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Yo Spencer,
"


7 captures
13 Nov 2014 - 12 Jan 2018
http://web.archive.org/web/20180112192129/http://www.atraonline.com/gears/1997/1997-12/gdec97p36.htm

DEC	JAN	FEB
	12
2015	2018	2019

About this capture

by Gil Younger

There's the mechanic now. He has gaping wounds around the head and shoulders. One shoe and sock is missing. He collapses into near unconsciousness, and his eyes roll upward you can see the whites are splattered with little pieces of pan gasket. He is fighting a noise, and is not winning.

History means nothing when you are working on a trans. You can stand there and tell the trans (and yourself) about all the parts and energy you've installed in it and it won't change a thing. Everything that gets fixed, gets fixed now or in the near future. Trying to find and answer from past data (what has been done or changed ) is like recounting three quarters over and over to try to get a dollar.

The supreme rule for correcting noise is to sop thinking and become an innocent observer. Don't even think about diagnosing. Pretend that a customer just drove the vehicle in and you don't know anything about it—period. Keep telling yourself to simply perceive—observe. The evidence you collect with perception will fine the noise.

Observation with your ears, eyes, touch and smell is now. Thinking is a review of past events. Thinking prevents observation. When you record (write down) your observations, you are placing a partition between you and history. Observation puts you in present time. Writing down what you perceive keeps you from continually returning to square one, mechanically and/or emotionally.

Working on noises is like hunting bear with a board with three nails in one end and a handle on the other end ... and the bear gets the handle. The trick to licking the bear is to get the board turned around so that the nails are on his end, while you stand back and record the fight. You do this by attaching a gauge to main line and having a pencil and paper to write down what your perception observes.

Noises will kick your butt as long as you fight by their rules (over busy). If you take them on using your rules they will fall into line. There are only a few "do" rules to follow when correcting noise complaints. They are easy and straight forward. It's the "don'ts" that are lengthy and difficult:

• Don't even think about what the noise might be.
• Don't start changing parts based on parts you changed or "past experience."
• Don't think that changing a part is going to fix the noise, unless you know exactly why that part is making noise.
• Don't change more than one part at the same time.

This paper covers more than is necessary to correct most noise complaints. Some physical principles will be expressed as we go along. Don't worry about, or struggle with, the explanations. The complaint gets fixed by perception and recording; not by some super brain power. Following the sequence is the short cut. Every five minutes of observation and recording will save one hour of hard work.

Tools required: 300-350 pound pressure gauge, clipboard, paper, and pencil.

Preparation: Check oil level. Attach gauge. Record the pressure in all selector positions while the engine is above an idle but under 1200 rpm. With the selector in drive and foot on the brake, step on the gas to about three-quarter throttle and then let off to just above idle. Pressure should increase and decrease as though the gauge was connected to the gas pedal. Pressure must always return to 50-92 psi at just above idle. (In drive range pressure should not exceed the listed repair manual pressure by more than 30 psi. If it does, forget the noise and fix the overpressure problem.)

Road test: Skipping this part almost guarantees that it will come back. Making and recording a road test is what gets you in present time and connected to the trans. Always make a road test before you tear into the job, making a record of when and how it shifts, especially the downshifts and lockup.

There are two types of noises at a standstill.

Mechanical: The needle on the gauge is steady. The noise changes with engine speed but does not go away. If the needle on the gauge vibrates with noise, it is not a mechanical noise.

Hydraulic: The needle on the gauge is busy. The needle will flutter or move with the same frequency as the noise. If the gauge is steady, it is not a hydraulic noise.

Gear Type Pump Noise
Whine, moan. This noise will not appear on the gauge as a bounce or quiver. It is noisy anytime the engine is running. The tone changes directly with engine rpm. At 2000 rpm is says "rheeee." At 1000 rpm is says "rahhh." If you run it up and down, it says "rhee rahh rhee rahhh." It makes noises in all selector positions. It may be just slightly louder in reverse or with more throttle. Pump whine never stops completely, regardless what you do with the controls or rpm. Cause (the one and only): The inner pump gear is hitting the crescent.

With luck, changing the pump or the whole front end might fix this complaint ... sometimes. Changing pars is not the answer. Fixing the parts you already have is the safe way to go. If you change parts, you are taking the risk of reinstalling the same complaint (and perhaps a new one).

Why does the gear hit the crescent? First, let us destroy the myths. The specs shown in the repair manuals for the clearance between the inner gear and the crescent have no real meaning, because on the bench, the inner gear is loose; the converter hub is not installed and no pressure is being applied that would force the gear towards the crescent.

When the pump is operating, pressure is created by the gears meshing tighter and squeezing out the oil between them. Look at the pump and see that the pressure area will push the inner gear up and the the right towards the crescent. When the pump is new, the hub clearance in the inner gear is about .002 inch. The pump bushing is installed and then bored in exactly the right place with .002-.004 inch clearance, so the inner gear cannot hit the crescent.

