Chevy Malibu Water Boiling Over And Overheating

Question:
Problem with my 2002 CHEVY MALIBU 3.1L V6. ENGINE REPLACEMENT, USED BUT GOOD. NEW WATER PUMP, T-STAT, INTAKE GASKETS, RADIATOR, HOSES AND COOLANT TEMP SENSOR. MULTIPLE T-STATS FROM DIFFERENT SUPPLIERS INCLUDING TRYING TO MAKE A LONG STORY SHORT. 2002 CHEVY MALIBU 3.1L OVERHEATED AND BLEW MOTOR. REPLACED WITH A GOOD ONE FROM A BUICK CENTURY. PRIOR TO INSTALLATION, REPLACED INTAKE GASKETS, T-STAT, W/P, spark plugs, OIL PAN GASKETS AND THE TIMING COVER (DUE TO SLIGHT PULLEY MOUNTING DIFFERENCE).

START AND RUN ENGINE IN BAY AND ALL IS GOOD. ROAD TEST GOOD. RECHECK GOOD. GIVE TO CUSTOMER AND OVERHEATS IN FIRST FEW MILES.

THEY PICKED IT UP THE NEXT DAY. AFTER RECHECKING MULTIPLE TIMES, FOUND THAT IT ONLY OVERHEATS FOR A MOMENT, PUSHES A LITTLE COOLANT OUT OVERFLOW, AND GOES BACK TO NORMAL AND REMAINS GOOD FOR THE REST OF THE DAY. IT WILL ONLY DO THIS AFTER THE ENGINE COOLS. IT WILL ONLY OVERHEAT ONCE OR TWICE DURING THE WARM UP CYCLE ONLY, THEN IT'S OK. TRIED MULTIPLE T-STATS, REPLACED HOSES AND RADIATOR. STILL DOES IT. TOOK T-STAT OUT OF VEHICLE AND IT STILL HAPPENS.

EVERY PART OF THE COOLING SYSTEM MULTIPLE TIMES, IT STILL HAPPENS! LAST IDEA WE HAVE IS THERE IS A CRACK INSIDE MOTOR THAT ONLY OPENS A CERTAIN TEMP ! AND SEALS BACK UP. WE JUST CANNOT FIND ANY EVIDENCE OF THIS. BUT CATCHING IT AT THE RIGHT TEMP IS NEARLY IMPOSSIBLE. DOES THIS SOUND LIKE A POSSIBILITY TO YOU? I WOULD THINK IT SHOULD SHOW ON A BLOCK TEST AT ANYTIME BUT IT DOESN'T.

BY-THE-WAY, MY NAME IS MATT. I AM THE SERVICE MANAGER IN JACKSONVILLE, FL. RECENTLY PUT DOWN THE TOOLS TO TRY MANAGER. 15 YRS IN SHOP PRIOR. 10YRS AT GM DEALER. THE TECH WORKING ON CAR IS ALSO GM CERT. AND 35 YRS EXP. OWNER ALSO EXPERIENCED AND AT A LOSS. DO YOU HAVE ANY IDEAS OR SUGGESTIONS? THANKS FOR ANY HELP, MATT P.S. LOOKING FOR A GOOD SITE LIKE THIS TO USE REGULARLY. I'M TRYING IT OUT FIRST AND IF IT GOES WELL, WE WILL MAKE REGULAR CONTRIBUTIONS. FOUND THIS SITE DURING A GOOGLE SEARCH FOR THIS PROBLEM.

Answer:
Well, I've go to say right off the bat, this is a head gasket problem. This sure does not sound like the original problem that blew the engine is still there. The tech may have replaced the intake gaskets because they were leaking, but the rear head, passenger side corner leaking coolant may have been wet because of the intake. Easy to miss that. Even if not leaking externally, this is a good sign of a head gasket problem.

Your GM tech should be familiar that the rear head is very common to have a blown gasket. Most of the time leak externally, but not always, Have seen these exact conditions a few times, as well as our tech JK.

They will overheat once or twice during the warm up cycle, burp, then be fine all day long. Sometimes you can catch it with the cooling system dye test looking for combustion gases.I would remove both heads and send them out to have checked for cracks just to safe.


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