My 1997 Dodge Ram 1500 with a 5.2 L. /318ci. is making a strange high pitched noise from the engine bay. This noise starts only after the engine has warmed up and quiets down somewhat at a higher RPM. I have checked all belt driven accessories with a stethoscope, applied a shot of belt grip to the serpentine belt and checked for a defective harmonic balancer but have drawn a blank. Only the cooling fan clutch has not been checked. Also, I noticed that the temperature gauge floats up and down a bit when the engine is fully warmed up. What have I missed?
That could mean that the clutch fan is the problem.
Remove the fan while the engine is cold and take it for a quick drive. If the noise doesn’t come back…it’s the fan clutch.
Thanks for the advice. Based on some other info, I tried spinning the cooling fan blades both cool and after warm up. The blades spun easier when cold but were stiffer and harder to spin when the engine was fully warmed up which seems to indicate that the clutch is working properly but I’ll try out your suggestion to confirm this result.
I have found noisy water pumps and idler pulleys on these trucks.
Belt dressing on a serpentine belt will make a lot of noise. When a vehicle comes in with belt dressing causing noise the pulleys must be cleaned and the belt replaced.
Have you run the engine with the belt off to verify that this is a belt/pulley noise?
Thanks for your reply. I knew that belt dressing on a serpentine belt was not advised but I only wanted to hear if it would make a difference in the squeak/squeal (it did not). Using a mechanics stethoscope I purchased at Harbor Freight, I didn’t detect any noise from any belt driven accessories (alternator, water pump, idlers, etc.). As the last piece of the puzzle, I will next remove the cooling fan/clutch and run the engine briefly to check for the squeak especially since the temperature gauge floats up and down a few degrees at full warmup. Thanks again for your input! By the way my 97 Ram has only 85K on the clock.
Next time that you want to put anything on a serpentine belt…to see if a noise goes away, or continues. Dribble a little water on the belt.
If the noise goes away…you know that the belt is affected, and the water will evaporate very quickly.
If the noise continues then most likely you have a bearing problem.
Thanks for the tip. I’m leaning toward replacing the cooling fan clutch but since it’s getting a little frosty here and I only use the truck infrequently, I’ll wait for a warmer day or spring!