Q: Overheating 335xi, new hoses/no leaks, waterpump is fine, no heat, used stop leak but car sat around for 2 months.

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My car was leaking coolant, and for several reasons which i won't go into, i ended up using a fair bit of stop leak, and then the car sat around for a couple of months. I finally had the hoses replaced and drove around (x4) for 10 minutes before the car overheated. I ensured the coolant was topped up, and it didn't disappear after driving a few times. The oil gauge also ends up past halfway and the car goes in to limp mode. Coolant temp also rises above normal. Slow or fast driving doesn't make a difference. Within ten minutes or so it's time to let it cool down. I hear water splashing around the upper hose to expansion tank after i switch off and open up the hood, which hopefully means that the pump should be fine. Could the radiator be clogged with stop leak? Should i add something to the coolant to dissolve any leftover stop leak? Thank you.

My car has 109000 miles.
My car has a manual transmission.

Hi Marc. Thanks for contacting us today. In most cases, if your heater does not produce hot air, then the issue is that the heater core is clogged with debris. Using stop leak products tends to create this problem. It’s also possible that you’ve got an obstruction of debris within the radiator. In cases where there is an obstruction, a full system flush is recommended to clear the obstruction. If this doesn’t resolve the problem, then it might be necessary to replace the heater core or the radiator.

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