The Stovebolt Site Forums The Shop Area Engine Shop Noise question

My truck has started to make a very loud shriek noise when coming on or off the throttle. I thought my generator might be the culprit but it is not. Driving me crazy because it does it only in gear when moving, thoughts? Engine is ‘54 235 mated to SM420 nothing aftermarket.

Have you isolated it to being under the hood? Doesn't sound like a fan belt, water pump maybe? If not under hood could a brake shoe be hanging up, Pilot bearing/bushing? Vacuum leak?

Coming from underneath, nothing when it is idling, I am thinking something clutch/bearing maybe?

Does it do it when you're at a steady speed or just when accelerating or decelerating? A friend had a squeal when first starting to move, which turned out to be brake hardware hanging up (that was on a modern disk brake truck however).

At first it was start and stop, now continues but it is intermittent sometimes nothing then begins again.

I think I would pull the wheels and check out the brakes.

A stethoscope might help locate it if you can get it to make noise when truck is stationary. Definitely a two person job. Are you able to easily remove tranny cover in cab? Might help get a little closer to culprit.

Brad, I would be suspect of a harmonic balancer going bad

Remove the fan belt and start the engine. If the noise is still there then it's not the fan belt, water pump, generator and possibly the harmonic balancer.

Rick

Thanks I will follow these up and report back.

Reason being, I just went through the funny scraping noise thing after I put a fresh engine together. Quickly found the smoking gun, a balancer was starting to come apart, even though the way they are put together, there really is no way of knowing other than the odd noises it puts out. Youtube faulty harmonic balancers and you will get a gamut of sounds. May even recognize yours if that is the culprit.

I am going to pull the brakes, pull the belt and make a quick run around the block. I would have never thought about the balancer? Other than noise how do you check it?

They tend to wobble when they start to go bad. You can see it while its idling. When they wobble they also cause a vibration which you can feel.

Thanks Carl, at present I see/feel none of that?

Take the belt off and rev it up, or drive it up and down the street a short while so as not to over heat it.

my throwout bearing does this when the clutch isnt pressed for a long time, not sure why but if you press the clutch pedal down does it stop? if this is a serious issue let us know..

Mr Dane, I think this is it exactly. Pulled the belt, noise continued, pulled brake and nothing dragging or loose, shoes are 2 months old, as well as wheel cylinders. I was planning to convert my SM420 from closed to open as I have the correct ‘54 trans and driveline. In addition my flywheel is sharp and occasionally grinds before engaging, I have the correct flywheel(s) as well. So in we go!

So dropped the trans and related gear out. Interestingly I think loose motor mounts may have been contributing factors? I upgraded my truck when I first restored it to a ‘54 bell housing and crossmember (they were pretty loose), everything looks okay at first glance except the flywheel gear, throw out turns free, clutch disc and plate were dry. Anyone have a good tip for pilot bushing removal?

Google has a lot of shade tree approaches. I have not used any. Possibly your local FLAPS has a loner tool program that could help.

Pack the bushing with heavy grease, then put the input shaft (or other close fitting shaft) in and smack it with a mallet. The hydraulic pressure will drive the bushing out.

Find a piece of round stock (wood, steel, nylon ) which fits the pilot bushring hole without any wobble.
Fill the pilot bushing hole with axle grease.
Place one end of the round stock in the hole.
Give it a well-placed, sharp blow with a hammer.
The pilot bushing should pop right out.

If that doesn't work, you can tap threads in the bushing, then run a bolt through it until the end of the bolt contacts the back of the crankshaft.
Then you just keep turning until the bushing comes out.

Brad,
Not as messy as the grease, use a piece of bisquit dough (pillsbury grands) . stuff it in the bearing and hit it with a piece of round stock, wooden dowel , bolt, whatever fits. It will come right out and much easier to clean.

That's an awesome idea. I definitely don't enjoy cleaning up grease.
Back in the old days of plumbing repairs on copper pipe, we'd stuff a slice of bread up the pipe to keep drips away for soldering. Once the job was done, the bread would blow out a faucet. Kitchen stuff works in various applications.

The piece of bread trick no longer works very well, Kevin. Today's bread is so puny and gummy it will just dribble out at you. Today you need to use a bagel and a real bagel at that.

Real men relish grease. In fact, often as a substitute for relish on a hotdog.

Screw a tap into the bushing, and keep turning when it bottoms out. The bushing will walk up the tap and out of the crankshaft. I believe a 5/8" tap is the right size.
Jerry

Not nearly as exciting as the grease trick and avoids the grease eruption and subsequent clean-up that Carl apparently enjoys.

I don't recall the size of the bolt I used (std SAE bolt, maybe 1/2" or 5/8") but it was course threaded and would just start into the pilot bushing. I ran it in like a tap until it was fully threaded into the bushing then used a short crow bar and large screw driver to pry it out. It came right out. In hindsite running the bolt all the way in until it bottomed out on the crank and continued with cranking to walk it out sorta like HRL said to do with a tap just might have made it easier.

Once you drive the new one in test fit your tranny's snout into it before you install the clutch assembly, you may have to ream it out alittle.
And grease it liberally.
Good luck
Dave

Well Carl I got the grease. I picked this up for $8 at the local Flaps. Spun it in about 5 threads, a few pumps of grease later success.
https://www.flickr.com/photos/advance-design_parts_co/48746492258/in/album-72157631868452754/

As long as you got some grease on you, and it came out, I'm happy!
That's a cool tool. Price is right too. I would have spent 2.5 man-hours gathering up the right size dowel and then have to make a special trip to the store cuz I'm outa grease.