Engine: Engine noise question - hammer

[chlenz62]

Before I pull the engine and transmission, I was hoping someone might be able to help me understand the source of this noise. It's a loud hammering sound that sounds like a main bearing failure. However, it diminishes significantly when I push in the clutch pedal. The previous owner mentioned to his daughter (she sold me the car) that the engine needed a shim or spacer? This is all I know and the previous owner has since passed away. The engine runs very smoothly. It was rebuilt with virtually no run time and the oil looks very clean. Absolutely no smoke on start up. I believe he transmission was also rebuilt. The car went through a frame-off restoration 10 years ago. It has been sitting since then.

[wittsend]

Sounds like a loose flywheel. Pushing in the clutch forces it tightly on the crank and also gives it throwout bearing support. I'm not familiar with the Studebaker engine but a lot of cars have a large, thin washer/spacer between the crank and flywheel. Maybe this is what they were referring to? It is a bit confusing when you say "It's a loud hammering sound that sounds ..." and yet, "The engine runs very smoothly." I would not run the engine in this condition. If it is a loose flywheel you can tear/elongate the bolt holes and if it comes loose - YIKES!

[Alan]

If it is a V8, it could need some shims between the crank front thrust face and the dampener hub. The noise could be the crank sloping back and forth at the front main. See if you can hear from which end the sound is loudest.

[altair]

Save all the guessing, take it apart and find out for sure.

[PackardV8]

First, you need to tell us year and model. Sixes and V8s have their own gremlins.

Before you take it apart, look all around the motor and transmission mounts and the exhaust system and anything else which could be hitting the frame or anything else solid. Old motor mounts "perish" and allow the engine to move when/where it shouldn't. A friend was about to sell his Avanti cheap when I found the "bad main bearing" was the exhaust manifold hitting the steering box. Your results may vary.

jack vines

[JoeHall]

Since the PO mentioned shim or spacer, the only one related to the noise you describe is behind the crank timing gear. But I doubt a missing shim would make a hammer sound. I once had a crank bolt come loose, and eventually walk the crank flange forward, which allowed the crank to shift fore and aft about 1/8", under certain throttle conditions. I found it by noticing the vibration dampner shifted back and forth, when I played with the throttle. It sounded like a main bearing. It had AC, so the pulleys carried a heavy load, and by the time I found the problem, it had all but destroyed the key and key slot on the crank gear.

If a shim is missing in yours, you can try the same experiment above, or probably can pry the dampner back and forth, if you remove the radiator for easy access.

[RadioRoy]

Save all the guessing, take it apart and find out for sure.

I strenuously disagree. Spend some time troubleshooting before taking it apart. You might be able to fix it easily, or at least figure out which component or assembly to take apart. Just jumping into taking things apart can cause secondary and tertiary problems, some of which may mask the primary problem.

The "shim" comment may also be a red herring, or it may have been someone else's guess, or it may be a mistranslated comment.

Think, test, use your head, test some more. THEN take apart only what needs to be taken apart.

And yes... tell us the year, model and all that.

[StudeRich]

It is very important for getting the correct response, to give us the Engine Type, Transmission Type and Year Model of the Stude.

[chlenz62]

Your feedback is very much appreciated! It is a 1950 Commander 6 cylinder

Thank you!

[tsenecal]

I agree with the loose flywheel response. OP said loud hammering, which I don't think would come from a slightly loose thrust bearing. The flywheel would be easy to check by pulling the starter and using a pry bar to check for movement. If the problem is internal, draining the oil and checking for visible metal, or taking an oil sample and having it checked , might tell him something without tearing it apart. If it is loud hammering noise, and internal, there will be metal in the oil.

[chlenz62]

Again, extremely helpfull suggestions. I will attack this issue with all of these recommendations in mind and I'll circle back with my findings to share with all. I'm currently on travel and won't have an opportunity to do anything for a couple of weeks but looking forward to resolving this noise. It appears to be the only thing keeping the car from rolling down the road. BTW, I am able to put the car into gear and move it forward and backward in spite of the hammering noise. The PO was a true "car guy" and restored several vehicles. From all indications, he was very good at what he did so I was hoping the "shim/spacer" comment would cause someone to come forward with and "Aha!" moment. Nonetheless, all very good feedback. More to come!

[Treblig]

Sorry...couldn't resist!!
Treblig

[jclary]

Perhaps I missed it, but I did not see a comment regarding the "dial in" check. I don't think six cylinder engines were exempt from this requirement. Even if the bellhousing is original to the engine, since there was a mention of a transmission rebuild...I would be checking for appropriate concentric engine to bellhousing alignment. Could be the dowel pins were disturbed or removed, pilot bushing, or the throwout bearing not properly installed. I once found a throwout bearing where one of those spring retainers had come loose. The bearing assembly was working, but eventually wore away part of the retaining washer & spring before it became noisy and required removing the transmission and replacing the bearing.

Stating that "Pushing in the clutch pedal diminishes it (the noise) significantly"...makes me want to concentrate on this area.

[wittsend]

What we know:
1. The engine was rebuilt and had near zero run time. Could something have been missed?
2. The daughter (seller) stated it needed a spacer or shim. Someone had to run the engine to determine that and tell her. It seems like the father was in the process of restoring the car but stopped (health???, discouragement after finding this problem???).
3. I'm not familiar with the 1950 6 cylinder. Did that engine have those half round separate crank thrust washers? If not dismiss the rest >. If so it might have been missed in the rebuild and the crank throws are hitting inside the block? As someone suggested check the crank end play/loose crank bolt. However, end play internally set so maybe not?
4. I think this is the biggest clue, 'pushing in the clutch diminishes the sound.' That would seem to either force a crank throw forward (possibly out of the way of), hold tight a loose flywheel, or slightly torque the engine should it be mount clanging/exhaust related.
5. Mark your calendars for early October as we will all hang in suspense until the owner gets back from their travels.

[Treblig]

Put a dial indicator on the front of the crank and force the crank forward (large crowbar) to see how much axial play you have...I'm sure someone here has that spec?? That should eliminate the washer/spacer issue??

treblig