I went to do a citric acid flush today on the 85. Car is newish to me and it was time to get rid of the green coolant.

Did the flush by the book and after about 10 minutes with the acid in my radiator started to leak at the bottom. Drip, drip.... Great. This cooling system functioned 100% before the flush - held pressure for days, stayed right around 85 C.

The last time I did a citrus flush on my 82, it took out the water pump after about 10 minutes as well. I also snapped the neck off the radiator at the time, but that was on me.

So I don't know what the heck is going on here, but I sure as heck am not doing a citrus flush ever again. I followed the FSM to the letter, food grade citric and the whole nine yards. I know how to mix acids and prep solutions from my bio-d tinkering, so Im sure I did the procedure right.

Shame on me for 1.) doing the citric thing a second time and 2.) Fixing stuff that ain't broke.

So if you are searching for info on doing a citrus flush, you've been warned. If you system is working just flush thoroughly with water, put in G-05 or MB coolant and leave well enough alone. Tomorrow is radiator replacement day now for me. I just hope nothing else has been pushed to the brink, like the (gasp, tremble) heater core (12 hour replacement).

Now I see why the older guys get, the more they go by 'if it aint broke...' Im learning, fast.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car