Bad Trans vs Bad Converter

[Bruzilla]

I wrote previously that I thought my transmission was bad, but now I'm wondering if the problem might have been the torque converter going bad. The problem was the car would not go into gear unless I revved up the engine, then as the RPMs would drop, the trans would go into gear and the car would move for about ten seconds and then power would be lost.

So how do you tell if a problem is the trans or the converter?

 

[PurpleBeeper]

That's a tough one for me....maybe a trans expert will chime in. If the torque converter is slipping, then the trans fluid temperature should go sky high, but I'm not sure if you can measure that now. If the front pump on the trans went bad, I'd think your line pressure would drop a lot, though I'm not sure what it "should" be. If you knew what it "should" be, maybe you could put a pressure gage inline with the trans cooler on the radiator? And now that I think of it, maybe you could un-hook a trans line at the radiator & see if it spray trans fluid or just drips (bad pump in trans)??? I'm not sure which line to remove & I'm also not sure if the car has to be in neutral or park or ??? to make sure the pump is working.

Either way, the trans has to come out (assuming your not just really low on fluid). If it were me (which it isn't), I'd change out the torque converter regardless. Are you planning to do the work yourself?

 

[AR67GTX]

I doubt it's the torque converter. It doesn't really have much to do with going into or out of gear. You might look in the factory shop manual or google a list of A727 problem/cause issues.

 

[1967coronet440]

I have a 727 manual I can try looking up some info in the trouble shooting section for you tonight. Great book for about 20 bucks on amazon

Torqueflite A-727 Transmission Handbook HP1399: How to Rebuild or Modify Chrysler's A-727 Torqueflite for All Applications https://www.amazon.com/dp/1557883998/ref=cm_sw_r_cp_api_tyr7ybQQ39619

 

[khryslerkid]

If I could'nt see anything obvious, drop the pan and see how much band material is in it.

Also it could be as simple as a clogged up filter. I had a Torqueflight that acted goofy when shifting and all I had to do was change the filter and fluid and that fixed it. Hell, I even drag raced the car regularly after that. Try simple things first!

If it was a GM trans, normally changing the filter and fluid makes them worse when they are having problems.

 

[Bruzilla]

That's a tough one for me....maybe a trans expert will chime in. If the torque converter is slipping, then the trans fluid temperature should go sky high, but I'm not sure if you can measure that now. If the front pump on the trans went bad, I'd think your line pressure would drop a lot, though I'm not sure what it "should" be. If you knew what it "should" be, maybe you could put a pressure gage inline with the trans cooler on the radiator? And now that I think of it, maybe you could un-hook a trans line at the radiator & see if it spray trans fluid or just drips (bad pump in trans)??? I'm not sure which line to remove & I'm also not sure if the car has to be in neutral or park or ??? to make sure the pump is working.

Either way, the trans has to come out (assuming your not just really low on fluid). If it were me (which it isn't), I'd change out the torque converter regardless. Are you planning to do the work yourself?

I got a great deal on a rebuilt 727 and a new torque converter, but I was going to sell the old transmission and torque converter to help cover the cost and I don't know which is good or bad. Plan A was to part the trans out, but now I'm worried it might be good and I hate to trash a good transmission.

 

[PurpleBeeper]

Hmmmm..... how does the trans fluid in the old trans smell? If clutch bands wear out, I would expect a "burnt" smell to the trans fluid.

Here's thinking outside the box. When you pick up the trans and shake it, can you hear parts rattle? What about the torque converter? Every time I've broken a transmission I could hear parts rattle around inside.

 

[AR67GTX]

If the bands or clutches are slipping from either wear, poor adjustment or low pressures - yeah, it will smell burnt. Yes, a torque converter if drained of fluid, will rattle if you pick it up and shake it (I actually have done this recently with both an old one and a new one). Don't know about the whole transmission - a BB 727 weights close to 175 lbs and my days of shaking something that heavy are way behind me.

 

[miller]

In the service manual...happens to be a trouble-shooting section, under trans. Be worth a look. Probably find a list of things possible, unless it was junk from the word go.

 

[dvw]

It is possible the converter is bad, but hughly unlikely.Take a pressure test per the service manual. Good pressure indicte good seals and pump. Generally this will equate to functioning unit. Like every thing else in this hobby. Read , learn, do it yourself and save money. Most Torque-flite rebuilds are less than $150 in parts.
Doug