u/cheesewheelfan

We're pretty far away. Started texting about a week or so ago. We were being fairly playful and flirty (as much as one can glean from texting) then called for 5 hours straight a few days ago. I admit I fall easily, but nobody would chat for that long if they weren't into each other. I've asked once or twice after that call, over the past few days, to call again, but she just outright ignores it, which seems fairly intentional (and a little rude). Otherwise, she will respond to other texts. I would rather just hear a yes or no answer. Perhaps I am too dense.

I get the impression that she's backpedaled a little bit. That's totally fine, and Im fine with being friends, but it is very difficult to read in between the lines over text, even with emojis.

I try not to be too pushy. It can be pretty lonely out here, even though I am still in college and in my 20s. She's cool and super my type, so its easy to get ahead of myself.

I would like to express my concerns over the phone, but I'm not sure how to ask about it, honestly. I just would wish that she tell me if shes got something on her mind, or if something is wrong, because the texting pattern has changed recently.

Sorry about the wall of text. Sometimes it is helpful to reflect.

TL;DR: 2003 Mercury Marauder, 90k miles, completely stock 4R70W (never rebuilt). Over three days (June 9-11) the trans went from a bucking/lugging sensation in D, to slipping in 4th, to completely losing 3rd gear, to cooking itself to 275F on the last drive home. Post-failure fluid is dark, burnt, and full of clutch material. Looking for input on likely cause, tips for pulling it myself, and how much (if any) my mods may have contributed.

Note: Claude assisted me with writing this up, hence the AI cadence. I have reviewed and edited as needed, however.

Car/transmission background:

One-owner car, I've had it since 35k miles, now at 90k miles.
Engine: original engine had an oil pump failure at 68k miles. I pulled the failed engine and installed a rebuilt replacement (sourced rebuilt, not rebuilt by me) - has been running fine since. Also threw on a set of Stainless Works long-tube catted headers during this swap; probably unrelated but mentioning for completeness.
Transmission: 4R70W, completely OEM/stock as far as internals go - never rebuilt, ever (not before or during my ownership), only modified externally (tune/cooler additions).
- Fluid/filter history: serviced at 14k, 44k (filter changed too), and 59k miles. The 59k service was not routine - it was done specifically because of a minor 3-4 shift shudder (likely OEM TC - I know TC shudder is a fairly common issue on the 4R series). The shudder went away after that fluid exchange and never returned.
- At the time of the engine swap (68k miles), I installed a Thor Odin 2800-3000 stall converter, sourced secondhand from a friend's failed transmission. He claimed it was flushed/cleaned; fluid inside was clean when I got it, and it's never shown issues since. Fluid was changed and level-checked at this point too. I don't suspect this TC caused the current failure but can't fully rule it out. I still have the original OEM torque converter in storage and plan to reinstall it once the transmission is rebuilt.
- All engine/trans work was torqued to spec per the shop manual.
- Cooling: factory integrated trans cooler is still in the loop, plus I added a Hayden 678 cooler in series sometime between 35k-68k miles.
- Tune: car has had some kind of ECU tune since new (390 miles). Switched to a Marty tune at 39k miles, which includes modified shift points and increased line pressure for firmer shifts. This has been in place since ~39k miles with no issues until now.
- Fluid has never been changed since the 59k service (so ~31k miles on current fluid), but it's always stayed bright red, and temps historically ran 150-170F, never above 190F - until this failure.
- Output shaft seal: replaced at 66k miles while doing some differential servicing. It weeped a small amount of fluid afterward - enough to get on the crossmember, but never enough to drip on the ground. Fluid level has always been fine.

One other relevant incident: After the engine rebuild, I had the trans cooler lines crossed (inlet/outlet reversed on the Hayden cooler relative to the stock cooler return). This caused the trans to hit 230F, go into limp mode, and lock the TC immediately (hard shifts). My theory is air got trapped in the Hayden cooler when I disconnected lines for the engine pull, restricting flow until it was corrected. A shop fixed the line routing, and the trans ran fine with no issues for the ~20k+ miles since - until now. Not sure if this is relevant but it's the only other time the trans exceeded 200F before this failure.

