FAQ’s: Cooling

It is best if you remove the thermostat and clamp off the by-pass loop so that all of the acid solution goes through the block and head. However, many folks do just warm the engine up first and then draw in the acid, and claim to have good success.

We’ve never heard of any damage of any kind resulting from the acid flush procedure, no doubt due to the very mild concentration of acid. – Updated: January 3, 2004

If I’m doing the math correctly, you’re only able to pump one gallon per minute through your cooling system. In most cases, blockages of this magnitude are not the result of general clogging of cooling jackets, but rather serious localized restrictions within a fitting.

Since you’re experiencing a restriction to total flow, I would remove the hose to the inlet of your thermostat housing (directly above the starter) and run the engine for a few seconds. If you have good flow there, reconnect the hose and remove the one from behind the manifold and run the engine for a few more seconds. If you have good flow there, reconnect the hose and remove the end of the hose that connects to the exhaust system and run the engine again. By this process, you should be able to identify the segment of your system that is blocked, and limit the fittings to check. – Updated: January 3, 2004

You only need the spacer if the top of the head is badly corroded, to the point that the base of the thermostat won’t be able to prevent water from forcing its way up and around the thermostat. In these cases, the thermostat will see the top of the spacer as a new head and work just fine.

There are also some aftermarket thermostats that require the spacer due to the fact that their operating mechanism is a bit too long and they contact the floor of the cooling jacket within the head.

It’s important to note that the spacer will require the use of manifold studs which are long enough to accommodate the thickness of the spacer.

You will not need a spacer for our bronze housing. – Updated: January 3, 2004

Our system actually requires no space above the engine. The very top of the fill neck of the heat exchanger itself should be an inch or so above the highest point in the engine’s cooling system, simply to avoid water spilling out of the exchanger when you remove the fill cap.

Many people are misled by the photo of our freshwater cooling kit in our online catalog, which seems to suggest that the exchanger is somehow mounted on the front of the engine. This is not the case. The heat exchanger can be mounted in any convenient location. In very small boats, the heat exchanger is sometimes mounted as far away as the lazarette.

In cases where folks have a hot water heater on their boat, the heat exchanger is usually mounted beside the hot water heater, and plumbed in series with its heating coils. – Updated: December 22, 2003

Freeze-out plugs were originally installed over a small ridge cast into the lower part of the hole in the block, head or manifold. Here are your options for repair, starting with the least invasive and leading to the more complicated procedures:

1) If the plug has some dome shape remaining, you could take a flat punch (like maybe a 1/2″ bolt) and flatten the plug. These plugs are designed to seal around their OD by flattening out their dome shape. Flatten the plug by pounding in a circular pattern around the center, but not directly in the center. The challenge is to flatten the plug without causing a concave dimple in the center, which would reduce the ultimate outward expansion of the plug. 

2) If the plug is already flat, you may be able to seal it using epoxy of the type West Marine sells in small repair kits. Before using epoxy, be sure to clean the surface of the head and plug extremely well.

3) You can replace the plug with a new one from our online catalog (Product
number: OBLK_14_125) and reseal around its circumference during installation. Old plugs can be removed by drilling a small hole in their center and then inserting a punch and prying the cup out by pounding on the side of the punch. Since the inner circumference of the hole will probably be less than perfect, we recommend the use of JB Weld to seal the new plug. Flatten the new plug as in the first option above.

4) If, after removing the old plug, you discover that the ridge in the casting is deteriorated to the point that it will not support the pounding it will take to seat a new dome shaped plug, you can ream the hole to a slightly larger size and install a “cup” type plug. In our own rebuilding work, we routinely ream holes for the larger plugs (used in the block and head) to 1-1/4″, and to 15/16″ for the smaller plugs (two used in the manifold and one in the head).

5) For on-boat repairs, where poor access prevents repairs involving reaming etc., there are rubber expansion plugs available from many automotive parts stores which may work to seal a hole (at least on a temporary basis) that is too deteriorated to accept a dome type plug without the need to ream the hole. – Updated: December 22, 2003

We’ve had many folks contact us with this concern, and in some cases (and for a variety of reasons), engines have sat all winter without being properly winterized.

