[jnymdnyt]

Happy New Year to all.

Okay so here's another tough one similar to joey's65 " 1965 mustang 302 engine knock" old thread. I have a 1965 Mustang with a 302 engine that has a knock that my mechanic and I are trying to figure out. I'm not an expert and I'm relying heavily on my mechanic's "expert advice". I had the car sitting for a month, decided I was going to have the hose replaced since there was a leak and have the whole car checked. On my way to the mechanic, I started the engine and reved it, stang shooked (like it was running out of gas) then had this knocking sound after. Towed the car to the shop and removed the head cover and checked, nothing was wrong, they removed the the oil pan and checked the bearings and it was still okay, some sign of shaving but nothing that would create that amount of noise but my mechanic suggested I replace it anyway. He said when he removed it was spun. After we replaced the bearings it still had the noise after which he said it was a cracked/collapsed piston. I'm a trusting person but something smells fishy now. On the old joey's 65 thread there were a lot of credible possibilities on of which struck my attention. I just recalled another situation that could be relevant if it is just knocking on 1 cylinder.
"A piece of metal gause from the air filter got sucked into a cylinder & got squashed against the cyl head. The piston would hit on it each time it came up making the noise but not really damaging anything." I took a video of the sound after replacing the bearing and would share it via email to anyone who would like to hear it.
My questions are:
1. What is the worse case scenario?
2. If it's a cracked/collapsed pistons, wouldn't that damage the wall as well.
3. Is it cheaper to replace the whole engine if that's the case?
4. Could it be something simple?

Much mahalo for reading my post. Not sure if you can post videos here but would gladly do so. I'm just frustrated at this point.

[steve sturgin]

I looked at your video on the other thread, that is not a nice sound under your hood.

Let me state for the record that i am no a mechanic but i do as much work as i can.

I would start with the simple things first, to eliminate the alt, w/pump/air-con pull the belts off and start the car again (not for too long).

Someone else will know if this is off the mark: the frequency of the noise seems too frequent to be piston related

Steve

[ultrastang]

If the engine internals check out ok, take your harmonic balancer off and see if it is cracked along the keyway.

I had a similar unexplainable engine knock that developed on my '66 fastback when it was my daily driver back in the early to mid-'90s.

The way I found there was something wrong with it is I was setting the timming on the engine. One second the timing mark would be visible in the stobe of the light, then the mark would just suddenly disappear??

I pulled the balancer off and found it was cracked. This allowed the balancer to spin in and out of phase on the crank causing a knocking noise when it moved out of phase.

I made the mistake of not replacing the Woodruff crank key when I replaced the balancer and the problem came back again. The second time I replaced the balancer, I replaced the key too and didn't have any more problems after that and the knock never came back.

[rocky289]

It is a disadvantage that you have now started another thread, perhaps a moderator could merge the two.
Your second vidio, under the hood is a bit more revealling. It sounds like it could be valve train related. I would be getting another mechanic if he can't diagnose that.

[jnymdnyt]

Originally Posted by rocky289

I would be getting another mechanic if he can't diagnose that.

My thoughts exactly. First thing tomorrow morning. First he said it was the oil they used at Jiffy lube, then Spun Bearings and last one was a cracked/collapsed piston. Someone's getting bussy while everything is slow during the holidays hmmmm....Thanks for all the posts.

[cindys_sn95]

find another mechanic! first, if a bearing is truly SPUN, you CANNOT just replace it. when it "spins" it does damage to whatever is holding it, i.e. rod or block. so this must be repaired first. sorry to say looks like engine time....

[hinrich]

sounds like piston slap. when the wrist pin through your piston wears the piston is not tight on the end of the rod it makes a nasty noise.