VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 ENGINE BOTTOM NOISE

IM BRINGING THIS SUBJECT UP, BECAUSE I WOULD LIKE TO KNOW WHEN BOTTOM ENGINE NOISE IS DETECTED LIKE A CLANKING NOISE, A CHATTER SOUND OR SOMETHING LIKE THAT, HOW DOES ONE GO ABOUT CHECKING IT BEFORE A ENGINE TEAR DOWN. IS THERE LISTENING DEVICES A PERSON CAN USE TO TRY AND DETECT WHAT THE PROBLEM MIGHT BE, ALSO CAN A ENGINE RUN GOOD AND STILL HAVE DIFFERENT BOTTOM END NOISES. ALSO BY RUNNING THE ENGINE AND PULLING ONE SPARK PLUG WIRE AT A TIME FOR EACH CYLINDER, CAN THAT ISOLATE THE PROBLEM TO THAT CYLINDER. NOT BEING A MECHANIC, THESE ARE THINGS I WOULD LIKE TO HEAR FEEDBACK ON. THANKS. :) :)

Maybe.

Don,Congradulations you left MrMack speachless...........................This can be a difficult subject as we all describe noises in a different way.Main bearing noises will be a heavy thumping or knocking on a pull.Some times you can hear a loose main give a few knocks when the engine is first started and before the pressure is up.This will only last a seconed or two. The main bearings are the big bearings that hold the crank shaft to the block(1932 has 3)Also if they make noise when driving they will get louder as the oil gets hot...
a loose connecting rod will make a lighter rapping or knock while accelerating,could also get louder when hot.Noise will stop if plug wire is disconnected on that cylinder.Piston will slap when cold will be heard under pull.Not real common with that engine unless cyls. are badly worn.Shorting out plug will also stop noise. Wrist pins will make a deep knocking noise at idle.Much deeper noise than tappet noise.Also could get worse at when hot.the pin noise can also be heard at other speeds when driving if very loose.The heavy iron pistons in those years developed pin noise and it could get quite loud.Timing gear can develope a hard to describe clatter ,can not be shorted out,and should always be replaced on a Chev.engine.This is the first thing to fail on many of these cars and the first thing I replace on mine.Also the oil passage behind the engine front mounting plate should be cleaned at this time as they sludge up causing the timing gear to wear out.As I said at the beginning we all describe engine noises in a different way and I tried to keep it simple,hope I suceeded

Well Donald and Chipper....Sometimes you can get folks to elaborate on what you would like to say but for one reason or another you don't or can't yourself ...just by saying ...."Maybe!" :p .......
Now if I can just get Chipper to answer my email about changeing tires and wheels on a '28 I will be satisfied for a while....a short while probably.

HI, MR MACK. I HOPE YOU DID NOT GET TONGUE TIED ON THE REMEDYS FOR ENGINE NOISE. I WOULD LIKE TO HEAR SOME OF YOUR THOUGHTS AND CURES FOR FINDING DIFFERENT ENGINE NOISES AND KNOCKS. I HOPE YOU HAVE NOT BEEN AROUND THOSE ONE CYLINDER ENGINES TOO MUCH, BECASUSE THEY COULD EFFECT YOUR HEARING AND THEN YOU COULD NOT EVEN HEAR THEM DARE TEXAS BUZZARDS FLY OVERHEAD.

BY THE WAY, WHAT IS THE TAXAS STATE BURD??????

Well, most of the engines I have are indeed one lungers, mowers, trimmers, chainsaws, pressure washers, most of the oil well pump jacks are now powered with electric motors so when we are dove hunting it is really quiet compared to when they all had Fairbanks & Morris gas engines.

I have tried to listen for engine noises and determine where the problems lie. But except for the odd times when it is a water pump, generator bearings. I haven't had much success. It usually requires a tear down to fix anything internally anyways. But the info from the Chipper is really informative, specially the stuff on the timeing gear and cam and the valve train was for me. .

The state burd is not Lady Burd or Lonney Burd but it is the Mocking Burd.

Just a small update...Chipper did answer my e-mail, seems like something was fouled up on my end (as usual ) and when I sent it the second time he received it and sent back an informative reply.

Thanks, Chevy Chip!

Don,
The best item that I have ever found to detect the source of engine noises is a mechanics stethascope. It has a probe that can be placed in various locations to pinpoint where the noise is the loudest. If you don't have one a large screwdriver, tire iron, metal rod or ? can be placed against the ear and engine.

CAUTION: DON'T stick it in your ear as damage is difficult to repair and may be painful.

