Thread: Gen I (1969) SBC 350 NEED HELP, TICKING SOUND

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I'll have to tell a story on myself. Had an old beater pickup, '91 Ford F150 regular cab, longbed. I drove it to Firebird one Friday night to do tech and shut it off as usual. End of the evening, I went to start it and the crank wouldn't turn. I thought maybe I had wadded up a rod bearing, so called my buddy to come get me. We towed it to his 40' x 90' shop and I began pulling the motor for a teardown. Got the motor out and separated from the transmission and all of it laying on the floor. Put the motor on an engine stand and began disassembly. When I pulled the starter motor, what do you think dropped out on the floor? Yep, a bendix tooth that had broken off and wedged between the bendix and the flywheel ring gear.

When the truck wouldn't start, I let the truck roll downhill and dumped the clutch to try to release the crank. All it would do was to skid the rear tires. Had I tried the same thing going backward, the tooth would have fallen out and I would have been able to start the truck with the starter until I could replace the starter later when it would have been more convenient. As it was, it cost me about $1200 to do an engine rebuild because it needed it anyway.

Let this be a lesson to you. Try to push it forward and then backward before you pull the motor.

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Originally Posted by rspears

From an earlier post where you were trying to ID the engine, Tech pointed out that it was originally either a Powerglide or TH350 engine. Wondering about the pilot bearing/bushing in the crank, which indexes the tranny input shaft into the back of the crank?

As far as I could tell when I had the jeep transmission off, it has a bushing. Im not sure if it was previously swapped from bearing to bushing to accomodate t150 trans shaft. I know I would be able to tell if a bearing was bad, but as far as the bushing, im guessing its brass and they dont wear too bad, and it did not look like the outer surface had any space or play

Originally Posted by jerry clayton

with valve covers removed run engine and look to see if the pushrods are spinning-if not, cam/lifter wiped--------

I will try this, but ive never looked for push rods spinning, didnt know they did, so I have never noticed, thank you/

Originally Posted by techinspector1

If it's not a cracked flexplate (because there is no flexplate) or the cam going south, then I would suspect an exhaust leak. They can sound like a tick-tick. Did you tighten the flywheel onto the crank and torque to spec while you had the trans out?

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Im not sure that I have a flexplate, unless it is mounted on the engine side of the flywheel. Not real familiar with a flexplate, but arent those with auto trans? I have never had the flywheel off, so never had bolts out. But that may be something to check, as the owner before me may have done that. Does anyone know torque specs for flywheel bolts?

Originally Posted by robot

Get a stethoscope and isolate the general location of the noise. Might be the timing chain, a rocker, a lifter,
a flex plate, or whatever. Then, once you isolate the general location, you can get more specific with the
find.

I will try the stethoscope, the engine is loud enough on its own that its really hard to get an idea by sticking you head in the engine compartment.

Originally Posted by 34_40

I had one a couple weeks ago that drove me crazy trying to locate it.
Long story short, the spring that holds back the bendix in the starter had broken and the starter drive gear would just sneak out and tap on the flywheel.
The stethascope got me close and after removing the flywheel cover the noise got louder, when turning the flywheel by hand I could hear it... still took me a bit to realize it was the starter drive!

I have thought about this. with my bellhousing off, I was able to look at gap between flywheel and starter drive gear, there is a very small gap, but you can see light between it. Is this something that you were able to see without turning flywheel? or did it only expose itself when you turned? also, was this something that may only hang up right after its been cranked? but spring may work itself back into place as it sits?

Originally Posted by cgw3

Im not sure that I have a flexplate, unless it is mounted on the engine side of the flywheel. Not real familiar with a flexplate, but arent those with auto trans? I have never had the flywheel off, so never had bolts out. But that may be something to check, as the owner before me may have done that. Does anyone know torque specs for flywheel bolts?

What Tech's saying is that a cracked flexplate is one of the first things to check with this symptom, but you don't have one. Torque for your flywheel bolts is 60 ftlbs, using LockTite thread locker - Small Block Chevrolet V8 Engine Specs | Torque Specs - Cylinder Numbering - Firing Order - Distributor Rotation - SB Chevy 267 305 327 350 400 Cid

Sounds like you have a bronze pilot bushing, which I prefer over a bearing. They last just about forever.

