Flushing the cooling system

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Tom.B

Tom.B

Moderator Emeritus
Joined
Jul 30, 2009
Messages
5,839
Location
USA
Vessel Name
Skinny Dippin'
Vessel Make
Navigator 4200 Classic
I have a couple of cooling questions.

I have a plan to flush out the heat exchanger with Peak radiator flush. Reading the directions, it's a pretty involved process of drain, fill with water, run to temp, drain, fill with water again (I assume to get the coolant out of the block that is behind the thermostat). Then fill with water and flush and run for a few hours with just the flush/water combo. Any pointers you all can give here? It seem pretty straight-forward. Is there any danger to running with just water or in leaving the flush/water mixture in the cooling system for a week between our trips?

Thanks.
Tom-
 
A good flush system will have a cleaner , then a nutrelizer as part of the kit.

Yes flushing multiple times is a chore but required,enjoy!
 
Hmmm... A multi-part system? I must know more! If there was a "tool" I could use... A portal or maybe some kind of engine that would allow me to conduct a search of the web. Lemme think. LoL!

Should the thermostats be removed for this process?
 
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What does the stuff do? Do you have the keel coolers? I just used a wet vac and blew the water out.
 
Clean any possible scale deposits out of the heat exchanger and water jackets in the engine.
 
So i nust finished flushing the cooling system. Basically, I chickened out of using the flushing fluid. What I did was just flush with clean water five times. I drained the heat exchanger, filled with clean water, run engine to temp, then repeat four more times. Then today I just blasted the hose thru it until the water ran clear. Took about 25 gallons.

My cooling system holds 5 gallons total and the heat exchanger holds about 2.5 gallons. When I was done flushing out as much of the old coolant, i just filled the tank with 100% Fleet Charge coolant and run engine up to temp one more time to mix coolant charge to 50-50 mix

That should do for a year or two.
 
So did you get a good look at, or better yet pull the heat exchanger itself and see what condition it is in?
 
Nope.

Certainly, had I attempted such a feat, I would have shared it here :lol::lol::lol:
 
When was the last time the H/E was checked and cleaned? They really need attention in our waters. I have mine done every couple of years. Also when was the last time the cooling system was actually cleaned vs flushed? If it has been awhile you will probably be amazed at what comes out when you do. By the way, here is IMO the best stuff for these exercises:

Marine | PenrayPenray
 
Not in the four years I have had it. I feel like if it was showing signs of overheating, I would go that route, but I am well within spec temps (190 degrees). I will talk to my trusted marine engine tech and see what they recommend. Thanks.
 
I always check my coolant with an ohm meter. This will show the current that the coolant is drawing and the electrolysis it's creating inside your engine eating away at the internal metal. It's best to change out coolant every 2 or 3 years regardless of hours on the engine. Antifreeze becomes acidic over time and acid with dissimilar metals makes electricity.

When I replace my coolant I always flush my engine a few times and I replace it with a 50/50 mix using distilled water so I don't make solids in the engine with mineral deposits.

When I clean out the salt side of the heat exchangers I use a mild acid and let it work about 30 minutes then start the engine. When I go aft and look at the water I can see small pieces of mineral or salt chunks coming out. I can inspect the exchangers by opening the end cap.

To test the coolant. Take your VOM meter and set it on the lowest DC setting. Place the positive in the coolant not the over flow tank and the neg against the block. It should read under .10 volts and .3 is acceptable but anything over that is bad.
 
Capthead said:
I always check my coolant with an ohm meter. This will show the current that the coolant is drawing and the electrolysis it's creating inside your engine eating away at the internal metal. It's best to change out coolant every 2 or 3 years regardless of hours on the engine. Antifreeze becomes acidic over time and acid with dissimilar metals makes electricity.

When I replace my coolant I always flush my engine a few times and I replace it with a 50/50 mix using distilled water so I don't make solids in the engine with mineral deposits.

When I clean out the salt side of the heat exchangers I use a mild acid and let it work about 30 minutes then start the engine. When I go aft and look at the water I can see small pieces of mineral or salt chunks coming out. I can inspect the exchangers by opening the end cap.

To test the coolant. Take your VOM meter and set it on the lowest DC setting. Place the positive in the coolant not the over flow tank and the neg against the block. It should read under .10 volts and .3 is acceptable but anything over that is bad.
Click to expand...

Thanks for the tip. That's a new one to me, will have to try it. I use the little "litmus test" strips from Penray or Detroit Diesel.

I just as soon not wait for the engine to start running hot as a way of determining if the HE is getting clogged. Kind of like waiting for your engine to start stalling out as a way of deciding when to change the fuel filters.
I am not sure there is a similar way to determine if your turbo intercoolers (or aftercoolers as the case may be) are getting clogged either, but I'm not going to wait around and find out....
 
I pull all heat exchangers apart every 3 years or so and clean them out with muratic acid, bore brushes, then flush clean, reseal and paint.
Last time I did that (a year ago) I found one the main mounting plate had broken at the braze joint. I don't know if I would have spotted that if I didn't completely remove it.
 
A quick underway check is to use a heat measuring gun on the output side of the cooler where the sea water leaves.

