Engine sounds like it's revving very high at only 45-50 mph

[davidwhitaker]

Driving down the road at 70mph for several hours and all of sudden the engine "sounds" like its racing at high RPM. Almost like it slipped into neutral or lower gear. I first thought that accelerator was stuck but as I exited the freeway and got down to lower speed, everything seemed fine. So I checked everything out and continued back to freeway.  It shifted into 2nd and then 3rd no problem but now the engine seems like its racing at extreamly high RPM but I can only go about 45-50MPH.
My tach reads 2500-2800 rpm at 45-50mph but it really sounds like its winding out at about 4000RPM.

Anyway, I finished my trip for 3 more hrs at 50mph.

Does this tranny have an overdrive that stopped working or what???

Does anyone know what tranny I have?
79 - 440ci Brave

[legomybago]

Sounds like another clutch fan froze up to me....

[HandyDan]

When the fan comes on, it will sound like a jet taking off.  Just the clutch on the fan doing it's job.  Check your temperature gauge and see if it doesn't drop a little when the sound quits. 

[legomybago]

Pull the doghouse cover and drive it. look and listen for the unusual sound your hearing.

You have a 727 Torqueflite Transmission with 3 speeds.

[davidwhitaker]

I was actually suspecting the fan after a while. Because everything seemed to be operating normally...beside the loud engine noise...or fan noise.
The temp gauge actually dropped after the sound started...but I was also driving slower and it got dark and temp outside dropped 15deg.

It shifted into 3 gears just fine, and the kick down works ok too.
I drove it with the cover off and it did seem like the fan was running faster....

So do you think the fan clutch froze up or something???

[davidwhitaker]

Sounds like another clutch fan froze up to me....

Never mind...I see

[jeno]

If it's the fan clutch why would the mh only go 50 mph now?

[davidwhitaker]

It will go faster than 50mph, But the motor sounded like it was running too fast...it makes sense that it "sounded" like it was running faster than it really was. The fan must have be running with the engine speed instead of at reduced rate.

[legomybago]

Reach in there and see how the fan feels, should feel like dragging peanut butter when you spin the fan by hand. Wiggle it front to back too, should not be any movement (a tiny bit front to back is norm). Get them hands dirty son!
We were just talking about this subject the other day, and a lot of people are thrown off guard when the engine fan kicks on, people aren't used to that type of engine sound.

[davidwhitaker]

I will have to check it when I get back to deer camp. (I left it there for the season). So what your saying is, it might be working properly and when the fan actually engaged it made the engine sound much louder?
That would also make sense as I had been running at about 220deg for a couple of hours and after it started making the louder sound, the engine actually cooled down to about 190deg.

As I said, everything seemed to be working OK expect it sounded like the engine was going to blow above 3000rpm.

[JerryP]

Had this exact same thing happen to me a couple of weeks ago, This forums members nailed it with the fan clutch locking up. scary aint it.  I thought I had blown something up.

I was looking at the fan the other day, and it has a lot of pitch, so fully locked up, I have no trouble believing it would be just as they describe, as it has a higher pitch than my plane prop

[legomybago]

Well, if your running a constant 220* going down the road, the fan is just trying to doing it's job. Your running to hot. The fan cools you back down to 190*. It sounds like you have some other cooling issues going on. Might be due for a radiator? Thermostat? Who knows..

Read up on what/how a clutch fan works on the web, then compare that info with what your rig is doing.

[davidwhitaker]

Sorry for the delay. It ended up being the fan clutch. Thanks for the help.