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Odd over heating.

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    Odd over heating.

    Yes i searched but nobody had quite the Same symptoms as my car.

    Good evening everyone, got some funny business goin on with my m50b25nv swapped e30.

    Issue: Recently started to Over heat almost to the 3/4 mark where the + is--> ( C...1/4...1/2..+.3/4...H ) on the highway at speed but goes back down to right passed 1/2 ( C...1/4...1/2+...3/4...H ) driving around town. Heater is always functioning normal and hot.

    Things to note: I do notice the hoses get rather hard but im assuming thats expected due to BMW using pressurized cooling systems. I dont seem to be losing very much coolant if any. There is no white smoke exiting the exhaust, no water vapor in the oil cap with clear honey colored oil. There is no oil floating in the expansion tank either and just smells like coolant (no notable exhaust fumes).

    Maintenance history: Before dropping this m50nv in my e30 I changed the water pump, thermostat with 85c unit, new radiator, original e30 expansion tank and cap.

    Any help is appreciated!

    **current status***
    Now the needle is officially hitting the 3/4 mark whether im driving streets or highway. Whays weird is if i string it out it cools down and moves in between 1/2 and 3/4 marks. Soon as i drive respectfully the temps rise to 3/4 again. I removed the plugs and they dont seem off. Kinda gray. Pistons dont look "steam cleaned" persay. Oil is still clear honey colored.

    Edit PostwaffleswaffleswafflesReplywaffleswaffleswaffle sReply With Quotewaffleswaffleswaffleswaffles

    Alright. So i pressure tested the cooling system and found 2 bbaby leaks that are buttoned up. I perfomed a cylinder leakdown test while the engine was cold and removed the expansion tank cap, dip stick. Maximum loss was 5% cylinder loss which is pretty damn good. Went for a 12 mile drive and it still went past the 3/4 mark. WTFFFF! Upper hose is pretty hot, too hot to hold longer than 2 seconds. Lower hose however feels really cool... like not even warm. But there is pressure on it. Im wondering if the tstat although new could have failed?