I recently purchased a 1986 300E. Yesterday while in a parking lot, someone backed into me and all of the sudden I had coolant spewing everywhere. It turns out that a previous owner had cut and spliced the hose from the engine to heater core. It popped off at the splice. So I went and bought a new hose and clamps and filled the radiator. Drove home 13 miles no problem. Later on drove 3 miles to the store and all the coolant overflowed out the expasion tank. I filled it back up with water and drove back home with no issues. What gives? How do I prevent this from happening again?

Dont overfill the expansion tank.

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WOW, that was real helpful. Thanks. Even if that is what I did, which it wasn't, it still wouldn't explain why ALL the coolant came out

All of it came out where? Do you have the correct pressure cap on the expansion tank? If the cap is compromised or the wrong one it will easily blast a lot of coolant out. The fill line (when cold) is approximately where the seam is on the tank.

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Probably an air bubble. You lost a lot of coolant and didn't bleed when you refilled. Refill while cold- max out the heat, crack the cap to the 1st notch and let it warm up a bit. When it belches, that's most of the air- add coolant to top it off then tighten the cap. Check coolant and add as needed until it settles.

PS must've been one heck of a hit to do THAT to it. Splices or not, you moved something you shouldn't have...

rjp

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