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Discussion Starter · #1 ·
good afternoon guys, i just installed a new flexplate and had a converter built for my 69 C10. its a sbc 406 w/671 blower and dual 750 quick fuels also installed a new radiator and upped trans cooler lines to 3/8 from 5/16. maybe should also mention i have a trans pressure diversion valve in stalled as well. anyway i got the trans fluid filled up and checked at running temperature. transmission engaged thru all the gears while parked. next day im getting ready to take out for 1st test drive and transmission is no longer engaging. ive checked all the vacuum lines not sure what else look for. any suggestions?
 

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good afternoon guys, i just installed a new flexplate and had a converter built for my 69 C10. its a sbc 406 w/671 blower and dual 750 quick fuels also installed a new radiator and upped trans cooler lines to 3/8 from 5/16. maybe should also mention i have a trans pressure diversion valve in stalled as well. anyway i got the trans fluid filled up and checked at running temperature. transmission engaged thru all the gears while parked. next day im getting ready to take out for 1st test drive and transmission is no longer engaging. ive checked all the vacuum lines not sure what else look for. any suggestions?
By "not engaging " I take that to mean the t-400 is not shifting at all? The trans stays in first gear? Is there 12 volts hooked to the side of the case connector for internal solenoid?

Where on the engine blower setup is the vacuum line hooked in for the vacuum modulator? What is the pressure diversion valve hooked in to?
 

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Discussion Starter · #3 ·
By "not engaging " I take that to mean the t-400 is not shifting at all? The trans stays in first gear? Is there 12 volts hooked to the side of the case connector for internal solenoid?

Where on the engine blower setup is the vacuum line hooked in for the vacuum modulator? What is the pressure diversion valve hooked in to?
hi crosley thanx for your response. it does not go into 1st gear or any gear. there's 3 ports on the pressure diversion valve the top center port which also has a check ball is coming from the large vacuum port that's underneath the float bowl . the right side vacuum line is coming from an 1/8 in fitting from the back of the manifold. and the left line is going to the vacuum modulator on transmission. and yes there is 12 volts going to the case connector. well at least there was i will check that to confirm.
 

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I misunderstood your [ost.. If the trans does not engage into any gear, Check the fluid level. If it was engaging into gear , then stopped. Something changed. You could loosen a cooler line too verify there is oil pressure as the engine idles.

Vacuum or not to the transmission, it should make pressure to operate the trans.
 

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Discussion Starter · #5 ·
thanx crosley, just getting off work. too late to fire up the truck in my neighborhood. will check fluid level tomorrow. ill let u know how it goes. thanx again for your time.(y)
 

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fluid level looks good. i have fluid coming out of 1 of the trans lines while idling but not the other. i dont get it, it was engaging .... next day not engaging.
where did you make this flow check??

While running, cracking either line fitting loose at the case should show pressure/flow(same on either side of the cooler)....one is going out to the cooler and the other is coming back at nearly the same pressure....or at least it should be.
Cooler line pressure spec is 60-90 psi at idle-1000 rpm.

If not, then somehow the line is plugged or the cooler is plugged.

If it's just a low pressure dribble, then maybe something has happened at the pump/pump drive tang area.

If that all proves good and you've got good flow, my guess would also be rooster comb came loose and lost connection with the actual manual valve in the valve body. A pressure test in each gear would prove that, since the valve woudn't move pressure will end up the same in every gear position selected, because the valve is directing fluid to any circuit.

I've had that happen once, put a valvebody on and missed getting the pin in the slot on the rooster comb and manual valve.....no gears at all, nothing even though the shifter and lever felt fine from the outside LOL.

"maybe should also mention i have a trans pressure diversion valve in stalled as well "

Explain??? Like a dump valve on the converter charge circuit?

Or is it the mechanical linkage for the modulator valve (conversion kit for no-vacuum applications/diesel) to replace the vacuum modulator?
 

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Discussion Starter · #10 ·
where did you make this flow check??

While running, cracking either line fitting loose at the case should show pressure/flow(same on either side of the cooler)....one is going out to the cooler and the other is coming back at nearly the same pressure....or at least it should be.
Cooler line pressure spec is 60-90 psi at idle-1000 rpm.

If not, then somehow the line is plugged or the cooler is plugged.

If it's just a low pressure dribble, then maybe something has happened at the pump/pump drive tang area.

If that all proves good and you've got good flow, my guess would also be rooster comb came loose and lost connection with the actual manual valve in the valve body. A pressure test in each gear would prove that, since the valve woudn't move pressure will end up the same in every gear position selected, because the valve is directing fluid to any circuit.

I've had that happen once, put a valvebody on and missed getting the pin in the slot on the rooster comb and manual valve.....no gears at all, nothing even though the shifter and lever felt fine from the outside LOL.

"maybe should also mention i have a trans pressure diversion valve in stalled as well "

Explain??? Like a dump valve on the converter charge circuit?

Or is it the mechanical linkage for the modulator valve (conversion kit for no-vacuum applications/diesel) to replace the vacuum modulator?
hi eric the trans pressure diversion valve i have is mounted on my firewall i got it from "the blower shop" its been a minute but i think stabilizes or lowers the vacuum that goes to the trans modulator. with out it trans doesnt shift properly. not to sound to stupid but a quick question for you...so im looping my tran cooler lines and if u take a look at the pic i uploaded just below and to the left of the top cooler line connection you can see some kind of a port(or somin) with an allen set screw. thats not some kind of a valve or something that would allow fluid to flow is it ?
Blue Light Motor vehicle Hood Gas
Blue Light Motor vehicle Hood Gas
 

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Since I don't know who's radiator(brand) that is, I can't really say....but this is what it looks like to me

The port with the blue AN male adapter in it I would expect to be a WATER port, a return location for a hose from the heater core. some applications use it.

The small allen plugged boss/port just below that blue adapter at 7 o'clock, and the matching size port down below near the yellow line in the photo, would be the in-tank trans cooler ports

Pull that allen plug and air check it, figure out where it goes.

Radiator has no intructions??
 
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