Engine Noise - Need Some Help

by 76 Malibu Sun May 21, 2023 6:27 pm

Got my engine back together today after doing valve seals, timing chain, new water pump, clutch fan conversion, and intake/carb swap. I am getting a God awful squeeking noise from the motor. I swore it was the drive belts, or PS pump (installed a new steering box). However, I disconnected the belts and ran it and same result. Using a mechanics stethoscope it sounds like the noise is coming from the front cover. It is a new cover too. I turned over the motor many times by hand and never any noise.

Any ideas on what is going on?

by 76Chevelle2Tone Sun May 21, 2023 9:23 pm

Maybe my hearing is going but that didn't sound like squeaking in the vid. There is a higher pitch steady noise. What kind of chain did you put in?

by 76 Malibu Sun May 21, 2023 10:08 pm

Maybe squeaking was a bad description, more of a squealing. It sounds like a bad alternator bearing. Regardless, it's pretty loud and not normal and I am worried I am damaging the engine. It does quiet down a little bit when revved, but does not go away.

I used a Cloyes C3001K timing set. It's supposed to be a stock type replacement. I also have a new Proform cover. So my only guess so far is that the new chain and cover are rubbing? Or maybe the timing sprocket is rubbing on the block? It seemed fine when I installed. I don't know if cam walk would cause an issue, but I didn't touch the cam, and it was fine before with the original parts.

https://www.summitracing.com/parts/clo-c-3001k

https://www.summitracing.com/parts/pro-141-783?seid=srese1&gclid=CjwKCAjwgqejBhBAEiwAuWHioC5YUOEVr1z0v8MzNABi9XpurzcqjLku1d_1KJYZIUNQTogPwVNekxoC_zIQAvD_BwE

Any ideas are appreciated.

by 76Chevelle2Tone Sun May 21, 2023 10:17 pm

Yes squealing is a better term. I agree that the timing chain should not be an issue. If you are sure that the noise is coming from up front I guess you are going to be forced to remove the cover and doublecheck things. Since you are not reporting vibration that does constrain what could be wrong.

by zucchi Mon May 22, 2023 9:53 am

76 Malibu wrote:…I disconnected the belts and ran it and same result.

I hate when that happens and genuinely feel your dread.

How's your oil pressure?

From what I could hear, it sounds rhythmic – not a steady "eeeeeeeeeeeeeeeeeeee" but more like a "sheshesheshesheshesheshesheshesheshe". The frequency of that rhythm will narrow the noise to either the cam or the crank; the cam will have half the RMP of the crank thus if the cam is the source the "shesheshe", the sound will pulsate at half the rate of the engine RPM. Using an adjustable timing light to sync the pulsing sound with the light will help make that determination much easier.

Assuming the frequency of the noise points to the cam, I would pull the dist., fully inspect it and "hope" that's the source of the noise. If that's not it, then I have to agree with 76Chevelle2Tone; you're gonna hafta pull that timing chain cover off and inspect.

Good luck.

by 76 Malibu Mon May 22, 2023 1:48 pm

Oil pressure seems fine, but I haven't put a gauge on it.

The distributor doesn't seem to be making any noise when I put my stethoscope on it. It is original to the car, I just cleaned it up and installed new mechanical advance weights and springs.

I ran it again today, and it is definitely coming from the front cover, when I listened with the stethoscope. I am thining it sounds like the cam sproket is rubbing as it spins against the cover. It is an embossed cover like I liked to above, so maybe that's why it's rubbing. But I mean it's only a single row timing chain, so it should have plenty of clearance?

I found this pic of someone who had a similar issue, but it was all aftermarket parts and it looks like it had a cam button. Mine shouldn't be rubbing like this one.

https://www.reddit.com/r/MechanicAdvice/comments/nt5i6j/timing_chain_cover_on_a_chevy_350_rubbing_the_cam/

by zucchi Mon May 22, 2023 2:29 pm

76 Malibu wrote:Oil pressure seems fine, but I haven't put a gauge on it.

Despite the hassle involved, you gotta put a gauge on it. If for nor other reason than peace of mind.

