Hot Rod Forum banner

Help diagnose this noise (video)

2K views 26 replies 6 participants last post by  64nailhead 
#1 · (Edited)
Figuring out what this sound is and what it's coming from has me at my wits end and about ready to pull the motor. It's a fresh motor with no more than 10 miles; broke in on a stand. I thought I had it tracked down using an inspection camera to look in the oil pan and saw there was marks on the sides of the pan in the front where it looked like the #1 cam weight was hitting. I swapped the oil pan to a stock type from Summit this weekend and it's still there. The sound is very pronounced in the front of the motor. When the oil is cold the sound is not there. When the motor warms up the sound starts. It's very rhythmic ...tap...tap..........tap...tap

Crank walk? Car is a manual, 82 Camaro.

I was also having a strange noise between 2 and 2.5k rpm and light throttle at cruise which I thought was detonation but after trying every timing combo and different distributors I figured the issue to be something else. This weekend I shimmed the starter and replaced the flywheel since I believe it was the mini starter gear hitting the flywheel by evidence of the gouged teeth. The sound I though was "detonation" is still there in the same rpm band but the tone is way different, it's almost muted now probably 3/4 quieter. Before it was loud and sounded like cold diesel chatter.

All opinions welcomed, especially educated ones :D

 
See less See more
#3 · (Edited)
On pump number 3 which is where I started with diagnostics. Pressure used to sit steady at about 6 then I started noticing my fuel filter draining. Heat soak causing vapor lock, moved fuel lines away from header. Added phoenolic spacer. replaced all rubber lines and carb feed. Pressure tested gauge - no leaks. Still erratic as seen. Changed fuel pump and pump rod and verified movement from cam lobe which was good. Changed pump again to utilize return line and further cool fuel. Thinking it's the gauge and going to replace with a liquid filled one.

Ran the car with the pump dropped and the pump push rod off the cam and noise still there.

Edit: Dave, yes short bolt in the front. Learned to hold the rod up with a hacksaw blade for a quicker change. Have a stethoscope and listened all over the place. Most pronounced on the driver's side front of the motor which is what led me to drop the pan and discover the forensic mark left by the crank hitting the pan.
 
#4 ·
did you find any shavings or pieces in the pan? Did you try running with no belts on it?Might be easier to isolate.Is anything seem to be binding or knocking if you turn it by hand, with a breaker par of course. How about disconecting one spark plug at a time? Could isolate rod or piston pin knocking. From what you explain it could be bearing or wrist pin. Just a couple of thoughts. Who built the motor? locally or offshore?
 
#5 ·
There have been no shavings in the pan. Dipped a piece of paper in there and it looks clean. Installed a magnetic drain plug and there were two very little jagged pieces on it when I drained the oil to swap pans. Nothing I would consider nothing worrying about. But? I haven't tried removing all the belts yet but I did remove one without change. Will remove them all tonight and test.

Stethoscope is loudest on the front drivers flange of the oil pan. Sounds like if you slap the bottom of the oil pan with your hand. That's where the marks were on the inside of the pan. I clearance the old pan past the depths of the marks and put it back on only to find it didn't work. That's why I swapped to a different pan altogether. There were no marks on the old pan when I removed it this time either...

I did run each cylinder without the plug to check wrist pin but no change. Also doesn't present itself on deceleration. Had a buddy turn it over by hand while I listened for the crank hitting the pan, didn't hear anything and nothing seems to be binding at all.

I built the entire motor after having the machine shop do the block and crank work and press the wrist pins. This is the first motor I've built from the bottom up, been a lot of fun and frustration both.
 
#6 ·
This photo is what lead me to believe the crank was hitting the pan. Sounds to me like it still is... which is why I have the crank is walking stuck in my brain. I measured the run out on the back side of the ring gear with a dial indicator and while turning the crank by breaker bar got .015'' max run out around the entire circumference of the flywheel. I think it would be a combo of end play and flywheel. Not sure I trust my mounting point entirely though.
 

