Automatic Trannie Makes Manual 'Clutch Chatter' Noise

[Dirtymech]

I worked on a 1990 Toyota Corolla with an automatic transmission a few days ago. I changed the timing belt, alternator, and water pump on it.

Before, it was supposedly running fine. Afterwards, it ran fine for a day, but then the next morning developed hard idling whenever the transmission is engaged. As well as this, during hard acceleration the transmission makes a muffled grinding sound that sounds *surprisingly* like an old manual car thats putting too much load on the clutch (as when going uphill in too low RPM or in too high a gear). In neutral or park, the engine sounds just great, and you can rev it up to high RPM. Purrs like a kitten.

I don't know whether this is related to the work I did on the vehicle or not. I had to unbolt the chassis bolt at the front of the engine. It's either a 4A-FE or 4A-GE, whichever of those has the single external camshaft sprocket. Could this have been caused by missing the timing by a tooth? Like I said the engine sounds just fine in neutral, but somehow the transmission is not working properly.

The guy who owns the car is not too happy. I need to figure out whether I screwed something up during the maitenance or its just a coincidence that the transmission has developed problems. Knowing what is exactly wrong with the transmission would be great, as well as knowing what might have caused the problem to suddenly come on like this. Either way I'm probably gonna be the one who ends up fixing it.

[corning_d3]

I say the engine had low power output when you serviced it, am I correct? Now then you get the timing set and she runs good, and now producing more horsepower and torque. This now puts an added strain on the transmission. My point is, the transmission was probably already weak, and now that the car is running at it's peak, the transmission is showing signs of failure. There is no possible way for you to damage the transmission by replacing timing components, alternator and waterpump...

[dogbreath077]

I concurr. A timing belt, WP, and Alt won't make a trans fail. Make sure the timing marks are correct. If I remember correctly, this is the same as a chevy rebadge-Nova, right? Not too hard to verify the timing marks here. If the marks are right on, then you're O.K.

[Dirtymech]

Yea I didn't think anything I did could have caused the problem. But still, it would be nice to know what exactly is the matter with this vehicle.

The sound it makes is pretty specific and unique. The hard idling in Drive and clutch-like grinding sound on acceleration HAVE to be something. Torque converter, oil pump, clutch band packs, something of that nature yeah? Automatic transmissions...are notoriously complicated. But still these symptoms should point to something specific.

I'm getting a transmission cradle here at some point soon. At the very least I could remove the old trannie and put in a new one should it fail, or even try to fix the problem with the current one. But before I do something like that, it'd be good to have an idea of what the problem might be.

That clutch chatter sound...something tells me thats going to be the key to all this. Has anyone ever experienced something like that on an automatic before?

[LeSabre97mint]

Originally Posted by Dirtymech

I worked on a 1990 Toyota Corolla with an automatic transmission a few days ago. I changed the timing belt, alternator, and water pump on it.

Before, it was supposedly running fine. Afterwards, it ran fine for a day, but then the next morning developed hard idling whenever the transmission is engaged. As well as this, during hard acceleration the transmission makes a muffled grinding sound that sounds *surprisingly* like an old manual car thats putting too much load on the clutch (as when going uphill in too low RPM or in too high a gear). In neutral or park, the engine sounds just great, and you can rev it up to high RPM. Purrs like a kitten.

I don't know whether this is related to the work I did on the vehicle or not. I had to unbolt the chassis bolt at the front of the engine. It's either a 4A-FE or 4A-GE, whichever of those has the single external camshaft sprocket. Could this have been caused by missing the timing by a tooth? Like I said the engine sounds just fine in neutral, but somehow the transmission is not working properly.

The guy who owns the car is not too happy. I need to figure out whether I screwed something up during the maitenance or its just a coincidence that the transmission has developed problems. Knowing what is exactly wrong with the transmission would be great, as well as knowing what might have caused the problem to suddenly come on like this. Either way I'm probably gonna be the one who ends up fixing it.

