Water leaking from back of engine compartment toward the firewall passenger side down to side of transmission so my question is it the bypass hose? or something else

Most likely problem is a leaking heater core. This is what usually causes water leaking into the passenger compartment. Quick fix on many vehicles is to get a hose adapter the same internal diameter as the heater hoses, remove the heater hoses from the firewall connection to the heater core, and install the adapter, making a bypass loop. This will allow operation of the vehicle without coolant loss until you can replace the heater core. Of course you will have no heat in the passenger compartment during this time.

Many Caddys have/had small "radiators" for heat to the rear passengers located under the front seats. Most shops (or owners) never check them or know they exist.

The drain on your evaporator core housing is most likely plugged. Condensation on the evaporator core drips down into the plastic housing and drips onto the ground through a hose on the firewall on the
passenger side.

Find the small hose on the firewall in the engine compartment. You should be able to pull off that
hose and see if its stopped up. If the hose is ok, you may need to remove some of the ac ducts
under the dash to get to the evaporator core housing to unclog the drain hole.

I have no doubt that thats the problem.

Hey John,
You should find two hoses leading into the passenger side of the firewall under the hood, one is input, the other is obviously output,. cut & splice,. you should be fine (as long as it doesn't get too cold where you are)...
Ck

In the dashboard,set down low is a driptray.It collects water that comes off the aircon.It has a hose (sometimes 2) that drains the water out of the car via the firewall so it drips onto the road.This is blocked or the tray has a buildup of gunk.The hose is about 1/2 inch thick.If you lay on the floor where it leaks with a torch you should find it.Or look in the engine bay,just to the left or right of centre(which side leaks?)and backtrace it into the car.You may find the inside hose has fallen off allowing the water to drip inside.Hope this helps you

it is the heater water supply and return, that supply water to the heater core to supply heat using hot water from the engine, the hose clamp my be loose or the hose has a hole in it you have to trace it from unner the hood fire wall to where it connects to the heater under the dash

Your car probably has AC so the box under the hood has a drain for removed moisture and this can often clog with environmental debris; when that happens, the water can't drain any more and may end up inside the car.

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-- locate where the air conditioner blower box is attached to the passenger side of the firewall – see photo #1 – look to the immediate right at the top of the gas pedal arm

-- condensation flows toward the front of the vehicle through the firewall at the leftmost edge of the air conditioner blower box – drain channel
-- open the hood and stand next to the front wheel on the driver's side
-- look down at the firewall over the battery and to the passenger side of the brake master cylinder – see photo #2

-- locate the small diameter metal tubes running horizontally and attached to the engine compartment firewall
-- locate the hole in the engine compartment firewall panel behind the small diameter metal tubes
-- this hole leads to the drain opening in the air conditioner blower box mounted in the passenger compartment
-- follow the brake tubes as they run from under the vehicle and turn toward the front wheel on the driver's side
-- locate the hole in the engine compartment panel behind the brake tubes
-- insert a short length of stiff wire into the hole through the engine compartment panel to unblock the drain hole

They are not always easy to see and they differ in length but yes they are typically on the passenger side firewall and may extend down towards the lower firewall or just drop out an inch from the firewall. a coat hanger is not always going to work and you will need to be careful not to put a hole in the evaporator that sits just inside from where that drain comes out. it is possible that the lower cover where the condensation is collected has a crack and may not be pluged at all. look above where it drips on the floor and see if there is any sign of damage to that cover. You may find that it is easier to take off the cover and clean. that will just depend on your confidence in dismanteling that part of the dash and heater box.

This sure sounds like the AC condensate drain is plugged, if it is allot of condensation water builds up in the heater/AC case and leaks in on the passenger side, the drain is located on the pass side under the hood down low on the firewall, it is most cases it is a rubber nipple about 1/2 inch in diameter sticking out of the firewall with a little flapper valve in it, stick your finger in it or a stick and see if water drains out.