Rydlyme and temp questions

[Paddy]

Decided to do the Rydlyme flush today. Got a similar setup as RobS posted and went for it. The input line was connected to the water pump side and the return from the exhaust side. Filled a 5 gallon bucket up with fresh water and flushed the water passages for 15 minutes, filling the bucket as needed and allowing the return line to flow out the scuppers.

When the pump completely emptied the bucket, I added 2 gallons of Rydlyme and it started to circulate. The flow was good but the pump seemed to pull faster than the return, so I needed to add fresh water throughout the 3 hour process. The small line to cool the shaft was clamped off with a vise grip. I did 2 hours one way, 1 hour the other way. I let the solution sit for approximately 1 hour of the 3 hours, without the pump on. I left last seasons anodes in, assuming they were gone and I would replace after the flush. For the most part, the water was clean, no major dirt or foaming. For all I know, the previous owner could have just cleaned out the cooling system, so the Rydlyme was not needed. I decided to do it for piece of mind.

On the test ride, the temp got up just over 180, needle was clearing over it, something I don't recall last year. I felt around and all the hoses were cool to the touch, and most of the heat exchanger was cool, but the short fat hose that appears to be connected to the thermostat housing was very hot to the touch, so was the housing. The same side of the heat exchanger was also very hot. As this is the first time I felt around on the Yanmar 6LP, I do not know if this is normal. Thinking of pulling the heat exchanger next weekend, but is it possible to have a partially hung up thermostat? The water pump was replaced last year. At the 3200, the temp held around 185, did not climb throughout the cruise, but again, I don't remember the gauge going that high last season. Boat has 760 hours on it.

Suggestions?

[ScubaPete]

If the hose leading from the thermostat housing to the heat exchanger was hot, then the thermostat must have been open. It is usually closed until the coolant in the engine block heats up, then it opens to circulate coolant through the heat exchanger. Learn the internal circulation pattern through the heat exchanger and you will understand what parts should be hot and what should be cold (learn how the hot coolant flows and how the raw water flows through baffles, channels, tubes, or whatever might be in your heat exchanger).

Get yourself an inexpensive infrared temp measuring gun and take readings all over your engine parts. Write down "normal" temps so you'll learn when something is acting up. I take readings every hour or two while underway just to make sure all is well.

Where do you think the Rydlyme solution was solution was going, if you had to continue to add fresh water throughout the process, thereby diluting your mix? Are you sure you hooked up your input after the water pump, and didn't just pump most of your solution out through the engine's intake through hull?
Leaving the anodes in just adds to the burden that the acid has to oxidize, and weakens your solution even more.

[Paddy]

ScubaPete, I am still scratching my head on the constant need to add water, from what I can tell, as well the pics posted from others, I believe i hooked it up properly, but I can't believe that the entire cooling system holds more than a few gallons. The input was at the raw water pump, connecting to the hose that goes up to the first anode. The return came off the heat exchanger and connects to the mixing elbow, the same hose that has the 3/8 line to cool the shaft. Wrong?

At the start of the process, I put the pump into the bucket and filled up just enough to cover the pump. Water sucked well and rushed out the return hose, but the input continued to outpace the return. The 2 gallons of rydlyme were sucked in and the return line spewed brown foam, but again, the pump would outpace the return so i added 1/2 gallon at a time as needed. Fearful of dilution, I shut it down to sit for 15 minutes at a time, and at initial pump start up, brown water would shoot out, along with minimal debris.

Today, I pulled all 5 anodes. 4 of the five were intact (minimal zinc remaining), the tough to reach one at the front of the exchanger was totally gone. On the ride today, the boat stayed ay 180. I will monitor. Previous owner appeared to be very on top of maintenance, so I'm wondering if he cleaned the cooling system within the past few years.

100% agree with you on the IR gun, will pick one up and start tracking temps. The boat could be fine and I am over observing normal ranges, the weather (and winds) have made it very difficult to get out.

[RobS]

Are you sure your vise grip on the shaft seal cooler hose was effective? That's the only explanation as to losing solution and not being able to see it. On first sign of having to add water I would have properly capped that hose off. The seawater loop is under 3 gallons plus what you need in the bucket to keep the pump submerged and the supply and return hoses full. I think I made a 5 gallon mix and never did add any water throughout the process.

[Paddy]

The vise grip was down pretty tight, so much so that I had to confirm it was not kinked after the 3 hours, but I should have just plugged it instead. Wondering if I didn't fill enough at the beginning (2 gallons Rydlyme / 3 gallons of water) for fear of diluting, but instead (and mistakenly) added up to 2 gallons as the bucket went dry? Since the cooling system was already full of fresh water, I decided to go with the 2 gallons of Rydlyme only, but the return flow didn't keep up and water was needed. Also, I used 5/8 garden hoses instead of washer lines, not sure if that would make a huge difference. I never filled the bucket up to the top, just half way.

[skye peak]

I recently did the same thing to my Cummins "C". I had a cheap bilge pump in a 5 gallon pail of muriatic
diluted 1:4. I made a fitting to pump into the hose that connects the heat exchanger to the wet elbow
and connected the return line to the bucket from the bottom zinc in the after cooler.

The solution was gray and frothy and I let it circulate for a couple of hours. I went for a run to flush all the
acid out of the system and check out the results. Before the flush the engine would "make heat" above
2100 rpm and slowly climb to 200 degrees where I slowed down. After the flush I ran to gov, 2600 rpm
for 10 minutes and the temps stayed rock steady at 175 degrees, I suspect you were losing solution back
thru the raw water pump, as my flush remained at the same level throughout the process.