The Stovebolt Site Forums The Shop Area Engine Shop 55.2 Chevy 3100 235 Engine noise updated

Hello Gentlemen- I wanted to ask if anyone would help me remedy/diagnose a whistling, metal-type, high-pitch skreetchy noise that my 55.2 Chevy 3100 235 has developed recently. I fear the worst, of course, have read dozens and dozens of thread posts, but I think it's time to ask for some specific help before I damage my engine.

Background: My 55.2 Chevy 3100 235 sat from January to March (50-60 days), and became somewhat seized; meaning the starter could barely turn it, but I couldn't (still can't) turn it at the fan belt. I Krill/MMO'd the cylinders, studied all the advice here, and while letting it sit, I replaced the starter switch and had the starter gutted & rebuilt. That needed to be done last year anyway. I also got a new battery, cleaned the cables, and replaced some wiring. Once I saw that the truck was going to start and run, I changed the oil and that's about where my videos pick up.

This video is from mid-April, and I wanted to see if anyone noticed anything with the valve cover off (my son the truck owner shows up in this one because he woke up from his nap, so my apologies on the video shifting around). There is also some chatter from the door frame and a loose screwdriver on the dash:

55.2 Chevy 3100 235 Running with valve cover off

And this video is the current situation only a few days later :

55.2 Chevy3100 235 engine noise

My bad ears hear a rusty ring particle scratching a cylinder wall but I am not a mechanic; I'm just trying to learn without screwing my truck up, so...? Any sound advice on my best next course of action would be greatly appreciated. Thanks!

Brad

Take a length of heater hose and use it as a hearing aid. Hold one end to your ear and the other to the water pump, valve train, generator and anything else that spins.

Take the belt off the water pump and generator and then start the truck to see if you still have the noise. If it's gone with the water pump and generator not turning, then check each of them.

But it sounds to me like a rocker arm may not be oiling properly. Hard for me to tell in the first video, but was there plenty of oil at the rocker arms?

i didn't see any oil coming from the holes in the rocker arms.

rolf

The fan belt is far too loose, and it will produce a high pitched squeal. Also, the rockers are not getting enough oil, if they're oiling at all. Where in "north Alabama" are you? I'm just above Ardmore near I-65 Exit 6. Drop me a PM and let's get together for a little diagnosis session.
Jerry

Sure does seem to be pulsing with the motor. Like not a bearing, but just a guess. Squirt soap on the belt, that will only prove it's the belt slipping. That noise will be real easy to find with a broom handle up to your ear as you touch all over or a hose or any of a dozen ways up to stethoscope. As crazy as is "sounds" it could be an exhaust leak because I keep hearing it pulse/puff/in-sync with motor. Not sure just guessing. Usually a squeaky belt will change pitch or stop squeaking when accelerated. But so does other causes. you didn't accelerate on video of eng.

One question, is your oil pressure gauge functioning? It seems somewhat low. One observance, there is too much silicone sealer that has been used on that engine, perhaps some of that silicone has worked its way into somewhere it shouldn't be, causing rocker arm oiling issues, or worse

I'll have to re-check on the rocker arms oiling functioning. Because there was still a lot of residual oil from me making SURE there was some squirted in the valve springs & arms on start... I don't know.

I thought about checking it from reading posts, but didn't really know how much to expect to see.



Thanks

Brad

Brad,

With the engine running, if you see any amount of oil continuously dripping from the rocker arms, you are most likely OK.

I like to see oil dripping from each/every rocker arm. This assures me that the rocker arm shafts are not clogged.

as said above, pull the belt off and try it a few minutes, the squeaking is the water pump or generator ... the valves are not oiling [the tube at top may be kinked closed], and they're badly out of adjustment, can see big space between rocker and valve stem in a couple places .... do a complete tune before getting excited about anything

Bill

All- Thanks a bunch!! A couple answers on this end before I get to checking out the truck:

The fan belt has been replaced & is tight as a guitar string now-everything positioned back correctly;

I removed the oil pressure line at the 't' fitting on the block, awkwardly maneuvered it to where I could see the gauge in the cluster, and pumped it with a bicycle pump. The gauge worked fine (or, the dial pulsed with each pump), so the oil blockage somewhere definitely has to be addressed;

And as high-def as that video camera is, I should have seen some oil coming off the arms after 10 minutes- so let me do some investigating & I'll check back in.

MANY THANKS!

