Odd question: Are our trucks supposed to sound loud?

[emil77]

I know, odd title, but keep on reading, hopefully I will explain myself.

I ask this odd question, because my truck is just plain loud. When I am driving, as it's attempting to shift into the second gear, the engine is really loud, almost like it's racing, then around 40mph, boom shifts into the next gear and settles down. Is this normal? Does it sound like this because our trucks are old, not much sound proofing, etc? I can't tell what rpm it's at, because I don't have a tachometer.

Now don't get me wrong, I love the sound of loud things. But is my truck normal?

[white71chevy]

Well yes and no. It depends on how high it is. Mine gets pretty loud around that speed but when it shifts its hard but not like wow u no wat I mean.
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[emil77]

Oh ya, I know what you mean. Mine sometimes shifts hard, sometimes it's smooth. I'm not worried about that yet, I know the truck is old, transmission is old, etc. I was just concerned about the "loud" sound.

[brn agn]

Something to consider: Do you have a direct cooling fan on your engine? I had one on my 69 and it was exactly like you described. In fact, one of my neighbors flagged me down and gave me a lecture for driving too fast (I was doing 25mph) and I think it was due to the loud fan and powerglide transmission...but I digress. I installed a newer clutch fan and it is much, much quieter.

[Stocker]

^ Ya beat me to it. I was thinking the roar of a fixed-blade fan. A clutch fan will be much easier on your ears, and provide better cooling to boot. And oh yeah, free up a bit of power and slightly improve your fuel mileage.

[emil77]

I don't know what kind of cooling fan it is. How do I tell the difference? Is the clutch fan install easy?

[brad_man_72]

clutch fan is a stock fan.
3 things to remember
if its loud it better be fast
if its low it better handle
if it has a wing it better fly!

[Stocker]

Originally Posted by emil77

I don't know what kind of cooling fan it is. How do I tell the difference? Is the clutch fan install easy?

With the engine off, you can rotate a clutch fan by hand. There will be some resistance, like it's mired in molasses. Clutch fans were OEM on A/C trucks, but many trucks came with a fixed-blade fan, which is rigidly attached to its pulley.

If you have basic mechanical skills, you can change to a clutch fan. You just need to get one that fits (diameter, depth, bolt pattern etc.).

A fixed-blade fan might look like this


A clutch fan will be more like this, with the fan blade assembly attached to the finned thermostatic clutch.

[72lb4x4]

I think if the trans is stock and its going into 2nd at 40, something is wrong. Maybe the shift linkage is maladjusted?

[yob2kanobe]

Check your vacuum modulator on the tranny. If this is bad or disconnected or a bad vacuum hose going to it the truck will shift exactly like you describe.

[emil77]

Does anybody have a picture of where to find the vacuum modulator on the transmission?
Once I find the vacuum modulator, how do I know if it's not functioning properly?