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Many people make the mistake of reusing the Oil Cooler/ Lines/ Torque-Converter...
Then they DESTROY their new Transmission, by circulating all that Debris from the Oil Cooler into the new Trans.
(Often blaming the Transmission Builder).
Yeah that would be a waste. 😁
Put the trans in this morning. To my disappointment it is slipping when starting in OD and manual 3rd.
Manual 2nd is good/ok or at least better, starts moving at 1500rpm.
Manual 1st is burnout firm.
At first I thought it was the converter stall, sometimes it was really firm in shifts at higher rpm. But when hot it was struggling to get moving and temp went 200F. Since it is different in manual 1st and others converter must be ok.
Really firm in Reverse and 1st.
I have got good pressures at idle. Higher during rpm. 200+ in LIMP.
P/N 70
R 120
D/d 120
1/2 145
Verified oil level.
Vaccum tested VB, see grey values in picture.
Had clear thump on reverse band, 4th, and the one engaged from rear bolt, intermediate I think it is called.
Got all the clutch plays in order.
Since it worked before, could I have misplaced a checkball?
I had to hone the small bearing on the strator supporting the input shaft. Kept that just tight enough to pass thru. Too tight for oil to pass properly?
Please let me know if you have any pointers… Getting crazy here..
Thansk!
Last edited by Lindberget; May 10, 2026 at 06:42 AM.
Removed the valve body again to verify checkballs and if any debris. Looks great even if I experienced some 30 km testdriving with some skipping starts.
Air tested clutches, all with clear thumps.
Direct, intermediate, 4th and low reverse holds air for 10+ seconds
Forward and overrun holds like 3 seconds from air boost until pressure is out. Seems great overall.
Nice to have confirmed that cleaning went good..
Any suggestions, I am out of actions. @vorteciroc @MaroonMonsterLS1@FranksCustomTrans
Condition 9 in above image could fit my case. But I have forward, just experiencing a slipping start.
The lower roller clutch, as pointed out for condition 9 must either work or not? Can’t be a slipping feeling? Did not do anything with that during the cleaning.
Last edited by Lindberget; May 10, 2026 at 11:32 AM.
Hey,
I vacuum tested the valvebody again and found that I had blocked several passages when testing the ”reverse checkball sleeve”. Vaccum was only 8hg. Same with Low/reverse checkball which was also low, around 10hg.
I did a DIY fix with removing both checkball seats and adding a o-ring in the valvebody before putting the seats back. Increased the vaccum to 17 and 15hg. Anyone tried that?
Assembled everything and it ran very well for about 40 minutes. Moving in idle, firm shifts, tires smoking in every gear. Working fine in all manual gears. Really perfect!
I did a victory burnout… Back to slipping start in 3rd and 4th and I lost first gear. Manual 1, starting in 2nd, same with other positions. Same behavior like before.
Feels like, at least in my head, that the checkballs are not finding its way when getting hot..
Temp was about 175 when it started to behave strange again, quickly increased to 200 when slipping started. Did not matter if I went increased line pressure in performance mode, still same slipping.
Are my vacuum readings ok? Should I replace the checkball seats with sonnax replacements? Anyone know if they fit pre 1992? Seems to be for later model 4l80e @vorteciroc
Do you have a new filter?
Are you 100% sure it is full of oil
If you did use a new filter...where did you get it and what kind of quality is it.
Sounds like you are sucking air. Temps shoot up because the pressure regulator cuts off converter/cooler oil to prioritize line pressure when it struggles for pump volume.
Check ball readings you've pointed out are non-issues for the symptoms you're describing.
I'd remove the o rings before they get beat apart and squeezed to the point they break down or get cut and start making debris
Here is what I would do. You seem to have issues all over the map as they say. I would pull VB and air check everything, The get an unmolested VB cleaned and checked but otherwise stock and put on it . See that I ended up with, If all good after driving a while pull it and do whatever performance HD mods I had planned . If with NEW VB things go south again then consider a case assuming no electronic/ control issues . I have seen VB that tested vac wise far worse than yours working great in 200k miles units
That would be the path I would take assuming you have covered what MaroonMonsterLS mentions above .
