4l80e line pressure
03-24-2012, 07:15 PM
#1
4l80e line pressure Hey guys, I tried to search my problem didn't really come up with anything. The problem i am having seems to be low line pressure. When i shift trans into reverse i get nothing, if i bring rpms up to about 1100 it will kind of slide into gear. I am having the same issue in drive. My trans is a craigslist buy condition unknown, the fluid didn't look to bad. I have installed a transgo shift kit and I am using a optishift controller any help will be appreciated.
03-25-2012, 09:17 PM
#4
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I would start by putting a pressure gauge on the unit to see where the pressure is at first. If you did not have the trans in the vehicle before the shift kit install you might want to start there first to see if a issue was built into the install. HTH Vince
03-25-2012, 09:53 PM
#5
Thanks, I'm going to try to get a pressure gauge this week. I pulled the valve body found a blown out place in the gasket between separator plate and trans case. I installed a new gasket trans worked slightly better but still slow to engage a selected gear. I'm not very trans savy I tend to have to learn things the hard way. If I find I have low line pressure is there a place I should start looking in the valve body. This was my first shift kit install highly possible I made a mistake.
03-26-2012, 06:55 AM
#6
is the fluid level correct-i have found they like the correct amount of fluid from filling and looking at a pressure gauge
def would be nice to have a gauge to look at when you engage diff gears
i assume you didnt try the trans before the shift kit, so your fighting wether the trans is good or a mistake installing the shift kit
not sure about the controller you have, but some of them you can dial in more pressure bet gears
what year trans
def would be nice to have a gauge to look at when you engage diff gears
i assume you didnt try the trans before the shift kit, so your fighting wether the trans is good or a mistake installing the shift kit
not sure about the controller you have, but some of them you can dial in more pressure bet gears
what year trans
03-26-2012, 07:29 PM
#7
I put a gauge on it today. 0 to 10 psi at idle only gets to about 35 psi when it engages reverse or drive. I am assuming I have a problem with my pump. Unpluging the electronics doesn't seem to change anything I was told with it unpluged you should get max line pressure. If anyone knows of anything else it could be other than the pump please chime in, thanks.
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03-26-2012, 08:25 PM
#8
I put a gauge on it today. 0 to 10 psi at idle only gets to about 35 psi when it engages reverse or drive. I am assuming I have a problem with my pump. Unpluging the electronics doesn't seem to change anything I was told with it unpluged you should get max line pressure. If anyone knows of anything else it could be other than the pump please chime in, thanks.
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Kawabuggy (04-20-2021)
04-01-2012, 03:53 PM
#10
I pulled the trans out yesterday, pulled the pan and started ionspecting the valve body. I was checking the shift kit install when i noticed a crack in the trans case in the hydraulic circut. I had another questionable trans so I started transfering the valve body and pump to it. I reinstaled the trans today now I have a whole new set of problems. In park it acts like a trans-brake in teverse it pulls forward. The line pressure will come up to about 75 psi then it will fall to 0. I'm assuming I have a valve body problem, any help will be appreciated this is my first time in a auto trans so I'm learning as I go.
04-02-2012, 08:36 PM
#13
I pulled my pan today, manual valve was hooked to rooster comb. I was looking at the manual valve, I seem to have two slightly different ones. Is there a difference in the valves from one year to the next. The only difference that I see without measuring them is that the one that goes with the case in the truck now is slightly thicker where it attaches to the rooster comb on the valve body side. I had the thinner one in the case I'm going to swap them, but before i put it back together does anyone know if this could be causing my problem or is it deeper in the valve body.
04-03-2012, 09:57 PM
#15
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There are only two valve bodies for these units that I'm aware of. The early front lube 91-96 and the late center lube 97 and up. You would not be able to swap these. Reason being the lube tubes are different for the two types and also the case changes to accommodate these tubes. As for the manual valve they are the same for all years. The only one I have seen in the after market is made by sonnax. Its a little beefier with the spools being slightly different.
Last edited by Vince B; 04-03-2012 at 10:03 PM.
04-08-2012, 01:06 PM
#16
Well, this week I removed the trans, took it apart to the pri drive to see if clutches were seized. I put the trans back together with the other pump i had. I disassembled the pump to inspect it everything looked good to me didn't check clearances. I reassembled the pump with a new seal and O-ring. I reinstalled the trans now I only have about 20psi of line pressure at idle and the max I get is about 75psi at 2500 rpm. The truck will drive but doesn't shift well. I know I should have more line pressure, where do I look now.
PLEASE HELP
PLEASE HELP
04-08-2012, 07:36 PM
#18
Not shure of the years they both have the cooler lines towards the front like a th400. The pumps looked to be the same except one of the pumps had a bracket with a nub on it that locates in a hole this was located on one of the bolts that hold the two halves of the pump together. I didn't put the tab on the pump in the trans now. I don't know if it needed it or not I don't think the pump in it now had this tab on it. One of the trans had the green tag that has 2001 on it.