CAUTION: You will hear sounds that you never heard before. Many of them (whirrs, humms, clicks, etc.) are normal engine noises.

You can also use it to check bearings in water pumps, generators, starters, distributors, etc.

In a Stovebolt 6 engine the likely cause is a worn rod bearing and this often causes a piston to slap.

Pulling plug wires one-by-one may tell you what cylinder.
A stethascope will give general direction.
Get motor up to operating temp and take notes on what and where you hear the noise.
Vary the RPM's and take note.

Then its likely that the rocker cover, push rod cover will need to come off so you can see if things are moving OK when it is running. Visually double check the rocker arms , push rods, and tappets just to make sure they are all moving OK and not sticking.

IT MAY rarely be "bad gasoline" or a funky detonation due to something in the ignition.... maybe its a sqeaky generator or water pump bearing or belt ....
but most often you will have to drain the oil (strain thru a nylon stocking and look for metal bits or gummmy stuff) and pull the oil pan off. Look up with a bright light and see if cylnder walls are scuffed and see if rod bearings are loose.

Most often the problem is rod bearings or main bearings. But as Chev Nut said, it might be the quirky timing gear known to cause problems in your particular year of engine.

DON"T drive the car till you find the problem! It will get worse and leave you walkin' !!

C.C. you also can use an Oklahoma gas credit card (a siphon hose of about 1/4" I.D.) the air column works in the hose acts as a monohascope! just be sure all the gasoline is dried up or you will get an ear full! at least that is what happened to me the last time........... Ya!

THE ENGINE IN QUESTION NOW HAS 308 MILES ON IT PLUS ABOUT TWENTY HOURS RUNNING TIME IN THE GARAGE AT DIFFERENT SPEEDS. THE ENGINE WAS SIXTY THOUSANDTHS OVER BEFORE THE REBUILD. THE ENGINE WAS RESLEVED BACK TO O AND THE RODS HAVE INSERTS IN THEM. ALUMINUM PISTONS ARE IN THE ENGINE WITH CAST IRON RINGS. BEFORE A TEARDOWN, THE ENGINE MACHINE SHOP PERSON CAME TO MY PLACE AND PRETTY MUCH SAID IT IS DEFINATELY A LOWER ENGINE PROBLEM NOISE. NOT BEING A MECHANIC, BEFORE ANYTHING IS TORN DOWN, IM TRYING TO GET ALL THE INFORMATION I CAN ABOUT POSSIBLE ENGINE NOISES AND PROBLEMS. THANKS FOR ALL THE GOOD INFORMATION SO FAR. I THINK THIS IS A GOOD SESSION FOR A LOT OF GUYS WHO CAN EXCHANGE GOOD INFORMATION AND IDEAS FROM GOOD MECHANICS AROUND THE COUNTRY, AND THEIR EXPERIENCES WITH ENGINE PROBLEMS THEY HAVE HAD IN THE PAST. :) :) :) :) :) :)

Don, if you drop the oil pan you can check the bearing clearances with Plastigage made by Perfect Circle and available at better auto parts stores, green package for .001 to .003 inch.
While the pan is off, thread a few temporary 1/4 20 screws from the top so they extend about 1/2" below the engine block. They will keep the gaskets in place and work like guide pins for getting the oil pan in place.

Don,

I took an old doctor's stethascope and cut the "cup"off and inserted a long metal rod. With this I can touch any part of the motor easily and safely. Like ChevyChip said you will hear a lot of things you never knew were there.

For the noise in your motor you might want to check out;

1. Page 49-50 of the "Chevrolet Repair Manuel" for '32's gives a lesson on how to "detect" what different sounds in the motor may be.

2. On page 16 the same book it tells you how to adjust the bearings if they are worn and making a thuding noise. When the motor was rebuilt I hope the rebuilders put the shims in the bearings.

Hope this helps you.

Gator, a question, when the rods have been modified is the clearance still adjusted with shims, like the babbit rods? I have never changed babbit rods for inserts YET! knock on wood, I may have to ,but, till then I will remain a BABBIT Head, or should it be a BOBBing Babbit head?

Knowing more of the history of the engine I'll go along with d2d2.The rod and main bearing clearences should be checked before you ruin the crank shaft or bearings.This is one area a stethascope can't reach but they do bring out some intresting noises that can scare you.Noises that are usually blended together.It sounds as if you had a good complete rebuild job.I am an aluminum piston fan too.The lighter weight takes a lot of load off from the conn. rod bearings.