Just want to confirm you didn't do anything to any part of the valve train?

I ask because a million years ago I used to know a good professional mechanic (a rarity) with his own shop who's since moved to a different State and is semi-retired – damn it. Anyway, he built his share of big blocks and he had one where the cam wandered in the direction of the back of the engine causing the cam gear to rub against the front of the block. He was completely baffled and couldn't figure out the cause. He ended up sourcing yet another all new valve train (cam, lifters, gears, pushrods, etc.) which solved the problem. He simply chalked it up to defective parts; never did determine the root cause.

Anyway, since you're convinced the noise is coming from the front, you will need to remove the cover and inspect. There is an ever so slight chance the harmonic balancer may be rubbing on the cover, seal, ??? I'm always one to hope it's something simple and easy yet still prepare for the worst.

Good luck.

by 76Chevelle2Tone Mon May 22, 2023 2:50 pm

76 Malibu,

this is the link to the timing cover I got and installed without any problems on my stock V8.

https://www.speedwaymotors.com/Spectre-42353-Timing-Cover-Kit,157601.html

the proforma does say "these Bowtie timing chain covers are designed as replacements for engines with a bolt-on timing pointer. "

by bracketchev1221 Tue May 23, 2023 8:37 am

I think you need to take the cover off again. Its rare, but I did have an issue with the cam dowel backing out and hitting the cover.

by zucchi Tue May 23, 2023 8:49 am

76Chevelle2Tone wrote:"…timing pointer. "

Did you eliminate the possibility of the balancer rubbing against the timing tab?

by 76Chevelle2Tone Tue May 23, 2023 11:57 am

zucchi wrote:
76Chevelle2Tone wrote:"…timing pointer. "
Did you eliminate the possibility of the balancer rubbing against the timing tab?

Are you replying to me or to 76 Malibu? I was just copying the usage notes from the item listing that 76 Malibu posted above. Don't know if he saw or missed them.

by zucchi Tue May 23, 2023 12:10 pm

76Chevelle2Tone wrote:Are you replying to me or to 76 Malibu?

76 Malibu.

When you mentioned the pointer, it occurred to me 76 Malibu's squeal could be coming from the balancer rubbing against the timing tab.

by 76 Malibu Tue May 23, 2023 6:06 pm

zucchi wrote:
76Chevelle2Tone wrote:Are you replying to me or to 76 Malibu?
76 Malibu.

When you mentioned the pointer, it occurred to me 76 Malibu's squeal could be coming from the balancer rubbing against the timing tab.

Eureka!! I just looked at my freshly painted balancer and it has a scratch all the way around its circumference, deeper at some points! Never have I been so happy to see my paint scratched! I think that has got to be the noise. I may not have time to get to it for until the weekend, but I am hoping that is my only issue. Wow, I can't believe I missed that earlier.

by 76Chevelle2Tone Tue May 23, 2023 7:06 pm

76 Malibu,

Are there any marks on the timing cover? Is the scratch on the balancer only the paint or the balancer itself?

by 76 Malibu Tue May 23, 2023 9:45 pm

I had to buy a bolt on timing tab as my new cover did not one tacked on like the OEM cover. It appears this timing tab is rubbing on the balance outer circumference due to insufficient clearance. This is odd because I turned the motor over by hand many times and did notice it scraping. Maybe I bent it or hit it when installing the PS pump. I will report back later when I have some time to work in the garage. It make sense now that it sounded like an accessory making the noise.

by 76Chevelle2Tone Tue May 23, 2023 9:59 pm

As I noted above I felt the lack of noticeable vibration ( I assumed you would have mentioned that) rather constrained what the problem could be. So I was not thinking it likely the engine was damaged. However I am very hyper about rotating parts so if it were me I would inspect the balancer very carefully for any damage either to the circumference or the spindle hole potentially inducing wobble over time. As for the timing cover, the listing did say it was intended for bolt on timers but maybe you can talk with Summit as to whether there are types that don't work well. Just my amateur thoughts.

by zucchi Wed May 24, 2023 8:48 am

76 Malibu wrote:I had to buy a bolt on timing tab as my new cover did not one tacked on like the OEM cover.

Back in the 1990's, rather than a tab, I went with a pointer that kinda looks like this…
Engine Noise - Need Some Help Msd-89884_xq_xl

To measure ignition timing, I use an adjustable timing light (similar to this one: https://www.summitracing.com/parts/sum-g1059).

