I think @Gary Kline has not only posted photos of the location but also a video from YouTube.

 

Hey @Flechtight ,

There's no procedure since of course it's not officially supported drilling through a PTU but here's the only video I've ever seen on the process. It's a guy in Kharkiv, Ukraine, the screen grabs below are from it.

• Basically there's a flat, thickened spot on the bottom of the PTU where the red arrow below is pointing to. You use a thin drillbit to drill through. Note, stay away from the yellow area. That's the ring gear that drives the propshaft pinion.
• The guy in the video then let's the old oil drain out (taking any shavings from the drilling with it). Then you can do a few drain/fills to clean it out. In the video they actually reverse fill it. They pump in through the new hole and fill from the bottom until it starts to dribble out through the fill plug. I'd probably go the 'normal' way (fill from the fill plug and let it drain through the new hole. No need to bring "up" anything in the sump into the gearing).
• In the video he just uses a small bolt w/ threadlocker to close out the hole until the next draining. The PTU isn't under any pressure nor is there any pump so you just need something to plug the hole.

I've been looking for a year of so for a cheap PTU to experiment on but the problem is that even junkyards know the value of an AD2 PTU so I haven't found anything cheap enough to experiment on.

Also, speaking of AD2, this procedure is only for AD2 PTU's. AD1 PTU's may not even need it since the drain/fill plug is much lower on the unit and not blocked by the big ring gear. It may be possible to suction pump it out like you do the RDM and then pump in new fluid both through the side-located fill plug.

 

Excellent!! I was ready to do the same thing…. Just wasn’t sure where to drill. Nice work!

 

Thanks Gary, how did you find that video, I’ve been googling every phrase I could come up with and every video is of the Ford PTU drill and tap.

That’s kind of funny, I was thinking of reverse filling as well, thinking it would make the process easier in the end, after seeing the post of how much actual clearance behind the fill plug there was.

I’ll keep checking for more info, but in the end it’s really think it needs to done ……it’s just a hole, the worse that can happen 😬

Stay Tuned

 

Thanks Gary, how did you find that video, I’ve been googling every phrase I could come up with and every video is of the Ford PTU drill and tap.

That’s kind of funny, I was thinking of reverse filling as well, thinking it would make the process easier in the end, after seeing the post of how much actual clearance behind the fill plug there was.

I’ll keep checking for more info, but in the end it’s really think it needs to done ……it’s just a hole, the worse that can happen 😬

Stay Tuned

Hey @Flechtight ,

There's actually a bunch of really good Ukrainian and Russian YT channels where they really tear the Cherokee apart and show the insides. For example, one has a complete disassembly of the actual EPS rack which is pretty cool. RDM, PTU, rear knuckle bushings and front balljoints ,CANBUS modules etc. also.

There are especially two good channels:

• Eugene Irimia Eugene Irimia

• VDL Service VDL-SERVICE (Харьков)

Go to their channels above, hit the 'Search' magnifying glass and type "Cherokee".

You need to turn English subtitles on and of course you won't understand what's being said, but between what you see and the subtitles, you can see the procedures they used on a lot of in-depth Cherokee things. Eugene's channel's especially good, he's really talented (and as a nod to @sanghill , he also does CrossTrek videos )

 

Thanks Gary. I could not find English for CC on my mobile device but when I followed your steps while watching on the Firestick, English comes up as an option. Go back to mobile and it only allows Russian subtitles.

go figure

I thought the wiring harness extension is a great idea. There should be a way to bench test the units before installing saving time and a little piece of mind.

That stupid little motor takes allot of abuse inside the case , I could see the motor blowing a shift and leading to other major issues.
Thanks again Gary, your working your way up my Christmas list….. but don’t get to excited, my kids never did

 

Thanks Gary. I could not find English for CC on my mobile device but when I followed your steps while watching on the Firestick, English comes up as an option. Go back to mobile and it only allows Russian subtitles.

go figure

I thought the wiring harness extension is a great idea. There should be a way to bench test the units before installing saving time and a little piece of mind.

That stupid little motor takes allot of abuse inside the case , I could see the motor blowing a shift and leading to other major issues.
Thanks again Gary, your working your way up my Christmas list….. but don’t get to excited, my kids never did

No worries! Just need is the ho, ho, ho

 

PTU drilled and drained. I did not verify level before drilling, but I got a solid 32oz of oil out. Plug magnet did not look bad, yes shining all throughout but expected for 70,000 + miles.

so before I got to drilling , I had to cut off the hex plug from the casting and polished the surface of the boss for the sealing surface.