By the time you get to work on it, the hub hole in the inner gear is worn bigger. The new bushing you install may have .005 to .008 inch clearance. Also, the converter hub may be worn slightly or machined smaller. The accumulated clearances can now allow the gear to hit the crescent.

Now that you know what to look for, it's possible to fix the problem by carefully selecting parts: A converter with a full size hub; an inner gear with no wear, on the inside; and a pump body with an unworn original bushing. But it's a lot easier to fix what you have. It takes less than 10 minutes to fix a pump. Many top notch shops fix them all before reinstalling them.

Fixing the pump: Remove .010-.060 inch of material two-thirds of the way across the inner face of the crescent from the right end (C3, A4LD, and 180 rotate the other direction: Start from the left end). Do not grind all the way across the inner face; only two-thirds, please (figure 1). This will leave close clearance to the gear teeth on the left to maintain efficiency. Be sure to remove metal all the way to the bottom of the crescent. Searches on the bottom face won't effect pump efficiency.

Figure 1​

Tools required: Straight side rotary file with no teeth on the bottom. If rotary file has teeth on bottom, grind them off.

In the car fix (about 30% effective): Shim the converter deeper into the pump so the hub can engage past the wear in the inner gear. Use flat washers between the flexplate and the converter mounting pads. Use equal thickness washers on each pad and remember: With the washers installed, the converter must still have 1/8 inch front-to-back clearance.

Rotor Type Pump Noise
Clatter: Gauge is busy. The needle bounces with the clatter at all rpm. There is no rpm where the needle holds perfectly steady.

Cause: Broken pump rings.

Comment: If job came in with broken rings, install a gauge for start-up and road test. Beware, if pressure is extremely high: Wrong pressure regulator valve; pressure regulator, slide or TV valve is stuck; or Int/Rev boost valve misassembled.

Tick tick or knock knock: Gauge is steady. This noise is not visible on the gauge. Louder at idle or just above idle. Gets quieter with more rpm. Sounds like lifter noise or a fan blade hitting the shroud.

Cause: The hub hole in the rotor is badly worn oversize from long periods of operation with high line pressure (pressure rise problem). The primary cause of nearly all pump rotor problems is pressure rise malfunction.

In the car fix (50% effective): Shim the converter deeper into the pump with washers, but must still have 1/8 inch front-to-back clearance.

Converter Noise
Swishing, whine, or moan: Gauge is steady. Has noise in forward and reverse; worse with slightly more throttle; goes away completely in park and neutral.

Qualification: Pull it into gear, add very slight throttle. If the noise gets louder, it's the converter.

Explanation: Converter noise is load sensitive. With your foot on the brake, and in gear, the input shaft is dead still (except ATX & AOD). The only things moving are the pump and converter.

ATX and AOD are somewhat different in that in gear, with the brake on, drums are still turning (splined direct). AOD direct drum needle bearings and the ATX needle bearing between second and third drums will sound exactly like converter whine. Replace both if you're fighting a noise.

Additional converter checks: Noise is most noticeable about half way to stall (1200-1600 rpm). During the 1-2 and 2-3 upshifts, you may hear a moan that cannot be seen on the gauge. Sorry about that; it is the converter.

Needle bearing and other noises (Gauge is steady) 400: Noisy first gear.
Qualification: Goes away towards the end of 1-2 shift.
Cause: Needle bearing on front end of sun gear.

350: Noisy first gear.
Qualification: Goes away toward the end of 1-2 shift.
Cause: Needle bearing in the front planet.

350: "Reeep" noise during 1-2 shift.
Cause: Needle bearing in the front planet.

350: A fast, very light rattling noise that goes away at the start of the 1-2 shift.
Cause: Weak springs in the second roller assembly. Steel plates with missing lugs.
Correction: New second roller or new springs and early steels with full set of lugs.

Noise in first and second. Also in park and neutral.
Qualification: Gone completely in third. Sounds like planetary.
Cause: Needle bearing between drums.

700-R4: Clicking/scraping noise in first and third that starts as vehicle moves forward.
Qualification: Goes away in second and fourth.
Cause: Reverse drum flared, due to slipping input sprag.
Correction: Straighten lugs on drum and replace input sprag.

Noise at Standstill (Gauge is steady)
350: Noisy in park and neutral. Changes with engine speed.
Qualification: Goes away in any gear.
Cause: Needle bearing between the drums.

700-R4: Noisy in park and neutral. Changes with speed.
Qualification: In manual, third, lockup, pitch changes when applying and releasing the throttle.
Cause: Needle bearing at the front of input drum.

ATX and AOD: Noisy in park and neutral. Changes with engine speed.
Qualification: Sounds a lot like a bad converter needle bearing.

