Auto Repair Q&A



Cooling System










Auto Repair Products

How di I replace a heater hose on a 1997 Pontiac Trans Sport?

The heater hose inlet pipe

The heater hose inlet pipe (37) and heater hose outlet pipe (36) extend forward from the dash front panel next to the heater module. The heater hose inlet pipe (37) is toward the left side of the vehicle from the heater hose outlet pipe (36).

On the 5.7L (VIN P) engine, the heated coolant supply for the heater comes from a fitting at the water pump.

On both engines, the heater hose outlet pipe (36) discharges coolant to a short heater outlet hose that is connected to a pipe mounted on the right side rail in the engine compartment. The forward end of the pipe is connected to an outlet hose that crosses in front of the engine and feeds the coolant into the water pump 5.7L (VIN P) or the serpentine drive belt tensioner 3800 (VIN K).

Remove or Disconnect

1. Engine coolant.

o Drain enough coolant into a clean container for reuse.

NOTICE: The heater core can be damaged if excessive force is applied on the core pipes during hose removal.

2. Heater hose (33).

1. Squeeze clamps with pliers and slide clamps (34 and 35 or 151 and 152) away from fittings.
2. Remove heater hose (33) by twisting and pulling. If hose will not come off heater hose inlet pipe (37) or outlet pipe (36) easily with this method, cut off hose forward of heater hose pipes. Then cut hose remaining on pipes lengthwise to remove it.
3. Remove and discard hose clamps (34 and 35 or 151 and 152) if hose (33) is to be reused.

Install or Connect

1. Heater hose (33). If old hoses are being reused, replace original hose clamps with worm-gear clamps.

1. Cut replacement hose(s) to same length as original hose(s), if necessary.
2. If replacing rubber hoses, remove aluminium crimp and replace it with worm-gear clamps.
3. Apply rubber lubricant to inside diameter of hose(s), if desired.
4. Squeeze clamp ends and slip new hose clamp (34, 35, 151 or 152) over one end of heater hose. Push hose onto fitting with twisting motion. Hose end should be 1.0 mm (0.04 inch) away from touching nearest surface (dash front panel, fitting hex head, etc.).
5. Install clamp (34, 35, 151 or 152) beyond any bead around fitting, but not closer than 3.0 mm (0.12 inch) to nearest surface (dash front panel, fitting hex head, etc.).
6. Repeat hose and clamp installation procedure at other end of hose.

2. Engine coolant.

o Use coolant drained earlier only if it is uncontaminated. Discard contaminated coolant and add fresh 50/50 coolant and water mixture.


* Be sure installed hose does not sag or rub against other components. Adjust or support hose as necessary to correct hose position.
* Operate engine and check hose installation for leaks.
* Check coolant level after engine has been warmed up. Add coolant as necessary.