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Old 10-12-2014, 21:59   #1
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Engine flushing

Anyone have any ideas on how to flush the freshwater side of the coolant system in my Aloha 32? Plan right now is to use a transfer pump to remove as much as the old coolant as possible, fill with a cleaning agent, run the engine for a bit, then pump/fill/pump/fill/etc with distilled water to get as much of the old stuff out as possible. Once that's done I'll add new antifreeze.

I don't really want to unhook any coolant lines because access is somewhat limited and I just know I'd end up dumping all the coolant into the bilge.

Just thought I'd see if anyone had any genius ideas
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Old 11-12-2014, 11:23   #2
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Re: Engine flushing

You can buy a tool that hooks to an air compressor to suck most of the coolant out. Then you use the tool to suck all of the air out and then you can fill the system again. Only takes about 5 minutes to do

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Old 11-12-2014, 11:42   #3
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Re: Engine flushing

Wouldn't one of those gizmos that suck oil through the dipstick tube work? Lots of places sell them, and they are designed to work in tight places. Mine (the WM model) has a capacity of 6-7 quarts, which would be enough for a small diesel engine. The coolant will get some minor amounts of oil in it from the residue in the oil container, but the coolant will have to be disposed as hazmat anyway.

Just stick it in the engine--the vacuum to draw out the liquid is created in the oil removal gizmo itself, and the hose is flexible to reach the bottom of the engine coolant system.
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Old 11-12-2014, 11:42   #4
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Re: Engine flushing

Hello from a fellow Aloha 32 owner (#15 built in 1983)!!

I've only owned mine since this summer so haven't tried flushing the coolant yet, but here's an idea... Is yours set up like mine with the hot water heater under the SB quarterberth? If like mine, it uses the engine coolant in a heat exchanger to heat the water when the engine is running and as such has a supply and return hose running to it. These would be much easier to access than working in the engine compartment so you could catch the old coolant in a bucket there relatively easily...

I'd appreciate it if you'd update this post once you've done the work so I could learn off of you since this is something I should do in the spring.

Cheers,
Don
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Old 11-12-2014, 12:21   #5
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Re: Engine flushing

Why are you using distilled water?
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Old 11-12-2014, 12:54   #6
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Re: Engine flushing

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Originally Posted by Pete7 View Post
Why are you using distilled water?
Plus, why not dump it into the bilge, diluted it's not a pollutant like say fuel is.
If you use a cleaner, you really need to flush that out well.
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Old 11-12-2014, 12:58   #7
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Re: Engine flushing

Then I look online to see, and find some sights that say you can be fined 25K for discharge of antifreeze?
They say antifreeze may contain lead and other heavy metals? When did this happen?
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Old 11-12-2014, 12:59   #8
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Re: Engine flushing

If your flushing then using some type of flushing fluid to remove scale and sludge you would definitely want to make sure you get all the residue out.
Most modern diesels and most older ones have drains on the block as well as on the heat exchangers, if your going that far it would be wise to drain those as well prior to adding new antifreeze/water mix.
Not sure what your using as a flush but plain old white vinegar works well and it's not harmful to the environment. Warm the engine, drain the existing antifreeze in a controlled manner, put in the vinegar/water mix, run the motor a bit to circulate then shut it off and let it sit for about 1/2 hour. Drain, rinse out with plain water and then drain that out prior to adding your antifreeze mix.
Sure your boat will smell like french fries for a bit but it is less toxic than many of the alternatives.
I've used this to run through outboards run in salt water and also on heat exchangers to demineralize them from time to time.
Muriatic acid works much better for the raw water side of the exchanger but is a pain to dispose of and is much more difficult to work with.
The old antifreeze mix has to go to a hazardous materials disposal facility, it's not good to just throw the jugs in the dumpster.
No matter what you decide to do your better off putting in the extra labor to pull the hoses and drain it correctly, the suggestion to use the water heater connection was a good one but won't get all the antifreeze out unless you have a way to pump clear water back through it to get the last remnants.
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Old 11-12-2014, 17:40   #9
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Re: Engine flushing

Quote:
Originally Posted by Canuck_123 View Post
Hello from a fellow Aloha 32 owner (#15 built in 1983)!!

