Installed new water pump, took thermostat out, flushed system, replaced fan sensor, but when I run it, and when normal temp is reached the water in the expansion tank starts to boil. There are no bubbles when first started, no water in oil, but I've heard it could have a air lock so how do you vent that? Someone told me he had to jack up the front end of his to get air out of the system, could this be the problem? I don't see any vent anywhere and there's not a radiator cap on this car. Is there something else I need to look for?
You have to check the thermostat on the dashboard to see if it is overheating. The expansion tank is located in such a position that the cooling system will bleed air into the tank as that is the "top" of the radiator. If you are seeing bubbles, it may just be the air bleeding out of the system. Something important about this engine is that the thermostat is necessary for proper operation. The fuel injection needs the engine to come up to temperature for it to go into closed loop mode. Be careful about the thermostat as it is unique to this car and has to be aligned properly with the arrow up on the thermostat housing.
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Re: VW Scirocco overheats
On some water pipes there are plastic bleed units. You could also try and bleed the system as follows. Inside the car set the heater to full. Then take the cap off the exspansion bottle. Now run the car and feel for the heat from the heater. Also check the bottle for bubbles. Do not let the engine over heat.
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Has the system been flushed? Correct temperature thermostat installed? Are you getting flow through the radiator? Rad cap sealing properly and is it the correct one? Are the fans actually coming on? Is the temp sensor working properly? Rad properly filled or still have air trapped inside? Water level correct? Water pump working or seized, leaking?
go to autozone rent the free tool called a block tester buy the fluid for it (about $8.00 us)drive the car make sure the resivour is about 3 inches down so you dont suck any fluid into block tester. pour blue fluid into block tester put it in antifreeze resavour. squeeze bulb sucking air from resouivour for up to 2 minutes if fluid turns yellow your head gaskets are leaking. I think you may find this to be your problem
the water flow through the heater system is part of the flow on these vehicles ,so reconnect them then check the thermostat is the right one as one version has a two part thermostat ,it has two water closing parts and the other type has one like conventional stat and if you fit this one in the other engine then it will overheat .start engine and see if any bubbles come up in the bottle when it runs ,i susp?ct the head is distorted or the water ports are corroded allowing pressure into the cooling system
thermostat is a good place to start. But be sure to replace that temp sensor too. If that doesnt work you can flush the radiator bad case replace the water pump. Worst case absolutely would be head gasket.
Thought I answered this one already. but here's the short version. Yes , change the t stat after servicing wp. They become unreliable after any high temps (above normal). Check the electric fan, and the mechanical fan to make sure both are working properly. If all else fails. remove radiator and back flush. often overheat or high temps can loosen block rust and obstruct part of the radiator core. When re-filling, turn heater on high to eliminate air pockets in system. Good luck with it If you need more info, just ask!
water pump. water pump. water pump. i am a vw dealer tech and on 2.0 and 1.8t beetles the water pump impeller is plastic, and what happens is usually another component, fans, fan control module (under battery tray), thermostat, fails and because the impeller is plastic with just one overheat the plastic becomes brittle and shatters, pull the water pump out and you will see the impeller in 3 or 4 pieces. replace water pump and make sure t stat opens, fans come on (a/c off) and proper water pump flow.
Yes. It could be several things: a)water pump defective b)radiator core blocked or grille restricted c)electric coolant fan inoperative or blades broken d)thermostat faulty e)radiator cap not maintaining proper pressure. Good luck!