Hello

How many miles on this car? Is the fluid level up where it should be? What color is it? When was the las fluid/filter change done? (probably never)

No...you didn't do ANYTHING to his trannie. What you worked on is totaly unrelated!

Take a look at the level and condition of the fluid. This will tell more.

Regards

Dan

[Dirtymech]

The engine has something like 220,000 miles on it. The automatic trannie fluid hasn't been changed in four years, but appears to be clean and is still slightly red. The fluid level was good when I checked it. Ummm, I think the car is red...

I really wish I knew what was causing that noise. I'm sure whatever is doing it will lead me to the problem and ultimately the solution. No one here has ever experienced anything like what I described above?

[corning_d3]

Automatic ransmission clutch packs will chatter when used beyond their service life. The chattering noise is caused by too much tolerance between the friction plate and the steel plate. Changing the fluid at this point will only make it worse. Another thing, although I'm not sure if this is applicable, is the ansmission drive chain. Like timing chains, these will slip on the sprockets as they age and strech. Many transmissions using a drive chain do not have slack adjusters, so they require a replacement. What engine/transmission does this vehicle have? I may be able to provide more info...

[zagrot]

another cause could be failing seals, which if caught early can be treated with a transmission seal coditioner with good results. but beware of this: the be all and end all remedy is really to replace the defective seals, especially if they are in very poor condition, and if the seals on the clutch pack piston are the ones in question the slippage will wear away the friction material. here are three cases that i have encountered:

1. my '84 mustang had slippage problems. after a long and painful death the transmission was "rebuilt" with bands, clutch plates, and seals from a junk yard transmission with what could be called success (new parts wouldn't fit my budget). immediately after the rebuild i'd get a very deep humming sound from the drivetrane when 2nd gear was engauged (as i seem to recall) and that was fixed by retorquing the 2nd gear band. on most transmissions the bands can be adjusted with a stud that protrudes from the transmission case. refer to a service manual for instructions.

2. a friend called one day to tell me that his auto trans. was difficult to put in gear on cold mornings, and would coopreate only after the car had idled for about fifteen minutes, then drive normaly after operating temp had been reached. this is a sure sign of seal problems, particularly of the seal on the clutch pack piston. the real solution, of cource, is to replace the seals. since he was a student at the time this was out of the question because money was an issue and i reccomended a seal conditioner on the basis of "what could it hurt?" he agreed with this way of thinking and three years later his dad is driving the car to work every day without trouble.

3. my room mate's 2000 civic's transmission would quietly rumble while in top gear, around 45 mph if accelerating ever so slowly. since the transmission had not been serviced in over a year it was decided that we would do a half-assed "flushing" by changing the fluid twice in two days (the filter is a lifetime service type of pleated wire mesh and it was clean anyway). this helped, but not entirely. again with the seal conditioner. since honda reccomends not using any type of additive we first used 1/4 the ammount that the conditioner manufacturer reccomended without avail. another 1/4 addition solved the problem.

moral of the story: if caught early seal problems can be "fixed" with seal conditioner. this did not work on the c-5 from my mustang because, as i found during disassembly, the seals were so far gone that they had to be scraped out in pieces.

if you have access to pressure gauges for the transmission in question perform a pressure test, it will give you some insight as to the condition of the seals. since the transmission is as old as you say it is the bands probably need to be adjusted anyway (if aplicable). there is some controversy over the "change old fluid in an old transmission" subject, so you'll have to decide your stance on the subject for yourself.

other factors that could cause the problems you are describing include pressure regulator condition and calibration, and the transmission's pump pressure output. now for a short aside to the topic at hand: since nearly all transmissions are cooled by the cold side tank of the radiator, if there is any trouble there the transmission fluid will not be cooled properly. excessive ATF temperature is one cause of seal degredation, so even if the radiator is ok an auxiliary transmission cooler is a good addition to any vehicle that will be operated in a warn to hot climate, especially if towing or stop and go traffic is involved.