[67gtospud]

So yesterday I began hearing a new noise I believe is coming from my engine. It is only present upon acceleration and completely goes away when coasting or if no load is on the engine. Also it seems to get louder under hard acceleration vs light acceleration and is louder as the engine is warmed up and oil gets up to temp. I don't hear the noise at all when the engine is cold. I have great oil pressure. 60-65psi cold and above 4000rpms. 40-45psi highway cruising once the engine is warmed up. 10-15psi warm engine at idle. Oil pressure is very steady and consistent and doesn't jump around. Engine has 2850 miles on it as of today and about 1000 miles since the last oil change.

I have a bad gut feeling I may have developed a rod knock but want to confirm. I will be pulling the oil filter and cutting it open this week. I will post pictures once I figure out how to do that again but what am I going to be looking for?

[ponchjoe]

Strange it goes away, a mechanical failure usually is there all of time. What about the torque converter bolts if automatic?

[Navy Horn 16]

Originally Posted by 67gtospud

......what am I going to be looking for?

Your wallet.

Just kidding. Some bearing material may be to big to end up in the filter, and could get caught in the pickup screen. Can you drop the pan and see what you have in there?

Are you sure that it isn't in the valve train? The kind of symptoms that you are describing could easily be in the top end. Pull the valve covers and see if anything is out of whack up top.

[67gtospud]

Originally Posted by ponchjoe

Strange it goes away, a mechanical failure usually is there all of time. What about the torque converter bolts if automatic?

Manual trans

Originally Posted by Navy Horn 16

Your wallet.

Just kidding. Some bearing material may be to big to end up in the filter, and could get caught in the pickup screen. Can you drop the pan and see what you have in there?

Are you sure that it isn't in the valve train? The kind of symptoms that you are describing could easily be in the top end. Pull the valve covers and see if anything is out of whack up top.

I will pull the covers and see first. If I push in the clutch then rev the engine quick I don't seem to hear the noise. How do I determine if I have a failing lifter?

[Will]

If you have a bearing going bad you will find obvious evidence inside the filter. Copper colored particles/"dust"

["QUICK-SILVER"]

Yep, need to try and figure out where the noise is coming from. Sounds like you've ran it enough the knock would be present reving it under the hood if it's a rod bearing.
Valve trouble does sound possible. Worn out/broke intake valve spring or exhaust lobe going south on the cam and it will back-fire loud through the carburetor when you get on it.

Do need to check for glitter in the oil filter before you run it much more. I've got a mean pair of tin snips that I cut the crimp ring off with to take them apart.

Think I'ld have to get under the hood with it hot and try to replicate the noise before taking too much apart. Rods will usually give you a double knock if you rev and let off quick from a fairly fast idle.
With a valve train problem, you might have to rev it hard for it to back-fire since the engine isn't under a load.

Hate to hear this and best of luck that it's something simple up top. If it's coming from the engine at all.

Don't know how loud the car is...But I've had header gaskets blow on one cylinder that would make you think something was knocking. That got louder the harder you pushed it under load. Not be loud at all reving in neutral.

Also have seen intake gaskets blown at the heat cross over. They'll give a good crack when you rev it under load.

Good luck all the same and keep us updated.
Clay

[Navy Horn 16]

Originally Posted by 67gtospud

How do I determine if I have a failing lifter?

My first Pontiac engine was a 350. The first indication I had that something was wrong was when it ate a push-rod. That was fairly easy to diagnose.

My 2nd Pontiac engine was a 400, with a hyd roller cam. This one went through several stages. It started out with slightly shaved 6X heads to get 9.5:1 compression. It ran good until one day I broke a rocker stud. Turns out that stock "coke bottle" studs don't mix well with anything above stock cams. I replaced that stud, and was about to go with BBC studs, then I got a deal on some E-heads that had been set up for a drag car. I was impatient, and instead of getting the springs replaced, I put them on the car and then realized that my lifters weren't going to work. I ended up running a hybrid setup with the HYD profile and solid lifters. That worked well for about 10K miles, and then the high spring pressures ate the cam.

I absolutely hated how the solid lifters sounded, so I resolved to go back to HYD rollers.

I'm on my 3rd Pontiac engine now, and quit trying to figure it all out myself. Jim Butler guided me through the build (new springs on the heads), 10.1:1 compression, etc. It's got his custom grind Comp Cam, and it runs really good. Shocking, this one hasn't had any issues. It does have a lot of forged internals, so it kinda sounds like a sewing machine for the first 5 minutes or so until it is warm. After that, it is smooth and runs like a raped ape.

When I was dealing with the solid lifters (and constant valve adjustments), I learned that minor valve lash issues could cause things like what you are talking about. Engine load was a huge factor. With a valve out of adjustment, it could run OK at constant speed and idle, but get on it hard and it would really show itself.

