Coolant system cleaning?

[soopad00pa]

New to me 1984 Catalina 30 powered with the original M30/5424...

Flushing the VERY junky fresh water system and wondering if those acid cleaner compounds are a good idea? I've read and heard broscience that implies they'll destroy an old heat exchanger. Or unclog a pinhole leak that had been scaled over and allow for sea and fresh to mix. Or blah blah blah.

Of course, others say they're the tits pajamas.

I know almost nothing about engines, so I beseech you, hivemind - yay or nay?

(currently doesn't seem to be either sea water or fuel or oil in the fresh water system.)

[MarkSF]

It's possible, in an old, neglected cooling system, that radiator flush might reveal some leaks. But it's probably a good thing, so that you can fix them properly. Do you really want to be depending on an engine where only corrosion and silt are keeping the coolant in?

I'd have a good look inside the header tank and so on, and if everything appears to have been well maintained, skip the flush. Just change the coolant. Best to drain, fill with distilled water, drain, and refill if the coolant type is unknown.

Are you trying to fix a particular problem?

Does your 5424 still have the original 2.5" heat exchanger? If so, cooling will always be marginal, and no amount of flushing will help. I upgraded mine to a 3.5" one.

Also you need to fix the terrible wiring between the engine and panel. It contains two pairs of trailer connectors which can be the cause of many woes. Write up here (and a lot of other great info) :

https://pbase.com/mainecruising/univ...arness_upgrade

In my case those connectors were the cause of an intermittent no-start condition.

[ranger58sb]

I've used both Barnacle Buster and Rydlyme for cleaning. Both work well.

If a heat exchanger is about to fail, the acid can maybe help it fail faster. But if a heat exchanger about to fail, you need a real fix anyway.

Were it me... with an old engine... I'd at least inspect and maybe consider pro-actively replacing all of the hoses and clamps on the engine as well as the heat exchanger, and maybe the raw water pump(and certainly the impeller). And I'd flush the freshwater coolant system and replace the coolant with new. Plus engine and gear oil/filter change, fuel filter change, coolant filter change.... IOW, fix/replace everything at once while creating a known service baseline...

-Chris

[thinwater]

I spent many years as a very active member on the ASTM committee that governed coolants and cleaners. The sort version:

• If you maintain the coolant properly, the system will never get gunked up. Distilled water, proper coolant, proper change intervals.
• Cleaners can work, but unless the need is proven (actual overheating) they can do more harm than good. Regular use is an invention of the marketing department. This was the opinion of most committee members.

The problem is two fold:

• They strip all surface passivization and coatings.
• They are very hard to completely flush from the engine. Even low ppm is problematic.

Unless the engine is actually running hot... don't. Change coolant as recommended. (No more than 2 years in marine engines because of seawater contamination--even ppm are bad.) If you do, flush with a LOT of water, several times. Rydlyme and BB both have ingredients that are NOT used in coolants because they are bad. For example, Rydlyme is based on hydrochloride acid (about 25000 ppm as used, IIRC). The limit for chloride in coolants is 25ppm and 75 ppm is the condemning limit; since there are always hard-to-flush-pockets, most likely the coolant would be well above the condemning limit even after several flushes! How about them apples.

[MarkSF]

If the engine still has the 2.5" heat exchanger, it's almost certainly running a little hot - and a flush won't help, as the problem is that the heat exchanger is undersized.

It might not be noticeable in winter, when the cooling water is colder. In summer, anything over 2K rpm will have the temperature creeping up.

I put a 3.5" one in, and can now run at full throttle with engine temp staying right at nominal.

[ranger58sb]

Originally Posted by thinwater

Rydlyme and BB both have ingredients that are NOT used in coolants because they are bad.

Ummm, yes, and I think neither Barnacle Buster nor Rydlyme are suitable for flushing freshwater (antifreeze) cooling systems... only for seawater systems (heat exchangers, ACs, etc.).

Our previous main engines were Cummins, for example, and Cummins/Fleetguard makes a product they recommend for periodically flushing the freshwater cooling system... before replacing coolant.

-Chris

[soopad00pa]

Thanks all.

Done lots of changing stuff including all filters, fluids, and some tubing. Gotta buy more tubing and an elbow, but I'm onboard with as fresh of a start as I can get. Turns out I also need an alternator and the bigger issue - crack in the exhaust manifold. Interestingly there doesn't seem to be any kind of cross contamination. Oil is good. Fuel is good. Sea water is good. But exhaust fumes come out of the fill cap of the manifold. Based on the history relayed to me by the previous owner, this has been an undiscovered issue for years. It 'just ran hot' no matter what they tried.

Googling tells me a new manifold is a unicorn and my mechanic tells me that while pulling it off isn't an enormous task, welding old cast iron is a crap shoot.

I have no idea what size my heat exchanger is. Is that an OD measurement?

[more]

best safe Coolant system cleaning is citrus acid .time for cleaning 24 +h

warm engine release water fill with distilled water with 1kg citrus aid.
use outside pump for circulation,because danger chips can damage engine pump.

[MarkSF]

This is a worry. Exhaust manifold failure is the most common reason for the death of older Universal engines. Let us known if you find a solution.