They are advising you to take the "tight as a guitar string" belt off and listen for squeak. Did you do that? I thought I saw some really, really clean oil dribbling, hard to see real clean oil on a video, you can see better as you said.

Pains me to watch that motor run with out oil everywhere, which is what mine would be like. Slow down the idle really slow and drizzle some oil on the rockers then listen for noises. Fan belt is a bit loose but not that bad. Also if water pump is making noise, give a shot of spray lube from the back side of pulley and see if it goes away. Try a good sized screw driver behind your ear and go around and check for noise.
Best of luck

The valves need to be set, but you have an oil problem. You should have oil dripping from the rocker arms when it's running. I see the tube that feeds the rocker arms is kinked almost closed,that's not good. If you take the side cover off, behind it is a small oil feed line that runs from the rear cam bearing to feed the oil to the rocker arms. Remove it soak it in something to clean it, blow it out with air,were it connects to the head, if you look on the outside of the head, there will be a small 1/4 inch pipe plug, take that out and clean that area with some carb cleaner . Good luck.

Well... last night I pulled the fan belt off as advised, reconnected my fully charged battery, re-checked everything and had my hearing hoses ready...

I didn't make it that far. Now, the metal noise (or, a metal nose) was LOUD on the full starting revolution, and sounded like it was from starter/clutch area (this noise barely happened ONE time prior to last night, and only for maybe 1/100th of a second- then the truck started).

I already had the flywheel cover off, so I turned it over with and with the clutch engaged, then without. I videoed it just for the noise, but you'll be looking from under the housing (warning-sounds BAD):

55.2 Chevy 3100 235 noise at start

Could the weaker battery have hidden this noise last month on the video? It just made the 'rerr, rerr, rerr then fire & start, and that's when I noticed the in-time noise we were supposed to be looking for.

I could only bear that noise twice, then for the video, but I did go ahead a pull off the side plate for the line removal cleaning later tonight... If I'm not toasted on the new noise. Thanks for ALL the advice on what needs done- valve adjust,oil line & oil issues, but I don't want to budge it again until it's safe to. (It would have started up, by the way). If anyone of you veterans can internet diagnose this- I'll do what I need to.

MANY thanks in advance; off to work, but I'll answer what/if I can during the day.

Glad your addressing that kinked oil line.

That squeak is metal on metal and in the area of your video.
Based on the area where it's at I'll swag that the throwout bearing is wornout and causing the squeak but I can't recall one making a as high a pitch noise like that. It almost sounds like a tin is rubbing either on the flywheel, pressure plate or crankshaft end where the flywheel bolts.
It sounds external if thats any consolation. (it would be to me )
Look for any shiny/bright spots on the flywheel and pressure plate. You may want to hand turn it while down below looking.
Put some good lighting on it too.
Good luck
Dave

For some reason, the last two you tube videos you posted aren't playing on my computer. If looks like you're dealing with more than one problem. I'd suggest dropping the transmission and clutch, and possibly the flywheel to eliminate the possibility of something wedged between the flywheel and the engine block. At least remove the sheet metal cover under the bellhousing and look for debris in the flywheel/block area with a bright light. DO NOT keep trying to run the engine- - - -you'll only be doing more damage. Once the rubbing noise is dealt with, then it will be time to manage the rocker arm oiling. A dry or damaged main bearing can also cause a squeal, but that's engine overhaul territory.

Pulling the side cover isn't likely to show you much about rocker arm oiling. The oil passages are internal, and aren't accessible from under the side cover. The 216's and pre-1955 235's had an oil line under the cover, but it was a PITA to deal with- - - -impossible to remove without destroying it as it went all the way through the water jacket and was secured with one-time-use compression fittings. You can remove the 1/8" pipe plug at the center of the cylinder head to see if you're getting oil flow there.
Jerry

I'm requesting a little more advice if it's not too greedy of me -I went ahead and dropped the transmission (heavy as a MK19 receiver!) to see what I could see, so here's what I saw:

55.2 235 Views of clutch splines with the transmission off. *pressure plate splines (I'm learning, right?)

The ONLY thing shiny indicating any wear was on the center of the pressure plate splines, and on the face of the throw out bearing where it greets the splines... Or, is this just normal wear? I have a new clutch kit at the ready.

I removed the clutch and inspected it & the flywheel (fw still installed), but I did not see any obvious signs of foreign material aside from dirt dobber dirt. The flywheel is now a LOT easier to spin (still with the mini crow bar, though), and I can definitely tell the metal noise when rotating is coming from between the uppermost rear of the oil pan and where the clutch used to be. A noise is still present, though subdued, at the slow 4 to 6 degrees of travel when I spin the flywheel.

