Need Help Understanding Source of Engine Noise

[JohnGunn]

I am puzzled by a noise my stock 94 Aspire with 81,000 miles makes.

So many times I have seen members post a question which included their own unfounded thoughts about what may be causing their problem. Then the discussion is dominated by reference to those questionable remarks. In trying to avoid a repeat of that process here, I'll limit my initial remarks to reporting how the recording was made and some remarks about what you will be able to confirm for yourself from the recording.

Of course, I've listened to this many times and thought a lot about what might be causing it, but, rather than prejudicing your minds with my own dubious speculations, I would ask you to just listen to the recording until you are able to imagine what parts of an engine could be capable of making such a sound at this particular rpm.

After members have had a chance to express themselves I'll return here with my own speculations, together with what I know of the history of the car, which may or may not be helpful.

The recording was made using an Olympus DS-30 digital recorder. While the owner of the recorder held it down close to the top of the engine, to avoid any wind noise, I manually operated the throttle to find the spot at which the noise is most pronounced. That seems to be about in the middle between the fast idle at cold startup (I would guess about 1200.) and the normal idle speed of 700. The noise is not noticeable at the extremes of that range when standing before the open hood. (The placement of the recorder so close to the engine brings out sounds that I did not hear as we made the recording. Like the faint whistle noise.)

In case your player reports playing progress in seconds, I'll identify some points at which the noise seems to reach its peak. Among those times are the ones at the following seconds: 2, 4, 6, 9, 11, 16, 26, 29, 32, 35, 43-44(This is the clearest example.), etc.

There is a certain rpm at which the noise is most pronounced. I was trying to find that point and stay at it but the engine was not responding to the throttle quickly enough and kept over and under shooting my efforts at control.

Here is the recording:

https://sites.google.com/site/followthevoice/EngineNoise-2.WMA

I look forward to your response.

John Gunn
Coronado, CA

[Twistiva]

John -

That is one weird sounding noise. Not to make light of an aggravating situation, but it almost reminds me of that old Walt Disney movie in which Fred McMurray discovers 'Flubber' and puts it in his car. Anyway, how long has your Aspire made the noise? Does it occur at all running temperatures? Do you get any other fluctations/odd readings, ie, engine temp or oil temp changes, etc? Does the noise ever subside after the car has been driven a while?

My guess would be maybe a belt is rubbing somewhere?

BTW, danged good idea to record the noise. Very, very smart.

[iceracerdude]

That sounds very dry to me, like you're not getting enough oil pressure.
How quickly does your oil pressure light extinguish when you first start the car?
You may want to pull the vc and see if it's dry up there, you may have, or are already on you way to a spun bearing. The slight ticking sounds are some of the hla's.

[Safety Guy]

Iceracer may be onto something. I'd further suggest hooking up a mechanical oil pressure guage in place of your oil pressure sensor on the back of the block. See what your oil pressure is doing at the different speeds, etc. (if anything).

Other than that, my limited experience agrees with Twist and says "belt noise." Could be something somewhere that is rubbing the wrong way.

Also, one final thought is to check your alt belt for proper tightness. I say that only because I think I tightened mine a bit too much and I'm getting a "whizzing" type sound. I should go loosen it before the meet. (Along with that last thought, do you have P/S, A/C or other belt driven accessories we should know about?)

Karl

[WmWatt]

Sounds like an early electric Singer sewing machine. Could be the recorder is limited in the frequencies it records.

If it's a restricted oil flow issue you could try an oil additive to clean out the system. I've used one you put in *before* changing the oil. The engine is idled for 5 min while the additive dissolves deposits. Then it's drained out with the old oil. It can't be left in because then it dissolves aluminum. I think most additives are safe in aluminum engines these days but read the label on the can before buying.

If that doesn't work it may be engine wear and you could try a heavier grade oil or one of those oils formulagted for older engines.

I use a 3' piece of garden hose as a stethescope to help isolate the source of noises. It works pretty well.

[econoaddict]

Sounds just like already stated, timing belt rubbing on the cover.
Pull the top half off and run the engine, see if it goes away.

[crazyrog17]

That sounds very dry to me, like you're not getting enough oil pressure.
How quickly does your oil pressure light extinguish when you first start the car?
You may want to pull the vc and see if it's dry up there, you may have, or are already on you way to a spun bearing. The slight ticking sounds are some of the hla's.

Don't the Aspire B3s have rollers on the rocker arms? No HLAs then. I too hear the clicking in the valve train though.

Sounds like a bearing to me. Might also explain why has a specific range of RPMs that create the resonant noise.

[scitzz]

That B3 is thirsty! No oil in that valve train! Bad oil pump? Does the oil light go out at all?

[JohnGunn]

After I finish this apology, I'll respond to each of the members who took their time to listen to my recording and give me their opinions.

I should have done this sooner, but when my car is sick, I'm sick. And the bigger the problem, the more likely I am to run and hide, hoping that if I don't think about it, for that period of time at least, both it and I am well. This in spite of my own certain knowledge of the foolishness of such behavior. Well, it's time to face the music.

John Gunn
Coronado, CA

[JohnGunn]

John -

That is one weird sounding noise. Not to make light of an aggravating situation, but it almost reminds me of that old Walt Disney movie in which Fred McMurray discovers 'Flubber' and puts it in his car. Anyway, how long has your Aspire made the noise? Does it occur at all running temperatures? Do you get any other fluctations/odd readings, ie, engine temp or oil temp changes, etc? Does the noise ever subside after the car has been driven a while?

