’99 Mercury Won’t Shift Out of Neutral HELP!!

You can view this as a sort-of-good-news/bad news situation, which would you like first? Okay, I’ll start with the bad news. It’s likely that when you let the tranny fluid drop down to critical levels (I’d say more than two quarts qualifies as that, wouldn’t you?) that certain key parts were left exposed to the transmission’s internal “atmosphere.” That “atmosphere” is no place for unprotected equipment to hang around. When you let the tranny fluid down, you left all kinds stuff exposed to the “elements.” The “elements” here are heat and the potential for metal-to-metal contact and wear, as well as major damage potential to the valve body because of all the gunk and grime that remained concentrated in the remaining tranny fluid.

Left exposed when the transmission fluid level fell were such items as the gears, clutch packs, bands, quite possibly the impeller on the torque converter, as well as the stator, not exactly inconsequential parts of the transmission. This situation also exposed the transmission parts to more heat than they are supposed to be exposed to (the parts are considerably heat-resistant, but there comes a point where even they get flaky and fail). When the fluid level fell, one of the key ways the transmission cools itself — by circulating the fluid throughout the case and the pan and valve body to the outer walls of the transmission where the heat is exchanged — was no longer available and you effectively turned up the toaster here from medium to red-heat mode.

Finally — the bad news does keep on coming, doesn’t it — when you overfilled the transmission albeit accidentally the pressure situation turned from famine to feast. It is possible that in the overfilled transmission pieces laqs and other deposits broke off, thanks to the new detergency of your tranny fluid, landing on places they are not supposed to be such as on the gearing itself or on the clutch pack blades. It is not a good thing.

Now that you’ve heard the litany of bad, here’s the not-so-terrible-news: you can save the Merc and drive it another 145,000 miles by ordering a rebuilt transmission for about $2,200 and have it installed for about $800. If you can find a used transmission in a junker in a salvage yard with lower mileage than your current transmission and it tests out cleanly, go for it. You will save considerable, maybe $1,000 depending on where you take it.