Motor noise

Logan

Logan

Well-known member
Motor noise ***Update***

Back in May i finally got my motor back from its rebuilder. About two weeks after we got it and started driving it, a lifter started making noise. And the builder told us to keep driving it until we went to the texas tour (our states regional meet) and he would fix it there. When i was driving it down there the noise continuously got worse. Long story short, he wouldnt fix it down there and told me to "take care of it on my own" when i got home. Not something i wanted to hear after just writing him a check for $4500 the month before. So i came back home and adjusted the lifters correctly, and that took care of SOME of the noise. I went threw every lifter and all are within spec now. Now the noise that I can hear is a cross between a knock, and a tick. We cannot tell if its in the valve train still or if its something else. I personally dont think its loud enough to be a rod. THE MOTOR STILL RUNS FINE AND HAS PLENTY OF POWER.

So maybe some of the engine builders can help me here, although i know this is a shot in the dark since you cant hear it run. Here's what the motor has in it
-SS valves
-1 lock lifters
-chevy pistons
-new rods for inserts
-inserted mains
-one piece guides
-snyders head
I'm sure im forgetting something else. I dont think the piston is hitting the head because this was the first time the block had been decked as far as i know, and it was a brand new head. I dont think its compression knock because it makes the noise all the time. It makes the most noise when its cold, and gets quieter when its warmed up if that makes any difference.

Ive pretty much thought of every possible problem that there could be, but before we tear it apart i want to hear what some of you may think it might be.
 
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Perhaps the Chev pistons were fitted a bit too loose but quieten down a bit when engine is warmed up. The Chev pistons also dont have a full skirt like"A" pistons so would have more of a tendency to rock in the bore.To me,its another instance of going modern isnt always better.
 
My question is though, wouldn't piston slap be there from the beginning? Especially since I only had like 400 miles on it when this started making noise, so i guess what I'm say is wouldn't piston slap be there from the beginning? If not is 400 miles enough miles to make it show up? I have about 1300 on it now. But I'm not driving it anymore until we tear it down.
 
Questions come to mind. Does the noise lighten up or change when spark retarded. Can you change noise by grounding out spark to each plug.
If noise changes when re tarting spark or grounding plug, problem is probably in power train. Pistons rod bearings. If noise does not change it is probably in valve train.
 
After dropping $4500 and guy told you to take care of it yourself I would post the rebuilder's name/co here so anyone else could avoid this in the future. Will he do anything about the noise now after you've taken care of the orig problem?? Just my rant.

Paul in CT
 
pull each wire (plug connector) off at a time and see if the knock changes or goes away.
also remove the fan belt for shts and giggles
 



Logan,,,



I had a similare problem with a reground cam...would "click" real bad no matter what I set the lifter's to...I got tired of hearing the clicking on this new engine...I had a spare reground cam that had a different grind on it...Also the other cam had a knock at the center Brg...this other cam I installed is quiet at the center brg...


I changed out the cam & was shocked at how quiet the different cam was !!!..This motor is now very quiet...I don't think it's the piston's...the piston's would have to be on the loose side to knock on a new engine...You can check if it's a piston knock by shorting out the cylinder...



Let us know what you find,,,I like that part from the rebuilder,,,"you fix it" after you spent how much,, 4+ grand !!!!



Greg out west
 
Agree with Mitch and Greg out West..

Sounds like a bit like the rebuilder is an "assembler" and is not much into troubleshooting from what I am hearing.

Gather some clubmembers around, spring for some snacks and sodas, get out the tools and start dissassembling/analysing and let us know what you find.. Also see if you can invite a machinist/local rebuilder out to give you his opinion?

- Dave
 
A piston slap will only make noise until the engine warms up...then will quiet to the point where it is almost not noticable.

Reground cams are made smaller so the ramps are actually sharper and that is what causes the smap sound...

I think I would pull the timing pin out... reinsert it as if you would do as if you were timing it...and run the engine at different speeds...possibly oil pressure is moving your cam...and the noise you hear is the cam pushing it's follower back so to hit the casting.... I accidently did this when I first pressurized my engine...had to lower the pressure some.. a rod knock is a thud, a wrist pin is a double knock and a main bearing knock you can feel in your bones...it hurts me to hear one of those...
 
I've shorted out the cylinders before, and it doesn't seem to make much of a difference. Third cylinder seem to slitely...very slitely get quieter when you short it out. Thanks for all the ideas guys, I'm not going to post the builders name just yet. Still waiting to see if anything will get resolved.
 
Logan said:
I've shorted out the cylinders before, and it doesn't seem to make much of a difference. Third cylinder seem to slitely...very slitely get quieter when you short it out. Thanks for all the ideas guys, I'm not going to post the builders name just yet. Still waiting to see if anything will get resolved.
Click to expand...

So far it sounds like my well worn temporary engine that also has a noise, which I still haven't pin pointed. Mine also gets slightly quieter when I short #3 plug. I'm thinking wrist pin or piston slap on mine, and I don't feel that it will blow on the road, so I'm just going to keep driving it until I finish rebuilding my original engine and reinstall it.
 
Tom Wesenberg said:
So far it sounds like my well worn temporary engine that also has a noise, which I still haven't pin pointed. Mine also gets slightly quieter when I short #3 plug. I'm thinking wrist pin or piston slap on mine, and I don't feel that it will blow on the road, so I'm just going to keep driving it until I finish rebuilding my original engine and reinstall it.
Click to expand...

I hope your backup motor was $4500 like mine 
 
You can feel both those if you use a pencil inserted into the timing cam hole...(use the flat end...and don't push very hard) you can feel and hear the knock at the same time...what you are looking for is forward or rearward movement of the cam...hitting the bottom of the spring pusher in the timing plate.

a piston knock will make a knock/knock as it changes direction..it is a double knock...
c
A rod is a thud...but a main bearing is a thud that actually hurts my bones... you can feel the power...it is definatly different than a rod knock.... once you locate the noise drop the pan and tighten it...you can still save the motor...

Joel (retired college auto shop teacher and Senior Chief Engineman USN )
 
The "Only" thing that will cause pistion Slap is Rods that are out of Alignment, and the more miles, the worse it gets.

Pistions can Hit heads whether New, or old.

Pistons can hit head gaskets.

Wore center cam shaft bearings will make different kindes of sounds.

Cranks that are not Positioned in the block right, will let the rods hit the piston Bosses, when the engine is warmed up.

There are many more things, this is just some.
 
Does the noise change a little if you push in the clutch? You may have a flywheel bolt extending too far through the crank flange, clipping the rear bearing area.
 
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