You might think CASE? it looks fine . trust me I have in the past chased issues with units that made no sense at all and nothing worked and in final desperation swapped the case and boom all fixed and then spend time literally with a magnifying glass. ., straight edge and all looking and could find nothing to explain it except that whatever it was swapping the case fixed it, Even VB the same spend hours pulling checking, fixing only to swap and boom all good .
Also check that your screen in PCS has not become clogged again .
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Do you have a new filter?
Are you 100% sure it is full of oil
If you did use a new filter...where did you get it and what kind of quality is it.
Sounds like you are sucking air. Temps shoot up because the pressure regulator cuts off converter/cooler oil to prioritize line pressure when it struggles for pump volume.
Check ball readings you've pointed out are non-issues for the symptoms you're describing.
I'd remove the o rings before they get beat apart and squeezed to the point they break down or get cut and start making debris
Thanks @MaroonMonsterLS1 !
I replaced the filter after the converter failure but not since then. It is a standard filter I got from a local transmission builder. Not sure of the details other than it is the low level pan design.
Oil level is 5mm above pan flange.
Anything I can do there? What filter should I use?
Any rebuild components available for those checkball seats for a 1991 case design? Do not dare to go 10hg vaccum..
I did according to the picture below,
Shift solenoid was rather dirty. Could that be a factor? Seemed to be some fiber like material, maybe rag fibers from cleaning cloths..
Has been the same last times I dropped the VB. Blocking a filter matches pretty good with my symtom, workes for some time then it stops working. Have cleaned it every time.
Here is what I would do. You seem to have issues all over the map as they say. I would pull VB and air check everything, The get an unmolested VB cleaned and checked but otherwise stock and put on it . See that I ended up with, If all good after driving a while pull it and do whatever performance HD mods I had planned . If with NEW VB things go south again then consider a case assuming no electronic/ control issues . I have seen VB that tested vac wise far worse than yours working great in 200k miles units
That would be the path I would take assuming you have covered what MaroonMonsterLS mentions above .
You might think CASE? it looks fine . trust me I have in the past chased issues with units that made no sense at all and nothing worked and in final desperation swapped the case and boom all fixed and then spend time literally with a magnifying glass. ., straight edge and all looking and could find nothing to explain it except that whatever it was swapping the case fixed it, Even VB the same spend hours pulling checking, fixing only to swap and boom all good .
Also check that your screen in PCS has not become clogged again .
Thanks!
I will try to get hold of a spare VB. Not easy in Sweden.
I have air tested all the clutches. 3-15 seconds pressure hold after a quick boost.
Really hope it is not the case. Shift solenoid was really dirty again, see picture in above post. PCS works great, clean!
I will try to get hold of a spare VB. Not easy in Sweden.
I have air tested all the clutches. 3-15 seconds pressure hold after a quick boost.
Really hope it is not the case. Shift solenoid was really dirty again, see picture in above post. PCS works great, clean!
Did you clean out the solenoid's first time? that could ha s come from with VB filter broke and let stuff through. And yes those screens blocked can cause wrong gear starts and slow or no shifts .
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Did you clean out the solenoid's first time? that could ha s come from with VB filter broke and let stuff through. And yes those screens blocked can cause wrong gear starts and slow or no shifts .
Thanks! Yes it was cleaned, since the converter failure I have dropped the valvebody 3 times.
1, Full transmission inspection and cleaning. Obviously very much aluminum debris.
2, Valveboby cleaning, air check, vaccum testing and temporary correction of checkball seats. Did notice a fibre like paste on the shift solenoid filter. Did not think much more about that at that point. Just cleaned it again thinking it is leftover debris from first rebuild and cleaning. Pictures for that drop,
3, Valvebody cleaning, permanent O-ring rebuild of the checkball seats. Vaccum testing.
