Coolant flush and fill questions

[4arch]

I am planning to flush my Perkins M50 with Rydlyme using the bucket and 12 volt pump method and a few questions have popped up in my head:

1. Rydlyme concentration - straight from the bottle or cut with water?
2. Procedure - I'm planning on taking one of the water heater hoses off the engine and attaching it to the pump and then putting a temporary hose from the barb on the engine where the hose was removed into the bucket. This should create a loop and the thermostat will be removed. My concern is the engine water (coolant) pump - how do the Rydlyme and subsequent water flushes get into and around the pump and circulated all through the engine and cooling system with the pump's impeller in the way and not running?
3. Coolants - there seem to be a dizzying array of options currently on the market. Color alone doesn't necessarily seem to mean anything anymore and there are also low-toxicity products available. Other than avoiding dex-cool, any specific recommendations on products? This engine has an aluminum block.

 

[thinwater]

I am in the coolant manufacture business with 1 patent.

1. Why flush? If the coolant in an engine has been properly maintained (good coolant, DI water), this should not be required during the life of the engine. The flush can do considerable harm and strips all existing passivising coatings. Unless you have SURE reasons why this is required, don't do it. Excepting the companies that make flushing chemicals (!) no coolant manufacture would recommend the use of Redilime.

3. Dexcool is not a heavy duty coolant, but in fact it gives very good cavitation protection. Another excellent option for aluminum is DELO NF, rated for HD but very similar to Dexcool. G-05 is a good HD choise. In truth, you won't go far wrong with any name-brand product; the performance differences are subtle, no matter what the manual leads you to believe.

3. Non-toxic mean nothing for engine coolant or blackwater systems. While the MAMMAL toxicity of EG is greater than PG, the aquatic toxicity is the same (check MSDSs) and biodegradeability is the same. You won't find PG coolant in any OEM lineup, for a number of functional reasons (doesn't cool as well). The EPA did a huge study on this regarding aircraft deicing.

The greatest practical difference between marine and vehical service is the risk of seawater leaks. Chloride above 50 ppm is a problem, and seawater is ~ 25,000 ppm. Thus, annual changes are recommended by some, though the the coolant can last 5 years in a leak-free environment.

 

[4arch]

1. Why flush? If the coolant in an engine has been properly maintained (good coolant, DI water), this should not be required during the life of the engine. The flush can do considerable harm and strips all existing passivising coatings. Unless you have SURE reasons why this is required, don't do it. Excepting the companies that make flushing chemicals (!) no coolant manufacture would recommend the use of Redilime.

I took the system apart and found a moderately heavy rust colored coating over the entire interior of the heat exchanger manifold with a heavy buildup of sludge of the same color settled to the bottom. The tube stack had a lighter orange color buildup heavily caked around all the tubes. I already soaked the tube stack and got the caked-on debris removed. Now I need to get the sludge out of the lower chambers of the exchanger manifold. I assume cleaning this gunk out will allow the system to perform better than just refilling everything and forgetting about it.

 

[thinwater]

I took the system apart and found a moderately heavy rust colored coating over the entire interior of the heat exchanger manifold with a heavy buildup of sludge of the same color settled to the bottom. The tube stack had a lighter orange color buildup heavily caked around all the tubes. I already soaked the tube stack and got the caked-on debris removed. Now I need to get the sludge out of the lower chambers of the exchanger manifold. I assume cleaning this gunk out will allow the system to perform better than just refilling everything and forgetting about it.

True. Flushing may be needed. Just make CERTAIN you get all of the acid out.

However, this is not normal. In order to generate sludge, something has gone very wrong.
* How long since the last change?
* Test the coolant for chloride (aquarium store test tapes--chloride, not free chlorine). If it is over 50 ppm you have a seawater leak.
* pH. If the coolant is/was green, at least 8. If the coolant was yellow/red, at least 7 as used coolant. If the pH is lower than this, something caused that.
* Any other symptoms? An exhaust leak or any air leak into the system can cause rapid coolant failure. Also any bad grounds (electrolysis).

 

[4arch]

I have only had the boat for 14 months. The PO replaced the water heater two or three years before I bought the boat and that was surely the last time the coolant was replaced - and even then it was probably just a top off. I know the cheap marine water heaters are prone to rusting out. I assume that happened and the PO never cleaned out the sludge. Also a freeze plug on the bottom of the exhaust manifold rusted to the point it had a pinhole leak. That is being addressed as part of this project. When I took the tube stack out, it seemed clear that it had never been removed in 21 years of engine life. That said, other than the buildup on the tubes, it looks good with no signs of deterioration of the metal or any signs of leakage between the sea water and coolant sides of the engine.

 

[Maine Sail]

True. Flushing may be needed. Just make CERTAIN you get all of the acid out.

However, this is not normal. In order to generate sludge, something has gone very wrong.
* How long since the last change?
* Test the coolant for chloride (aquarium store test tapes--chloride, not free chlorine). If it is over 50 ppm you have a seawater leak.
* pH. If the coolant is/was green, at least 8. If the coolant was yellow/red, at least 7 as used coolant. If the pH is lower than this, something caused that.
* Any other symptoms? An exhaust leak or any air leak into the system can cause rapid coolant failure. Also any bad grounds (electrolysis).

I actually find this quite a bit on marine engines. I suspect it has to do with improper mixing of types of antifreeze or the numerous dissimilar metals in the cooling system. Not at all uncommon. doing a Westerbeke when it warms up a bit and it is a mess. owner says it has always had the fluid Westy recommends and it pressure tests perfectly... Owner has had the engine since new....