View Full Version : Won't start after thermostat and water pump.

November 18th, 2017, 15:23
I just did a thermostat, water pump, and heater core flush on my 99 xj 4.0. After I top off levels I let it idle in the driveway to get up to temp and the heat is working great now. Ran fine for probably 10 minutes in the driveway and I took off down the road and made it about 500 ft and the engine died and won't start. Heat never went over 200. I saw a thread saying the temp sensor in the thermostat housing can cause it to flood so I put in a new sensor and still nothing.

November 18th, 2017, 16:24
Are you sure there isn't any air in the system? The temperature sensor does not do a good job reading air or steam. It should have taken about 8 quarts to fill, not including the coolant reservoir. When filling, you can use a high tech vacuum filler, remove the upper radiator hose at the thermostat housing, or try pulling it up on ramps or parking uphill. You can probably get it started again by flooring it while cranking.

November 18th, 2017, 16:47
Where did all the water from the heater core flush land ?

I would guess that you might have a dampness problem causing a short in a wire connector, that got the distributor wet, or that the stall and no-start are simply random bad luck. You should start basic troubleshooting of the fuses, relays, and wire connections for a no-start. Then you might want to test the Crankshaft Position Sensor.

I would like to see this post about the Coolant Temperature Sensor causing a flooded engine, because that doesn't make any sense.