what works best as a water jacket flush and descaler

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I have an old motor that's been taken care of but mainly used in salt water. its a 2002 model Suzuki df40 and becxause of an illness it sat for a few years without being flushed well or used at all for a few years after some heavy salt water use. well about 5 years ago I was able to take care of all the neglected maint issues and was saddened to see I had to clear the water pump and lower unit water passages from corrosion flakes that covered everything and actually blocked the water intake solid above the prop.

I took my time with a metal coat hanger and dug it all out then soaked the lower unit in oil overnight. I also removed the thermostat and found the interior of the water jacket "frosted" with corrosion but no loose flakes so I plugged the water tube and filled the block completely with oil and let it sit overnight as well. I then drained everything and let all the remaining oil drip out before reinstalling the thermostat and replacing the impeller then I let it sit for a second day so it got a full 48 hours for the oil to neutralize the corrosion inside the engine.

the engine only has about 300-400 hours on it so im wondering if there is a recommended descaler or something I can run through the engine to be sure it cleans out all the areas I cant see or get to like the heads and such or is it best to just do as I did the last time?

I am trying to keep it in good shape and get this thing back to as close to new condition as I can and the only thing that worries me is the corrosion eating at it from the inside.

at this time I have no blockages or overheating issues so this is preventative maint. before I do have any issues show up.

so is there something that's safe to put in a drum with water and run the motor to dissolve and flush it all out?

 

[jrs_diesel]

Re: what works best as a water jacket flush and descaler

When I cleaned out the water jacket and cylinder head of my 86 Johnson 9.9, I used my Dremel tool with a straight sided cutter:

9901 Tungsten Carbide Cutter / Model: 9901

I have a variable speed dremel so I set it for low speed and took my time so I wouldn't damage the aluminum block. That bit got 95% of the crap out. I had to use two other bits to get the rest in the nooks and crannies. One bit has a ball shaped cutting head, and the other bit has a pointed cutting bit on it. It took about 2 hours, and I could have gone faster but I did not want to cut into the aluminum.

The trick with chemical removal is finding something that will dissolve the deposits without hurting the aluminum or the paint in some way. I didn't want to take that risk with my block so I chose mechanical removal.

Hope this helps.

 

[limitout]

Re: what works best as a water jacket flush and descaler

The trick with chemical removal is finding something that will dissolve the deposits without hurting the aluminum or the paint in some way. I didn't want to take that risk with my block so I chose mechanical removal.

Hope this helps.

yep, that's why I just used oil to neutralize the corrosion last time but im thinking its about time for a good flush and cleaning but im not willing to go tearing the engine down to do it. once you start tearing things apart you develop leaks and strip or break bolts and such, just too many things that can go wrong once you start taking things apart.

there shouldn't be any risk of chemical solution damage if you follow directions correctly and IMO most issues that arise from it is not that it ate away the aluminum but that it was already eaten away by the corrosion and the chemicals just removed the corrosion that was blocking the hole.

 

[hall832]

Re: what works best as a water jacket flush and descaler

I have used diluted muriatic acid with great success. drop the lower unit. open up thermostat housing. put a bucket underneath the lower to catch the acid. have a fresh water hose standing by.

 

[Chris1956]

Re: what works best as a water jacket flush and descaler

Gee, I did not think oil would neutralize corroded aluminum. Did that work for you? I would think some kind of acid would be better. Maybe some acetic acid or phosphoric acid? Something kinda mild. You did flush with freshwater to get all the salt out?

 

[kahuna123]

Re: what works best as a water jacket flush and descaler

I agree with hall. We also use it down here to flush out the water jackets in the air conditioners. Just not much.

 

[limitout]

Re: what works best as a water jacket flush and descaler

Gee, I did not think oil would neutralize corroded aluminum. Did that work for you? I would think some kind of acid would be better. Maybe some acetic acid or phosphoric acid? Something kinda mild. You did flush with freshwater to get all the salt out?

the oil neutralizes it the same way it does on your battery terminals of your car, it doesn't "do" anything to it it just stops the chemical reaction from continuing to corrode, at least until the oil gets washed off.

yes I flushed and back flushed it and got all the loose stuff out before I oil soaked it otherwise it would get trapped.

I have used diluted muriatic acid with great success. drop the lower unit. open up thermostat housing. put a bucket underneath the lower to catch the acid. have a fresh water hose standing by.

I agree with hall. We also use it down here to flush out the water jackets in the air conditioners. Just not much.

how do I mix diluted muriatic acid? what strength?

is this just like a straight through flush or do I let it sit and if so for how long?

@ kahuna I was thinking about using the coil cleaning acid but wasn't sure the strength to mix it or how long to let it work but I wasn't sure if it even worked on corrosion (35 yrs ac tech)

 

[hall832]

Re: what works best as a water jacket flush and descaler

start out with a 30/70 mix. I have used muriatic acid on older Yamaha outboards all the way up to a newer style ETEC that was neglected. I usually start out with a quick run through and watch how fast it comes through and the amount of crap that drops into the bucket. I increase the the time i let it set as needed for blockage.

 

[hall832]

Re: what works best as a water jacket flush and descaler

you can buy muriatic acid from Home Depot or Lowes. In the pool section. Its a real easy chemical to work with. it comes in 1 gallon containers and in liquid form.

 

[Home Cookin']

Re: what works best as a water jacket flush and descaler

I wouldn't do any more to it than you already did. That's way more than 99% of the saltwater motors ever get during their 40 years of use.

 

[limitout]

Re: what works best as a water jacket flush and descaler

thanks guys