The Stovebolt Site Forums The Shop Area Engine Shop Engine block flush

I've got a very rusty 235 block cooling system and I would like to flush the rust out before installing the new thermostat, waterpump, and radiator. Is there a product out there that would knock most of the rust out or are there home remedies that would work just as well. Blocking off waterpump and thermostat housing should be easy enough with a couple of homemade gaskets. Any thoughts or experience with this would be helpful. Thanks, Gary

is it out of the truck? If so, knock out the freeze plugs and take it to a carwash and blast out the water jackets by spraying in each hole you pulled a freeze plug out of. If it is real rusty, you may want to pull it and replace the freeze plugs anyway ad I have had them rust through and leave me stuck away from home!

I did what 69Cuda said with my engine. Here's a shot of what I saw when I pulled the rear freeze plug out. Even after pulling them all and flushing the block with a power washer, I'm still going to use some coolant system flush when I get it reinstalled in the chassis. Coolant flush products work best when you can run the engine to heat it up.

[on edit] You might try Evaporust if you can't run the engine, although it works best when warm. It would take a few gallons to fill the system, and it may not get thru the sludge blanket on the bottom of the coolant passages.

Make sure the water drain valve has good flow, frequently get clogged up with dirt and rust, keep block from draining. It’s a stiff wire, nail, etc., to open up the drain.

Ed

The biggest issue I have run into with 216 and 235 engines in original condition is not rust. It has been what is very likely lots of stop leak products put into the cooling system to seal a leaky radiator.
Back in the day (when HRL was still an old man) labor was cheap, but parts were expensive. A brass radiator must have very expensive then. Stop leak was cheap and easy.
That caked up black stuff can be miserable to remove even when you are down to a bare block on an engine stand. I doubt that there is a chemical known to mankind which will dissolve it without dissolving the cast iron block.

The stuff I found in my block wasn't that hard. It was gooey but flushed out pretty well.

52Carl,

Did you mean when HRL was still a “young man?”

Ed

A trick I have used in the past was to fill the cooling system with water and toilet bowl cleaner. This of course is on a running engine, although you could probably use it in a pressure washer. Once the engine is brought up to temperature I would just let it run a little above idle for an hour or so, on a really dirty block you could run it several times allowing it to cool between runs. Afterward you just remove the thermostat and run a garden hose into the radiator and run the engine at idle with the drain valves open until the water comes out clean. I have used this on several engines with good results, it does leave the shop smelling "minty fresh".

It would take a bit of product, but could you clean a bare block with a long soak in Evapo-Rust?

Dennis

Have you not met HRL in person?

Yes, he helped me on the road.

Ed

If you have plenty of time, you can use CLR. Leave the engine at its normal sloping mount and pour it in. A couple of bottles or until it dribbles over the water pump hole. Then go to your library (in person or online) and check out "Stormy Weather" by Carl Hiaasen...it is a good book with lots of odd characters, humor, devious twists and turns...all about a bad hurricane in Florida. Or "Tropic of Stupid" by Tim Dorsey...another Floridian. This book is about a guy who decides to check out his own DNA with one of the on-tv ads and discovers he may be related to a serial killer...who hasn't been caught yet. Of course in both will be swamps, some wildlife and other things you might associate with Florida. Or if you're fortunate enough to have access to a well-stocked library, look for "The Girl, The Gold Watch and Everything" by John D. MacDonald. Don't worry about the CLR until you've finished at least one of those and then poke a coat hanger from front to back and jiggle things up for a few minutes. Then back to reading. If you get through with all 3 of these, look for "The Judas Goat" by Robert B. Parker. One of the Spenser series and in this one Spenser has 8 or 9 terrorists to deal with and his only help comes from Hawk. Action, humor, mayhem, a wee bit of romance. Great man's book.

HRL is a good egg.

CLR may be the answer then. Thanks Jon for the suggestion and the detailed list of other tools and technique needed for the job!

Dennis

CLR success. Used a 50/50 mix and left in the block overnight. Converted the rust to what looks like dirt. using a coat hanger I got as much crap out of the block as possible, including the drain plug hole that was plugged tight, hand drilled that out, and ramed the coat hanger around in there. All flushed out and ready for the next step. Thanks again Jon.

Carl Hiassen is hilarious. I've read nearly all of his books and some of them twice. I read Star Island on a flight to Salt Lake City in May. It made the flight seem like it was only an hour instead of 4 hours. People near me probably thought I was crazy because I was snorting and chuckling to myself the whole time.

If for some reason you haven't read the books he wrote for tweens/teens, you ought to do so. Start with "Hoot" and read all of them including "Skink - No Surrender."

I mentioned these in the Greasy Spoon...I always read any book before suggesting it to the grandkids. These were really enjoyable. Wish I'd had stuff like that to read when I was young.

I worked at a Kenworth Dealership at a diesel mechanic. We used Cascade powder that came in type you put in your dishwasher. It work very well. I use it in all of my automobiles.