Timing gear problem or not?

Lona

Lona

Well-known member
A loud clacking/rattle noise started in my engine on my way home at 45 mph. Sounded like marbles in the engine. Noise got louder by the time we reached home. It was louder than a valve tap so I thought it was a bad rod but the noise is not a deep knocking sound like a bad rod. The noise is at all speeds but loudest at higher rpm. Shorted our each cylinder & noise didn't stop. Also shorted out No 2 & 3 to check the center main but no change with the noise either. There was little change in noise level as ignition was advanced and retarded. I used a stethoscope and found the noise was loudest at the timing cover so I thought the timing gear might be the problem. Took off the timing pin, reversed it and pushed it into the gear with the engine running but the noise did not stop.
Before doing anything, I researched every thread I could find on the forum and felt all of the comments pointed to a bad timing gear, loose timing nut or broken plunger and/or spring. I then took off the side timing cover and ran the engine. It was a bit messy with oil flying all over but the noise was much louder so this seemed to confirm the problem was in the timing gear area.
Next step was to remove the front timing cover, hoping to find something damaged but everything seemed to be ok. Both the fiber and the crank gears seem to be clean and unworn. Tried to measure gear lash and was able to get a 0.015 feeler between the teeth but did not feel comfortable this was a good reading as the radiator is still on the car and the crank pulley makes it a little difficult to get a feeler between the teeth. Maybe someone can offer a tip on how to measure lash with the engine in the car and the radiator on or do I have to take the rad off to get a good reading?

Turning the engine by hand, I cannot see any play between the teeth as the engine is moved forward and back.

The timing gear was tight against the block when the cover was removed but the cam shaft could be pried forward about 1/4 " but could not be pushed back by hand. Needed a rubber mallet to get it back in place. The plunger face seems to be a little worn but the slots are still about 1/8" deep and the spring is intact and stiff, although I have no way of measuring the tension.

I should have checked to see if the noise stopped with the fan belt removed to rule out the generator, water pump and crank pulley but neglected to do so because the noise was so loud near the timing gear. Both the oil pump and the distributor shaft were replaced about 500 miles ago. Also changed the front motor mount and the springs are new and tight.

Does anyone have any advice as to what my next step should be? Should I replace the timing gear, plunger and spring and put everything back together and test drive it? What would be a prudent course of action at this point?

Glen
 
You don't by chance have one of those 2-piece timing gears where the center is metal and the teeth are fiber do you. Those have been known to make a noise like you describe just before they decide to separate themselves.

Another place "up front" to check is the 2-piece crank pulley. Those have been known to get loose and start quite a fuss as well.

Just thinking out loud.
 
If the timing gear is tight, I would drain the oil and look for pieces of babbitt in it. Use a funnel to drain the oil into a container with a coffie filter in it or some cheesecloth to seine the oil for particles. You may have lost a main, just MHO
 
Thanks, i reread the thread and he said he thought they were good but didn't
know how to measure them.

Like i said i'm a nubee and well inquiring minds would like to know in case something
comes up with mine down the road. :)
 
Thanks for the quick replies.

CarlG...... my pulley is one piece so that's not the problem

James Rogers...... good idea to look at the oil for babbit particles but wouldn't any solid material drop to the bottom of the slinger tray and not move down to the pan plug? If that's the case, draining the oil might not show anything. Or, do you think babbit pieces would migrate down to the bottom of the main pan? If I drain the oil, would you recommend stirring it up first by turning the engine with the starter or just draining it cold? It has been sitting for 3 weeks & I can't start it to warm it up with the timing covers off.

Mitch..... how do I check crank end play with the engine in the car? Do I just put my dial indicator on it and pry the crank forward and back or is there a proper way to do it?

chopnchaneled........thanks but I mentioned the plunger and spring seem to be in good shape. I need to measure the spring tension to confirm this.

Glen
 
Measured the spring pressure today and got 32 lbs when fully compressed in the plunger so a bad spring or plunger doesn't seem to be the problem.

Any other suggestions would be appreciated

Glen
 
Just drain the oil. The babbitt will migrate to the bottom of the pan even if some stays in the tray. If you want, you can pull the fill tube out and look in the hole with a light to see if any is in the tray. The tube is just a press fit and will come out if you knock it side to side to loosen it.
 
The last thing you did was replace the distributor shaft, and the oil pump 500 miles ago. I would look to see that you didn't tighten down the Distributor screw and lock nut and put a bind on the driver. The distributor needs to be snug, but when it is really tightened down you can create the same symptoms and loud racket you are describing. I had to rework the distributor shaft end that mates to the driver to eliminate that noise. so I have experienced this myself.
With a two piece distributor shaft there is some flex, but there has to be some clearance.


Bob
 
James,
Drained the oil and screened it thoroughly and also removed the oil fill tube and saw no evidence at all of Babbitt pieces or flakes. None in the hollow of the pan nut either. Just some small pieces of sludge which I could dissolve between my fingers.

Bob,
I have a two piece distributor shaft that has not made any noise since being replaced. I would need to put the timing cover back on to start the engine to verify if that is the problem and am reluctant to do that until all other ideas about the noise are addressed.

Am still looking for any I other ideas you and others might have. Thanks for the input you both have given.

Glen
 
The 2 piece distributor shaft needs to have some fitting done so that the contact to the short shaft out of the distributor, and the end that engages the driver are free enough to not bind the driver, which in turn will cause the cam to hammer.
Also the distributor screw and lock nut on the side of the head are set so that the distributor is held in place but not rigid. A little easier to show you than to explain, but I believe you have created this hammering with the replacment of the shaft, If you also replaced the driver then I am more sure of this possibility.
 
Just had something similar happen to a Model A that I was working on. Got it running with no problems, but had a loud knocking. Took off the belt and it went away. Started checking and it turned out to be the fan on the water pump shaft. It wasn't easy to get the part to move until I pulled on it in just the right way, then it was easy to see what was going wrong. Lots of things could make the same sound, but it would be worth a try to run the engine without the belt and see what it isn't.
 
I think I have the same trouble. it has been doing it for a long time, and not getting any worse, I think I will drive it in till it brakes, then I will know what it is
 
Marshall57,
I think you got it right! As I said in the original post, I knew better than to start tearing the timing covers off but with the stethoscope, the noise was loudest there and from reading so many other posts about timing noise, I went ahead and took the covers off but found nothing wrong. Without putting the covers back and starting the engine, I grabbed the fan and tried to move it fore and aft and was surprised to find it moved about 1/4" at the fan tips. It was loose on the shaft although I had put on a new water pump last year but probably didn't torque it down enough. The fan key way is shot & much wider than the key which will require a new fan. The shaft looks salvageable if I can find a way to get the stuck and macerated woodruff key out of the slot.

At this point, I'll order the parts to get everything back together and start her up and hope this was the cause of the engine noise.

I'll also check the distributor shaft as Brentwood bob suggested before cranking her up.

Thanks to all for your suggestion and I'll post a reply in about two weeks when everything is back together.

Glen
 
I had a noise similar to what you describe on the way home from a tour. It was a warm day and there was plenty of shade just ahead so that was where I pulled off the road. Took the fan belt off and found the noise was still there. AAA took us home and pushed me into my garage. There I grabbed a light to start taking the timing cover off and lo and behold, front motor mount bolts had backed out and the one on the drivers side would contact the pulley and raise a racket. Put them back in snugly and no more noise. Someday I may confess to the error that made it possible for them to back out. Til then just guess. Hint is lock washers.
 
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