Marine Diesel Cooling System Upgrade 2020

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
Symptoms: Apparent decrease in water volume at exhaust. Temperature RPM limitation at Wide Open Throttle. Steam from exhaust at idle.
Solution: clean heat exchanger, optional general upgrade.


When I took over Thelonious II four years ago, the boat would run at near seven knots all day at 180 degrees on the engine temperature gauge. Lately, above 2300 rpm, the temperature began to rise. Also, I didn’t like seeing a lot of steam at idle. Our cooling systems send raw water from the heat exchanger into the exhaust system at the exhaust elbow. The water lift muffler accepts the hot exhaust and water, then burps it into the long hose that goes to the transom. The sporadic spray of water and exhaust proves the cooling system is working, which is why we check it every engine start.

Recently I concluded that the volume of water coming out was less than previously. Steam was one indication. There’s a bucket test to see how much water is expelled with the exhaust in, say, one minute. But I had no baseline for such a test. Anyhow, cleaning out the heat exchanger is routine maintenance and mine had not been removed since 2012. Perhaps it was clogged?

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I’ll say. Those fossilized pencil zincs cut flow by at least half. Heat exchangers suffer a buildup of scale over time, and cleaning them requires an acid wash. I’ve used muriatic acid (phosphoric acid is better) in the past, and it’s not difficult to observe the deposits boiling away and control the reaction by eyeball. But this time I wanted a pro to “boil out” the Hx. Times have changed, however, and finding a willing radiator shop was a struggle. Enter Carlos at Blanco Brothers, 446 S Union Ave, Los Angeles, who calls himself the Last of the Mohicans. Fifty bucks and the job done in a day. What happened to radiator shops? “LA County doesn’t like us messing with acid disposal.”

As everyone knows, removing the heat exchanger—even from a 381, one of the larger Ericson models--is jujitsu in a gopher hole. So I determined I might as well replace all the hoses while in there, revise the Isotemp water heater coolant connections and solve its Qest fitting leaks. It’s all just a labor job, but I now understand why the estimates from boat mechanics are high: awkward means time. Some specialty tools really help for this work, notably a small socket wrench to fit the many hose clamps (forget a screwdriver in confined spaces). Some old hoses are fused to their barbs or stubs. For that, a 10-dollar “Drake Off Road 4521 Hose Removal Tool” is a luxury. A heat gun is required too, along with towels for spillage for the inevitable mess of drained fluid, raw water and knuckle blood.

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The old hoses make a satisfying pile. Mine ranged in age from 1997 to 2004, and frankly looked good for another 20 years. But hoses do have a lifespan, and a mere $400 worth of new ones starts the clock all over again.

On Thelonious II the raw water path starts with a through-hull with no exterior screen. A Graco filter assembly is mounted inside to strain the sea water. Mine rarely picks up any weed, but the strainer basket was dirtied by time. The raw water hoses showed about 10 percent constriction by salt buildup--probably not an important impediment to flow.

Sea water is drawn in by an Oberdorfer pump. In the past, I have found heavy salt deposits clogging the pump fittings. The pump is new and so is the impeller, but I did scrape away a 20-percent salt buildup in the bronze hose connectors. My guess is every salt-water boat has such buildup there.

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The Oberdorfer directs raw water to the heat exchanger. It circulates there, absorbing heat from the engine coolant, then exits to an anti-siphon valve tucked high above the waterline. From there the raw water descends to enter the exhaust elbow on the engine. The elbow is hot when running. The point of raw water entry is subject to rust or clogging. Mine was clear, but others have found the source of overheating to be corrosion at that connection.

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The hot exhaust and water mixture then has a short path through 2-inch hose to the waterlift muffler. That hose looked fine, but I could compress it with two fingers. The new hose is hard as a rock. Apparently some boats have a flap valve installed at this point to prevent backflow from the exhaust. The consensus seems to be that such a valve is more trouble than it’s worth, and can be removed if present.

The exhaust then rises from the muffler in a 2-inch hose to the transom exhaust. I left that long hose unchanged, assured now that the raw water path was clear.

On the Universal/Westerbeke 5432 four-cylinder engine the coolant (“antifreeze”) is held in a manifold tank with a pressure cap. The coolant is circulated by a “fresh water” pump on the engine. The hot coolant is cooled by the heat exchanger and routed back into the engine block. The heat can also be used to warm water in the yacht’s drinking water system. Often, or usually, the coolant is diverted directly to the water heater from the heat exchanger before returning to the engine block.

