Yellow Bullet Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
286 Posts
Discussion Starter #1
What would cause a 700r4 to have delayed engaement after sitting over night? Once primed, trans shifts fine. Only does it after sitting several hours.
Seems to be a converter drain back issue, but searches have not revealed any other 700r4 with this issue.

The trans is a 84 model 700r4 with updated 30 spline input/pump using a TCI constant pressure VB. Converter is an Alan Pope 9.5"
3600 stall.

I have instructed my brother to clamp the cooler line and park it over night, and remove the clamp before cranking the next morning and see if it still does it, but he hasn't done that yet.

Thanks for any input,
Rick
 

·
Registered
Joined
·
217 Posts
That's not going to help converter drain back. If your looking to update with a better core and performance, you would be better to use a 1987 and up core. They were a better unit when they added the aux. valve body. Burt
 

·
Registered
Joined
·
286 Posts
Discussion Starter #4
Likely the regulator valve had the converter regulation land ground completely off and or a big hole drilled from lube to line pressure.


Hutch
I just thought of something. The constant pressure kit was for a 82-84 trans and came with the pressure reg boost valve and springs. I changed the pump and input shaft to the later 30 spline and used the boost valve and springs from the kit in the new pump. Could this be the issue?
 

·
Registered
Joined
·
286 Posts
Discussion Starter #6
Don't think so. Was the regulator valve stock or had it been modified?


Hutch
The reg. valve was stock, should have been any way, (rebuilt pump), but the boost valve was the TCI boost valve for the 82-84 pump. Would that have made any difference?
 

·
Registered
Joined
·
2,642 Posts
If you updated to the 30 spline input and stator that is fine.Just be sure it is an early 30 spline pump or you will have the forward clutch feed hole that feeds oil to the pipe and auxilary valve body open to dump in the pan.Is there a delay in reverse as well?If not suspect a forward clutch feed issue.If it has a delay in reverse and drive put a pressure gage on it and see if oil pressure is @ or less than 50psi at 1000 rpms and goes up to around 100 @ 1500.This is usually a sign of a gouged or un parallell pump cover or body.Drainback could be excessive if the i d of the pump rotor is worn where it keys to the converter.I have shut off converter feed completely on the dyno and seen a worn pump rotor allow as much as 20 psi converter charge pressure and 1/2 quart of oil volume in 30 seconds,so dont overlook this.Pump bushing to converter neck worn can do the same thing.Also as Hutch stated converter charge is off the main regulator to the cc upshift valve .Unorthodox mod can cause same issue and you will usually have a big pressure drop on the shift if the 2 circuits are cross connected improperly.There are also several air bleeds in the form of cup plugs that are present in the circuit .1may be missing.
 

·
Registered
Joined
·
602 Posts
Check the pump cover (stator) you updated with for hole in casting for feed tube to aux valve body. Early case would not have the aux valve body.

Excessive clearance in the pump slide - rotor area will cause drain back. Keep clearance down to .0015 , maybe .002... surfaces need to be smooth, not rough or have grooves
 

·
Registered
Joined
·
286 Posts
Discussion Starter #9
Check the pump cover (stator) you updated with for hole in casting for feed tube to aux valve body. Early case would not have the aux valve body.

Excessive clearance in the pump slide - rotor area will cause drain back. Keep clearance down to .0015 , maybe .002... surfaces need to be smooth, not rough or have grooves
That is probably the problem, (aux feed hole). Other that the drain back, will it cause any other issues down the road??

Thanks,
Rick
 
1 - 9 of 9 Posts
Top