Will overfilling the power steering reservoir cause the rack and pinion seal to blow and leak fluid inside and drip onto the floormat? I'm being told that overfilling P/S fluid will not do that, but I'm suspicious. 2002 Honda Civic EX w/110,000 miles on it (not a typo, it's low mileage).

I'm not an ASE certified mechanic, just a pretty good shadetree one, and it seems to me that a sealed system like the rack and pinion, when overfilled, will either pop the cap on the reservoir (had it happen on another Honda) or blow the seal on the rack and pinion.

I've been looking for TSB's or other documentation that would support or remove doubt and haven't had much luck swimming through them all...

 

I would think if anything, it's going to force it's way out of the cap. I can tell you it's not dripping inside on your floormat...

 

Unfortunately it is power steering fluid leaking from the rack and pinion inside the car. It's leaking inside from where the steering column goes into the firewall mounted rack and pinion, and the rubber boot around the steering column is filled with P/S fluid and dripping onto the floormat. I've never seen it leak from there before, there's no stains on the carpet indicating it was leaking before (or on the original floormat I replace a couple years ago with a rubber one), and it wasn't until after I took it into the dealership for a clunking noise coming from the right front, due to a failing strut it turns out, that the leak appeared (along with a new steering wheel shake at ~60 MHP because they didn't use the right lug pattern holes on my aftermarket rims & a stripped lug and nut, among other "odd" things).

Basic mechanics tells you that overfilling fluids on a car is not a good idea as the excess fluid has to go somewhere. I would agree that you'd think it would come out the reservoir cap (as has happened to me before on a different Honda, a 2002 Odyssey), but there's no sign of it doing so here, just the leak inside the car at the firewall.

I've talked to several other mechanics, both ASE and Honda Certified, and they tell me that overfilling P/S fluid can blow the rack and pinion seal and/or blow it out the reservoir cap, but the dealership is telling me there's no way.

 

The hydraulic pump used for the system doesn't create more pressure if the reservoir is over-filled. And, honestly, I don't know how PS fluid would travel upwards to get in through that boot. Have you checked your brake fluid? The master cylinder is above that boot.

Going further through your post, I don't see how it would be possible to use the wrong bolt pattern on a set of wheels... even if it has a multi-pattern setup. The bolt spacing won't lineup at all, and the wheel studs will not go through the wheel without improper amounts of force (ie. a hammer).