Why do pushrods spin?????

Because------on flat tappet camshafts, the lifter bottoms have a slight curveature to them and the camshaft lobes are ground at a very slight angle------this angle lets the pressure thats transferred to the cam from the valve springs hold the cam back into the block and also control forward/rear slop caused by the angled gear on distributor/oil pump drive----
ALSO----this angle will cauce the lifter to spin on the cam lobe presenting a continuous change in the contact wear pattern that spreads the wear pattern and increases the life of the cam/lifters. If for some reason the lifter can't spin--indicating a worn lobe, the cam will be wiped out within a VERY SHORT time cycle. If the lifters can spin, they will spin the pushrods----so non spinning pushrods will indicate a worn cam

This doesn't happen on roller cams-----------

Here's a diagram illustrating what Jerry is talking about....I think the radius on the lifter crown is about 50 inches and the ramp on the lobe is about 0.004" difference side to side....some fellows will tell you that the lobe difference is 0.0025" on OEM stuff and more like 0.005" on aftermarket stuff....
http://www.crankshaftcoalition.com/w...lobe_angle.jpg

Here's another that shows the point of contact being off center, that's what allows the lobe to spin the lifter....
http://s171.photobucket.com/user/vet...db730.jpg.html

Anyone wanting a flat tappet camshaft to survive should read and heed this tutorial....
http://www.crankshaftcoalition.com/w...ips_and_tricks

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Originally Posted by cgw3

I have thought about this. with my bellhousing off, I was able to look at gap between flywheel and starter drive gear, there is a very small gap, but you can see light between it. Is this something that you were able to see without turning flywheel? or did it only expose itself when you turned? also, was this something that may only hang up right after its been cranked? but spring may work itself back into place as it sits?

On mine the starter drive would slide out and the flywheel / flexplate would tap it and push it back into the starter. the running engine vibration would then shake the bendix back out until it was tapped by the flywheel again.. rinse and repeat... I only found it while turning the flywheel/flexplate by hand. And I noticed the clearance disappeared between the two gears.

ok guys,still stuck. Here's an update on what all Ive done. Checked starter/flywheel, no issues there. Bought a stethoscope (kind with metal rod) and it amplified the sound but I could not pin it down, pretty much heard it everywhere, with a slight increase in rear of engine from top of distributor all the way around flywheel. When I touch metal stethoscope to block, I can hear bearing (im guessing), but they sound like they are rolling as usual with no odd sounds to make me believe that one could be out. Im assuming that with a stephoscope, you should be able to hear a bearing even if it is lubricated, if touching the location of the bearing. If not, please correct me, and this could be my culprit. Ive done everything but pull the flywheel off, drop my pan, or pull the engine. I want to limit and unnecessary dis-assembly if possible. My only thinking outside of it being a cam bearing, would be somewhere on the distributor-gear on cam-down to oil pump and oil pump itself. The gear on the rear of the cam that turns distributor, does it have a pin through it that could have worked loose, or are there any parts from there down to the oil pump that could fail and should be looked at? If you can suggest any other culprits , please let me know. Thanks Guys

In post #18 you said you were going to look at the pushrods with the engine running, verifying that each one is spinning which is one step to eliminating a wiped cam lobe from the list of gremlins. Did you do that?
If you did then my next step would probably be to adjust the valves to eliminate the lifters from the list.

I don't think he wants to get his hands dirty

Originally Posted by rspears

In post #18 you said you were going to look at the pushrods with the engine running, verifying that each one is spinning which is one step to eliminating a wiped cam lobe from the list of gremlins. Did you do that?
If you did then my next step would probably be to adjust the valves to eliminate the lifters from the list.

I did check pushrods and they are all fine.

Originally Posted by cgw3

I did check pushrods and they are all fine.

Just to be sure, you understand that this is to check that the lifters are rotating on the cam lobe, which in turn causes the pushrod to rotate while the engine is running, right? Wiping a cam lobe has become a much more common event in the last twenty years or so due to changes in oils to keep from fouling CAT's ....