Flushing the Engine Block?

JoLin

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The boat's out of the water and I ran it on muffs to flush out the salt before I drained the blocks. On the older of my 2 motors (2003 Merc Reman), I had to work to clear both block drains, and a lot of rusty water and debris gushed out. Is there a good way to force water (with a garden hose) through the block and try to flush it out? Like, pull the drains and force water through the big (water pump) hose? Just looking for the best method if there is one.

If I can give it a good flushing I'll fill it with the corrosion inhibiting AF.
 

Bondo

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Is there a good way to force water (with a garden hose) through the block and try to flush it out? Like, pull the drains and force water through the big (water pump) hose? Just looking for the best method if there is one.

Ayuh,..... Unless ya wanta pull the motors, 'n remove the core plugs to flush out the crud,....

I suggest ya run it on the muffs, with the drain plugs out, til the water runs clean,....
That's 'bout as good as it gets, without yankin' the motors,....
 

Scott Danforth

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Make one of these from the plumbing section of your box store.



Remove plugs and stuff it into drain hole to front of water jacket and turn on the hose
 

shaw520

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Scott,.. get the bird crap off the front of your Bug!!
 

Scott Danforth

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Scott,.. get the bird crap off the front of your Bug!!

Not birdcrap. Some dillbag backed into the wife while she was at the gym. The car has had 2 hits in the front and 3 in the back in last 18 months and it's been parked all 5 times. The funny thin is she parks at the end of the lot to avoid dillbags
 

JoLin

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Thanks for the suggestions, guys. Now I need to ponder which method to try. Scott, can you tell me offhand what size hose you used and what fittings?
 

crazy charlie

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Bondo has it right.Run the motor with removed petcocks one at a time.Not opened but removed totally.Make a right angle out of coat hanger or dollar store screwdriver and insert in hole and turn 360 degrees and all kind of crap will come out.Been there....done that! Charlie
 

tpenfield

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I am considering the same sort of thing . . . flushing the engine blocks. My research tells me that olaxic acid (wood bleach) dissolves rust and holds it in suspension so that it can be flushed. I do like the idea of running the engines with the block plug fittings removed.

Removing the core plugs is about the best way IMO, but usually requires an engine pull to get at them.
 

JoLin

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Ted, I'd personally be leery of introducing a strong acid into an engine unless you could keep it out of the water pumps. I don't know how a big block Bravo engine is laid out, but I assume you'd add it through the t-stat housing and let it sit? Then flush out on muffs?
 

tpenfield

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Ted, I'd personally be leery of introducing a strong acid into an engine unless you could keep it out of the water pumps. I don't know how a big block Bravo engine is laid out, but I assume you'd add it through the t-stat housing and let it sit? Then flush out on muffs?

My engine is closed cooling, so not something that the sea water pump would see. Depending on the concentration/dilution the acid can be as strong or weak as you see fit. I think I will test a few pieces of iron beforehand to get an idea of how fast/slow the acid works.

I think with an open cooling system, you would have a more difficult time, as you would have to fill the block and let the acid sit.
 

JoLin

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Yeah, that's the issue I'd face (open cooling system). Thanks for clarifying
 

tpenfield

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The more I think about it, you could temporarily alter the plumbing of the engine and turn an open cooling system into a closed cooling system to get the benefit of recirculating a flushing additive
 

mickyryan

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yup o acid works slow but it does work I soaked a block for 3 days in it and it did not remove all the rust but a good portion and especially lose stuff I would do closed system on it with radiator hose and schedule 80 pipe run it for a few minutes each day and let it sit for a day and drain if it causes problems well truthfully you were about to have them anyways and better to find out in the driveway then on the water, I did not use it at full strength either I used it about 50 % it did leave a yellow dust on everything after I cooked the blocks.
 

JoLin

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The more I think about it, you could temporarily alter the plumbing of the engine and turn an open cooling system into a closed cooling system to get the benefit of recirculating a flushing additive

Offhand, I don't see a way to keep it out of the engine circulating pump. Anyway, I'll decide over the winter. Weather's changing fast and I HATE playing with water in cold weather. I fogged the motor and filled the block with AF. It'll have to keep until spring.

Thought of another variation, too. With the drive off (or the intake hose disconnected at the transom), I could use a garden hose to force water directly into the engine. Bypassing the Alpha water pump should give me more water pressure through the block.
 
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shaw520

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Yea, you're going to want the drive off for that proceedure, as to not run the impeller dry.
 

JoLin

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Yea, you're going to want the drive off for that proceedure, as to not run the impeller dry.

Duh, I forgot that part of Bondo's and Crazy Charlie's suggestion was to run the motor :facepalm:.

So, it's either run it on muffs or pull the drive
 
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