Failure timeline:

June 9: Was leaving dinner with friends, shifted into D, and got noticeable jerking/bucking plus an odd noise. The bucking felt similar to letting a manual transmission's clutch out too early when starting to move - a sort of lugging sensation. Drove ~30 min to the gym and back later that night - bucking mostly subsided, WOT and normal driving felt fine aside from the noise. Checked all fluids, engine oil pressure, and monitored trans temp via my tuner - everything nominal, temps maxed at 170F. Also re-flashed my tune just to rule out something I'd messed up on my end.

June 10: ~1hr commute each way.

On the way in: bucking was more pronounced. Tried starting in 2nd gear - bucking was worse.
On the way home: trans started slipping in 4th, so I manually locked out OD. Shifts also felt less firm overall (wondering if this points to a line pressure issue).
Temps still nominal, fluid still bright red, no burnt smell.

June 11 (last time driven): Same symptoms as before, but on the commute home the trans completely lost 3rd gear. Tuner wasn't hooked up at the time. It felt like 2nd would engage fine, but 3rd would fail to engage, causing the trans to repeatedly drop back to 2nd and re-engage it. Drove the rest of the way home in 2nd. About a mile from home, I smelled burning. Hooked the tuner back up - trans temp was reading 275F. The O/D light started flashing for the first time at this point (no codes thrown before or after, at least nothing my SCT X4 or factory gauges show). Car can probably still limp in 1st, but it's done - needs at minimum a rebuild after cooking at that temp.

Post-failure fluid check: Pulled a sample after the fact - fluid is now much darker and clearly burnt, with what looks like a significant amount of clutch material suspended in it.

What I'm hoping for input on:

Possible causes - given the history above (secondhand TC at 68k miles, additional aftermarket cooler, and one prior overheat incident to 230F), does anything stand out as the likely root cause, or a contributing factor? I don't think the tune itself is the cause, but wanted to flag the modified shift points and increased line pressure (since 39k miles) in case that's relevant to anyone's read on this. Trying to understand what to look for/replace when it's apart so I don't put a rebuilt unit back into the same failure mode.
Tips for pulling the transmission - I'll be doing this myself with two friends who are experienced with wrenching (I'm a hobbyist, not a technician). Setup is QuickJacks/jackstands, and I have the factory service manual. I've pulled a transmission before (95 Miata, manual), so I have a general sense of what to expect, but any 4R70W/Panther-platform-specific gotchas, things commonly missed, or tips on access points/tools would be appreciated. I'll likely pull the pan and valve body myself for a look before it goes to the shop, then let them take it from there for full diagnosis.
Preventing contamination of the rebuild - since I'm reusing the factory cooler lines/integrated cooler and the Hayden 678 (and reinstalling my OEM TC, which I still have in storage, onto the rebuilt unit), what's the right process to make sure no debris/metal from the failed unit ends up in the new transmission? Flushing procedure for the cooler lines, the Hayden cooler itself, and the factory cooler in the radiator - and anything else in the system (cooler lines, fittings, etc.) that could be holding contaminated fluid or debris.
How much of this is "my fault"? - Given the modifications (firmer shifts/higher line pressure since 39k miles via the Marty tune, the secondhand TC, the added cooler, and the one overheat incident from crossed cooler lines), does this failure pattern point toward those mods/my work as the likely driver? Or does this look more like a "just wore out"/bad luck situation similar to the original engine's oil pump failure - or some combination of both?

Thanks in advance - happy to provide more pics/details if useful.

Been texting a girl but she's giving me mixed signals and leaving me confused. Did not stop me from having a good leg day. Chicken and rice.

2003 Mercury Marauder (4V 4.6L, 90k miles) - 4R70W failure, looking for input on cause, possible partial teardown for diagnosis, and contamination prevention

My Oro 875s after about 5 years of regular use