The Stovebolt Site Forums The Parking Lot Big Bolts Strange knocking sound

I won't be doing anything with this till spring, but wanted to get some ideas. It's on the '59 Viking 40 I just got.
I got the 283 running, and it actually runs quite well--sat there and idled as nice as could be. But when I drove it around the yard it sounds just like a rod is knocking. I assumed the worst and that the engine was knocking because it was now under load.
I mentioned this to the PO and he and his brother both said , "it's not the engine--it's the transmission--it's done that for years."
So I'm thinking--"how can I put the engine under load without the transmission turning in order to test this?' So I drove it up against a big oak tree and lugged it down. Even killed it once. No knock! So apparently they were right. It must be in the transmission or drive train somewhere.
I haven't driven it out on the road yet or at high speed, since it currently has no brakes. Just around the yard in first and second gear. It also does it in reverse.
As I mentioned, it's getting too cold to do anything more with it now, as it won't fit into my shop. We'll look into it in the spring. But just wondering if anyone had any idea as to what might be going on in there.
Thanks in advance!
Sorry this got to be so long!

Does this rig have a transmission mounted park brake?

Your U-joints could be bad causing a snapping sound. To check them chock the tires so the truck can't roll, then release the parking brake and put the trans in neutral. Now slide under and twist the drive shaft back and forth and see if there is any slop in the U-joints.

You shouldn't have to wait till spring to make this simple test...

Mike B

It does. I used it when we were towing the truck home, as the other brakes are not yet working.

Mike, I'll try and get under it one of these days and double check those U-joints. I was under there once, and they didn't seem too bad, but probably worth checking again.

Jack up both rear wheels and support the axle tubes with heavy duty jack stands. Start the engine, put the transmission in gear, and listen for the noise. Then carefully inspect all the moving parts to see if you can locate the noise. Stay well away from the moving wheels if you choose to crawl around under the truck.
Jerry

All good recommendations, but I like the KISS principle. A loose transmission brake can make a lot of noise.

Just curious, what's your oil pressure. I would suspect U-joints also. Mine is 160.5" wheelbase with 3 piece drive shaft and two midship bearings - lots of chance for noise in this set-up.

Just as a follow up to this--I didn't realize this at first, since the truck was making so many other noises, but I eventually realized that it was making the noise even while standing there idling. It goes away when the clutch is depressed and starts up again when you let the clutch pedal out.
It's currently up at my mechanic's shop getting the brakes fixed. He has driven it and listened to the noise. His opinion is that the input shaft on the transmission probably has a chipped gear on it. He also suggested that for as little as I will be using the truck that I could probably just run it as is. Not sure I want to do that, as the noise drives me crazy! Plus, I don't want to risk doing any further damage. So at some point I will probably have to deal with it. I may have a lead on a different transmission or two and may eventually end up replacing or repairing it.
Anyhow, just wanted to update.

When I bought my current '65 C20 in 2015, it made a noise that drove me nuts. I replaced this and that with parts I had on hand, and it still did it. I deduced it down to transmission bearings. More so, the front bearing. Rebuilt the transmission, the kits came with new bearings, and the noise was gone. The noise did go away when the clutch was depressed, but was there when driving, idling, coasting, as the input shaft kept turning. Depress the clutch pedal, the input shaft stopped turning and the noise went away. Granted this was in a Saginaw 3 speed, not an SM420 or anything heavy duty, but you should be able to get replacement bearings for yours.

My money is on the chipped tooth on the tranny input shaft.

My ‘52 3100 with a ‘59 235 and original 3 speed made noise with the clutch pedal fully released and not when pushed in. I rebuilt the tranny and found the bearing on the input shaft was going bad. Now it’s silent regardless of which position the clutch pedal is in.

I had to share an experience on this point not tranny related, but on the second run ever around the block with my panel truck, I had so many noises going on that I was in a panic- alot of clanking and banging. I was wondering what was going to need to be rebuilt next!

I suddenly remembered that I had made a small pile of all of the metal scrap parts that were in the truck when I first got it 4 years ago, and they were still in the back by the passenger barn door. I removed them all, and voila! No more noises! And, I didn't have to pay a mechanic for that fix LOL

Rich's toys If not u-joints take off your pto cover feel for shapnel in it's belly,look at gears for damage,once had one with no oilsounded like it was over. Put in oil run fine no noise'suspect a chip in yours though. dry one just squalled .

Update: Due to a number of circumstances, this project had got put on hold. In the past year we used the truck very little and just put up with the noise. Finally this fall we got back at it.
I have had this Viking 60 around for quite some time. It also has not been run for many years, and the cab is in much worse shape than the other one. The decision was made to pull the transmission from this truck and put it in the other one. My mechanic just finished it up last week. Brought it home the other day and drove it over to winter storage this afternoon. It felt good to finally be able to drive it and not have it sound like the engine was blowing up!!
Still have a few other issues, including the Hydro-Vac situation I posted about a couple weeks ago. But at least we're making progress! Looking forward to using it a lot more next summer.

Two ton truck, so you can add 5/10 disc brake hubs/spindles to your front axle without the tires sticking outside the fenders.

Ed

Actually, the 2 ton truck shown here is the donor truck. The transmission from it went into my 40 series 1 1/2 ton.

That axle in the 2ton, if can be switched to 1.5 ton, can use the disc brake setup.

Ed