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Old 07-05-2020, 11:19 AM   #23
30 Closed Cab PU
Senior Member
Join Date: Aug 2018
Location: Wisconsin
Posts: 2,290
Default Re: Radiator Overheating

Originally Posted by saxman657 View Post
I used Thermocure which s made by Evaporust. Shouldn't this do the job on the cooling jackets? Maybe a course of Rust911 too just to be sure? If I go with a new radiator I would really like to ensure the block is in as good of shape as possible.

Sometimes the amount of build up requires multiple treatments. Cylinder 4 jackets are usually the worst. Cylinder 4 comparatively has poorer circulation than the other cylinders. In some cases a speedometer cable flayed on the end is used with a drill to break up the deposits. There are also other methods.

A rough idea of how bad it is is to remove the hose necks on the head and block, and see what things look like. Additionally you can take the water pump off and give a look/see. For further inspection use an inexpensive borescope through the openings to probe deeper into the head and block.

When I had issues, tried white vinegar and thermocure. When using white vinegar you have to do a final treatment with baking soda/water to neutralize the acidic content of the vinegar, required because it works into the pores of the metal and is not flushed during draining/flush/back-flush. Downsides of vinegar - it can wash out the grease in your water pump, and if running the motor it creates a huge rusty water mess and can ruin paint. It also can cause rust flakes so you want to insure your coolant filter is installed if running the motor.

Nice thing about Thermocure and Rust 911 are they are not acidic and will not hurt anything metal/seals or rubber/vinyl, and should not flush the grease out of the water pump. Water/baking soda flush not needed. It typically does not cause flakes, they kinda "disolve" the rust into the solution, less chance of plugging up a radiator. Still recommend running a filter if running the motor.

The method of taking the radiator off is also a good way to do it, add solution to the radiator and and block after sealing them. Let them soak. Ive even heard of those who hook up a small circulation pump with a timer to circulate the liquid to increase the effectiveness of the solution.

I was just lazy and did as like above with the system together and ran my truck every day for 20 or more minutes with solution in it for a week or 2.

After 3 months of on off treatments and getting a ton of rust out discovered someone had put in an undersized 2 row core radiator. Had to replace it. However all my flushing raised the overheating speed from 25 mph to 45 mph, so it was still a good thing. Got a Bergs, and now have to run a 160 degree thermostat or the truck mostly will not get up to operating temps.
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