5.7 Mercruiser convertion to CCS, stainless risers also?

[Lou C]

Just for the heck of it I pulled my old intake manifold out of the garage today. Waiting on the machine shop to determine if the heads are still good enough to make doing a valve job worth it. The intake is fine really. In the water passage just below the thermo housing, there was flaking rust but just a thin layer of small particles that easily scraped off. Not big chunks or hunks of rust like you get from an exhaust riser. While I still would not try to put closed cooling on an engine this old, even if you ran your raw water cooled engine as it is, it would be years before you'd have a problem due to corrosion as long as you change that exhaust system every 5 seasons. On mine as long as I have had it (since 2002) when I winterized it I always filled the engine and manifolds up with the best -100 marine antifreeze with corrosion inhibitors. I really can't say if this helped having nothing to compare it to, but maybe so. So check the inside of your intake and post up some pix....

 

[GaryDoug]

Here are the photos. I can't say it looks like rust inside. It's very thin black film with tiny particles that can be scraped off with a fingernail, and then they crumble to a mud-like film.




Why do my attached photos get so small no matter what size I select?

 

[GaryDoug]

More:

Looks like I am out of attachment space already


Sorry about the photo size. This site wont let me make them larger no matter the file size.
Here is a link to the files in full size: http://www.mediafire.com/?fidxpo32degf8

 

[Lou C]

I'll leave the assessment to those who have experience with closed cooling systems but those pix look pretty good to me. What say the experts, can this engine be adequately flushed out?

 

[tpenfield]

It is a judgement call, but I would do the oxalic acid and salt-away treatments and then make a final decision.

Worst case is that the H.E. clogs up to the point that it will need a new one. . . it won't happen all at once, so you can keep an eye on the temp gauge throughout the seasons.

 

[GaryDoug]

It is a judgement call, but I would do the oxalic acid and salt-away treatments and then make a final decision.

Is there a procedure for the acid flush? I know it can be used on the fiberglass hull for cleaning but can't find a reference for internal engine use. The Salt-Away is a no-brainer.

 

[tpenfield]

Is there a procedure for the acid flush? I know it can be used on the fiberglass hull for cleaning but can't find a reference for internal engine use. The Salt-Away is a no-brainer.

I had to Google around the Internet to find the acid flush information . . . pieces here and there, mostly on auto restoration and hotrodder sites. A member here had recommended a radiator flush product, and that led me on a search about cooling system flushing.

It seems that oxalic acid (wood bleach) when mixed with water dissolves rust and holds it in solution until neutralized with baking soda or borax.

The information that I came across on the web touched on those 2 points . . . . acid flush, then neutralize.

I think I kept the acid in the cooling system for about 8 hours . . . maybe even overnight, can't remember exactly.

Here are a couple of pix of the rust that dropped out of solution once I drained and neutralized the acid flush.





Sort of wished I had done this before adding closed cooling . . .

 

[tpenfield]

Almost forgot . . .

Procedure-wise . . .

I drained the cooling system (it had coolant in it since it was already closed cooling

Ran plain water through the cooling system . . . drained

Filled the block with the acid solution . . . I think I ran the engine briefly to move the solution around a bit.

After 8-12 hours I drained the cooling system. (that is when I made the rust slicks on the pavement, as I neutralized the stuff that was on the ground.

flushed the cooling system w/ water

mixed up some neutralizing solution and filling the cooling system ran the engine briefly to move it around a bit

drained the neutralizing solution

drank a beer

flushed the cooling system with water.

had another beer

filled the cooling system with coolant and buttoned everything up

went inside and had some more beer.

 

[GaryDoug]

Thanks for the information. I will do that even if I don't add the CCS. I may want to move around and replicate the steps involving the beer though ;-)

 

[Lou C]

Let us know what you wind up doing. For sure I can see why you would want to do the conversion.
Another test for flaking rust you can do:
Run the boat on the water hose till it reaches normal operating temp. Let cool off a bit; then remove the block drains. Watch what happens if you do not poke a thick wire or thin screwdriver in the drains. If as soon as you remove the drains you get a good flow of water that's good; do it several times over several days to see if it drains well with no poking. I can tell you with a raw water cooled engine in salt about 50-75% of the time, of the 4 drains I have (2 engine 2 manifolds) at least one would not drain without being poked, sometimes 2 or more needed poking due to rust flakes clogging the drains. If you do this once a day for let's say a week as a test and it always drains with no poking that that's another good data point .
I like Teds procedure as well

 

[GaryDoug]

OK Lou, I performed the test you specified and none of the drains were clogged to any degree noticeable. On each drain, a small amount of brown water came out first, which was quickly followed by clear water. No flakes or solid particles were visible. And I did not poke anything.

 

[Lou C]

That sounds good maybe try Teds acid flush next and see what comes out.

 

[HT32BSX115]

OK Lou, I performed the test you specified and none of the drains were clogged to any degree noticeable. On each drain, a small amount of brown water came out first, which was quickly followed by clear water. No flakes or solid particles were visible. And I did not poke anything.

Howdy,

I installed a complete San Juan Engr (FULL) closed on my 454 in 2006......... It was about 10 years old, mostly ran in fresh water (and, according to the PO, once in salt) and had 122 hrs total since new.

I still have the closed system installed and it works just fine.

For yours, I would suggest you do a treatment using the following: https://www.cumminsfiltration.com/sites/default/files/LT16551_0.pdf

Then do a thorough flush after removing the core (AKA incorrectly as "freeze") plugs

It will probably ensure long heat exchanger life.

Cheers,

RIck