Attachments

#7 ·
I was going to suggest a loose flywheel. Have you checked the balancer and made sure the the bolt is in the end and the key is in good shape.

That is a strange noise. I noticed the rythm was in tune with a pattern but it was always slightly different each time. Cam gear on tight??
:cool:
 
#8 ·
Yeah, I have the balancer install tool and put it on right and was turning it over by wrench last night. It was new along with the bolt. You think the balancer could be to blame??

Just replaced the flywheel and torqued. I read about the potential cause of cracked flywheel and mini starters hitting the wheel so ruled those out.

IIRC I used a timing cover that holds the cam in place of a button and the bolts were torqued properly. I have to pull the radiator at some point so I'm not beyond tearing the front of the motor off if necessary.

Uploading a second video. Sounds deep and heavy like the crank hitting something.

http://www.hotrodders.com/forum/crank-rubbing-oil-pan-176517.html post #7
 
#17 ·
i had a similar problem with my sbf engine.. drove me nuts, tried the probe with ear plugs.... got brother over to listen and he said it the fuel pump. the lever is not returning and crank is taping it.
bingo new pump= no more noise.
I could've swore that's what it was too the way the fuel pressure gauge was acting but after changing pumps and installing a new rod and checking that it wasn't binding ruled it out.
 
#18 ·
I had that same result with the very first small block I ever built.

It was a 265 and when I was putting it together I bought TRW main bearings and my crank was 10 under. I bought the 10 under bearings and put them in the block and set the crank in with out measuring or using plastigauge. After all I thought no problem with a fresh 10 10 crank and stock block no need to check. I started putting the pistons and rods in and when I turned the engine right side up I heard a funny kind of thunk. I kept going and when I was putting the last piston in I was turning the crank I felt a double thunk and then after looking at the crank I saw the verticle movement in the crank.

When I tore the engine down I was looking at the bearings. The bearings were stamped at 10 under but when measured they were actually stock bearings. The store said they never heard of that happening before but when we got out the measuring tools lo and behold they were stock bearings. They gave me a set of replacement bearings and this time I measured them before I left and I also bought me a bunch of plastique gauge. I confirmed my clearences from then on and that motor went on to win a lot of street races. Of course that was when I was young and stupid to race on the street!!

What I am trying to say is this problem could have hit anyone but it got this rookie good. My lesson learned was I have never built another engine without measuring and measuring and verifying my clearances. To this date I have only had 1 engine failure of all the engines I have built over the years and it has been a bunch of them.

Don't feel bad or beat yourself up if this is a parts mis match. It happens to everyone but please take this as a learning experiance and push on.

Because the engine was run I would seriously consider having the crank checked for out of round and especially for cracks.

Good luck and let us know what the ultimate failure was.

:cool:
 
#20 ·
Problem sloved

I measured the crank journals and low and behold! Machinist said it was turned .010 and even supplied the bearings. Measurement came across at 2.43 on each journal. Wait, that's .020 right?!?

No wonder this thing had an oil pressure issue. My question is does that extra .010 equate to that much movement?
 
#23 ·
I don't see anything catastrophic so I'm considering getting the correct .020 bearings and running it. There was a little trash that went through rod #2 but most of the bearings have coating still left on them.

Have a look at the #4 cap bearing... worn to copper. My thoughts are this was what was taking most of the abuse from the weight of the flywheel and clutch which is why?

Crankshaft looks good. Main bearings have more coating than silver left on them which I think is due to me running 20-50.

Having trouble uploading pics
 
#24 ·
Here are the pics
 

Attachments

#27 ·
I have to tell you. I'm building a Nailhead presently that had to be sleeved to keep the block numbers matching and the crank had to be straightened and cut. I mentioned to the crank and block guy that I'd check the bearings with plastigage and he mentioned that I'd be stupid to not check his work - he recommended it.

It's insurance to confirm that all is as it should be.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top