Did notice the same fibre like residue on the shift solenoid filter this time. If you rub it between your fingers it kind of sticks together, very fine, would that be from my alto clutches? Fibers from a cleaning rag?
More on the 2-3 shift valve solenoid. Also found some tiny bit in the AFL filter too. Totally a very tiny amount but enough to restrict flow slightly when blowing in the solenoid.
The PCS filter and PCS had less residue this time.
Plan to assemble it all again today and ”hope” it is the shift solenoid filter restriction causing this.
Is reusing the VB gaskets and oil filter a problem?
I am out of stock with all these VB drops..
Should be able to reuse VB gaskets a few times. DO NOT USE A RAG TO CLEAN PARTS. If you are reusing the trans fluid, (I get it that stuff is not cheap) I would flush cooler and lines again and clean everything again and start over with new fluid. You may have other things going on too, but that debris in your fluid is not helping.
Last edited by bbond105; May 17, 2026 at 02:49 AM.
I put it all together again and took it for some test drives.
Drive 1. Everything working fine for a long 1 hour drive. Varying speeds, all gears, hard and soft driving. Operation at below 165 F.
Pressures,
P/N: 75 PSI
R: 110
D/d: 120
1/2: 145
Drive 2,
Same as above! Below 175F temp.
Drive 3,
15 min after drive 2. After start I had same symptoms as in the past.
-Starting in 2nd gear in all forward gear selector positions
-Slipping feeling when start moving. More in D/3rd less in 1st/2nd position.
Hypotesis,
2-3rd shift solenoid filter clogged again.
Cloud a continuous ”on” or blocked 2-3rd solenoid filter cause above symptoms?
Option 1 fix,
- Verify blocked solenoid filter. Clean it
- Buy new cooler, replace
- Replace main filter and oil
- Drive!
Option 2 fix,
- Verify blocked solenoid filter.
- Buy new cooler, replace
- Buy a rebuilt VB, replace
- Replace main filter and oil
- Drive!
Please share your hypothesis and suggestions.
Could I remove the shift solenoid filters to get the very small debris to pass thru to the main filter instead?
Will a rebuilt VB introduce more new parameters then it is solving? Could I complement with more vaccum measurements to verify function of my current VB instead?
Do you know any good/trustworthy rebuilders in US?
I have a 1991/92 case but an updated wire harness with temp sensor. What VB will fit my case?
Really appreciate your engagement, have none of this expertise in Sweden for these transmissions!!
Last edited by Lindberget; May 17, 2026 at 04:48 AM.
I did some more reflection on challenges I had when building the transmission initially. I had the same symptoms after the initial rebuild 5 years ago. @vorteciroc you supported me then. See post below,
The resolution, at that time, I thought, was that my shifter was build together wrong.
The shifter cable was attached in the wrong spot on the shifter itself by the prior owner. The shift cable length matched correct in P and 1 position but was slightly off in D.
Once I changed that, the transmission has worked excellent for 5 years until the converter failed.
Maybe that was not my problem back then.. or is it possible to have the manual valve position slightly adjusted by forcing the spring load mechanism back or forth slightly when bolting the VB to the case. I did not feel significant play on the mechanism but maybe 0.01 inch if forcing it before bolting it the the VB. Common problem and matching with symtoms? Should I try adjusting the manual valve slightly forward or backwards or am I just hallucinating that it could be related to this?
Now the shift position selector has a perfect match with the shifter cable in all positions.
Manual valve does not look worn or bent but I have not vaccum tested it and have no reference to what is ok and not..
Don’t really see why manual valve position would would change after 2 hours of driving either, there the hypothesis of a blocked shift solenoid is a better match. Otherwise if it has to do with temperature expansion it should start fine cold every time, which it doesn’t.
I would let the trans cool all of the way down and test drive again to see if the problem comes back with a cold trans. If problem comes back sooner than test drive 1 and 2, pull solenoids and check for debris. If you find restricted solenoid screens again you need to figure out what the debris is and where it is coming from. Could be debris stuck in the cooler from when the converter clutch let go.
