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Followup To
Question -
I HAVE A 97 SEVILLE SLS 4.6 32 VALVE ENG.THE ENGINE WILL IDLE FOR HOURS WITH AC ON AND NOT OVERHEAT,BUT AS SOON AS YOU DRIVE IT ABOUT 1 MINUTE IT OVERHEARTS.REPLACED WATER PUMP,THERMOSTAT,RADIATOR,& RADIATOR CAP.THEIR IS NO WATER IN THE OIL,NO WATER COMING OUT OF TAIL PIPES AND THE COMPRESSION IS OK. HELP PLEASE.
Answer -
Is the radiator fan operating ?.yes
Are you POSITIVE that you have the serpentine belt installed correctly ?. As it IS possible to have it installed INCORRECTLY thus making the water pump spin in the WRONG direction.water pump is turned by a separate belt from the overhead cam.
Whare did you get the radiator from ?.the radiator was roded out and new tanks on both sides.
I ALSO TOOK THE CATALITIC CONVERTER LOOSE TODAY THINKING BACK PRESSURE WAS MAKING THE CAR OVERHEAT BUT NO HELP
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AnswerUsing your compression tester hose, Remove the check valve from the bottom of the hose and thread it into each cylinder and apply about 90 lbs of constant shop air supply to the top of the hose where the gage usually goes and watch for bubbles in the radiator. Do this for each cylinder. ANY bubbles would tell you that you most likely have a head gasket leak where combustion chamber pressure is getting into the cooling chambers of the engine.
I have NEVER cared for cleaning and rodding radiators as I have had to many radiators that tend to collapse the coolant chambers within the radiator after the coolant gets hot. Especially when an engine has previously overheated.
The cooling fan is a multi-speed cooling fan and are you SURE it is running at different speeds ?.
Are you SURE the timing is set correctly ?.
Did you TEST your nEW thermostat BEFORE you installed it. I have seen many a faulty thermostat right out of the box, Which is why I always test mine before installing them.
Try putting some large electric fans in front of the radiator to help blow more air thru the radiator and see what you get and let me know.
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