Oil pressure problem in the oil pan of a 42RLE automatic transmission

[Adcoski]

Hello,

I just reinstalled the 42RLE transmission on my 2005 KJ Liberty 3.7.
This transmission and the converter were completely reconditioned by a specialized company.
I also changed the oil cooler and the hoses that go to the cooler.
I filled the transmission with ATF+4 as indicated in the workshop manual.
I tested it by operating the selector lever while cold, then checking the level each time, and then checking the level again while hot after driving several kilometers.
I was at 8 liters of ATF+4 and the KJ was idling in the garage. I was about to check the level again when suddenly the engine seemed to stall, followed immediately by a noise like a balloon deflating, and the engine returned to its normal speed.
I looked under the vehicle and saw that the gasket paste on the crankcase had failed, and oil was leaking through the gasket.
I immediately turned off the engine.
There was clearly too much pressure in the crankcase; the oil was hot, around 60°C, and I couldn't keep my hand on it.
However, the oil pipes and the cooler were barely warm.
I checked that the circuit was working properly, and there is oil in the radiator.
The rubber hose on top of the gearbox does not appear to be blocked.
What could have happened and where did the problem come from?
I don't have a DRB3 to diagnose the gearbox.

Thank you.

 

[24turbo]

Modern transmissions are very complicated and the 42RLE is no exception. Hopefully your specialized company was a transmission shop.
Based on most of your description, I would suspect the torque converter wasn't installed properly. if its not fully engaged into the oil pump drive it will put pressure on the pump gear and soon after running it, the pump will pile up and seize (the balloon sound and engine labouring you describe) and ultimately break the weakest link. This would have caused a lot of heat in the transmission due to all the friction of the pump running and eventually failing. Only baffling thing is why the pan gasket blew out.

The other red flag I see is you must do a re-learn on the PCM to reset the clutch volumes (CVI). If this is not done will lead to clutch apply/release problems which could also quickly destroy a transmission.

Unfortunately regardless of the cause I would say most likely the transmission will need to be removed and taken apart and fully inspected. Fingers crossed its something easy....

 

[Adcoski]

Hello,

Thank you for your reply, which unfortunately does not make me very happy.
The company that carried out the repair specializes in automatic transmission repairs and is located in Spain (I live in France).
The transmission arrived with a converter that looked new.
It seems to me that the converter was correctly engaged during reassembly.
The vehicle was immobilized for several months with the battery disconnected.
I read on a French forum that simply disconnecting the battery overnight was enough to reset the PCM, but perhaps this is false information.
Is there a special procedure for resetting it?
I only followed the gearbox filling method recommended in the workshop manual after a complete overhaul.

Thank you.

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[24turbo]

When you installed the transmission was the torque converter tight to the flywheel or did you have to pull it forward about 1/4 inch? If it was tight the torque converter wasnt fully in place. From the picture it was not fully installed.

As for the re-learn. this is usually done with a higher end code scanner. On my scanner it is called a quick learn and is a procedure where you follow the prompts on the scanner. I put it in drive with the brakes applied and the transmission feels like it is shifting even though its not moving. It is fairly common procedure on newer transmissions to do some kind of re-learn so I would hoped the rebuilder would tell you it was required.

 

[Adcoski]

Hello,

Based on your response, I think I probably reinstalled the converter incorrectly.
When you say that the weak link broke, do you mean the converter or the pump?
Since I have a leak in the crankcase, I haven't restarted the engine and I don't know if the gears are working.
The transmission broke down for the first time on the highway. There was a loud bang, the transmission oil temperature light came on, and after the vehicle stopped, it was impossible to move it forward or backward.
I had to remove the drive shaft to be able to load the Liberty onto the truck.
I know I'll have to remove everything again, but since this incident occurred while the engine was idling and the high pressure in the crankcase caused the paste seal to explode, perhaps the damage is less severe than the first time. The seal may have acted as a fuse, especially since I immediately stopped the engine, which resumed normal operation after the depressurization whistle.
I have another question: can you give me the name and model of your diagnostic tool? Is it specifically for Jeeps or is it multi-brand?
DRB3 are impossible to find. There are some for sale on eBay, but the prices are prohibitive for single-use.

 

[24turbo]

Hi

When I said the weak link broke, I just meant whatever the weakest part at that particular moment (probably the pump) was. My guess would probably be the pump itself, but possibly the converter snout. Only way to know for sure is take it apart.

Given the pan is already leaking I would say first step is to remove the pan, that will give an indication how bad the damage is.

I bought a Snap-on Solus scanner for cheap on a local classified. It is outdated but still works for what i need. There are other aftermarket brands such as Launch that will probably do the same. If you know someone in the industry maybe you can borrow one as it doesnt take long to do the procedure (or slide someone some cash to stop by and do it after shop hours).

Good luck and keep us posted

 

[Adcoski]

Hello,

I have been thinking about what you told me regarding the converter assembly.
At first, based on what you wrote, I thought I had moved the converter too far forward.
But no, as shown in the photo, it is indeed too far forward because the factory installed the mounting bracket upside down.
The elbow of the bracket should normally fit into the box.
But during installation, I did insert the converter into the pump correctly.
For the installation, the box was placed on a pit jack, and with a friend, we carefully positioned it and bolted it to the crankcase, then we moved the converter forward to screw it onto the flywheel.
There is no possibility of installing it incorrectly, as there are two mounting surfaces that are not adjustable: the engine casing with that of the box and the flywheel.
Apart from putting shims between the flywheel and the converter, I don't see how to push it in further.
As for the excess pressure in the housing, I'm also surprised because there is a breather above the gearbox with a pipe located next to the filler pipe, which I assume is normally used to release air.
I checked the valve at the end of this pipe and it is not blocked.
Of course, I contacted the company, and the Spanish technician was supposed to call me, but to date, despite several reminders on my part, he still hasn't contacted me.
I don't know what they found and did to repair this gearbox, and I don't have any test reports.
They just told me that they found mud in the gearbox.
So I changed the radiator and the pipes.
These gearboxes are quite tricky to repair; if just one seal is fitted incorrectly, it will fail.
This Liberty is 20 years old this year, and no one in France knows how to repair these transmissions anymore. Jeep France refused to repair it.
I saw a well-explained tutorial on YouTube on how to repair these 42RLEs, but seeing all those stacked parts, I decided to go to a professional.
Maybe I should have taken on the challenge...

 

[24turbo]

If you had to pull the converter forward towards the flywheel it was installed correctly. I still think your next step is to remove the pan and see if there is any shavings (or anything else) in the pan. You have to fix the blown pan gasket anyway... I rebuilt my 42RLE about 1.5 years ago and they are fairly complicated. I'm a licensed mechanic but Ive only ever done a few automatic transmissions so Im not an expert. The only thing I can think as far as the overpressure goes is there are 2 accumulator pistons above the valve body. Maybe one of those seals wasnt quite installed properly and let go? if the pan waas clean and you get it running again there are numerous pressure ports on the transmission you can check pressures- may tell you where a potential leaking piston seal may be (low pressure in that circuit). Wish I could help more but they are hard to diagnose.