Bad Torque Converter Symptoms?

[mdregister]

What are the symptoms of a bad torque converter??

I have a 1985 K20 4X4 Suburban with the TH400 3-speed auto.

On a recent morning, I had a loud "buzzing/rattleing" noise that seemed to be coming from behind the torqu converter cover. I thought I had a piece of debris or an old bolt rolling around in there. After pulling the cover, I found nothing, but the rattle stopped.

I have not heard the noise since, but I think I may have a slight vibration at idle- but only when in gear.

How do I check and diagnose my torque converter??

Mike

[Robyn]

Any time you get noises from an automatic and the oil level is ok its not a good sign. you could have a cracked flex plate ot it could be the convertor. The only real way to diagnose it is to start by dropping the pan on the tranny and seeing if you have metal. if there is junk in the pan things ae not all sweet in River city.
There is no canned answer to your problem. convertors can loose thrust bearings and this will cause the internal parts to scrape on one another and make noises. there is also a sprag in the stator assembly that can break up. The only real way is to take it out and go through it. The longer it runs making bad noises the worse its going to be when you do tear into it. If you are getting vibration its time to get that box on the bench. If you find metal be sure and flush the cooler and install a return line filter when you reinstall a new box

[mdregister]

Thanks for the reply,

If I determine the torque converter to be the problem what should I use as a replacement?

I am not sure if the stock converter is a 4-pad or 6-pad converter or if it is a 9-inch or 10-inch etc.

Should I go with a stock stall speed?? Should the stall speed be a little higher or a little lower?

Here are a couple I am considering:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&tc=photo&item=7946963122&category=33727

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7946168746&category=33727&sspagename=WD1V

thanks

[TimK]

Be sure to get a 6 pad unit. When I got my truck the stub shaft developed a fracture lengthwise on the shaft 90 degrees to the oil seal lip. It started leaking oil. The old TC was a 3 pad unit. The replacement TC from NAPA was also a 3 pad unit. About 30K miles later on a very long trip from Portland OR to Phoenix AZ, the TC parted ways with the flex plate. What a mess. I didn't find out until later that they made a 6 pad TC. Now I know.


TimK

[Robyn]

The older torque converters had small round pads mand the heavy dury ones had 6 of them and the light duty ones 3. They are a simetrical patern and either can be used.
Most converter rebuilders now are going to a 1inch wide by about 2 inch long pad and using 3 even on the HD stuff.
I just recently built a tranny for a Hummer replica I am building and ordered a 6 pad converter and learned than that the heavy rectangle pad unit is the new way and is very reliable. Three bolts will hold almost any engine that you are going to be using.
Use a stock size converter that is rated at stock stall speed and has a heavy duty or towing rating. All the big rebuilders offer a welded unit that has all the internal fins welded so they dont work loose. Stay away from the "stall" converters or the little guys for truck use. They are for wild thumpers that wont idle below a grand and shake the door handles off. You need a low stall torque converter made to pull heavy loads and do 4X4 things. If if you are goingh to the trouble of pulling the box, do open it up and check it over and always replace the front pump bushing and front pump seal. If the tranny has any metal or black flakey stuff in it you definately need to find out where it came from. A 400 is an easy box to work on too.

[Robyn]

TIM
Many converter rebuilders have turned out some real junk. The pump drive stub and the pilot have got to run concentric if they dont you will have trouble from the get go. I have seen these things so bad out of concentricity that the convertor will wobble big time when the engine is running. They can shake so bad that the door mirrors will wiggle. Even if its a small wobble it raises hob with crank bearings as well as the front pump bushing and seal and will if let go tear itself up eventually.
One needs to stick with a major brand of converter. RPM is a national brand. You may have a great shop locally in your area that builds wonderful converters but shop around and find out what the big boys in your area are using. If they have problems with a particular rebuilder they will tell you or at least they will advise you to use a particular brand.
Hope all goes well.

[Robyn]

MDREGISTER
I looked at the two units you listed from ebay.
Dont buy the purple one. I have personal experience with this rebuilder and well ahhhh just look the other way. I think the other one is probably a good deal.
The last one I had come through here that was purple (company reference) was junk and it lasted the customer about 3000 miles from the time it was installed.
I hate to talk smack about anyones products but its just too much work to pull trannies out and repair what a bad convertor tears up.

[mdregister]

Thank you for the replies. I did not realize you were from Oregon, I am glad I asked.

I spoke via e-mail to the other shop. He says he can build me a converter with an approx. 1000 rpm stall for an additional $50. I guess I just do not understand what I need.

Here is what I have and what I do with it:

1985 K20 Suburban 4x4 TH400 auto 3.73 rear 128000 miles.

Mostly a run-about vehicle. Some driving in deep sand on the beach when fishing. Some light towing in summer months (5X8 utility trailer and with photo equipment ~2300 lbs. or less).

1000rpm stall seems too low, but I am unsure.

[Robyn]

OK
This is a simple one.
Tell your converter rebuilder to build you a stock stall speed heavy duty converter. Tell him the engine you have and the gear ration. He will be able to give you exactly what you need.

[NH2112]

I don't know if automotive torque converters are tested the same way as those in construction equipment or forklifts, but the way we test those is by hooking up a tach, pushing the brake to the floor as hard as possible (block the truck if you want, it just can't be allowed to move or spin its wheels), tranny in forward or reverse, and pushing the gas pedal to the floor. Engine RPM with the pedal on the floor should be the same as the converter's stall speed. If it doesn't go that fast you've got engine problems, if it exceeds stall speed you've got a bad converter.

1000RPM does seem way low for a 6.2l, conceivably you could stall it trying to get a heavy load moving. I think stock stall speed is around 1800RPM.