My guess would be maybe a belt is rubbing somewhere?

BTW, danged good idea to record the noise. Very, very smart.

I don't know how long it has been making this noise. From the driver's seat it is not very evident. I first noticed it showing a friend the whine noise that the engine was producing. He wasn't too concerned about that, but when I let it drop back down to idle, he said, "that noise sounds worse to me." That noise was the noise this recording highlights. Since then, of course, I can hear it from the driver's seat and at any other time I am within earshot of it. My guess is that it may have made that noise all the time I have owned it, I just managed to ignore it until someone made me listen. In my defense, the sound is much louder in the recording than when standing before the open hood.

The noise is pretty consistent and I have not noticed any other conditions that accompany it. Whenever at that rpm the engine will produce the noise.

I appreciate your good words about the usefulness of a recording in diagnosing engine problems from a distance. So much of what we do here is trying to find words to accurately describe the sounds our ailing engines are making.

[boydg1]

.... So, what's the answer??

.

[JohnGunn]

That sounds very dry to me, like you're not getting enough oil pressure.
How quickly does your oil pressure light extinguish when you first start the car?
You may want to pull the vc and see if it's dry up there, you may have, or are already on you way to a spun bearing. The slight ticking sounds are some of the hla's.

This is exactly the problem I was hoping not to have. But I thank you for your opinion. Even though I tend to agree with you, I'm still hoping we're both wrong.

After sitting over night the oil light goes out exactly 1.5 seconds after starting or 45 frames at 30 fps. How does that match yours? I don't remember what my Festiva did.

Thanks for your responses.

[JohnGunn]

Iceracer may be onto something. I'd further suggest hooking up a mechanical oil pressure guage in place of your oil pressure sensor on the back of the block. See what your oil pressure is doing at the different speeds, etc. (if anything).

Other than that, my limited experience agrees with Twist and says "belt noise." Could be something somewhere that is rubbing the wrong way.

Also, one final thought is to check your alt belt for proper tightness. I say that only because I think I tightened mine a bit too much and I'm getting a "whizzing" type sound. I should go loosen it before the meet. (Along with that last thought, do you have P/S, A/C or other belt driven accessories we should know about?)

Karl

Thanks for joining in, Karl.

Last week I rode my bicycle to Harbor Freight (2.5 hour round trip) to buy their "Engine Oil Pressure Test Kit". I hope to install it tomorrow or the day after.

I like your suggestion that the alternator belt (I've removed my AC belt to exclude it from consideration.) might be too tight. That is one of the things I thought might be causing the noise, the belt pulling so hard on the crankshaft that it forced metal to metal contact at the first bearing surface.

Normally, I try to put the least amount of tension on a belt that will keep it from squealing, but that takes experimentation and time, and sometimes I don't allow myself the time to do it right. I've removed the belt and cleaned it thoroughly and cleaned all three pulleys with simple green and rinsed them well. When I start the car up to move it to where I can install the oil gauge, I'll carefully set the tension to the minimum and see what effect, if any, that might have. Also, I've even wondered if applying some belt dressing might not make it possible to reduce belt tension even more, while still avoiding squeals. (Recommendations anyone?)

[JohnGunn]

Sounds like an early electric Singer sewing machine. Could be the recorder is limited in the frequencies it records.

If it's a restricted oil flow issue you could try an oil additive to clean out the system. I've used one you put in *before* changing the oil. The engine is idled for 5 min while the additive dissolves deposits. Then it's drained out with the old oil. It can't be left in because then it dissolves aluminum. I think most additives are safe in aluminum engines these days but read the label on the can before buying.

If that doesn't work it may be engine wear and you could try a heavier grade oil or one of those oils formulagted for older engines.

I use a 3' piece of garden hose as a stethescope to help isolate the source of noises. It works pretty well.

Thanks, WmWatt. I must say I liked a lot of what you wrote. I've been giving a lot of thought to using an oil additive to clean out my engine. Some tests I've done on to measure how long it takes oil to drain back to the pan after shut down, have convinced me that there is some blockage in the oil drain holes in the head. I've bought some Seafoam and some Mobil 1 ATF thinking I might use them in cleaning the engine.

I've also read that diesel fuel makes a good cleaner and that diesel engine oil has more cleaning properties than regular engine oil. I think I'll definitely try something, even though it sounds like damage has already been done. My hope would be than if cleaning increased oil flow the pressure might rise to the point that it prevented any metal to metal contact that might be taking place.

I would welcome all suggestions about what to use in cleaning the engine. (There are several observation about this engine that make me doubt that the previous owners were much concerned with even the most basic engine maintenance. More on this later in this thread when I discuss the state of the engine when I bought it.)

Also, your thought of using a higher viscosity oil to improve the cushioning qualities of the oil around the journals strikes me as worth trying, for diagnostic purposes if not as a long term solution.

My thanks to you for your efforts on my behalf.

[JohnGunn]

Sounds just like already stated, timing belt rubbing on the cover.
Pull the top half off and run the engine, see if it goes away.

I've had the top cover off to check my timing belt alignment and looked for any signs of rubbing. The cover is very straight. Not swollen and distorted as is so often the case. Nevertheless, your suggestion is duly noted and added to the list of things to try. Thanks.