Chev Nut,
I haven't quite digested the part of the aluminum pistons makeing it easier on the rod bearings....let's see..... the piston pushes down on the rod on the power stroke.... then the rod pushes the piston back up on the exhaust stroke,.....and then the rod jerks the piston back down..... and then the rod shoves the piston back up against compression and it starts all over again.....Yes!... I see it now!!.... since the rod does most of the work in a 4 cycle engine and the piston has it's one claim to fame on the power stroke!, then it spends most of the time getting shoved and jerked around, it looks like the lighter the better!
As one guru would say...." Ya!"
I just say.... "That right Kemo Sabe?"

At one time I thought I was an aluminum piston fan too. But once I put them in a '32 and ran it for several thousand miles I became a cast iron piston fan!!! The engines run much smoother. They maybe a bit slower to rev. but the flywheel also has a big affect on revs.

Yes, for you guys that believe it was balance, the rods were weight matched to +/- 2 grams overall and end for end. The pistons were also weight matched to ~ 1 gram. No I have not gone to the same efforts with the cast iron pistons didn't think it would make that much difference. :(

Ever wonder why Chevy used aluminum pistons in '28 and then did not use them again for 50 years? Me too. :confused:

I haven't decided for my self which would be better for me, I put Aluminum in a Model "A" years ago, but my brother jerked it and put in a flathead V/8 before it was worn out. Now I try to put back what it comes with new.

Alex Taub once said cast iron pistons reduced the manufacturing cost. When asked why the crankshaft was not drilled for oil to the rod bearings he said for the volume of engines they were producing there would be a higher rate of bearing failure due to the inability to completely remove the drilled out metal. When asked why the 6 has 3 mains instead of 4 he said this engine is really two 3 cylinder engines, each of which is inherently balanced.

Is that why the exhaust manifold has 4 ports and theintake has 3 ports? maybe the 265 is 4 H.D. twins grafted together. Then there is the 9 cylinder Cadillac engine in the WWII tank?

Well.....wadda know! The Chipper and the Dog agree again! I'm with Chipper on this.......I love the cast iron pistons, and I have them in my 1930 coupe. Everything was totally balanced, and with the engine running at idle you can balance a nickel on its side on top of the cylinder head! :eek:

Really JYD? I had a Nickle like that once!

Oh I forgot was your Nickle round or obblong? Mine was mostly round and flat on both sides one side had an Native American's head (heads) and the other side had a American Bison! (tails)

Hey wake up down there JYD...I thought they called it a Hot Water Six!

Really! Why do you think that they called the six cylinder Chevy the "Cast Iron Wonder"? Because of the cast iron pistons.....that's why! Yep!

"when the rods have been modified is the clearance still adjusted with shims"

Nope....the clearance is NOT adjustable once you pick the final size of the bearing insert. No shims on the rod caps.When wear makes the clearance open up, you replace the insert with a bigger size insert.

{BUT I have seen a guy put a piece of shim stock under the insert and thus tighten up the clearance! Motor ran OK , but I wouldn't try it!
Heck I've seen guys check the clearance with a tiny piece of paper on the bearing and then swing the rod & piston around on the crank to see if it was too loose!
It worked when I double checked with a micrometer.}

Oh...and the cast iron pistons. Well I always heard that the various "cast iron" and "cast alloy irons surface" pistons were used cause they were cheap, great at low rpm's, and lasted a very long time. Somes Chevy sales hype even said they were good for "quiet" economy and preventing oil consumption because of the close piston skirt fit. At higher racing rpm's they werent good on the rods and had a tendency to break near the lower ring groove.

The 1953 Powerglide 235 had cast aluminum pistons, it was full pressure oiling with the new rod bearing inserts. The trend in the 1950's was the push for more horsepower thru higher rpm's and the aluminum pistons had been very much race proven. The aluminum clearance is wider and thus they are noisy, use more oil, and wear will be worse than iron. But they weigh about 1/3+ less than iron; they accelerate better; combustion is cooler; and they are better for the rods.

Most post 1937 216 & 235 engine rebuilds I've seen are with the aluminum pistons.

As to Chevys' problem: the only time I could find a reference to a KNocking in a rebuilt engine was in an old tech manual that said an engine will knock for a "few hundred miles" if new piston pins are used in old pistons. This doesn't sound like Chevy's problem.

Chevy, me thinks ya gots ta pull the oil pan off.

Hi CHEVY,

Just re-read some of the posts and it appears you had to sleeve all cylinders? You could have a loose sleeve.