also sounds like you had a problem before, though. A Harry Homeowner handheld laser level gives a nice straight line to check for anomalies.

 

[tc1959]

Is the steel bracket cracked ?

 

[joesregalproject]

Is there any play in any of the pulleys?

 

[Opie Knievel]

I went back and took another look at the truck. I found the problem. The harmonic balancer is moving forward on the crank. The crank bolt is stripped out and the balancer is slowly working it's way forward.

Can the crank be drilled and tapped to a bigger size reasonably easy or should I just rob the crank from another engine?

 

[pontiacgp]

What about using a helicoil to repair the crank

 

[olds307 and 403]

Either a Heli coil or tap to the next size larger. What parts have you tested or changed for the no idling problem?

 

[joesregalproject]

I'd go for a helicoil or a timesert. I certainly wouldn't be tearing a crank out if I didn't have to. I'd also carefully inspect that harmonic balancer to make sure it wasn't the reason the thread stripped and/or it didn't get damaged due to the thread stripping.

 

[Texas82GP]

I went back and took another look at the truck. I found the problem. The harmonic balancer is moving forward on the crank. The crank bolt is stripped out and the balancer is slowly working it's way forward.

Can the crank be drilled and tapped to a bigger size reasonably easy or should I just rob the crank from another engine?

I've never done it but the crank is cast iron so it shouldn't be problem to drill it. I've seen crank snouts drilled to 'pin' the balancer to them on modern setups that don't have a keyway and where a super charger is being added so I don't think it would be a big deal. Like others stated, I think I would try a helicoil repair. Probably the biggest pain will be getting everything pulled out of there to give you enough room to get the drill in there. Good luck with it and let us know how it turns out.