Without knowing the symptoms, I can't pinpoint an answer. However, the most common problem with heater blowers are the resister stacks. When they fail, the fan only works on high speed and does not work on the lower speeds. It is strictly a dealer part around $30. Easy to replace.
Drain plug for what?
Only the 2.3L HSC Inline 4 will fit in the 1986 Mercury Topaz. If everything in the engine bay were gutted, perhaps something larger such as a 3.0L V6 from a 1992-1994 model MIGHT fit but it would require a complete running 92-94 Ford Tempo or Mercury Topaz with the V6 engine as a donor car (and, if you could find such a car, it would be more worth your time/money to invest in it v.s. a 1986 model). The automatic transmission from a Taurus WILL NOT WORK in a Tempo/Topaz.
open the hood, look down between the rad. and the engine. There it is.
Just take the covers off the steering column, switch is there.
THE FUEL FILTER IS UNDER THE HOOD ON THE WHEEL WELL, LEFT OF THE ALTERNATOR.
For automatic trans, should be good with Dexron 3, but just in case check for type F. The dexron works in the standard also.
It's in the heater core housing.
Mercury Sable was created in 1986.
Cloud About Mercury was created in 1986-03.
Mercury House - publishers - was created in 1986.
can I buypass the rear heater valve and run two heater 1986 gmc van
If it is an automatic it will be a 727.