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Old 02-15-2006, 09:39 AM
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TH350 wont do anything - a few questions

I read through many th350 problems using the search function.

There were only a couple with a similar problem (but not quite), so I wanted to ask about mine.


This is a 94 Z28 with a th350 and LS2 crate engine that I just put back together a month ago. I had the th350 (built by a friend at his trans shop)for 12k miles or so with no problems at all. The car sits for two years prior to the engine swap. This last december I put in the new engine and a new converter with the same th350. I have driven the car about 150 miles over the last few weeks, never more than 4000rpm or 20% throttle. About 40 miles ago I changed the pan to a polished aluminum part, and changed the filter. There were some line leaks from the swap, so I fixed those too. The line going to the modulator is new, and I re-checked the connections prior to driving it (they are still good now). The shifter cable to my quarter stick is also in correctly.

The problem:

I pull up to a light after a 15 minute drive and upon leaving the light, it takes a little gas to make the car move. It was like neutral until I hit 1500 rpm or so. At the next light it does nothing at all, no forward or reverse. Fluid was full, vacuum connection good, etc. I got the car towed back to my shop and loosened a trans fluid line, and there is nothing coming out with the car running in park.

I called the guy that built it, and he said the easy things to check without pulling the trans are the spring behind the servo piston (he said it can get cocked over a little) and the governer. He couldn't remember what he had done with the valve body (it had been 3 years), so he couldn't say for sure if either of those things would cause the problem, but he told me how to check them. I talked to him before checking the fluid flow from the line.

If I have no fluid coming out of the lines, I assume that the converter isn't turning, the pump is gone, or there is a restriction somewhere.

Should I proceed with checking the governer and servo piston - or is that not the right way to go now that I know I have no fluid flow?



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Old 02-15-2006, 10:54 AM
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Have you checked fluid level in trans (cold)?
Sure you got the filter on right , I think I found one that was turned backwards once , hence restricting flow.
You may be low and its aeriating (sic) the fluid , If motor is running the torque converter is turning and it is turning the pump, the only thing that would let the torque not turn would be missing bolts to flexplate.
So if it worked alright before you changed the filter , pan and lines,tis possible it's something you overlooked.
Just a thought, been there,done that.
We learn by our mistakes, but some are very costly
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Old 02-15-2006, 11:56 AM
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When the problem happened on the street, I walked over to a gas station and bought some fluid. After about 1/2 quart it was coming back out of the dipstick tube.

Sorry about the confusion on the converter. The output of the converter is splined and turns the pump, I was thinking about it wrong and was meaning to say that the converter could be bad and not allowing the car to go.

I got the governer off and it is good. I am a propopent of checking what was touched last, and that was the filter - so I am about to drop the pan and see if I made a mistake (I really doubt it though).

Thanks for the reply.

EDIT: I dropped the pan and the filter was fine. I have driven it maybe 40 miles since I changed it, but there were more metal flakes than I expected for such a short period of time. I had expected to see something, but this was like a few shakes from a salt shaker, if that provides a proper visual.

I think I will pull the transmission in the next few days and have a look at the pump.

Last edited by justchris; 02-15-2006 at 01:43 PM.
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