Just fired up my new combo and ran into some issues right off the bat. I went through my 4l80 myself and obviously screwed something up.

As of right now the trans has no forward gears at all, it has a very weak reverse and you have to bring rpms up around 1500-2000 to get it to move.

This was a full rebuild, before install I dumped 1qt in the converter and put 7 in the trans before starting. Right after startup I told my buddy to put the rest in and check it. He put 2 more in and for whatever reason stopped. It ran for prob 10 min before I shut it off. I then added the rest of the fluid I had (11 quarts total). As of right now it shows just below full according to the mark I made on the dipstick. (With pan off I marked where the vb meets the case)

I have a gauge hooked up and pressures at idle measure as follows
Park=40 psi
Reverse=60 psi
Neutral=40
Drive=40
3=40
2= will spike up to 160psi when I first shift then settle back down to 40
1= 40

Trans was a rebuild using stock clutches and steels, internal dual feed, sonnax self regulating boost valve, rollerized tailshaft, billet roller forward hub, billet input. Springs/snap ring/ minor parts from an HD2 Kit. Using a stock separator plate instead of the hd2 plate, yank 3400 stall

All clearances looked fine, everything checked out like it should according to the the ATSG manual. Just wondering where I should look first when I drop the pan/ rip it back out.

Thanks!

 

Pressures seem low across the board, dont have specs in front of me at moment, but you should have more line pressure than that, boost valve, pump and a leak internally somewhere whether valve body or a weak seal somewhere.... How were the o rings on the pressure manifold? Have also seen a few times in 4l80s where a roll pin wasnt tight enough in the hole and allowed a valve plug to fall out of the valve body.... Did you put a new seal in the pump for the filter?

 

Seal in the pump? Only seal I replaced in the pump as the front seal for the converter and the pump to case gasket, o-rings on pressure manifold looked ok, just cleaned the entire manifold, and put it back on. I did put a new seal in the case that the filter pushes into

 

Meant a seal somewhere in the trans.. You air checked all the clutch packs correct?

 

4l80 and oem converter takes about 14-15qts..what kind of dipstick are you running?

 

I air checked the rear servo, and checked all the clutch packs with feeler gauges but I did NOT air check the clutch packs, the manual I had wasn't clear on where to check, or at least that I could see.

The dipstick I am using is the one that came with it out of a 2500 truck, I also marked the dipstick with the pan off, I had also read it takes around 14 but I didn't have anymore fluid and the stick shows just below my mark. I would gladly throw another 3-4 qts in if needed converter is a yank 3400

 

Get fluid level right first, before going off deep end trying to find an issue.... If the dipsticl came with the trans there shouldnt be any issues...

 

I am pretty sure that fluid level is right, it's above the factory marks, and just slightly under the mark I made, where its a factory 80e dipstick I would think that even if it was 1qt low it's still in the factory marks and should move.

 

Doesn't sound like a fluid level of fluid type problem to me. Sounds like a pressure modulation or hydraulic leak problem. Your idle pressures are at the low end of what's considered "in-spec", 40 for forward gears and 60 for reverse is okay. Pressure should rapidly come up as you give it throttle, especially in reverse. Probably should test that just make sure you don't brake-stall it more than a couple seconds or you could overheat the converter. Fair warning though - if the clutches are slipping doing a stalled pressure test will completely roast the forward clutch pack, or the rear band and direct clutch pack if testing reverse.
Another consideration is that a converter with a 3400RPM stall speed is unlikely to creep the vehicle at idle unless it's got a very low axle gear ratio. A high-stall RPM converter will feel like the trans is slowly coming out of neutral if just applying light throttle from a stop, and that's normal. However, if you get on it from a dead stop line pressure has to immediately come up, the converter will multiply torque at the maximum possible level and the rear tires should have no chance at traction. I don't recommend screwing around until you can confirm no clutches are slipping - they only have to overheat one time to be ruined.
If you have the ability to log PIDs, log transmission input RPM, output RPM, and gear ratio. That will tell you if the clutches are slipping. The PCM might also pick up a P1870.

 

Thanks, I will log those pids and see what it looks like. I have been pretty careful with it, I have driven quite a few vehicles with stalls before and this does not feel normal, I have only brought it up off idle a few times as I am worried about frying the clutches if they are slipping.

I was also told to disconnect the main connector and get some pressure reading. If I read right that should default to max line pressure. Like 150-180 psi?