So should pull the flywheel off while I have the access? Or just install the new cutch hoping that shiny clutch evidence was it for the noise? It took 34 years to happen, but that was my first transmission removal.

I'll probably need an extra set of hands for the flywheel.

Thanks-
*Edited for correct "pressure plate" splines

When you spin the through out bearing is it smooth and quiet? I you still hear the noise pull the flywheel and take a look.

Don- the removed bearing spins feely, no noise, and actually spins better than the new kit one. It was just shiny at its pressure point. I'll go ahead on removing the flywheel after I read up on that. Any surprises to look for? I read a thread I should mark its location before removal.


moderator-
I didn't know whether I was supposed to start a new thread on this issue?...

I'd suggest pulling the flywheel as long as you're into things this deeply. I seem to remember there's a freeze plug at the back of the block that might have been pushed out against the flywheel from a freeze-up? The flywheel removal only involves 6 bolts, and it's really not all that heavy, but wear a pair of leather gloves to prevent the ring gear teeth from digging into your hands as you lower it out of the bellhousing. Once the flywheel is removed, you can put 2 or 3 bolts back into the crankshaft hub and use a pry bar to turn the crankshaft. If it still makes noise with the flywheel removed, the noise just about has to be internal. Good luck!
Jerry

All-
I would have posted this in the driveline forum, but I wanted to keep this thread updated for someone searching down the line (it’d be helpful to someone like me if an updated diagnosis was always given in threads :))…

After removal, the flywheel looked fine on both the crank and clutch disc side with no obvious scratches or heat damage. The inside of the bell housing was also undamaged. The casting “freeze” plug was in place, and as new. It looked aluminum or stainless, and if it had have popped out and wedged in, that would be the exact noise I was hearing. I still can’t get enough mechanical advantage to turn the engine at the crank with a pry bar through offset positioned bolts in the crank face (& spark plugs out). But remember, the starter will turn it, and I can turn it prying the flywheel at the bell housing. Doing this produces a noise, I mentioned, but after further listening it is not the same scratchy scraping noise that spawned all this investigation- it is more of a “tight” turning sound.

Here’s what I have found after removing propeller/drive shaft, transmission, clutch, and flywheel:

Pressure plate fingers are shiny at the tips, and one is about 1/32” raised more than the others toward the TO bearing, or just enough to notice by running an index finger over them. It would cut you if you tried to make it, though;

TO bearing spins freely;

The clutch disc shows some uneven wear viewing its faces, but still has some ‘meat’ or disc material between its grooves extending from its center (though less at the ends). Looking at it on end, & unlike the new clutch kit disc, it has some squeezable separation between its sides exposing the rectangular flat springs inside; but they do not protrude outward. I have a replacement clutch kit.

So, would the (chipped at its 5 o’clock) pilot bushing have made the metal scraping noise I was looking for? It has a small hang-nail sized piece of itself that has come off, but I did not find it when I removed the flywheel, and the bushing is going to be heck to get out. The main shaft of the transmission showed no evidence of wear.

I’m being cautious, but can (should) I put just the flywheel on & turn the engine over with the starter? Just for clean everything & work-backwards elimination? This would be working under a HUGE, but somewhat warranted assumption that the noise was external to the engine. Or, should I treat this like a seized engine and wait a while?
Thank y’all for your advice!

Wow Brad. I watched both videos and they were painful to watch and listen to. Being as you have the clutch off have you tried to spin it with just the flywheel on? If so and the noise is still there it looks like a rebuild. Possible broken ring scrubbing on a dry cylinder wall.

The pilot bushing just holds the front shaft of the tranny in place and doubtful that it would cause the noise. They're really easy to take out. Just fill the hole with thick wheel bearing grease and stick a dowel the same size as the hole and smack it with a hammer. Larry

Your second video pretty much tells the story. You have very little oil pressure according to the gauge on the dash. I suppose many engines have lived a long time with only 5 or so pounds of oil pressure at idle, but when you revved the engine up the gauge did not budge. You have no oil flowing to the rockers. I think your noise is internal in the engine. Time for exploratory surgery. Start with pulling the oil pan and checking the bearings. There is a good chance the pickup screen on the oil pump will be at least partially plugged with silicone

I didn't realize posting on here made my question thread keep bumping up the engine list--Sorry about that Stovebolt! Not my intention, but thank you all for ALL the tips- I listen & we will be having "exploratory surgery" now, and not budging the engine until I find out what made that noise...

