"Transmission Fluid leaking from fitting below radiator cap after replacing radiator on 99 surburban
The right side (passenger side) would be the transmission cooler lines. The plastic radiator tank is probably cracked near or at that fitting. Replacing the 12 year old radiator would be best.
there is a transmission cooler inside your radiator and it must be leaking. probably replace the whole assembly
get a different hobby
First undo them at the radiator, then follow them to the transmission and remove there. After fitting new ones,check for leaks then fill trans fluid to required level.
The reason the fluid is a milky color is that water is getting into the transmission. How you ask??? Well the cooling lines go into the radiator to cool the fluid. It is at that spot it is picking up water as the cooler inside the radiator has a leak. the best solution would be to change the radiator. You could block the fitting ports for the lines at the radiator and put an external cooler on it. YOU MUST thoroughly flush the transmission and change the fluid and filter.
that is the transmission return cooler line
replacing the fittings
In the top radiator hose fitting opposite the radiator, on the engine.
The thermostat is on the intake where the hose comes from the radiator to the engine. Look at the top of the radiator and follow the hose that goes from the radiator to the engine. the hose fits on a fitting on the intake of the engine. If you remove that fitting, there's a thermostat inside.
let engine cool -open radiator cap -move a large container under radiator drain fitting( it's hard to see- located on lower left corner of radiator)-attach 3/8" diameter hose to fitting to direct coolant into container- turn fitting counterclockwise-pliers may be needed.
On the transmission cooling line connecting to the radiator there is a metal 'C' clip that secures the line into the fitting. Does the plastic ring clip on the line have to snap over top of the metal clip in order to completely secure the line?
The ECU is actually called the PCM (Powertrain Control Module); however, the "brains" are located on the driver's side of the neon between the radiator and the transmission. It sits down near the bottom of the radiator. Be careful not to hit the transmission line going into the radiator because the radiator is made of plastic and that fitting is metal. Mine sheared at the radiator and you just have to replace the entire radiator. You will know the ecu as there are two receptacles with a multiwire plug in the top of the unit. These wires go to various sensors all over the vehicle.