There is an alternate water heater hookup: to connect the heater hoses at the thermostat bypass on the front of the engine. The idea is to put the water heater on a separate path, so the heat exchanger is dedicated to engine-block cooling. Since the pressure of the coolant flow should be the same in either configuration, I don’t quite get the theory. I wanted to make the change for another reason.

The former owner had created a clumsy heat-exchanger-to-water-heater manifold that hung over the transmission like a cloud of bronze. Access to my heat exchanger pencil zinc was already awkward, and the manifold connections made it a struggle.

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Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
(Continued)

The new hookup is straightforward. The short bypass hose on the thermostat housing is removed. Hoses run from those ports directly to the water heater. One hose snakes under the air filter before heading aft. The other, because the engine barb is vertical, rises up to run over the top of the fuel injector lines before paralleling its sister. The hoses, with their necessary slack, are almost seven feet long. Several of our members have the connections this way (that's also the mother link for heat exchanger issues). A good write-up on the thermostat bypass option is here.

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This configuration makes at least one of the new heater hoses the highest point in the system. In imitation of forum member Mike Jacker (“Joliba”), I installed an in-line bleeder valve at that point for easy evacuation of air in the system. They’re hard to find in 5/8th inch. This one was $49 (“RxAuto Easy Bleeder Auto Coolant System Air Remover.”)

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One of the issues that slows progress on jobs like this is sourcing parts. I came to rely on Internet ordering. When Home depot says "6 in stock," it can mean zero in stock. Too many good hardware stores have closed. Three stops to find a simple lead-free ½” brass elbow for the water heater? No, just order on line with free delivery. The exception were the hoses. I needed three diameters, wire-reinforced and not, and the old ones were distorted by time and some the wrong size to begin with. At West Marine I was able to see, touch and compare replacements—more sure-fire than an order from Defender relying on logic and a measuring tape.

This job took a week or so, working some each day. That includes cleanup of the area, painting, and time confirming procedures and sourcing of parts.

When I started the engine, salt water filled the empty heat exchanger and exhaust in less than a minute to produce a hearty belch of sea water at the stern. It was immediately obvious that the volume of water in the exhaust had doubled.

I put five quarts of new coolant in the engine, which was all I could get out when draining it. The reported capacity of the Universal 5432/M40 is 4.5 quarts, which doesn’t take into account a water heater and its new, long hoses.

As soon as the engine started, the coolant level in the manifold tank went down and I was able to add another quart and a half. I ran in gear at 1500 rpms. Engine temp shot up to 180 after 10 minutes, then plunged down to 160. I have a 160-degree thermostat, and tested it in a pot of hot water with a meat thermometer. It opens a little at 160, but not fully until 180 degrees.

I prepared to bleed the coolant lines, but when I opened the new $49 in-line valve, coolant, not air, came out. The engine had bled itself through the open pressure cap despite the long path of the new heater hoses. I hadn't even primed them before connecting.

It took me all afternoon to clean up the tools, debris, soaked towels, paint cans, and fragments of my own skin. But no leaks!

Next day I ran the engine for an hour in the slip and then set out on a sea trial. The temperature gauge never rose above 180 after a hour at 7 knots in calm water, and then some motoring in three-foot swells. Steam was entirely absent at idle.

At 2300 rpms and 6.8 knots: temp 180, no steam.

At 2500 rpms, temp 180, 7.1 knots. That’s the speed when the stern squats and the exhaust is in the water. I don’t run that hard because the hull form makes too much drag, but it’s good to know that the engine temperature pegs at 180 and stays there (I did see steam, perhaps because the exhaust was underwater).

In summary, the solution to my minor overheating was simply servicing the heat exchanger—a periodical necessity for all salt-water boats. But it was good to upgrade the hoses, simplify the water heater path, and tidy up the nether regions of the boat. Patience, not skill, is all that’s required.

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(Also indexed as entry in Thelonious Blog.)
 

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gabriel

Member III
Nice post! You’re the kind a guy I would want to buy a boat from!

PS We can thank our friends in Sacramento for all the needless regulation.
 

David Grimm

Squid!
Christian! Great write up as usual! Just the other day while running wires I caught a glimpse of my water lift muffler wondering what it was. It appears on the 38-200 they started with this part and continued to build the boat around it. :rolleyes:
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
Yes, on the E381 the muffler and hose are what block lazarette access to the heat exchanger. I was surprised to find how easy it is to remove them.
The long 2" exhaust hose pops off the top of the muffler easily, and its end can be temporarily stuck into the cockpit well.
The 2" hose connecting muffler to exhaust elbow comes off easily, too.
Now the four screws of the muffler can be removed and the muffler easily lifted out.
Engine access becomes much better, although unnatural human contortion still required. Adam should have had two elbows per arm, the Designer really cut corners on that one.
 