Then to make sure the hole is as perpendicular to the polished surface I made a drill guide to mount off one of the heat shield bolts which is running parallel to the drain plug boss (casting)

first drill block was drilled as a pilot hole so I could dip gauge the depth around the hole to see what I had to work with on depth, which gave me about 1/2” for threading.
I also probed the area around the hole and never could touch anything behind the hole.

next was a metal drill guide for a #3 bit for 1/4”-28 tap

Drilled and cleaned out hole with craft pipe cleaners. Tapped hole

Reverse filled….. PTU

This got interesting, I stayed under the car to make sure I did not blow out the fill line going to PTU after over a quart into it and probably a half quart more than I should, no oil was coming out the fill plug.
I decided to stop and wait. 15 minutes later it started dripping out the fill plug and I ended up letting it drip all night and I caught an extra half quart.

so it takes awhile to migrate across the PTU, as thin a viscosity as the oil is ( like water) it does not rush out.
Next time I need a better pump set up and verify and measure in.

Lastly I had ordered bonded o-rings for the flange head bolt but they are late arriving and I needed the car so I went with copper gasket, and ultra black RTV then cap sealed the plug head and let is cure over night.
You do not want a leak at this point

 

PTU drilled and drained. I did not verify level before drilling, but I got a solid 32oz of oil out. Plug magnet did not look bad, yes shining all throughout but expected for 70,000 + miles.

View attachment 237609



so before I got to drilling , I had to cut off the hex plug from the casting and polished the surface of the boss for the sealing surface.
View attachment 237612
View attachment 237613
Then to make sure the hole is as perpendicular to the polished surface I made a drill guide to mount off one of the heat shield bolts which is running parallel to the drain plug boss (casting)
View attachment 237615
first drill block was drilled as a pilot hole so I could dip gauge the depth around the hole to see what I had to work with on depth, which gave me about 1/2” for threading.
I also probed the area around the hole and never could touch anything behind the hole.

next was a metal drill guide for a #3 bit for 1/4”-28 tap
View attachment 237616
Drilled and cleaned out hole with craft pipe cleaners. Tapped hole

View attachment 237617

Reverse filled….. PTU
View attachment 237618
This got interesting, I stayed under the car to make sure I did not blow out the fill line going to PTU after over a quart into it and probably a half quart more than I should, no oil was coming out the fill plug.
I decided to stop and wait. 15 minutes later it started dripping out the fill plug and I ended up letting it drip all night and I caught an extra half quart.

so it takes awhile to migrate across the PTU, as thin a viscosity as the oil is ( like water) it does not rush out.
Next time I need a better pump set up and verify and measure in.

Lastly I had ordered bonded o-rings for the flange head bolt but they are late arriving and I needed the car so I went with copper gasket, and ultra black RTV then cap sealed the plug head and let is cure over night.
You do not want a leak at this point View attachment 237619

View attachment 237620

Awesome write-up! Nice & thanks for posting such good photos!

I think the reason it took so long for the fluid level to 'equalize' is that on the AD2 PTU, there's the big ring pinion gear (yellow box below) that separates the left casing half (where you drilled the drain plug) and the right casing half which has the fill plug. It takes time for the gear oil to migrate the tight passage around this gear to get to the right side. This gear is also the reason we can't just put a small tube in and get it down to the sump on the left hand side to pump old oil out. You can't get a tube around that big gear.

Again, awesome write-up!!!

 

If it takes overnight to drain out a half quart from the till port then do you believe pumping in oil from the fill port has enough time to equalize in the case?

Yes, any oil is better than none. I wish I had checked the level before I started, because I do not like to “assume “ it was full from factory.

I do think a fill from bottom up is the way to go on the AD2 PTU but you need to be very confident about your skills here.

I will add that when I pull the plug down the road, I should have put a slight taper on the end of the flange head plug, because when you pull the fill line out of the new plug hole, the oil runs out like waters d a taper would help align the bolt to bore quicker than you can turn 1/4-28 threads trying to align threads as oil runs down your hands.

I liken it to jumping out of a perfectly good airplane, once you make your move, your committed till the end, whatever the outcome.

 

Thanks Gary, I won’t lie, i was all set up for the first drill and decided to wait…have a cup of coffee….wait…..look at it…oh hell, just do it.

 

assuming there's no loan on it, eh?

 

Nope Been paid off for a couple of years.

I do have the extended warrantee on the PTU becuase of the input spline issue, and to cover this PTU it “must”throw the code for the spline or it’s not covered. So no biggy

 

I was gonna ask if you were included in the PTU warranty extension or if you had the lifetime Maxcare warranty.
I think it’s cool what you did BUT may be an issue for any warranty claim on it the future.
Before I got rid of my Cherokee I was already having fights with coverage and 2 dealers said that Stellantis/FCA had been making it harder to get things covered and denying coverage on Lifetime warranties. Recently on this forum I have seen others that are being refused coverage for Lifetime Warranties . Again great job on your making it easier to service fluid changes 😎

 

Here are those skid plate installation/removal specs again. Main thing is that the rear-most two bolts in the cross member plate are just loosened, not fully removed (yellow highlighted below). You'll see on your CM skid plate the notches to slide it off those two bolts.