The Stovebolt Site Forums The Shop Area Engine Shop using evaporust opinions wanted

I just got back home after a winter in the south, and am chomping at the bit to get back to work on my truck. It's a 53 chevy 3100 which I put a 1962 235 engine in. I'got it running well, but quickly discovered that the block is caked up with rust in all of the water passages. A lister on here recommended blowing it out by connecting a pressure washer to the block drain hole. I found a fitting for that and bought it. He stated that he blew the rust out and then ran evaporust as a coolant for a short period, and it has been fine since. That sound's great to me, but after thinking about it for a while, I'm wondering if it might be even better to pour evaporust into the block, through the temp sending unit hole prior to using the pressure washer. Do you think that it might soften up the rust enough that the pressure washer would do an even better job of cleaning it out. Then using evaporust as a coolant. I guess that I'm mostly concerned about cleaning our the passages at the rear of the block. Once I get it pretty well cleaned out, I'll remove the freeze plugs on the side to get it even better. I know that I'm perhaps being a little lazy here, but I really don't want to pull the engine / transmission, and all back out. It's all hooked up and working so nicely right now. Yes, I know that I should have checked into this before installing the engine. I feel stupid enough already without any lectures about that. Thanks folks for your help and thoughts.

Hi Mike
I think you read some of the posts I was commenting on

Don’t waste expensive evaporust before flushing as much out as you can with water or other cheap means

Evaporust does not loosen rust, it dissolves it away into the liquid there will be no need to poke or prod after you finish with the evaporust, if there is still rust after the first treatment that rust will be as hard as ever, it will take more evaporust to continue dissolving it

All traces of rust will be gone, only pure metal bits and sand and stones will be rattling around in the bottom of your block when you are done

Evaporust works faster when it’s hot and moving
But I suggest you leave it in until it’s black as night or you have driven the truck daily for a month.
Evaporust had to be soaking on the metal it’s cleaning so full the system to it’s normal operating level.

Do not pull your “frost plugs” those are meant to be permanent and should not be necessary.
-stan

I remember a discussion about this years ago. Washing soda was recommended.

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/70498/2.html

A pressure washer only works when the jet from the nozzle hits the crud. So just hooking it up to the drain plug won't help much. Not much better than just a garden hose, anyway.

If it's got lots of stuff in there, it might be better to pull the core plugs and knock whatever's accessible from those openings loose and flush it out first. Evaporust is expensive, and too much rust and crud will exhaust it prematurely.

It definitely works better warm than cold, so filling the system and running the engine would help. Of course, the core plugs would have to be reinstalled to do that.

The only reason I connected the pressure washer to my block directly was because in my case I couldn’t get any flow out of the back drain hole with even a 1/4 inch rod pounded into the hole and wiggling around wire hangers
Yeah if it’s flowing you can skip that step

I wanted to know I could drain the rinse water and subsequently the used evaporust from my block before I put it in
So adapting the pressure washer directly was required
And when the block is empty the action of the pressure washer was much more dramatic coming out the top of the radiator than you could get with just a garden hose
It really froths up the water and makes a lot of turbulence

But anyway there are many ways to fix this issue

Washing soda won’t do anything agains rust in a block
That’s just gonna clean oil residue and easily flushable particulate that would have been rinsed with hot water
-s

If I was going to hook a hose or pressure washer to the drain plug and back-wash the block I would make sure the radiator hoses were not connected, you don't need all the loose junk clogging the radiator up and you don't want to accidently pressurize the radiator and split it open.

Mike B

What Mike B said. I might even remove the water pump, but that's not essential. Thermostat should probably be removed also.

Thanks, I was definately planning to remove the radiator and water pump. I should have mentioned that.

If you pull the core plugs and plan on power washing, use the RED pin point nozzle in your washer. My 3000 psi washer and pin point tip will peel paint and concrete pretty and fast. Getting a direct shot at the drain holes will be the biggest issue, so maybe look at making a very short wand for you washer, pistol style! Rig up a radiator by pass hose, so coolant leaves engine and goes right back to the block, run just long enough to heat the metal and the coolant, you sure don't want to eat the radiator up. If you pull the water pump, still run the engine to heat the cleaner and metal. Don't forget about the heater core.

If you have the pump off, you can get a clothes hanger and open it up all the way. Bend about a 1/2 or 3/4 inch hook in the end and force it through to the last cylinder and start jamming it in and out. It will take a while, but you'll loosen things in there. Also remove the block drain and work your coat hanger up until you get some water flowing through there. Then replace the block drain, get a bottle of CLR or two and pour them in until the CLR is right up to your pump opening (remember your block slopes backward a lot). Now leave it alone for a few days, drain and flush. Repeat if needed.

Alternatively buy a pound or two of powdered citric acid and make a very strong mixture of it and tap water and pour that in there. Either will dissolve rust.

And for a third alternative, buy a gallon of 45% vinegar and pour that in there...but don't leave it for a couple of days. 45% acetic acid is vicious stuff. You just want it do to the work and then get it out. 8 hours might be plenty.

And if you bought that citric acid, you can make a really good cleaner to use in your house. Mix two tablespoons into a quart spray bottle to get about 6% solution. You can clean toilets, lavatories, bathtubs and especially stainless steel sinks like a wizard with this...BUT NOT GRANITE, COLORED GROUT OR STONEWORK. You'll just ruin those things if you use it for them.

Good luck.

I used thermocure (made by evaporust)....https://www.evapo-rust.com/crc-thermocure/

Worked amazingly well

That Thermocure looks like it's going to take all the fun out of cleaning it up.

Granite is composed of silicates such as quartz, etc., which are relatively impervious to acids; marble, concrete, etc., are carbonates which are easily dissolved by acids.

Ever notice the difference between marble headstones used in military graveyards and granite headstones used in classier graveyards.

Ed