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Joliba

Contributing Member
Yes, on the E381 the muffler and hose are what block lazarette access to the heat exchanger. I was surprised to find how easy it is to remove them.
The long 2" exhaust hose pops off the top of the muffler easily, and its end stuck can be temporarily stuck into the cockpit well.
The 2" hose connecting muffler to exhaust elbow comes off easily, too.
Now the four screws of the muffler can be removed and the muffler easily lifted out.
Engine access becomes much better, although unnatural human contortion still required. Adam should have had two elbows per arm, the Designer really cut corners on that one.
Great work, Christian. I’ve gone with the 180 degree thermostat. I’m convinced that either thermostat works though everyone seems to be dogmatic in the debate. It’s like politics these days.
David Grimm is right. On the 38-200 the muffler is virtually invisible. MAJOR disassembly of the cockpit lazarette is needed for full access. I still have never seen the entire muffler. In this model, fortunately, the heat exchanger is easily accessible (well relatively so) via removal of the ledge in the aft cabin located directly above the heat exchanger. It’s a secret some new E38-200 owners may not yet have discovered.
Mike Jacker
 

Tin Kicker

Member III
I know vinegar will clean will but iirc it is something like 5% concentration and a lesser acid so it'd probably take a very long time.
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
Big fan of vinegar. My garage smells like a salad. I soaked my Graco assembly overnight, and it removed scale with a little help from a bronze wire brush. But it's slow. A heat exchanger might take weeks and many changes of vinegar. There's no reason not to do this yourself, and I think probing out the tubes individually is required with a gun barrel brush or maybe just a soft dowel. "Barnacle Buster" at WM is mostly phosphoric acid and what I'll use next time, rather than driving 40 miles.
 
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Joliba

Contributing Member
Big fan of vinegar. My garage smells like a salad. I soaked my Graco assembly overnight, and it removed scale with a little bronze-wire brushing. But it's slow. A heat exchanger might take weeks and many changes of vinegar. There's no reason not to do this yourself, and I think probing out the tubes individually is required with a gun barrel brush or maybe just a soft dowel. "Barnacle Buster" at WM is mostly phosphoric acid and what I;ll use next time, rather than driving 40 miles.
A few years ago a mechanic recommended CLR for the heat exchanger. One overnight soaking followed by a second dose had our exchanger looking like new and ready to paint.
 

goldenstate

Member III
Blogs Author
Thank you, this is very informative.

I was just congratulating myself on following the directions printed on my Forespar extendible aluminum whisker pole ("Rinse with white vinegar") that hadn't been extended in a decade or two. But the white vinegar, after a time, did the trick and the pole became in fact, extendible.
 

Tin Kicker

Member III
Thank you, this is very informative.

I was just congratulating myself on following the directions printed on my Forespar extendible aluminum whisker pole ("Rinse with white vinegar") that hadn't been extended in a decade or two. But the white vinegar, after a time, did the trick and the pole became in fact, extendible.
I recognize you are done and not going to take it back apart for now. But for the future, aluminum is a bit different because when done it will corrode, especially exposed to salt water, and needs a surface treatment. The 3 options are anodize (an electric process), two part epoxy (powder coat is best), or Alodine/Iridite (same thing from different companies) and treating only a short time after exposing the bare metal to air.

How bad is this needed? For small items I use Alumiprep and Iridite which come in clear and gold tint. As an example our hatches are anodized in clear and after cleaning my hatch frames to put new lenses in I knew there'd be some bare spots where the old sealant had been scrubbed out. All I had on hand was gold Iridite on hand but the new butyl tape would cover the area. Even though the areas of bare aluminum could not be visually picked out the gold Iridite made them stand out.

If your boat supply doesn't have these, then: https://www.aircraftspruce.com/categories/building_materials/bm/menus/me/metalprep.html
 

Tin Kicker

Member III
I'm sure it was originally but scratches happen. Even the untouched exterior of my hatches picked up some gold areas.
 

goldenstate

Member III
Blogs Author
I'm sure it was originally but scratches happen. Even the untouched exterior of my hatches picked up some gold areas.
The pole is anodized, and has some scratches. I am hoping that by using the pole with some regularity, I will avoid similar freezing problems for the foreseeable future. Approval of a brief blog post is forthcoming:

 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
That should work. I used to wax the sliding parts of my aluminum pole and keep it in a bag. Even so, the end pins still stick and require periodic working and silicone lube.
 
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