If you are hearing the noise under a load and not at a specific RPM, I'd be less inclined to suspect a rod bearing. Rods feel the centrifugal force of RPM regardless of if it is pulling a load or not.

[tom s]

Actual CR?Detonation?Tom

[67gtospud]

Originally Posted by "QUICK-SILVER"

Yep, need to try and figure out where the noise is coming from. Sounds like you've ran it enough the knock would be present reving it under the hood if it's a rod bearing.
Valve trouble does sound possible. Worn out/broke intake valve spring or exhaust lobe going south on the cam and it will back-fire loud through the carburetor when you get on it.

Do need to check for glitter in the oil filter before you run it much more. I've got a mean pair of tin snips that I cut the crimp ring off with to take them apart.

Think I'ld have to get under the hood with it hot and try to replicate the noise before taking too much apart. Rods will usually give you a double knock if you rev and let off quick from a fairly fast idle.
With a valve train problem, you might have to rev it hard for it to back-fire since the engine isn't under a load.

Hate to hear this and best of luck that it's something simple up top. If it's coming from the engine at all.

Don't know how loud the car is...But I've had header gaskets blow on one cylinder that would make you think something was knocking. That got louder the harder you pushed it under load. Not be loud at all reving in neutral.

Also have seen intake gaskets blown at the heat cross over. They'll give a good crack when you rev it under load.

Good luck all the same and keep us updated.
Clay

Definitely no backfires. The engine pulls as hard as it has from day 1, no noticeable performance losses. I just installed the efi and new/modified intake this past spring. If I had an intake or exhaust leak I would see an afr issue and it would be running super rich, neither of which are problems I'm having. The springs are all new however the heads weren't rebuilt so valve issues are possible. I will look at valvetrain first and cut open the filter before I get too deep.

Originally Posted by tom s

Actual CR?Detonation?Tom

Actual compression ratio is 9.78:1. This weekend was upper 70s- low 80s whereas I've driven in upper 90s no issue. Highest engine temp while running has been 197, normally 190-195. I've ridden in and driven vehicles that had detonation issues and this doesn't sound anything like that. I filled up with the same premium fuel as I do my other vehicles at the same station I always do and those vehicles are not having fuel related issues so I ruled that out.

[67gtospud]

Now I'm thinking about it more and I do notice occasionally upon startup I usually have what seems like a misfire for a moment espiecially noticeable if I touch the gas immediately upon startup and try moving the car. If I let it idle for 20+ seconds it'd fine. I suppose this could lead to a lifter issue? Is it possible I have lifters that aren't pumping up enough when driving and it's causing my noise under acceleration? If so what are good lifters to get? The current ones are lunati. (I'm not sure who actually makes them.)

[track73]

A rod knock is generally all the time. I had torque converter bolts loosen that sounded like a rod knock but only when not under a load. Exhaust leaks can sound like knocking and is heard under a load.

[surfsama]

Originally Posted by "QUICK-SILVER"

But I've had header gaskets blow on one cylinder that would make you think something was knocking.

If you haven't yet, get a piece of hose and try to isolate the location of the noise. Header leaks are notorious for sounding like a serious issue.

[goatman65]

If you have headers check that they are not hitting somewhere. My Dougs are very close to the lower control are mount and would hit when I would rev the engine, Cut off tool fixed that. Or loose/broken engine or trans mount?

[steve25]

If its still making even some light noise when fully warmed up at or near idle then pull plug wires one at a time and see if the noise goes away.
Does advancing the base timing at idle make for more noise?

[track73]

I built a late model engine for a friend and when he came back to the pits after the race the engine banged like all the rod bearings were loose. We started to remove the engine and discovered that the header was broke on one cylinder. Do what Steve25 said.

[Squidward]

Yes, check for exhaust leaks first. Those are cheaper and less taxing on wallet and body.

The timing of the knock can be key. My experience with 3 rod knocking 400's is that the knock can "float" during free rev, with a higher frequency and shorter period than spark frequency on a timing light. Pulling one plug wire at a time to identify a misfit cylinder can also help diagnosis. Removing spark should diminish a rod knock.

A collapsed lifter will knock with the same frequency as the spark firing, which is once for every 2 revolutions.

[67gtospud]

At idle there is no noise whatsoever. Also completely silent as soon as I take my foot off the go pedal.

Just thought of something. . . . is it possible I'm not using heavy enough oil? In running brad Penn 10w-30. Should i maybe run a 10w-40 or 15w-40?

[67gtospud]

Alright took a few minutes today and pulled the valve covers quickly, everything looks good there. Nothing loose or broken. I did however notice there's a small but very deep ding in one of the primary tubes in the driver side header. I fired the engine up and it's not leaking there but I will be replacing those headers when I do my 428 build anyways. I did find an exhaust leak between the header collector and the slip-fit reducer. It's very slight at idle and I could barely feel it. I would imagine it'd be louder under load so I'm going to see if I can seal it up enough to test that the noise goes away.