Removing sludge from heat exchanger-Yanmar

[Dubo]

Has anyone found an effective way to clean the brown sludge out of their heat exchanger(HE)? I am in the process of replacing the coolant and would like to clean this accumulation since it keeps showing up in the overflow reservoir. I'd hate to replace the fluid with this sludge remaining inside. I know there are radiator flushes, but don't know how save they are for Yanmars. The engine is a 3GM30FV. I've considered filling with distilled water only and let it circulate, drain and then refill with coolant. Also, considered a bottle brush shoved into the fill opening, scrub what I could, fill with water and drain. The stuff is easy to remove with physical contact. Or I can just ignore it and refill with new coolant. I searched the forum but didn't find anything specific to removing the sludge without total removal of the HE. You can see the brown sludge through the cap with the cleaned brass showing after I wiped it clean.

 

[smokey73]

Before trying to clean it you might want to figure out what it is. It looks very much like oil that has gotten into the coolant side and "emulsified".

 

[jssailem]

You can take the heat exchanger to a radiator shop. They can flush and clean the unit. Then pressure test the unit and prepare it for next season. Cost me $69 when I did this.

 

[Ralph Johnstone]

I cleaned out my2GM20F HE last winter and replaced the gaskets. Really quite easy and the two blocks look similar in the drawings. This was done only for the interior of the tubes (sea water). The AF side is spotless because of distilled water for refills.

I searched the forum but didn't find anything specific to removing the sludge without total removal of the HE.

That information is 100% incorrect (that's the internet for you) as sludge is removed by flushing the entire system with a chemical cleaner and scale from salt water is removed by removing the HE as it is inside the tubes.

You've got a real collection of sludge in the reservoir. As @smokey73 mentions, is there oil in that sludge ? Take some of the sludge out and be sure it disperses completely in clean water and leaves no greasy residue on your fingers. If it's not greasy, you may want to use a chemical flush. Can't recommend one. How much is in the hoses ? Or in the block ? I suspect it's sludge from hard water. When you refill with AF, use distilled water.

Clean out the interior of the HE after you use the flush. It's a walk in the park if you're careful and it probably needs it. Interior of tubes can be cleaned with a small tube brush. If interior is really dirty and hard, off to the rad shop as per @jssailem .

Coat the new gaskets with NON PETROLEUM grease such as SuperLube for a perfect fit.

 

[Dubo]

Before trying to clean it you might want to figure out what it is. It looks very much like oil that has gotten into the coolant side and "emulsified".

That's an interesting thought. My first guess was rust. Is there a way to determine if it is oil? Scoop some out and put in clean water and see reaction? Feel for oily texture, though AF is oily too? Lab test it? Oil inspection shows no water mixing in.

 

[smokey73]

A lab test would be definitive but I'm not sure it is necessary. Emulsified water in the oil will still feel greasy but then again so does antifreeze to me. Other things might feel oily to. Just doesn't look like rust or scale to me from your picture. Maybe you can try to suck some out, put it in a glass jar with some water and if it floats, it is probably oil. I would think if it is rust it would settle to the bottom. Just a wild guess though.

I only said the "emulsified oil" comment because on an old VW diesel Rabbit I had many many years ago I had some oil in the coolant that looked a lot like that. There was no water in the oil but there was oil in the water that had that characteristic "brown" sludge type look and it did feel oily. If I recall correctly (and that is not a given) when I put my hand on the open radiator cap I could feel "pulsing" which I think indicated a leak from one of the cylinders into the cooling water jacket. Just my recollection from what it looked like and felt.

 

[Ralph Johnstone]

Now let me see if I've got this straight.

You can follow the instructions in post #4 "

As @smokey73 mentions, is there oil in that sludge ? Take some of the sludge out and be sure it disperses completely in clean water and leaves no greasy residue on your fingers.

This would cost $0.00.

OR :

Lab test it?

Send it to a lab for $100 +/- and get the same result.

What am I missing here ?

 

[SycloneDriver]

That sludge might be caused by additive dropout. This can happen when incompatible coolants are mixed. I would try using a standard cooling system flush from an automotive store.

 

[Ralph Johnstone]

That sludge might be caused by additive dropout. This can happen when incompatible coolants are mixed.

Good thought. Looks like a lot of sludge from just hard water or, maybe rust from a lack of corrosion inhibitors in old anti-freeze.

 

[karellen]

I'll second the cooling system flush. Worked well on my 3GM30 that had muddy brown cooling water (suspect previous owner never changed it.)

 

[Ralph Johnstone]

Worked well on my 3GM30 that had muddy brown cooling water

Do you have a brand name ?

 

[Ralph Johnstone]

Coat the new gaskets with NON PETROLEUM grease such as SuperLube for a perfect fit.

That should have read "coat the new O rings with NON PETROLEUM grease"

Don't coat the gaskets with grease as their seating surfaces are flat and they will slide laterally. The two O rings sit in bevels and will be slid into their best possible seats.

 

[karellen]

Do you have a brand name ?

Hey Ralph, I didn't use any cleaning chemicals when I did mine. I believe what I did is referred to as a "reverse flush" using a garden hose on low pressure. I tried doing a couple drain and fills prior to that and the coolant still looked like nasty brown mud. At least on my engine, the flush cleaned it out. That was not quite two years ago and my coolant is still bright orange.

 

[Richard19068]

I know there are radiator flushes, but don't know how save they are for Yanmars. The engine is a 3GM30FV.

Okay, does anyone know if an over the counter radiator flush would be safe and effective for a 3GM30FV?

 

[SycloneDriver]

Okay, does anyone know if an over the counter radiator flush would be safe and effective for a 3GM30FV?

I have used the standard Prestone brand flush on my Volvo Penta and my Yanmar. I figure if the coolant is safe, the flush probably is too. The cooling systems are made up of many of the same metals and rubber. I bet the bottle states that it's "safe for all cooling systems".

 

[Ralph Johnstone]

Agreed.

I would think if Prestone flush will handle an automotive engine safely, it will handle a small diesel.

 

[JoeWhite]

I would use only distilled water to flush as it does not contain any impurities that may damage the seals on the water pump. House water contains salt and fine particles of mud that may scratch the surfaces of the water pump and cause it to leak.

 

[seadaddler]

I know friends who used Preston auto flush and happy.

 

[Justin_NSA]

I used Blue Devil radiator flush back in '20. I think I will drain it again next spring and see what comes out.

winterization/routine maintenance project complete!

I don't know why, but I'm feeling really proud of myself. I was able to flush and fill the freshwater, aka heat exchange closed loop system coolant on my Hunter's Yanmar 2GM20F. I had no idea when it was done last. Not in the few years I've owned her. I did a lot of researching here on SBO of...

forums.sailboatowners.com

 

[MikeHoncho]

I have the same deposits on the underside of my cap when I check levels. It breaks down when rubbing it between your fingers which isn’t indicative of a petroleum product. It appears soluble.