Strange popping/slipping when under load (1 Viewer)

cbmontgo

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Two times now when I am driving up a loooooong hill, the FJ40 will "slip" or "pop" when under load. The first time it happened, I could swear that I smelled burning rubber. My clutch seems solid, and the engine runs great. It rarely does this. Any ideas?

100% original engine and drivetrain, by the way.
 

65swb45

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WAG only. Bearing starting to stick in air pump or alternator, causing a fan belt to drag.

:meh:
 

John Smith

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It does not have air conditioning. What is WAG?

So you guys don't think it is clutch-related?

Thanks--

WAG = Wild Ass Guess

No, I doubt it is clutch related. Follow Mark's advice and check the smog pump. Mine did the same thing right before the bearings seized. The "slip or pop" you hear is the belt overriding the pulley and the rubber smell is from that rubbing.
 

cbmontgo

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WAG = Wild Ass Guess

No, I doubt it is clutch related. Follow Mark's advice and check the smog pump. Mine did the same thing right before the bearings seized. The "slip or pop" you hear is the belt overriding the pulley and the rubber smell is from that rubbing.

Thanks, John Smith. What would cause this to happen when the vehicle is under load instead of just normal driving?

It really makes the whole truck "buck" for a split second. I am surprised that a bearing could do this, but I guess it does make sense.
 
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Check and tighten your fan belt so we can try to rule this out. The couple times I have seen a bearing freeze there was a loud screech from the frozen pulley.
Can you recreate this if you go up the hill again?
It couldn't hurt to check the color and condition of your spark plugs.
 

John Smith

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Thanks, John Smith. What would cause this to happen when the vehicle is under load instead of just normal driving?

It really makes the whole truck "buck" for a split second. I am surprised that a bearing could do this, but I guess it does make sense.

The high RPM load puts more stress on the bearings than if they were just spinning at idle. Once you open up the smog pump you will probably find the bearings full of carbon, ready to fail at any moment.
 

cbmontgo

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Just replaced the belts with OEM about 2 weeks ago (maybe this has something to do with the problem?) and the tension is fine. Plugs are good. New wires, rotor, cap, etc about 3 weeks ago.

I could probably recreate the issue, but it has only done this twice in the last week or two.

It still seems to me that a bearing going out would make noise, but wouldn't shake the truck like this. Hmmm.
 
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The only thing I can think of is the carb. base getting too hot on this hill. If this is stock exhaust then check the thermactor, (I think that's it's called) that spring operated exhaust valve.
 

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