AOD: Direct drum needle bearing. Gets quieter in third and fourth.

ATX: Bearing between the drums. Loud in first, quieter in second, gone in third.

Hydraulic Noise
These complaints are fun to watch on the gauge. Gauge needle will quiver or drop in tune with the noise and stabilize when the noise stops. Noises are rpm and temperature sensitive. A restricted filter (even new) causing air to get into the suction system aggravates these complaints. To fix them, correct the problems in the suction system first.

Suction noise: Whine, moan, or whistle-like scream. Gauge is busy. Quieter at idle. Gets louder as engine speed is increased. Gauge is steadiest at idle, will bounce more as the engine speeds up. On quick throttle, needle may even go down instead of up.
Cause: The actual source of the noise itself is air entering the suction system. The whine is the pump pumping air. The whistle-like scream is the air being sucked into the system through small spaces, around the filter O-ring, between the valve body and case, or between the pump and pump cover. In short, air is getting into the suction system. The filter, filter tube and O-ring are almost always the actors in this show. A defective or partially restricted filter is the star. This complaint is similar to other noises. Qualify it to distinguish it: Add four quarts of oil. Run the engine in drive at above idle, but under 1200 rpm, for one minute to warm then new oil. Recheck the noise. If it's gone or almost gone, work on the suction/filter system.

Gear Type Pumps
Whine or buzz. Gauge is busy: Needle quivers in rhythm with noise.
Cause: Hydraulic.
Qualification: If you change filter (or add oil) on a 400 and the whine goes away, the noise was not pump whine. It was valve bounce/buzz. A pump gear whine (mechanical noise) will not be corrected by adding oil or working on a suction problem. A restricted filter encourages pump to suck air, and pressure regulator valve goes crazy.

To correct pressure regulator buzz (and reduce rough reverse), grind four flat sports (figure 2). Leave about a 1/8 inch wide portion of original diameter between flats.

Figure 2​

205C & 350C: Not necessary to grind pressure regulator valve. Drill holes shown to correct pressure regulator buzz, eliminate engine killing in reverse, help soften reverse, and increase cooler flow (figure 3).

Figure 3​

Fixing gear type pumps: While a pump is apart, it takes about 8-10 minutes to prevent most of the moans and groans, stop drainback and dramatically improve pump performance. Here's how: While the pump gears are still in the pump, enter punch a dink on the flat surface of both gears. Lightly grease the back side of a sheet of 40-60 grit emery to the floor. (A work bench is too flexible.) Place the pump, with the gears in it, on the emery. Press down hard and push/pull the pump directly away from and towards you. Every third or fourth trip across the emery and back, rotate the pump about 45 degrees. After two minutes of sanding, slide the pump onto a gasket set cardboard (or another piece of emery) to pick it up and turn it over while the gears are still in it. Continue sanding until you are removing metal from both gears. You now have zero clearance. Clean the gears and the pump, and set the pump aside.

Using a one inch micrometer, measure the thickness of the inner gear directly over the dink you made with the center punch. Now pay attention: Place the inner gear on the emery, with the same side down that you already sanded, and push/pull it back and forth while rotating it, just as you did to the whole pump; give it about 12 strokes. Measure it again. As soon as you can see that it is any smaller, you're done. Do the same thing with the outer gear until you remove about .002 inch.

Assemble the pump, drop it on converter and spin it. It must not have any drag. If it drags, stop at the draggy point and remove it from converter. Reach in with a screw driver and see if the inter gear is free. If the inner gear is not free, sand it .001 inch thinner. If the inner gear is free, sand the outer gear .001 inch thinner. You now have a pump that is five times better than a new one and it will stay that way. It also lets you re-use, now get this, the stator supports (pump covers) with the half moon wear in them, if a .004 inch feeler won't slide into the deepest part with the outer gear laid across it.

Flat-sanding the pump, making additional gear clearance at the crescent and installing the converter deeper to engage an unworn portion in the inner gear cures a dozen complaints and stops drainback cold.

Rotor Type Pumps
Buzz, moan, or zipper sound any time, including when moving selector, and especially around or just above idle. Noise will be visible on the gauge, but will stop by revving the engine slightly, or when the engagement is completed. If the noise and needle bounce continue at all rpm ranges, suspect broken rotor rings or a suction problem (filter, etc.). This pressure regulator valve does not bypass oil to regulate line pressure; it sends a signal to the pump slide. It is the slide which regulates the pressure by opening or closing intake. Grinding the pressure regulator valve as shown in figure four, will eliminate this noise (700-R4).

Figure 4​

C-6 Valve Noise
Buzz or clatter, any gear. More often in reverse. More often cold. It is visible on the gauge. If the gauge is steady, it is not valve noise. It may change some with engine rpm, but isn't tied to rpm completely. At some rpm it goes away. It may go away in neutral or some other gear or if you pull the hose off the modulator.

