Torque Converter Control Valve

[Belle66]

Hi,
I've just wiped out the second thrust bearing, yes the engine was built right both times. The torque converter is near stock and most likely not ballooning. I'm looking at the FSM and there is mention of a torque converter control valve and it is illustrated in the color hydraulic schematics. But when I Google "torque converter control valve" I get no results. Is this part called by a different name?

 

[493 Mike]

Hi,
I've just wiped out the second thrust bearing, yes the engine was built right both times. The torque converter is near stock and most likely not ballooning. I'm looking at the FSM and there is mention of a torque converter control valve and it is illustrated in the color hydraulic schematics. But when I Google "torque converter control valve" I get no results. Is this part called by a different name?

Most likely it is not in Google's dictionary. Possible a stuck valve although I have never encountered one.
Mike

 

[Nate S]

In GM transmissions it's a torque converter pressure regulator. It would take a hellacious amount of pressure in there to actually wreck a thrust bearing. Other notable point is that it only has pressure when running but the engine has lube then too. If you unbolt the outer TC screws does the TC push into the tranny easily? maybe 3/8" or so? How does the rest of the center main look? Is it getting enough oil in the first place?

 

[69Bee]

A few questions:
1) Was the block align honed for the mains?
2) Did you assemble the motor yourself?
3) What was the crankshaft end play?
4) Was one bearing worn at the center top/bottom, and the opposite center on the other?

 

[Dipstick]

From what I understand, the malfunction that causes the converter pressure to rise enough to affect the crank thrust bearing isn't caused by the TC control valve. Some malfunction in the pump causes pump pressure to be routed directly to the converter, bypassing all the regulator valves.

 

[Belle66]

In GM transmissions it's a torque converter pressure regulator. It would take a hellacious amount of pressure in there to actually wreck a thrust bearing. Other notable point is that it only has pressure when running but the engine has lube then too. If you unbolt the outer TC screws does the TC push into the tranny easily? maybe 3/8" or so? How does the rest of the center main look? Is it getting enough oil in the first place?

Yep have a .190" gap. Haven't looked at this main yet, last one looked fine except on the aft side.

 

[Belle66]

A few questions:
1) Was the block align honed for the mains?
2) Did you assemble the motor yourself?
3) What was the crankshaft end play?
4) Was one bearing worn at the center top/bottom, and the opposite center on the other?

1) yep
2) nope, a reputable racing engine builder
3) 0.007"
4) I haven't looked at this one yet. Last time the only affected surface was the aft face of the thrust bearing and the mating surface on the crankshaft.

 

[Belle66]

From what I understand, the malfunction that causes the converter pressure to rise enough to affect the crank thrust bearing isn't caused by the TC control valve. Some malfunction in the pump causes pump pressure to be routed directly to the converter, bypassing all the regulator valves.

Interesting, I'll look into that.

 

[69Bee]

1) yep
2) nope, a reputable racing engine builder
3) 0.007"
4) I haven't looked at this one yet. Last time the only affected surface was the aft face of the thrust bearing and the mating surface on the crankshaft.

It is possible, that the thrust cap (#3), was cut at an angle by mistake, thus causing a clearance issue (don't ask how I know). The only way to check is to install a new thrust bearing and check the endplay.