1998 Pontiac Sunfire Overheating

PONTIAC SUNFIRE
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GT_BALDO
  • MEMBER
  • 2 POSTS
pontiac sunfire gt 1998 58,000 2.4l twin cam: my problem is that my engine is overheating and i dont know what to do , ive already clean the radiator, change the water pump for a new one, and its still overheating, there is no problem with the cooling fan or anithing related with that.
when the temperature gauge reach the normal temperature in the middle it doesnt comes down and after that it says to check the oil and when it gets too hot it drops the antifrezze.
so i dont know what to do
can you help me?
Jun 1, 2007 at 8:22 AM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
Try replacing the thermostat-not it do the following below:

Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat,Pressure test the Rad. cap,Clogged radiator,Fan clutch,Radiator electrical fan,collaspe hoses,water pump.
Jun 1, 2007 at 9:57 AM

Suggested Repair

Replace the thermostat and have the engine block tested for combustion gases entering the cooling system before any cooling-system pressure test. If those checks pass, pressure-test the radiator cap and inspect the radiator, cooling fans, hoses, and water pump.

Conversation Summary

A 1998 Pontiac Sunfire with a 2.4L engine overheats even after the radiator was cleaned and the water pump replaced. The cooling fan appears to work, the temperature stays high, the oil warning comes on, and coolant is expelled when the engine gets too hot. The expert recommends replacing the thermostat, testing the block for a combustion leak into the cooling system, and then checking the radiator cap, radiator, fans, hoses, and water pump if those tests pass. A pressure test should be avoided if a head-gasket leak is suspected.

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