Coolant blowing out of radiator into overflow bottle at start up.
1990 mitsubishi montero 3.0L V6, engine rebuilt, cooling was fine before, now cooling system pressurizes at statup and blows coolant into over flow bottle. i thought it might be a cracked head or the head gasked installed wrong,swapped heads and another new gasket, still doing it, engine does not overheat and no coolant in the oil.
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Re: coolant blowing out of radiator into overflow bottle...
Typically would not overheat until enough coolant was lost. Find out if they mag fluxed the heads, or had it done. A lot of shops rebuild without doing this step as it's expensive. If they got a rebuilt head, again they need to know if it was mag-fluxed. It's harder to mag flux the block while in the vehicle and assembled.
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You need to have your cooling system pressure tested. This will let you examine the engine area without the hazards of the engine running. You may have head gasket issues. Depending on the area of the leak, your cylinder compression can actually pressurize the cooling system. When the cooling system pressure exceeds the rating of the cap, the cap seal opens and can blow coolant back into the overflow bottle where it eventually leaks while driving. Check to see if your overflow bottle is full.
first check coolant level in radiator coolant level sound low.if coolant overflow jug empty.coolant sysyem low, when add coolant to coolant overflow jug coolant level should stay at full cold mark.if coolant level okay,engine overheat while sitting or moving in slow traffic either coolant fan relay or fuse could be bad.or engine coolant temperature sensor could be bad. coolant sensor turn on cooling fan at certain temperature.hot wire check to make sure cooling fan motor not bad or short in wires.if all is good have pcm check it controls fan relay to through the coolant temperature sensor signal when coolant get hot.
A tank used for storing excess coolant; connected to the cooling system with a small-diameter overflow hose.
The coolant reservoir is the bottle,under the hood, that holds the
radiator fluid. it is also known as a overflow bottle. When the car gets
hot,the overflow bottle, releases steam to relive the pressure in the
radiator. excess coolant is also stored here.
You don't need to bleed the coolant systems in 1999. Fill the radiator and fill the overflow to a point mid way between the cold and full lines. Warm up the engine until the fans cycle on and off. Let engine cool down and check level in the overflow. Add as needed and keep a watch for a couple of weeks. Any air in the system will be pushed out of the radiator into the overflow bottle. When the engine cools down it pull coolant from the overflow back into the radiator.
If you dont have an external coolant leak anywhere under your hood that has shown up on your driveway it could be the intake manifold or the headgasket leaking. Also check the thermostate to solve the heat issue.
That sound could be whats called air-bound, need to purge system, Fill radiator, run engine for about 4 minutes at idle, turn off let cool down for about 5 min then being careful recheck coolant in radiator, top off fluid then repeat, make sure overflow bottle is full, After about 3 times when radiator stays full run about 15 min and listen for radiator fan motor coming on
It sounds to me as though you have a thermostat valve problem in the cooling fluid cicuit. The test is to remove it, let it get to room temp. and then place in a cup of boiling hot water. It should open. If it does not, replace. They are fairly inexpensive 5-10$. If you do not know were it is follow the top hose of the rad to the engine block it will be in the housing that the hose clamps to at the block. Caution!!!! when you remove that thermo stat housing you will drip coolant. Catch it in a pail or similar. If you miss the pail, hose down the driveway or whatever because it tastes great to pets but is deadly. ( Ethylene Glycol ).
You may need to ask AAA to put a radiator pressure tester on the resevoir bottle and pump it up to operating pressure(Pressure cap rating) and see if it over pressurises while it is running at operating temp,rev engine up and down and watch what the testers pressure readings do,it should move up and down in sync with the water pump.If the pressure keeps building i would have to believe that combustion chamber gases are over pressurising your cooling system.Also test the pressure cap is functioning within factory specs.
If the gauges read normal and the fans are working properly and the vehicle dosen't overheat. I would suggest that it's the normal operation of the vehicle.
The overflow bottle is there because when the vehicle get's hot it draws in the extra coolant from the overflow. When the engine cools down it will push the extra coolant back into the overflow, that's what the radiator cap is for, it's not just a cover for the radiator. At a certian pressure the radiator cap will release the coolant to the overflow bottle. Otherwise the super heated coolant would have nowhere to expand to and blow apart hoses and such.
One other thing to check is if the coolant is a proper mix of antifreeze and water. You can buy a coolant check tool from any auto store, they don't cost too much.
Tip: Use distilled water instead of tap water (or use pre-mixed antifreeze). In some cars regular tap water will speed up corrosion in the cooling system.