Heat exchanger problems

[sv.antea]

Some years ago I skippered and maintained a boat with a low hour Yanmar four cylinder turbo diesel. On sea trial, the engine ran well but overheated quickly at full throttle. Since everything else checked out, I removed the heat exchanger bundle and had it boiled out by a radiator shop. It wasn't visibly clogged, and afterwards it looked perfectly clean inside and out of the tubes, but there was no improvement to the overheating problem.
Someone suggested that there was a thin tough film coating the outside (coolant side) of the tubes from using too high a concentration of ethylene glycol antifreeze, combined perhaps with one or more overheating events, which the radiator shop treatment failed to remove.
The bundle looked really clean, perhaps with a slight dark discoloration on the outside of the tubes. I was incredulous. But: new heat exchanger bundle was installed and problem was solved.
Does anybody know more about this problem? Is it true? If so, is there a chemical that would clean the ethylene glycol deposit?

[Arcady]

Yes I can attest to that.

We had the same problem with 100 hp Yamaha Turbo four. After a lot of effort trying to solve the problem, I was advised by a Yanmar agent to flush out the system with masonry cleaner and then to use only the best quality antifreeze and ionised water. I did so and we've never had a re-occurrence of the problem since in over five years motoring.

Follow the service recommendations - it really can make all the difference!

[foggysail]

Antifreeze! I'll share an experience with a Ford Taurus, no not a boat. I was not fussy about the antifreeze I used BUT I SHOULD HAVE BEEN especially in an engine that has mixed metals.

Might be worth a Google to get better info. Essentially antifreeze SHOULD have a VERY HIGH electrical resistance to avoid galvanic corrosion INSIDE the engine walls. Also recommended is distilled water mix unless you purchase the antifreeze premixed.

My old Taurus suffered from a timing chain gasket failure because of galvanic corrosion. Simple fix NOT. To repair the problem was going tocost over $1000 labor alone. The water pump, alternator, crank shaft pulley, AC pump all needed to be taken off or moved to get at the timing chain cover. Finally the oil pan had to be removed!

Enough! My only point is if your cooling system contains mixed metals, get do some research on antifreeze before adding anything regardless if the container states--- fine for iron or aluminum engines.

[pbiJim]

Originally Posted by Arcady

Yes I can attest to that.

We had the same problem with 100 hp Yamaha Turbo four. After a lot of effort trying to solve the problem, I was advised by a Yanmar agent to flush out the system with masonry cleaner and then to use only the best quality antifreeze and ionised water. I did so and we've never had a re-occurrence of the problem since in over five years motoring.

Follow the service recommendations - it really can make all the difference!

What is masonry cleaner? Can you list a brand name or an active chemical ingredient?

Also, did you mean deionized water, rather than ionised?

Thanks,
Jim

[sailorchic34]

Originally Posted by pbiJim

What is masonry cleaner? Can you list a brand name or an active chemical ingredient?

Also, did you mean deionized water, rather than ionised?

Thanks,
Jim

also called muriatic acid. Found in the paint departments of the average hardware store. Also good for cleaning calcium off the hull, Used diluted.

[pbiJim]

Originally Posted by sailorchic34

also called muriatic acid. Found in the paint departments of the average hardware store. Also good for cleaning calcium off the hull, Used diluted.

Thank you sailor chick. That name I know, muriatic acid, aka hydrochloric.

[JRM]

Originally Posted by sailorchic34

also called muriatic acid. Found in the paint departments of the average hardware store. Also good for cleaning calcium off the hull, Used diluted.

Muriatic is hydrochloric acid. A strong acid. Also likes to eat metal. It's used by pro radiator shops because it works fast, and time is money.

I did my entire raw water cooling system with phosphoric acid, which I got at my local stone place. All chemical cleaners with any sort of hazmat must have an MSDS which tells you exactly what's in them. Just take in a smart phone and google the name and "MSDS" and you'll get everything you need to pick a product.

There are several advantages of phosphoric over hydrochloric. It's safer for the soft and disparate metals found in most heat exchangers. It won't eat the tubes, or brazing, regardless of how long it's in contact. It loves to eat carbonates. It won't eat rubber like hydrochloric. It's much safer if you spill it on the boat. It's safer if you spill it on yourself. They put food grade phosphoric acid in soda. Depending on where you are you can safely (and sometimes legally even) run it down the sink drain back on land (DISCLAIMER: check first!).

I built my own back flush system and did all the work in place in the engine room. The biggest PIA was getting the buckets of used acid out of the boat and into the back of the truck. The whole thing was cheap, just a small bilge pump, some tubing, and five gallon buckets with lids.

Muriatic works, but it's unforgiving. Give phosphoric a look.

JRM