Strange noise from front of engine?
 

My 400 has been making an odd noise from the front of the engine for awhile now. I replaced the water pump (leaking) and its still making the same noise. It's a cyclical, whirring crunch-grind-pop, crunch-grind-pop, crunch-grind-pop that's mostly noticeable at idle. It sounds like a combination of belt noise and alternator bearing noise, but the accessories are low miles.

It sounds like the alternator or the timing cover area. I changed the fuel pump and the water pump for other issues, but the noise hasn't changed. If it still makes the noise after I disconnect the belts, where should I look next?
Does a fuel pump eccentric ever fail? I re-used it when I changed the cam and timing chain about 2K miles ago.

Have you tried using the stethoscope method to localize the sound?

George

I have put the pump eccentric back on wrong once by mistake and only noticed it two days later when putting the cover.

Sorry but I can’t tell you what a bad one would sound like, I tell you what I would pull the balancer off just to see if the keyway is cracked or starting to crack.

Lower pulley crack is where i would look next.. Pulling the belts would tell alot, then you could spin the alt. by hand to inspect that new doesn't always mean good... Same with the water pump

Could it be timing chain beginning to fail? How many miles on the motor?
Have you changed the oil since you stated hearing this? It might have some tell-tale signs in the oil. Hoping its nothing serious for you!

Check the big balancer hub bolt for looseness. Should be 160 lb. ft. Next check the bolts that hold the balancer itself and the pulley to the hub. Should be 25 lb. ft. Also check the power steering (if equipped) pulley. Should be 70 lb. ft.

Also since the motor is a 67 it would have a full length windage tray and they have been known to crack and slap around.

On a 67 the balancer can seperate and make noise even if the bolts are tight. Easy to check. I had this happen when the rubber on the balancer completely went away. I noticed it when shutting off the engine the balancer outer ring continued to spin for a short while and made a whirring sound. The outer ring is captured so no danger of it coming off.

Check the Crank Pulley for 4 ovaled holes ( red rust from them holes).

Might be time to dril 4 new undersized holes, and use 4 fresh bolts ( or cooling fan studs).

Rub a bar of soap on your belts and see if it changes the noise. Sometimes antifreeze on belts and pulleys is really noisey, even when it gets washed off.

I would run it with no belts, and see if the noise goes away. If it does, then add the alt belt and see if the noise comes back. If noise is still not present, add the ps belt.

You could also half split with the fuel pump too. You could fill the carb bowl manually, and run with the fuel pump disconnected and removed.

I remember years ago pulling a fairly fresh motor because an exhaust leak sounded like a rod knock. That is why my Firebird now has a 350. Noises are tough!

He has tried running it with no belts folks.

Not yet steve. My next course of action is going to be to pull the belts Crank it up and let it run. About how long can I let it run before worrying about it getting hot?

See if your 4 studs are too far through the water pump.

I'll pile on and say that a mysterious 'scratchy' accessory drive noise on my 67 GTO ended up being old belts. This is after I rebuilt the water pump, alternator, and PS pump.... I would have never guessed the belts could make such an odd and loud sound.

With a ambient temp of 60 degrees you could run a cold motor at idle for 3 minutes safely no sweat.

Follow BB70's advice. You won't have to pull the belts and you can do 1 at a time. Besides soap I have used a crayon or candle.

Yes, check on this suggestion. It cost you nothing to check. I had the same kind of noise in the front of my motor. Sounded like a bearing noise, or as I put it, marbles in a can making noise. I took the valve covers off and checked the rockers and it was not that. So I changed the water pump because it sounded like a bearing noise, it wasn’t that. Then I went to check the balancer, and it was the four bolts holding the pulley’s on. The bolts were almost sheared off. I was lucky to catch it before everything in the front of the motor let loose. Good luck…

It's a '69 400 with the 11 bolt water pump and the later balancer.

Here's the results of today's testing:

Similar noise with both belts removed
Some belt and fan noise went away, making the rattling sound easier to hear. It sounds like sheetmetal contact/rattling/tapping near the center or front of engine.
All rocker arms adjusted and all pushrods spinning
Balancer is a nice SFI piece, not slipped or coming apart
Bottom pulley bolts are tight. RARE billet aluminum bottom pulley
I need to check balancer bolt with a socket, but the balancer didn't have any slack when I pushed/pulled on it.

On start, It doesn't make the noise for the first 15-30 seconds, then the noise starts. I stopped/started the engine 3 times, and there is a slight delay between engine start and the onset of the noise. Can hear it topside, loudest near the front. Can't hear it under the car, at least not over the exhaust. It almost sounds like the exhaust hitting something, that sort of rattley tink tink noise. But coming from inside the engine.

I pulled the fuel pump and used an inspection camera to get a few pics of the fuel pump eccentric. I used a screwdriver to move the outer ring to the front. It seems to have about .100 or so of forward/backward slack on the inner eccentric. The outer ring will sit flush against the gear or move forward as the pics show. Sorry for the weird angle, its hard to get in there and take pics.
Is this normal? I got a video too, but will have to upload it to YT later.

