Hi,

I have one of the under engine mount freeze plug leaking. Before I change it I'd like to flush and clean the rust out to the coolant system.

I replaced the radiator a little over a year ago and at the time ran a couple of bottles of Preston flush and flushed it clean with the garden hose. After I got the dex-cool out I refilled with the 50-50 green stuff. Because of the coolant leak, over time I've watered (distilled) down the coolant and it's turned brown from rust. I've read about vinegar, CLR and other auto part magic potions to clean out rust. Since these a prone to LIM gasket failure and this one seems to be holding I'm hesitant to put anything strong in there.

I don't think vinegar would hurt anything since it's such a mild acid. I'm more inclined to think it wont do much more than flushing with plain water.

What do you guys think?

Dave
1995, Blazer

 

Your 1995 had Dex-Cool? I may have the wrong coolant in mine. If that's hurting anything..

You can even use CLR to flush it out, if you have a garden hose etc and get it out SOON. That's stronger. Used White Distilled Vinegar as you say. Cleans well. You can get it cleaner, but.. Garden hose is the best way.

 

Don't underestimate vinegar. It has one aspect to it that makes it dangerous in an engine. It's a strong solvent for silicone based joints and gaskets! On plumbing silicone used for joints in the kitchen or bath it makes the silicone soft, sometimes even jelly like. The solvent in many silicone based sealers is actually the acid of the vinegar.

 

At around 100,000 miles I switched to the green stuff when I replaced the radiator after a plain water flush. After the LIM gaskets I stuck with the green stuff, just a drain and fill. I’m at 205,000 miles with no coolant related issues.

i would be careful with any type of roll your own flush, especially if you don’t have an actual problem to solve. Your best bet is proper coolant which has corrosion inhibitors in it. Acids, coolants, metals, gaskets, and sealants do have some bad combinations. Look what happens when you mix Dexecool with the green stuff. Don’t be trying to solve a problem that you may not have.

George

 

I would tend to agree with you George. Truck doesn't overheat and no indications of the lower intake gasket failing. I would normally not risk messing with it.

That said, the truck never get's used. It can go weeks or even a full month without moving. The few time it does get driven, my sons will take it around town if there daily driver is out of order. Every now and then I'll hitch the trailer and dump branches or pickup something at home depot. In the 2 years I've had it, I don't think we've put more than 1-2k miles.

Last month someone rear-ended my commuter car and it's a total loss. I'm thinking it might get to see more use and a 70 mile commute in Atlanta traffic isn't the same as a 5 mile trip to the store in suburbia.

I ordered a $15 bottle of Thermocure. Suppose to clean rust and be safe in the engine.

 

My Blazer sat in a garage for two years unused at the 100,000 mile mark. Shortly thereafter was the radiator and coolant change in my previous post and then it went back into routine use for the next 100,000 miles and is still going strong.

George