Low line pressure after it gets warm.

[DougP]

Can someone tell me what would cause low line pressure after transmission gets warm. I took tranny out to change converter to a ptc NLU from a 9/11 LU. I thought I was blowing thru the converter or maybe slipping in the tranny 2nd and 3rd gear. Was slight burn on 2nd band and 3rd clutches nothing to bad. I put non lock up valve and had tranny guy put new 2nd gear band and 3 gear clutches in. Every thing else looked good. Car shifts fine at low to mid throttle nice firm shifts. At wide open throttle it shifts 1-2 at 5000 rpm then goes right into 3rd.
Line pressures are as follows
Cold
idle 850 rpm Full TV 850 rpm Full TV 1500 rpm
95 115 240
165 115 240
95 115 240
95 115 240
95 115 240
240 115 240
240 115 240

Hot transmission temp 180
idle 850 rpm Full TV 850 rpm Full TV 1500 rpm
100 115 200 - 250 Bouncing
90 115 215
100 125 215
90 100 180
90 100 180
90 100 180
90 100 180

Valve body is a BR3 in a 86 GN.
Could the TV valve be worn ?

 

[TexasT]

I'm not a guru and hopefully one with swing through. But, as I see it the boost stack has some thing wrong. I'm assuming that that list of pressures is top=park and on down to last on the list=first. This leads me to thinking the rev boost valve isn't in there correctly(not sure about that as it does put the pressure up when cold) or the low rev clutch has a bad seal or something as that list shows drastic drop off in low, 2nd and rev. it is bleeding off a lot as it is shifting into 3rd quickly.

 

[Steve V]

Check the pump real close. Rotor clearance .002 or less, as suggested above pr valve train in correctly? Billet rings in the pump? new viens?

 

[DougP]

Yes top of list is park.
We did put new viens in pump just for the hell of it pump looked good but didn't ck any clearances. Didn't see any billet rings it looked stock.
Rev boost valve wasn't removed. But I know pr valve ( this is the valve that goes to tv cable ?) was out. In fact the rod that goes to tv cable was backwards at first. I noticed this after changing the tranny pan to a deep one. Could this have caused damage to the valve or spring.

 

[mikestertwo]

Yes top of list is park.
We did put new viens in pump just for the hell of it pump looked good but didn't ck any clearances. Didn't see any billet rings it looked stock.
Rev boost valve wasn't removed. But I know pr valve ( this is the valve that goes to tv cable ?) was out. In fact the rod that goes to tv cable was backwards at first. I noticed this after changing the tranny pan to a deep one. Could this have caused damage to the valve or spring.

The valve the T.V. cable goes to is the Throttle Valve not the pressure regulator valve. The pressure regulator valve is in the pump above the boost valves. When you replaced the vanes did you put a new seal on the pump slide? Are the pump haves aligned properly? What else did you do to the pump besides replace the vanes?

 

[DougP]

All he said was that he replaced the vanes. I'll ask about the seal and alignment. He does build transmissions for a living. Vince Janis rebuilt the tranny back in 2002 so we didnt want to mess w valve body. We did replace 3 Teflon seals w steel ones has the Teflon one looked slightly cooked.
I seen a picture of the pr valve and see it has 2 o rings could one of these be leaking.

 

[mikestertwo]

All he said was that he replaced the vanes. I'll ask about the seal and alignment. He does build transmissions for a living. Vince Janis rebuilt the tranny back in 2002 so we didnt want to mess w valve body. We did replace 3 Teflon seals w steel ones has the Teflon one looked slightly cooked.
I seen a picture of the pr valve and see it has 2 o rings could one of these be leaking.

The valve with the two O-rings is the boost valve. I doubt that a bad O-ring on the boost valve would cause the problem you are seeing but you never know. If the builder does this for a living I would assume he put new seals in and aligned the pump properly.

 

[77 cruiser]

Some of the guys that do it for a living don't know 200's. I had one done by a PRO many years ago & it wouldn't even hold a stock 305.
Needless to say I did my own after that, thanks to this forum & a few others it's held up to some abuse.

 

[GBGN1]

Id also look at pump but Id think 180 at full tv is enough to hold the clutches on. Cross leak at the plate?

 

[V6sleeper]

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