Causes: Pressure rise: Barely above idle, pressure is 52-72 psi and goes to 140-180 with the hose off modulator. If pressure rise is not normal, disregard the noise complaint and fix the pressure rise problem first.

Low oil: Loosen but do not remove the modulator. Start the engine and run selector through all positions. Stop the engine and quickly remove the modulator. Oil must run out of the modulator hole. If it does not, then oil level is too low regardless of what the stick says. If oil did not run out of the modulator hole, reinstall the modulator, add some oil, and re-check noise.

Different design modulator: The diaphragm in some modulators is too far away from the trans, and the normal modulator pin is not long enough to reach it. The modulator valve is then free to oscillate from-to-rear, and the pressure regulator valve starts banging end-to-end in an attempt to regulate.

Adjusting the modulator won't fix this because the diaphragm is already seated against it's stop inside the modulator. However, it can be corrected in the vehicle by installing a longer modulator pin. How much longer is the mystery question. If the real problem is valve body tightening sequence, a long pin may hide the problem temporarily, but you'll soon lose the friction. Somewhere between 1-1/16 inch and 1-3/4 (not longer) will be OK. Install the modulator before the valve body is installed, adjust the pin length so that the exhaust is open .030-.060 of an inch and you'll never have this problem.

Over-tightening and warp leaks: The pressure regulator balance hole shown in illustration is supposed to keep the pressure regulator valve from banging back and forth. It works until the valve body warps. Area shown has pressure at all times, and warp is always a problem. Wherever there is heat, pressure and time, warp is normal, not abnormal. Don't fuss around checking it with a straight edge, just fix it (figure 5). It takes five minutes. Flat-sand both castings as explained later.

Figure 5​

C6 valve bodies have problems because our attitude about them can cause mechanical difficulty. The need is to treat them with the respect they deserve. If they are assembled the way they like to be, instead of how we like to do it, they work right. Here's how to fix a C6 valve body.

1. Loosen all the screws on the end plates one-quarter turn. Do not clean the valve body; just dump the oil out of it.
2. Set two shop rags on top of each other on the bench and set the valve body on the rags with the passages against the rags.
3. Push the valve body down against the rags and tighten the end plate bolts.
4. Sand the valve body on a sheet of 80-180 emery on the floor. Raise it straight up to look at it. Never turn the valve body over while sanding. Keep sanding until the whole surface is shinny.
5. Let valve body down slowly into solvent without turning it over. Brush under it to clean off the chips. Swish it around to clean the oil out; the chips will fall out with the oil.
6. Without turning it over, set it down on something that will drain.
7. Flat-sand the channel casting; wash and blow dry.
8. Blow the valve body off and loosen all the screws one-quarter turn on the banana plate.
9. Install gasket and tighten all the screws including the screen screws without the screen. Then remove the screen screws and install the screen.
10. Tighten the screws on the banana plate last.
11. Go road test a winner.

C4: Buzz or clatter. Same complaints and fixes as C6. If the customer cannot show you the complaint when he gets there, add one quart of oil and give it another chance. Flat-sand the valve body, install a valve body gasket, and correct the oil level. This most often eliminates C4 valve noises.

AOD: Buzz on cold start. May disappear warm. Gauge is busy. Pressure rise has been qualified and/or corrected. Cause one: Low oil level. Restricted filter. Bad filter gasket. Valve body warp. Cause two: Converter relief valve bouncing. Partial solution: Install long relief valve part number E2FZ-7E217A. If valve body has long stem relief valve, flat-sand valve body and align gaskets carefully.

The first step is to always attach gauge and check pressure rise. If pressure rise is not correct, fix that first.

FMX: Buzz or clatter, worse cold. Gauge: If you cannot see it on the gauge, it is not valve noise. If the customer complains, but it is OK when he gets to you, add one and one-half quarts of oil and it may be fixed. If the noise is there when you have the vehicle, with gauge on and watching the noise, add three quarts of oil. If the noise goes away, it is a suction problem.

Correcting suction problem: Flat-sand the regulator casting. With a taper punch, enlarge both ends of the big tube slightly. Overfill the trans one and one-half quarts. Run engine in neutral at 1500-2500 rpm for one full minute to purge air from the system. During that one minute of running, check the oil level several times. If it is bouncing up and down, add another quart of oil and run it again. As long as the oil level keeps bouncing up and down, you are either still low on oil or have an air suction problem. If it is still bouncing or making noise when you are two or more quarts overfull, the problem is a warped pump and/or pump cover. (This is fairly common on hard-working trucks.) When you are satisfied that the oil level is no longer bouncing, loosen the pan with the engine idling and let the overfill run out. Then add oil to 3/8 inch above the full mark." by Locating and Correcting Noise