I've only owned mine since this summer so haven't tried flushing the coolant yet, but here's an idea... Is yours set up like mine with the hot water heater under the SB quarterberth? If like mine, it uses the engine coolant in a heat exchanger to heat the water when the engine is running and as such has a supply and return hose running to it. These would be much easier to access than working in the engine compartment so you could catch the old coolant in a bucket there relatively easily...

I'd appreciate it if you'd update this post once you've done the work so I could learn off of you since this is something I should do in the spring.

Cheers,
Don
Our water heater is actually under the port side settee, but isn't plumbed into the engine yet. Your suggestion does give me a pretty good idea though, I think I could probably take off the bypass loop (the one I'd remove to plumb in the water heater), then hook a hose to one side to pump water in, and another hose on the other side to catch the water. Then I can just flush the engine like you would on a car. I think I'll just get a 5 gallon bucket with a few gallons of water in it and a spare bilge pump.. I think I can make this work anyway.

Quote:
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Why are you using distilled water?
So I'm not adding any contaminants/minerals/etc to the cooling system. What would you use?
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Old 11-12-2014, 17:44   #10
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Re: Engine flushing

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Originally Posted by lifeofreilly57 View Post
If your flushing then using some type of flushing fluid to remove scale and sludge you would definitely want to make sure you get all the residue out.
Most modern diesels and most older ones have drains on the block as well as on the heat exchangers, if your going that far it would be wise to drain those as well prior to adding new antifreeze/water mix.
Not sure what your using as a flush but plain old white vinegar works well and it's not harmful to the environment. Warm the engine, drain the existing antifreeze in a controlled manner, put in the vinegar/water mix, run the motor a bit to circulate then shut it off and let it sit for about 1/2 hour. Drain, rinse out with plain water and then drain that out prior to adding your antifreeze mix.
Sure your boat will smell like french fries for a bit but it is less toxic than many of the alternatives.
I've used this to run through outboards run in salt water and also on heat exchangers to demineralize them from time to time.
Muriatic acid works much better for the raw water side of the exchanger but is a pain to dispose of and is much more difficult to work with.
The old antifreeze mix has to go to a hazardous materials disposal facility, it's not good to just throw the jugs in the dumpster.
No matter what you decide to do your better off putting in the extra labor to pull the hoses and drain it correctly, the suggestion to use the water heater connection was a good one but won't get all the antifreeze out unless you have a way to pump clear water back through it to get the last remnants.
I don't remember what I have to flush it with, it's some commercially available radiator cleaner from the auto parts store. Vinegar sounds like a good solution too though. I'm only flushing it bc there's some kind of red sludge in the overflow tank, which I'm assuming is in the rest of the system also, and the boat is running warm. I've already flushed the raw water side of the system, so it should be good to go.

I figured the engine would have a drain plug, I'm just hesitant to pull it since it'll be really difficult to catch everything as it comes out.
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Old 13-12-2014, 13:29   #11
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Re: Engine flushing

You really should pull the drain valves on the lowest part of the engine, provided you have them.

And allow the antifreeze to drain that way build up of scale and stuff will not be surrounding your soft plugs, and rotting them out.
If you drain into the bilge, shut the overboard pump off then suck or pump it into something you can remove.

NEVER, overboard any engine products into the water, overboard discharge of any water in the bilge by law has to have No residue from the engine.


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Old 18-01-2015, 22:13   #12
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Re: Engine flushing

Well, finally got around to doing this. Ended up plumbing in a small bilge pump and used a few 5 gallon buckets and a bunch of distilled water to flush everything out. It seemed to work ok, but still a messy process, think our boat is going to smell like pancakes for a bit now. Managed to keep everything out of the bilge anyway, so that's good. Here's a picture of the setup I used:



The pump is plumbed into the bypass loop for the water heater.

