F engine block flush/ muriatic acid

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bugsnbikes

bugsnbikes

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i have some serious blockage in the rear of the block (about 2"depth from block fill hole in rear of engine) and ive read a few old posts about people who have done a pump/flush setup with muriatic acid.

do i have to remove the water pump or can i just hook up hoses to this and the drain plug hole and flush between the two?
 
I don't think it will work. The acid will just wash around the blockage, not through it. You need to get in there with a piece of wire or something to get it started so the acid can get into the blockage itself.

I also don't know if you would want to put it in full strength. Maybe if you were planning to replace all the hoses and water pump afterwards.
 
yep-got in there and poked around the goo..........its like a 2" layer of bottom rust/silt/goo in the bottom of the water passage......this wont drain out of the block currently. the water drains out--but the rusty-goo is behind.

my plan is to fill the lower 1/3 of the block (crimping the block drainplug hose end) for 3-5 minutes and let the acid work its magic on the lower third where the rust is sitting like silt in the cooling passage.


Does anyone know how much fluid the total block can hold???(no rad included) im looking to get a 1/3 volume of that.
 
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Remove the rear freeze plug and flush out from there... I would not use muriatic acid at all, it will eat away the back side of the freeze plugs and start a whole different problem....
 
so i probably should have prefaced this with:

the engine is in- with marks headers so freeze plug access is not a great option.

i didnt intend to fill the block to the height of the freeze plugs---i was hoping to simply flush muriatic thru the lower end of the block with the drain open enough that theres a pretty constant flow of the muratic acid and it doesnt actually sit and fill the block up.

with the blockage about 2" above the height of drain hole---i would guess that using my 1gallon per minute pump (pretty slow) and a 3/8" tubing that the stream will wash over any rust/sediments in the bottom 2inches of the block and do more "washing" away of the rust vs. sitting and eating away at other portions of the cylinders/block and never get up to the level of the freeze plugs.

The other caveat was that i intended to park on a slight slope so the rear/lower part of the block was at the lowest point and promote draining....vs pooling.
 
Muratic acid will not hurt steel or iron or brass or rubber or plastic. It will not hurt anything in the block. It will attack rust and mineral deposits. It WILL eat aluminum.

Kerosene won't do squat to any of the materials involved here... or to anything that would be forming any sort of blockage. Absolutely pointless to use.

The blockage in the area of the drain plug is usually not rust or minerals but various sediments introduced in small quantities over the years as water is added to the rad. it is common for muriatic acid to not affect this stuff. manual removal is usually called for. I have encountered a couple of blocks where even that was unsuccessful with the block in the rig. :(

If you use muriatic acid to flush the block, you will want to remove the water pump and if you have a manifold pre-heater installed, take that out of the loop. Some external tank heaters have AL in them, so make sure they are not involved either.

I use muriatic acid all the time. a little common sense and there is no reason to be afraid of it. It is not all that nasty.


Mark...
 
If you want to try to attack the blockage at the Drain plug with muriatic acid, a way to do this and use a lot less acid is to insert a fitting where the drain plug goes, attach a hose to that, raise the other end of the hose and put a small amount of acid in the hose... give it a while to become exhausted, lower the hose to drain it out, and do it again... possibly several times.

If the acid is doing anything you will have some fumes appearing at the top of the hose most likely... and the acid will be heavily discolored yellow as it drains.


Mark...
 
Have you thought about using vinegar? Used it on mine this summer and it turned out pretty good. Tried the acid route but didn't feel comfortable with leaving it in long enough. Put vinegar in and on the side, I put vinegar in a jar with a piece of steel. Once it started etching the steel, I drained, flushed, and backwards flushed the block. Did that a couple of times and I was good to go.
 
thanks mark,

when i finally got the coat hanger tip to break thru at the drain plug- there was tons of reddish brown water vs black goo. The drain plug passage itself had a puff of reddish brown dust when i ended up drilling the rust out of it. I have no history of the block other than it appears this plug has never been removed and it took a 3foot breaker bar to break the rustlocked plug free.

My hope is that if the muratic acid frees some of the rust in that area-- that this black sedimentary goo will become a bit more free to flush out. Heck id be happy getting 10% more water flow in this area and my overheating issues would probably be kept at bay. (im currently lingering at the 3/4 mark on my temp guage when it used to linger at half)

Just getting the block clear of the brown water is probably a major accomplishment in terms of my overheating problem as i think this brown "heavy" water was just lingering in the lower third of block when i flushed and reflushed the rad. (ie the water pump wasnt pumping it around anymore.)
 
scoutin cruiser said:
Have you thought about using vinegar? .
Click to expand...

Ive used muratic acid before on a radiator. It was fairly uneventful but the stuff works like magic. The stuff needs to breathe.....so my only concern on the block is to have enough venting for the gas to get out. Which is why i intend to pump it thru with a hose from the front block hole at the water pump. The hose in only 3/8" and i will stick it down into the block so no fear of it backing out but it will allow the gasses to vent at the entry point. The drain is going to have a pipe fitting that has a barb and hose and go right into a big bucket so i will have a good view of whats coming out.

The muratic acid gets fairly neutralized when its working well (at least it did on my rad which had a ton of scale/rust/stuff). so i guess the key is that if its working on the problem---it should also be getting fairly neutralized as this occurs.

From a few other threads that have tried this--it appears people needed to cycle about 3gallons of muratic as a gallon or two was neutralized enough that a third was still producing a neutralized slurry.
 
True but with the vinegar not being quite as harsh, you can flush the entire system without pulling all of the hoses nor do you have to worry about disposal as much as the acid. Just giving you an alternative. :D
 
i deal with lots of industrial engines (natural gas burners) in which the same type problems occur and we NEVER use full strength muriatic acid, but rather we do use block flush sold at auto parts stores. back flush the system if you can by connecting a water hose to the top of the block, probably where your heat sensor is located and drain out of the bottom of the block, let it run for awhile onto the ground - that is the opposite direction of the flow of coolant provided by the water pump.
 
I have yet to find any off the shelf radiator flush that does much moire than straight water will.

I've been using Muriatic acid for 20 years or so. It does the job and nothing else will match it.

You can get your block /rad/heater core clean and flowing. Or you can putz around with half steps.


Mark...
 
I've used that Acid Magic stuff before. I get it at Ace hardware. Its Muriatic but doesn't have that choking smell and wont tear up your skin if you get it on you. I've only used it on heater cores but I imagine it would work alright on blocks.
Note. Dont get that stuff on your driveway!! Dont ask me how I know.
 
scoutin cruiser said:
Have you thought about using vinegar? Used it on mine this summer and it turned out pretty good. Tried the acid route but didn't feel comfortable with leaving it in long enough.
Click to expand...

FYI, vinegar is just diluted acetic acid; anything vinegar can do in your cooling system, muriatic (hydrochloric) acid can do better/faster.
 
Agree 100% but I could monitor the vinegar easier than the muriatic acid. Didn't feel nearly as comfortable with leaving the muriatic acid in. Probably why I use a .22 instead of a .308 when squirrel hunting. Could I do it? Yeap. Would I trust myself to make the shot and still have meat? Not so much. :D
 
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Well I tried the m-acid flush once and it turned the back side of the freeze plugs black and eventually caused premature failure. Come to find out the plugs have a zinc coating on them and zinc doesn't play well with the acid:frown:
 
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