Well your eliminating some sources of the noise, so that is good. You could start and run it without a fuel pump and see if the noise changes. (sounds different, goes away or gets louder). That might help you zoom in on the fuel pump drive. if you don't have one, you could make a fuel pump cover out of cardboard for this test. Shouldn't make too much of a mess in 30 seconds. Any way to check if the thrust plate bolts have backed out and are contacting the camshaft sprocket? Not sure if you can see well enough in there. Also, is this a manual or auto trans car?

Is it possible that the oil pan baffle is rattling?

Personally, I'm a duct tape guy. Lol.

Good mention about cam thrust plate.

Once you posted the photos my thoughts went to the same possible issue as stated in post 20 that the Cam retention plate might be loose.

You should check this possibility out before you fire the motor again because the Cam moving forward and back too much will shorten the life of the lifters and Cam lobe’s.

Good luck, hope you find this problem.

I was going to guess fuel pump eccentric, loose/damaged. It looks pretty worn, you may want to pop the cover.

If it's loose, the tab can slip out of pocket and drag, pop could be it coming out of the pocket.


.

The best way to rule out EVERYTHING......
 

You've eliminated the easy stuff, so dig on in.

Just pull the timing cover off and you should (hopefully) know EXACTLY what the noise is.

Agree with Steve25 that you should not run the engine any more until you rule out that the cam retaining plate has gotten loose. Don't kill your cam and lifters.

It's gonna take you a couple hours and then you'll know if the engine needs to come out or not. Fingers crossed for you.

Less damage = better.

Spent the last couple of nights pulling the front cover off to get at the timing chain assembly.

The fuel pump eccentric was in place, but high miles and worn. It will be replaced. The cam timing gear bolt was tight, and the retaining plate bolts were tight. I loosened all the rockers to check the endplay before I loosened any of the cam bolts. Not much endplay, hmmmm, the clue phone is ringing.....

Looks like I've got insufficient camshaft endplay. There is a groove worn into the factory retaining plate. I re-used this plate when I slapped the cam in there, but I know I wouldn't have reused a plate with that much wear. The front of the cam shows some metal transfer from the plate. The snout on the cam gear measures .126-.127" and the plate is about .123-.125" depending on how you measure it. So I'm guessing it was on the tight side of spec? What is allowable camshaft endplay?

I'm not saying this is is THE problem, but it's for sure A problem. Can I clean up the cam snout with 400 grit?

I've got new plate, eccentric and bolts coming from Butler. What else do I need to check while I'm in there?

Is it normal for there to be that much forward thrust on the camshaft? Possible it wasn't getting oil?

I'm thinking there might be a bearing problem - either the front cam or main bearing?
 

My thoughts exactly. That looks a LOT like it's been run dry.

If that was my motor, I'd pull the distributor and use a priming tool and see HOW MUCH oil you get pumped out around the camshaft and that front bearing.

I suspect that you're gonna have to dig in all the way to fix whatever has caused that wear.

Question: How much fore and aft play is there in the camshaft if you re-install the retainer temporarily??

Could the cam bore block plug be driven in too deep pushing the cam forward?

The rear cam plug can only go in so deep because it stops on a intentional lip machined into the cam tunnel, but this does not mean that when that cam plug was drivin in that it did not mushroom some in its center area.

This would happen if it was driven in with too small of a socket.

Maybe that cam retention plate was installed the wrong way and was blocking off 1/2 of that oil feed hole slot , that is if it’s possible to flip that top to bottom.?

I believe the spec is .003-.010

All the stuff in your pics shows significant wear. But, IMO, you haven't found the source of the noise you described yet. A light scraping noise is all you would hear from that stuff. At worst a single (tap) when you snap accelerate the engine. Going to have to go in deeper unfortunately.

I was afraid you'd say that.
It seems that the noise starts after the oil pressure builds.

The rockers clack for a few seconds and then go quiet, and about the same time the noise starts. So it may be related to oil pressure, like the load from the oil pump tries to move the cam forward/backward in the block. It could also be oil pump shaft or oil pump, but I would not expect that to be loudest in the front. It sounds like the lifters are hitting the valley pan, but this is HFT lifters and a stock replacement Butler pan, so there should be no chance of lifter to valley pan contact.

This is an engine of unknown history, it's a '69 400 transplanted into a '67 car. The car was restored in the early 1990s, so I assume the engine was rebuilt about the same time. Looks like a basic stock rebuild with a crane cam. I swapped the cam out for a 2802 because the crane cam was losing a lobe but I caught it early. Even had the stock oil baffles under the valve covers. Engine is very clean inside and has good compression, good oil pressure and runs strong. The only debris I found was some fine glitter in the head's oil returns, so I suspect the engine has been making metal for a long time. TH400 line pressure was VERY high 210PSI+, so I reduced line pressure to take some load off the thrust bearing.

