97 GMC Jimmy revs up

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buckswife

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93 GMC Jimmy revs up while driving and while in park. Vehicle doesn't speed up but it sounds like it is revving up really high. It doesn't have an rpm gauge so I don't know how high but by the sound, it makes me think it would be close to red lining. Changed TPS but no difference. Any help would be appreciated.
 
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buckswife said:
93 GMC Jimmy revs up while driving and while in park. Vehicle doesn't speed up but it sounds like it is revving up really high. It doesn't have an rpm gauge so I don't know how high but by the sound, it makes me think it would be close to red lining. Changed TPS but no difference. Any help would be appreciated.
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You could have a faulty fan clutch if there is no any other issues like transmission not shifting ect.

Good luck and keep us posted.;)

Molson02536
 
That was quick! Thanks~ No problems with transmission shifting, but my hubby recently replaced seals because of leak. We were thinking maybe a sensor, but we will definitely check into the fan clutch. Thanks again
 
The fan clutch is very hard to turn at all by hand. I know it isn't supposed to freewheel, but it's very difficult to turn. Could it be a sensor?
 
buckswife said:
The fan clutch is very hard to turn at all by hand. I know it isn't supposed to freewheel, but it's very difficult to turn. Could it be a sensor?
Click to expand...

The fan clutch is a viscous type clutch and has no sensor. The fan clutch sounds like it failed in the stuck on position. This type of failure can also decrease fuel economy, and at worst,a fin can break off and fly into your radiator.

You can inspect this by starting the engine with the hood up and watching how much air the fan is pulling from the radiator. The fan should be pulling in air at low rpm and as you raise the engines RPM, the clutch should disengage the fan in till the radiator starts to throw off heat.

The heat of the radiator will cause the viscous clutch to engage and you'll hear the roar of the fan again, if the fan never disengages, then your going to need to replace the fan clutch.

OE clutch is an AC Delco 15-4684 thermostatic control, reverse rotation, with A.C. Those are more expensive then the Hayden fan clutch but they will last many more years. Both will do the job, the OE will out last the non OE fan clutch.

Good luck and keep us posted.

Molson02536;)
 
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