I HAVE A 1999 CHEVY S10 TRUCK W/5-SPEED MANUAL TRANS.
What I have noticed was occasionally while driving downhill, the engine RPMs run high. This occurs when I am not using the gas, but the clutch is in, and I am using the brake. Usually, this lasts a only a second or two it just sounds like the pedal is pressed and it just dies off to idle.
Now that alone is not a big problem, but recently this happened but much worse. The RPMs went sky high and to me seemed higher/engine louder then it usually goes, they engine speed was getting too high for comfort, so I just shut her down and coasted into a parking spot.
This truck does not have a tachometer so I can’t give an numbers out.
Other then these occasional downhill episodes, the truck runs just fine.
The only things not standard to the factory parts are a few vacuum hoses and fog lights.
Thanks for any advice!
Why are you riding the hill down with the clutch in? Your over using the brakes, and risking serious injury if the brakes overheat and fade out. Once that happens, you have NO BRAKES AT ALL!!! The engine RPMs are probably going up as the power brakes are sucking more vacuum for power. Now, the power booster maybe has a leak.
Use the engine drag with the clutch out to control your speed down hill. Downshift if you need to keep the speed from rising. Your not hurting the engine at all, and could save some fuel, since the engine needs a bit of fuel to keep idle, but will cut the fuel when the RPMs are higher than idle, and your foot is off the pedals.
The only things not standard to the factory parts are a few vacuum hoses and fog lights.
Odd vacuum could be a problem. Why do you have non standard vacuum lines?
That said, I agree with Busted on this one. Why would you not use engine braking?