I don't think it is a manual valve problem. I feel once the manual valve is working it's not going to change with temp.
Last edited by bbond105; May 17, 2026 at 06:33 PM.
I would let the trans cool all of the way down and test drive again to see if the problem comes back with a cold trans. If problem comes back sooner than test drive 1 and 2, pull solenoids and check for debris. If you find restricted solenoid screens again you need to figure out what the debris is and where it is coming from. Could be debris stuck in the cooler from when the converter clutch let go.
I don't think it is a manual valve problem. I feel once the manual valve is working it's not going to chance with temp.
Thanks! Problem is still there after it has been cooling down 24 hours.
As I mentioned above, what sits in the solenoid filter has been a fibre like paste, very fine and binding together.. very small amount, not magnetic and small enough not to feel it when rubbing between fingers.
It was not the TCC burning up, the inside split in three pieces. A lot of aluminium.
Will be in Australia this week but will inspect next weekend.
If I understand correctly, after cooling all of the way down the problem shows up right away. If this is the case, whatever it is that is clogging up the solenoid screens is the problem. You need to find where it is coming from and remove it.
Add an in-line spin-on filter to the cooler line.
In a typical application, I put the filter between the trans and the cooler on the "out" line from the trans
In your case, I might consider plumbing it on the return side between cooler and trans to catch whatever seems to be in there.
Cooler lines if FPM could be degrading. PTFE not as likely
Stuff in the cooler that gets broken loose with flow and temp
I've seen fiber washers like what's on the pump start to get worn and they make a hell of a mess that'll clog anything.
Etc Etc
There's debris somewhere...gotta find its source
Solenoid pattern for an 80e is
A/B
On/Off
Off/Off
Off/On
On/On
If B is getting the debris and holding it on...you'll basically be starting in 4th even when first is commanded. Honestly I'm surprised the car wants to move at all in that state. The oil temps make sense...that converter is FIGHTING
Add an in-line spin-on filter to the cooler line.
In a typical application, I put the filter between the trans and the cooler on the "out" line from the trans
In your case, I might consider plumbing it on the return side between cooler and trans to catch whatever seems to be in there.
Cooler lines if FPM could be degrading. PTFE not as likely
Stuff in the cooler that gets broken loose with flow and temp
I've seen fiber washers like what's on the pump start to get worn and they make a hell of a mess that'll clog anything.
Etc Etc
There's debris somewhere...gotta find its source
Solenoid pattern for an 80e is
A/B
On/Off
Off/Off
Off/On
On/On
If B is getting the debris and holding it on...you'll basically be starting in 4th even when first is commanded. Honestly I'm surprised the car wants to move at all in that state. The oil temps make sense...that converter is FIGHTING
Thanks guys!!
I have no idea where this comes from. My only hypothesis is that there is still some debris left in the cooler, thus trying to clean it.
Could also be something left in the torque converter. Bought if from a transmission rebuilder that told me it was involved in a transmission failure. He had sent it for cleaning.
I will take following actions,
-Inspect and clean solenoids again
-Replace inline filter and oil
-Mount a 3/4-16 spin on filter on the return line, between cooler and transmission.
Any recommendations on choice of filters? Limited availability in sweden but will make my best.
In-line filter, I bought a 8684221
Spin on, what to go for to limit restriction?
PPE 128059150 would be a great option for a spin on filter.
15 micron
LOTS of flow area so, not super restrictive.
You'll of course need a filter adapter block to make it work
The reason I recommended the Allison filter is because its a large truck application so I figured you might be able to more easily source one in your country.
Otherwise, you can find one of Caterpillar equipment or Komatsu or any other big equipment that uses hydraulics.
You're going to want to find something that is around 15 micron and rated to flow around 5gpm or greater...the more the merrier for flow rating.
You can use the Wix Filter Finder to cross reference Caterpillar numbers to get a good idea for flow rating and micron size. WIX does a good job of matching the OE spec.
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