Under 140F is required ,lower is better! otherwise salt is slowly plugging the heat exchanger.
 
I have a not so funny story about Muriatic acid. Several boats down from me is a Striker with twin Cat's in it. Their friend was telling them to flush with it to get all the salt build up out of their cooling system. They went out and bought nine gallons of it and flushed and flushed and flushed. When they tried to start one engine the acid had eaten all the way through and water was inside two cylinders. They hydrolocked it. They had to tear the engine down and do a rebuild.


A little goes a long way with that acid. I use a mild phosphoric acid like lime away and it works fine and will wash away with water.
 
Would citric acid do the trick? It's safe (classified as foodstuff) and can be discharged as normal waste.


I have used it in getting rid of rust from pot iron parts and especially when it is heated it works wonders in rust removal purposes.
 
Don't know about citric acid, but I do use it to descale the coffee maker!

For the HE, I use white vinegar. Empty the HE, fill with vinegar, leave for a few days then empty and turn the raw water intake back on.

I do this every 2 years and notice a few degrees drop in operating temp each time.
 
And then your exhaust smells like pickles. Talk about a win-win!!
 
Most heat exchanger can be taken apart , rodded out (use a proper sized dowel) and reassembled for only the cost of a gasket or O ring set.

No acid required.
 
FF said:
Most heat exchanger can be taken apart , rodded out (use a proper sized dowel) and reassembled for only the cost of a gasket or O ring set.

No acid required.
Click to expand...

This was kinda my plan too.

I think I am using the wrong terminology. What I flushed out last weekend was the fresh water tank and not the raw water H/E. What is it called? The manifold?
 
"Rodding out" the heat exchanger only cleans, not necessarily completely, one side of the system, and risks damaging the tubes. Sometimes used as a last step once the solution has loosened things up. It does not address the other side where significant scale and growth can build up. Actually, ultrasonic cleaning is the current state of the art but you have to send it out.
 
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I have seen most boaters here r & r them and have a radiator shop do an acid bath, rinse and pressure test. It isn't expensive and worth the pressure test.
 
I run a product called CLR through the outboard on my ski boat every time i get back home. Last year I stripped down the outboard and shaved the heads and to do the rings and bearings etc etc etc and the water jackets were as good as they were from day one.

Not sure if its available over there but if it is, give it a go, it's awesome! I'll absolutely be using it in AXE when it's time

http://en.wikipedia.org/wiki/Calcium_Lime_Rust

Less savage than Hydrochloric Acid and won't eat ya block or heads.
 
Just came back from local Volvo dealer and picked up their newesy catalog. It clearly states that their eco friendly flushing fluid consists of citric acid and a neutralizer. So it could be used...
 
If the purpose is to clean the entire coolant system then I would use one of the well known brand name products, like Volvo or Fleetguard (Cummins). Their products are designed to clean without damaging other parts, like seals, gaskets or metal parts. If using acids then there is no telling what can be damaged...

For the HE only, I would have no problem using the acids.
 
Is it ok to flush the fresh water side with regular tap water or should you use distilled or soft water? If you flush three or four time and have to use distilled or soft water it could be quite a chore hauling all that water to the boat. It would seem that you could use tap water for all the flushes with the exception of the last flush and then use soft water for that one.
 
It would seem that you could use tap water for all the flushes with the exception of the last flush and then use soft water for that one. __________________

Works for me , tho most folks choose to forget that the antifreeze should be changed out every 2 or 3 years .

And flushing is REQUIRED , at least according to the folks that mixed the antifreeze.
 
There is something to be said about zero soft water, which distilled is. It will clean without soap and there are commercial carpet cleaners who only use distilled water to clean carpets. The water that comes off from the first cleaning will be soapy and black if that is their first zero res cleaning. It takes a lot of cleaning to get clear water off it too.

We have a green machine I use to clean my boat cushions and beds with. I only use distilled water in it. You would be amazed at how clean and fresh they are after cleaning with only distilled water. I'll only spot dirty or greasy spots.

Try it with tap water and then finish with distilled, it takes a lot of distilled to clean it.

I can buy distilled water for 80-90 cents a gallon here so I stick with distilled only. It's less than a 20 to flush and fill for me, not counting the antifreeze.
 
Is this thread confusing the coolant system and the raw water cooling system?? Coolant can be flushed with acid or detergent-based cleaners...for example, Cummins/FleetGuard makes Restore (best for oily/greasy contamination) and RestorePLus (where rust/scale deposits is more the issue). Success with these requires running the engine at operating temps for up to (but not exceeding) 3 hours, then freshwater flushing and refilling with an anti-freeze/anti-corrosion coolant additive.

Fresh water flushing of the raw water side is totally different. Just flushing with fresh water and leaving the raw water system charged with fresh water when back at the dock is a BoatDiesel recommended practice if you can manage it. Annual rod'ing of heat exchangers and aftercoolers is good preventative maintenance too. But if you experience a step-up over normal operating temps, a full-system flush (preferably circulating) with one of the established products like BarnacleBuster, TracEcologic or similar could be the appropriate first step.
 
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