If Sedgewick happens to read this, I finally found an almost identical scenario to mine in a stovebolt thread and would love to know the advice he was giving his neighbor that fell "on deaf ears," but I'm sure it is very close to everything y'all posted here.

I don't see a problem. Just post and let us know what you find. I for one would be interested in what you find. These old motors have been around a long time and we as a whole can never get enough of them.Larry

That's the way the forum works, every time someone posts a reply it bumps back to the top. By all means tie into that thing and let us know what's up

Alright, Gentlemen

Here is the view from underneath with the oil pan removed . Definite oil passage(s) blocked.

Nothing felt broken or scored that I could reach, but experience (and lack thereof) tells me to continue reading the assembly manual on my new 2000 lb engine stand (I returned the clutch kit I had bought )... My neighbor has a cherry picker he can wheel over...

Unless there is a substantial amount of advice from all of you contrary to me pulling the engine, that's the direction I'm leaning toward. So can anyone weigh in from what the pictures show ???

Thanks!

Boy #4&5 sure look like they were running without oil.

Brad
Definitely looks awfully dry on what looks like number 4 and 5 rods and cylinders. You could pull those rod caps off to verify damage, but I am pretty darn sure at least those two are smoked with probable crankshaft damage. If it were mine, I would yank it for a complete teardown, cleaning, and rebuild. You are going want to do some very thorough cleaning of every oil passage in that engine. Do a very careful teardown, mark everything, especially the rod and main caps, and study everything you take apart, so you can find the culprit. Upon re-assembly of the engine, silicone sealer only needs to be used in very small quantities, in a few places. If any of the rod bearings have "spun", do not use those rods over again.

Here’s what I have found out with the 55.2 235 engine since removing the oil pan, and finally pulling the engine out of the truck & mounting it on a stand to disassemble.

These are pictures of what the rear intermediate main bearing and numbered four spun rod bearing look like:

De-motivational pictures

So, I most likely found where the awful squeal racket was coming from. Maybe the crank can be ground, but I may just go with a new one (advice on this?). I have not detail/boot camp scrub cleaned the block yet, and oil passages were found blocked at two spots on the initial cleaning (one gunk plug at oil gallery plug & one somewhere else- I forget now, but wrote it down).

This is just an update on where the (cranking) noise came from last month, and it was mentioned a bad main bearing would squeal. Maybe this thread will help someone later on, as they will now have a video of mine to let them know what they're dealing with should they become so misfortunate.

Thanks again!
Brad

Ouch! That one's painful to look at! Be absolutely sure to pull all the oil gallery plugs out of the block and scrub the oil passages with rifle or shotgun cleaning brushes and plenty of solvent. If you haven't picked out a machine shop yet, talk to Alan at Lincoln County Auto Parts in Fayetteville. He will be able to give you good advice on whether to regrind or replace the crankshaft, and he will probably have a reasonable-price supplier if you choose to go with a "crankshaft kit"- - - -reground shaft and rod and main bearings as a package deal. Get him to recondition your connecting rods also. I've been doing business with him for 25 years or so, and he's VERY good!

If you need a hand with reassembly, give me a shout!
Jerry

WILCO, Jerry- you saved me the trouble of calling ALL the shops in Fayetteville, asking if they knew you, then hoping it wasn't an old racing rival of yours looking to settle a score or something! (instead of just admitting that I forgot who it was you recommended, and asking again)

On the same note, my pride also kept me from posting those bearing pictures immediately. "Ouch!" is an understatement. I didn't necessarily cause their failure, but I was reluctant to share it. I love reading/studying on "the Bolt" and I see a lot of that same reluctance here sometimes. A long, interesting, educational thread will be going... then nothing. The facts are the facts, folks, so it's ok to fess up if you had half the United States helping you get your truck running on here, then you saw you left a coil wire off.

Just don't do it twice, right?

If we ever muster up a video section in the Tech Tips called "Engine Noises: Ouch! That Means A Rebuild!" , I've got us a good starting point here!

Brad

For the most part, round track racers are best friends until the green flag drops- - - - - -we even help each other build engines sometimes, or share spare parts with a competitor to get him back on the track after a pileup.

When I raced at the Merced County Fairgrounds dirt track in California, the top driver there had a slogan painted on the back of his car:

"WHEN THE GREEN FLAG DROPS THE BS STOPS!"

LOL!
Jerry