Frothy The Coolant

On the run up to Christmas, as Frosty the Snowman played joyfully on our speakers, something else was cooking inside our engine. Read on. 

As I mentioned on a previous post, back in San Carlos I did preventative maintenance to our engine, and soon afterwards it started to show precisely the symptoms I was trying to avoid. Something went wrong.

Pesto has a large Volvo Penta main engine. We use it a lot, for nearly half of our passage time is spent either motoring or motor sailing. And I try to be ahead of the engine’s maintenance curve, to keep it working smoothly and delivering its great utility to us without glitches. It was under this philosophy that I did a preventative maintenance “project” in San Carlos which consisted of revamping the engine’s cooling system. Not that it was overheating, no. But I didn’t know what was the last time this system had been serviced. Moreover, the warm waters of the Sea of Cortez would likely accelerate the formation of deposits inside of it.

Anyway, the project started. Some parts of the system were removed and professionally cleaned (example – the Heat Exchanger). Others were even replaced by factory originals (example – the Exhaust Elbow). Possibly the most trivial task of this whole project was the replacement of the engine’s coolant. But the devil thrives in the details, and it did so big time on this case.

Coolant replacement is a normal regular maintenance task for combustion engines, pretty much like regular oil changes. Our Volvo Penta’s coolant was already looking old, and it was time to replace it. In order to give the engine “the best”, I flushed the system with clean fresh water a couple times, and then filled it with a pre-mixed, “modern technology” red coolant. All seemed alright for the 30 minutes I ran the engine to test it afterwards, and I switched it off happy that afternoon, feeling proud of an important maintenance task crossed off my to-do list.

A couple months later, upon our departure to La Cruz, the engine started to overheat as soon as we left Marina Real. Heck, it had never overheated before, and precisely now, after I had beefed up its cooling system, it did so. I felt confused, and even betrayed for a moment. But reason took over and I realized something must had been done wrong during the project. The engine was in fact “speaking to me”. I went to the engine room and noticed the coolant had changed color – from its originally clear bright red aspect to a murky brownish thing. Worse yet, it was forming a frothy creamy foam inside the expansion tank. Not pretty (I would find out later that Frothy The Coolant wasn’t the sole responsible for the overheating phenomenon, but that’s another story).

So, there we were, floating free at the middle of Bahia Algodones for the first time in five months, an overheating engine, and an ebbing tide that would soon make the channel back into Marina Real too shallow for us. I was instantly tempted to turn back, but there were trade offs to consider. We were on a tight timeline to reach La Cruz, and if we turned back at that stage to troubleshoot the engine that would certainly mean us NOT getting to La Cruz on time for Christmas. Besides, the forecast was for plenty of wind for most of the way there. And finally, despite the engine, Pesto IS a sailing boat ! So, I made the unorthodox decision to keep going. We switched off the engine, set our sails, and shot off towards La Cruz pushed by a brisk breeze.

On the approach to La Cruz the wind died and we anxiously switched the engine on again. I monitored the temperature gauge constantly, as well as other aspects of the engine, and realized it was still safe to use it, despite the higher temperatures. By the time we reached La Cruz, the coolant had become even creamier, with a thick froth built up inside the expansion tank.

 

The muddy sludge that formed inside the engine. Looking at this now - and all the trouble I went through to remove this thing from our engine - I realize I should have used the other finger for this picture.
The muddy sludge that formed inside the engine. Looking at this now – and all the trouble I went through to remove this thing from our engine – I realize I should have used the other finger for this picture.

Luckily, there is a wealth of knowledge available right on the docks here, and it didn’t take long to find out valuable clues of might had gone wrong.

As it turns out, the coolant type I bought has been the subject of controversy, lawsuits and even a major class action in the US nearly a decade ago. This product was developed with a new technology aimed at dramatically increasing the time between replacements. Based on the little research I did, when this coolant is used on engines that were designed for it, it delivers on the promise. However – and this has been the center of the controversy and lawsuits –  when used on engines not built for it, bad things may happen. Truth or not, that fact is that the symptoms described on this article from 2007 almost perfectly matched what I was seeing on our poor Volvo Penta: the coolant turned into a muddy color, and formed a rusty sludge (the “froth” that was disrespectfully floating inside the expansion tank).

A sample taken from inside the heat exchanger. The creamy froth floating above, and a lot of sediments seating at the bottom of the container.
A sample taken from inside the heat exchanger. The creamy froth floating above, and a lot of sediments seating at the bottom of the container.

So, while the turkey baked slowly inside the oven, and “Frosty The Snowman” played on Pesto’s speakers, I energetically proceeded to remove Frothy The Coolant from inside our mighty engine. I took samples of it, and it came indeed with a lot of sediments and sludge – a horrific signal that the coolant might have been eating away internal components of the engine. I then proceeded to flush the engine with purified drinking water. It took 5 complete flushes (with new, clean water in every time) to eliminate the sludge from inside the system in a satisfactory manner. I then filled it with the “good old” Green coolant, based on ethylene glycol, as it should have been since the beginning. In a ways, our engine room also got a Christmas decoration of its own, with the Green “Good Old Coolant” inside the engines, and the Red “Frothy the Coolant” on jugs, as it was flushed out.

One of the engine's thermostats. Even after having being cleaned thoroughly, there was still a bit of red sludge attached to its upper ring.
One of the engine’s thermostats. Even after having being cleaned thoroughly, there was still a bit of red sludge attached to its upper ring.

It was s slow process, since every flush cycle required me to run the engine up to regular temperature to ensure the thermostats opened and the cleaning water flowed through the entire system, and them wait for the engine and water to cool down again, until I could evacuate it and pour in the water for the new cycle. And when I finished with the main engine, I did it all over again with the generator. By the time all was over, we were well into 2016 already. Frosty The Snowman had already melted away, but Frothy The Coolant was still sitting inside the engine room, awaiting to be discarded.

Pesto-08Jan16-034
Halfway through the flushes, the accumulated sludge in the system was still forming some froth inside the expansion tank

At the end of all this, we now have bright, clean Green coolant flowing through our engines, and the piece of mind that they are not being eaten away from inside.

Oh, and one thing is for sure: Frothy The Coolant WON’T be back in here another day. Never ever again !

2 Replies to “Frothy The Coolant”

  1. Learned 2 things from this adventure. First I guess the finger thing is an international gesture and go for the green!

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