On a side note, once I drained the overflow tank, the sludge that I thought was red ended up being more like brown mud. Anyone have any ideas about that?
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Old 19-01-2015, 08:14   #13
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Re: Engine flushing

Most people don't realize that you have to change coolant/antifreeze from time to time also, after awhile it can break down and become less effective.
Most engine antifreeze/ coolant has a rust inhibitor as well as other components that help with temperature tolerance, etc, etc, it's not a basic as it seems.
I have a bunch of experience with industrial heat exchangers through my profession; the most common source of sludge in those applications is particulate matter from the antifreeze/coolant that breaks down if it flashes to steam in a hot spot and also some byproduct of corrosion. Usually there may be corrosion if the antifreeze/coolant is not kept up to date and has broken down and lost some of it's effectiveness.
Overheating is one major source, try to avoid this condition.
Also in an engine you can get localized hot spots that can produce this same effect, usually around the exhaust valves in the head. There are other contributing factors as well. If the cap on your closed loop system is not working properly you may not have enough pressure in the system, the cap is there to help raise the pressure in the system and with that raise the boiling point. This more than anything increases the boiling point of the coolant, it's a small thing but an important one.
Air in the system is another, if there is air in the system due to insufficient fill or lack of an overflow bottle directly plumbed to the cap you can also produce localized flashing (when the coolant flashes to steam) due to air bubbles in the coolant. The reason you have an overflow bottle plumbed into the system is so that when the coolant heats up and expands it has somewhere to go other than the bilge. Also, when the engine cools and the coolant contracts the coolant in the overflow bottle is drawn back into the system, that is if the overflow bottle has the hose run to the bottom of the bottle, if it is working correctly this will eliminate air from the closed loop system and give you longer coolant life.
Only demineralized water mixed with coolant should be used in a closed loop system, any minerals in tap water can also add to the sludge you see in your system.
Keep it clean, refill with demineralized water/coolant, make sure the cap has the correct pressure rating, keep the air out and the fluid in (with a proper catch bottle) and your system should give you years of dependable service. Oh, and don't forget, change the coolant out periodically, in a boat diesel it usually means about every 3000-5000 hours or 3 years, whichever comes first.
I'm sure I've forgotten something here but I'm sure others will remember if I don't.
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Old 04-02-2015, 03:22   #14
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Re: Engine flushing

Hi all
I have read everyone's posts thanks for all the info,
I have two 4 year old Yanmar 4JH4s which run perfectly, I live in Sydney and plan an extensive cruise soon.
I have replaced the coolant twice, I plan on flushing the fresh water side with tap water twice then replace the coolant as per Yanmars recommendations
On the salt water side I thought I would remove the salt water pick up and flush from a bucket with fresh water and maybe add vinegar or Salt Off or acid then flush with fresh water then reconnect to the salt pick up.
What do think? Just fresh water, vinegar,Salt Off or acid?


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Old 04-02-2015, 08:07   #15
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Re: Engine flushing

Quote:
Originally Posted by two fast View Post
Hi all
I have read everyone's posts thanks for all the info,
I have two 4 year old Yanmar 4JH4s which run perfectly, I live in Sydney and plan an extensive cruise soon.
I have replaced the coolant twice, I plan on flushing the fresh water side with tap water twice then replace the coolant as per Yanmars recommendations
On the salt water side I thought I would remove the salt water pick up and flush from a bucket with fresh water and maybe add vinegar or Salt Off or acid then flush with fresh water then reconnect to the salt pick up.
What do think? Just fresh water, vinegar,Salt Off or acid?


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Muriatic acid is the best but should only be used when the heat exchanger has been removed and can be dipped in a pan or bucket, it may not play nice with the other components in the system, hoses, seals, impellers, may not like it. It has a definite reaction with the mineral deposits in the exchanger and tends to bubble and boil so it releases mildly toxic fumes while doing so, not a good idea in a closed system in a confined engine compartment.
When I've done it the way your describing I've used vinegar, it's not as aggressive as muriatic acid but it is also not as harmful to other components or as difficult to dispose of.
Best to warm up everything first, then run fresh water through, then run the vinegar through until it comes out the exhaust and your sure the exchanger is full. Then stop the engine and let it sit for an hour or so, vinegar is milder and takes longer to work.
Flush with fresh and your ready to go.
When using vinegar your boat may smell like fish and chips for a week or so but it's much better than smelling like battery acid for a year or more.
I did it on a Yanmar 3GM years ago and it took about 3-4 gallons of vinegar, your should require about the same.
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