Roaring Sounds 1985 Nissan Pickup

My 1985 Nissan 4x4 pickup seems to have roaring sounds coming from the engine. It seems to correspond with the rpm going higher. It happens on and off but when I drive it hard or accelerate fast and raise the rpms quickly the roaring starts. One time the idle speed was excessively high in conjunction with the roaring sound and I had to play with the idle to get it back down. Any idea what is causing the roaring?

Radiator fan?  

What is the RPM during this event?

The RPM is usually around 2000 to 2500 when it is really loud. It gets louder as I accelerate and then when I shift into the next gear the sound gets a lot quieter. Also, when I push in the clutch and the rpms immediately drop the sound almost dissapears.

The noise might be caused from a defective radiator fan clutch. With the engine cold, open the hood and try spinning the radiator fan by hand. The fan should spin at least one revolution. If not replace the fan clutch.


The noise sounds similar to a semi-truck when it is in a low gear and accelerating. You know…that roaring sound.

One other thing I forgot to mention is that the battery light has been coming on and off ever since I’ve had the roaring problem but the battery has never died or failed to start the car.

I spun the fan by hand it wasn’t super easy to turn but I could turn it many times. Maybe not the fan clutch? The noise is super loud and I don’t know if the fan could make that loud of a noise.

The fan should be easy to turn. It sounds like the fan clutch is defective.


Thanks for the help. I’ll replace the fan clutch and see what happens.

Some of the Japanese cars and trucks of the eighties used to have a funny air system connected to the air cleaner housing. A stuck check valve or a disconnected hose may be letting the noise out. I know that is way too general a statement, so have fun with it.