I think the pointer looks tidier than a tab and the adjustable light allows me to measure my timing beyond the scale of the tab such as @ full advance\full vacuum.

76 Malibu wrote:Eureka!! I just looked at my freshly painted balancer and it has a scratch…

Good to hear. I completely empathize with your feeling of relief. A few months ago, my Monte Carlo was exhibiting symptoms of a leaking intake gasket – bad vacuum leak on one plane of the intake manifold. I set aside an entire weekend to tear into it and that Friday evening after I removed the air cleaner, I noticed a vacuum line had come off the manifold vacuum port. My first thought was, "No way it could be something that rudimentary." I reconnected it, started the engine, and voila, she ran purrfect. Thumbs up

What a relief that was.

by 76 Malibu Sun May 28, 2023 6:38 pm

So I got to the car this weekend and yes it was the timing tab. I am wondering if I bumped it when installing the accessories because it doesn't take much to bend it. After that was fixed then I heard a rattle and it was my heat riser valve. I had disconnected it and it closed up and was rattling. I will have to keep it wired open or remove it from the exhaust.

I set the timing and idea mixture and the car ran ok. The qjet seems to be pig rich when I get on it even just revving it in neutral. Still nice to hear the Qjet moan compared to the old 2G carb. I have lots to carb tuning to do...

by 76Chevelle2Tone Sun May 28, 2023 6:54 pm

With respect to the Heat Riser, they are dangerous when they malfunction. I have a riser delete in my 76 Malibu for that reason since the winters are not bitterly cold where I am. I guess you'll have to judge whether in Canada it has utility. Also what are the regs in Ontario concerning emissions? I have an operational Thermac which supplies some manifold warmth to cold weather starts without the danger to the engine.

by 76 Malibu Sun May 28, 2023 9:11 pm

The car lives in a garage and is never used in inclement weather, so I will be deleting it. I have run other cars from this era in the warm months without it or the heat stove and they work fine. I had just forgot to wire it open so it couldn't move, but I plan on some exhaust work this year too, so I will delete it then.

What exactly is dangerous about them? Back when these 70s era cars were old rusted beaters, they used to rot out or seize up all the time. Most people never fixed them.

by 76Chevelle2Tone Sun May 28, 2023 9:44 pm

What exactly is dangerous about them?

The issue is that they can seize up in the closed position even when the car is warmed up. Most of the time risers stick open or simply rust out which is merely a nuisance. The heat stove is benign and given your circumstance should be sufficient. I gather cars of this vintage are not examined for emissions functionality in Canada? The laws in the US are variable but some states do require emissions equipment over and above a catalytic converter to be present if it was part of original equipment. Enforcement is inconsistent admittedly.

by 76 Malibu Sun May 28, 2023 10:38 pm

Gotcha, yes seized close would be bad. Emission compliance checks have gone by the wayside here for all vehicles, except for commercial vehicles. About 25 years ago they were doing roadside enforcement, going after old cars. Even then, half the inspectors didn't know what emissions equipment was correct, and they'd mostly write up guys who removed cats.

by 76Chevelle2Tone Sun May 28, 2023 11:52 pm

That's interesting that only commercial vehicles are checked now in Canada. The US seems to be going in the opposite direction with the rather extensive requirements that Nevada put in place.Yes I can readily understand the lack of knowledge about various makes and their OE.

by zucchi Wed May 31, 2023 8:02 am

76 Malibu wrote:So I got to the car this weekend and yes it was the timing tab.

I'm sincerely happy for you. Glad it worked out.

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