Sludge In Coolant System

[Fallen_C10]

Hey guys! So i'm working on a 1983 C10 350. Currently not operating due to carb & start up issues. I fixed a vacuum leak after getting the truck & went to fill up the coolant & found the freeze plug rusted out & I went to replace it & found A LOT of sludge in the system. I hosed out what was just sticking to the surface but I still have a lot of brown, mud like, sludge in the system. What are the best methods for cleaning out the system?

 

[1987 GMC Jimmy]

I would pull the thermostat and tee in a flush kit to the heater hose and backflush the system. They sell the little kits at Walmart. Once the water’s blowing out clear, I would run a cleaning substance in the system. Some people use CLR/Zep or white vinegar. All good stuff, but they’re strong acids (CLR <1 pH and vinegar is about 2.5) so you’ll need to neutralize with sodium bicarbonate. Baking soda only has a slight basicity, about 8.5, so you can be pretty liberal with it. Then flush with water to bring the system pH back down to sevenish depending on your local water treatment protocols. By the book, you’d need to get rid of the tapwater and use 50:50 coolant/distilled water. I’ve also had great results with the Prestone flush and fill if you run the vehicle per the deep clean instructions.

 

[Salty Crusty]

Flush like crazy and flush some more. I'd use a specific radiator flush and run until it got to operating temp a few times, then let it sit overnight. Get 'er warmed up the next day or two and flush again with water. Some of the radiator flushes I've seen are fairly high detergent but non foaming.

I go against the tide, but I run straight antifreeze in my junk, have done this for many years without issues. I have no sludge or corrosion, water jackets in block are as clean as they were when the block came out of the vat and the radiator is clean. I generally swap out about every 4-5 years.

 

[bucket]

Did the sludge look something like this?

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For that mess, I removed the radiator cap, started the truck and then put the garden hose to the radiator. It made a mess in the driveway and the water spewing back out at me got a bit warm at times, but it cleaned up the system fairly well. I did that for around 5 minutes.

That was a month or two ago and it still looks ok, but the truck only gets used a little bit here and there. I'll probably do the same thing again again in the near future, but refill with coolant when done.

 

[Snoots]

Use a BRASS freeze plug to replace the rusted out pos.

 

[gotyourgoat]

How did you get your square to make chocolate ganache? Wish mine made snacks, it just makes foul smells.

But loosening a few hoses to help drain and a garden hose to blow out gunk. Fill and repeat, run until hot. Don't forget to turn the the heat on and blow out the heater core. Drain and fill with coolant mix.
If I use a hose I try and get all that water out of there. I try to only use distilled water with coolant.

Did the sludge look something like this?

You must be registered for see images attach

For that mess, I removed the radiator cap, started the truck and then put the garden hose to the radiator. It made a mess in the driveway and the water spewing back out at me got a bit warm at times, but it cleaned up the system fairly well. I did that for around 5 minutes.

That was a month or two ago and it still looks ok, but the truck only gets used a little bit here and there. I'll probably do the same thing again again in the near future, but refill with coolant when done.

 

[bucket]

How did you get your square to make chocolate ganache? Wish mine made snacks, it just makes foul smells.

But loosening a few hoses to help drain and a garden hose to blow out gunk. Fill and repeat, run until hot. Don't forget to turn the the heat on and blow out the heater core. Drain and fill with coolant mix.
If I use a hose I try and get all that water out of there. I try to only use distilled water with coolant.

I'm not exactly sure what caused it. Probably a combination of abuse, neglect, running hot and a very tired engine. Very likely a blown head gasket too.