Lots of air bubbles in radiator - 2010 Bennche Megelli 250r

Or you installed the t-stat upside down.

make sure no air is in the cooling system
heater on
run motor
fill radiator
wait till water flows no bubbles

if lots of bubbles or water spouts
blown head gasket

thats what its designed to do, when the engine cools it will pull the coolant back into the radiator, if it is blowing an excessive amount and you see a lot of air bubble the you could have a blown head gasket

when the motor is off open the lid and slowly squeeze the top radiator hose and it will bubble the antifreeze at the radiator some may spill out but after u squeeze it simultaneously it shouldnt bubble anymore and then just refill what spilt out

With the engine cold remove the radiator cap. Start the engine. Watch the coolant. If you see bubbles constantly perkulating out of the coolant than you most likely have a head gasket that has failed. If you don't see a constant perkulation of air bubbles it probably wouldn't hurt to replace the upper hose and see if the problem is resolved.

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Try this.

With the engine cool remove the radiator cap. Now start the engine and let it warm up to the point where the thermostat opens. You can usually tell when this happens by checking the temperature of the upper radiator hose, and the coolant level in the radiator. It will start getting a lot hotter quickly when it does and the coolant level should drop.

While the engine is warming up, watch the coolant in the radiator for air bubbles. Fill up the radiator as needed while continuing to watch the coolant level. Having the radiator cap off while doing this allows the trapped air to escape more easily. If you do have a large air blockage then when the thermostat opens you should see a large drop in the coolant level. You want to keep the Radiator full. Once the air bubbles seem to have stopped you can replace the radiator cap.

You may have to repeat the process a couple times if there is a large amount of air trapped in multiple pockets.

A cracked head or block you can usually diagnose as there will be a lot of small bubbles coming out constantly while the engine is warming up, and even more bubbles if you rev the engine higher as the compressed air/fuel will be forced into the cooling system.

thermostat or headgasket

If you squeeze the upper radiator hose and it feels like the coolant is running thru it, your pump is working. The system should bleed itself within a few minutes if you keep the radiator and reservoir full. If it continues to bubble, you have a blown head gasket. :-(

Let us know if you need more help.

You have a new radiator and thermostat, so your coolant was flushed. Was the radiator "burped" afterward to get rid of air bubbles? If not, that needs to be done first - it would explain virtually every symptom you're seeing.

Jack up the car so that the radiator cap is elevated. With the coolant topped off, start the car and let it run until it's about 3/4 of the way to overheating. Then shut it down and go have a beer. When it cools off enough to safely open the radiator cap, do so, and any air trapped in the system will bleed out.

What you're doing is circulating the coolant and the air bubbles inside. The bubbles get lodged behind the thermostat and stay there, keeping it from opening (this causes the car to heat up). When you later pop the cap off the radiator, the pressure is vented from the system, the thermostat opens, and the bubbles pass through. They'll work their way to the radiator (since you've got it elevated) and pop out the open cap opening.

Your coolant level will likely drop somewhat after doing this, as the air bubbles will be gone and the space they took up in the system is now available. You may need to add a little more coolant, so top if off (with the car back on the ground) and recap the radiator, fill the overflow to the marked point on the tank, and you're good to go.

Try this if you haven't already, and post back up with your results. If it doesn't solve the problems, we'll take it further.

You need to verify that the gage is accurate, if it is then the cause is the thermostat, but check the gage first, a repair shop can do this or you can feel the air coming off the radiator fan, if it is really hot changing to cool rapidly then the T-Stat is sticking open.