Where does a stock windage tray usually fail? I have an inspection camera, I can snake it in while the cover is off and take a look around. At this point where should I look next?

I found cracks on my full length tray near the area where it was attached to the #2 main cap.

On the full length windage trays, the cracks can be anywhere, honestly. But the most common areas are: Where the tray attaches to the #2 and #4 main cap. There is a steel plate spot welded to the tray where the bolts go through. Cracks often radiate outward from the welds and where the pan is bolted. Second area is on the side of the pan where the slots are punched in the tray for oil drainage. Cracks start in the corners of the punched windows and move toward the outside edges. Very much the way a windshield cracks from a rock chip for example. I don't believe the 4/5 short trays have any of these problems because they are thicker material. Possibly a better material as well.

I am sorry to mention this now. But did you look at the flex plate/torque converter to see if the bolts were loose, or the flex plate cracked? Either can make noise that mimics a fuel pump or other noise from the front of the engine. It doesn't make sense, but it can. I say this because you said the AT line pressure was excessively high and the noise starts after 15-30 seconds. This is the approximate time it takes the trans pressure to build as well as engine oil pressure. Before you possibly take the engine out, take the converter cover off and check the bolts. Also get your camera up in there and look at the flex plate bolts. When the plate cracks, it will usually leave a rust trail, radiating from the bolt holes. Give that area a look before going too far into the engine.

X2.
I had an unusual noise from the front of my '07 Cadillac. Most noticeable whenever the AC compressor was pumping. Dealership replaced the compressor but discovered that wasn't the cause. A senior mechanic, "the old guy", as my service advisor put it, opened up the inspection cover and discovered a cracked flex plate. Evidently the compressor put a slight load on the crankshaft to enhance the noise.

I gotta sadly say that from look of all the metal removed from the front of your Cam that I doubt that just a new Cam retention plate is going to anything for you .

If you're talking about the 45* bevel on the OD face of the front cam journal, it came from Summit like that. I've got another 2802 in a box I can compare it to.

Would a windage tray have to be very broken to make this much noise? I should be able to see a badly split windage tray with the camera.

Is is possible to remove the flexplate without pulling the trans? One reason I got a good deal on this car is the converter was loose when I bought it. The knocking sounded bad, but cinching the 3 converter bolts fixed it. Its entirely possible the flexplate is wasted and I didn't catch it.

How deep is that groove in that plate?
It’s hard to tell exactly from your photo, but that metal went somewhere !

Groove is 1 to 3 thou deep. I assume it's been self-clearancing. I dropped the oil and there is fine metal in the oil. Filter pleats show the same but no hunks.

I took a good look at the flexplate and its suspect. Reinforcing ring is missing. There are strange gouges near the bolts, but I can't tell if they are cracks or where some moron went after the flexplate bolts with a chisel.

Will a cracked flexplate make noise if I disconnect the converter? If I can prove its the flexplate, that's a good excuse to swap in the 10" Continental sitting on the shelf!

My plan is to fix the front of the engine, then dig into the back of the engine. Anybody got a lower radiator hose PN for a '67 GTO?

I would just pull the engine and tear it down. Find all of the issues out in the open instead of crawling around and under the car for days.

Yeah, I know. I'm just trying to stretch this engine's lifespan. I know it's long in the tooth and deserves to be put out to pasture as a future builder. I'd like to do that before it comes completely unglued, LOL.

I've got a 4" stroker combo on the stand that needs a few things to finish. The plan is to sort the car and then swap the engine. I'm pretty close to sorting the car out, I need this 400 to last just a bit longer. One of those things is swapping the converter and proving the Conti and this TH400 are happy, prior to swapping the engine in front of that combination. I'd really like to get this 4" combo on an engine dyno prior to install to be sure it's happy.

With the torque converter disconnected and pushed back, the noise should go away. If the flex plate is badly cracked or very loose, it may rattle. At any rate the noise will be different than if the converter were attached.

When you put the cam gear back on make sure the cam sticks out a little bit for the eccentric to fit over. (the gear should bottom against the cam journal face)

I have seen the eccentric not seated fully (because gear wasn't bottomed out).
The cam bolt must be tight, should not bottom in cam.

That situation it did make some strange noise but can't remember what noise it was like if compared to this?

Then run it and see if noise is gone before doing the flexplate idea.

:confused:

Got it all back together. Cam endplay ended up about .011" with the .117" thick butler retainer plate. Fired right up. Ignition timing is the same, so I got the timing chain reinstalled properly.

Still making about the same noise. Oh well, at least I fixed the cam thing.

Next step is disconnecting the torque converter and see if the noise changes.
If that doesn't solve it, I'll try to capture the noise on video and see if you guys recognize it.

That sounds like a good plan. Sure hope you find it.

Also just for S & G try disconnecting 1 plug at a time to see if what you hear changes .

The cam retainer plate is sandwiched between the timing gear and cam face it is possible the step on the cam gear is to short and pinched the plate inducing extra wear...... you can measure the step and it should be taller than a good plate by whatever the stated cam end play is