There’s really no way to know for sure how much damage (if any) may have occurred to an unwinterized engine that has been subjected to freezing temperatures, until it is started and checked for water leaks. However, it’s equally true that the Atomic 4 is quite forgiving of even relatively hard freezes, so there’s every reason to hope that no damage has been done to this point as a result of the minor episode you’re describing.

Here are some steps you can take which should protect your engine for the rest of the winter:

1) Make an attempt to get a small heater on your boat as soon as possible, and thaw out your engine. If you don’t have electricity at your boat, a small propane space heater that attaches to a 20 pound tank (barbecue grill size) will work well. These heaters (we use them in our shop, and call them “butt heaters”) are available at Home Depot type stores for about $30.

2) If your cooling system has been flushed somewhat regularly, you should be able to remove the two drain plugs in the block, the one in the aft end of the manifold and the one in the bottom of the water pump (all of which are 1/8″ pipe plugs), and drain most of the water from the engine.

3) If you can’t remove the drain plugs, or if you don’t observer much water draining from the water jackets after the drain plugs are removed, you can draw in a gallon of RV antifreeze through a “T” fitting between the raw water through-hull and the water pump, by turning the engine over on the starter. 

Before performing step 3, I would remove the spark plugs so that the starter and battery don’t have to work so hard, and I would also remove the thermostat and clamp off the bypass hose. This precaution will insure that all the antifreeze goes through the block and head before passing over to the manifold and into the exhaust system. By the way, the bypass hose is the one between the “T” fitting in the center of the water jacket side plate and the inlet to the thermostat housing (just above the starter). The short hose from the thermostat housing to the manifold is NOT part of the by-pass system.

IMPORTANT NOTE: Since the engine is not being started, the exhaust will not blow the cooling water out the back of the boat. This means that the RV antifreeze, as well as any water that was already in the block and head, will collect in the water lift muffler. To be certain that the antifreeze and water do not flood the exhaust system, flow back into the exhaust manifold and back into the combustion chambers, I recommend that you disconnect the water hose from the back of the manifold and collect the antifreeze and water in a bucket after it passes through the engine.

After thawing the engine and drawing in the antifreeze, you can inspect the engine for any external sign of water leakage (looking especially at the freeze-out plugs in each end of the block, top of the head and the two in the front face of the manifold) and for any indication of water entering into the crankcase (like milky colored oil). Absent any of these indications, you should be able to rest quite easily until you start the engine in the spring. – Updated: December 10, 2003

This is a good question, and I suppose the answer depends on which expert you ask.

Universal, of course, felt that it was important, since they installed the cap in first place. However, there is a consensus among the current generation of experts with whom we network that the factory configuration might have been a bit of an overkill.

Historically, early model engines had side plates with three 1/4″ holes which directed the incoming water somewhat evenly into the block with respect to fore and aft distribution.

The concern now is that by directing all of the incoming cooling water aft in late model raw water cooled engines, we may tend to give the rear cylinder a “cold shower”. This same rationale is used to explain the fact that the number 4 cylinder (on many engines) tends to have sootier plugs than the other three.

In our own rebuilding operation, we provide a cap with the factory recommended hole facing aft, plus a 1/4″ hole facing toward the manifold, so that some of the incoming water flows through the space between the center two cylinders, and over to the valve side of the engine (which is also the hottest side). We believe that this second hole provides a more even and more effective distribution of incoming raw water.

It should be pointed out, however, that this concern relates mostly to raw water cooled engines, in which case, the incoming water is cold. In the case of freshwater or “enclosed loop” systems, the incoming water is already partially heated, so the factory configuration is much less of an issue.

Finally, if you’re asking this question out of a concern that your distribution cap might be clogged and causing overheating and you’re trying to claw another week or two out of your sailing season, we recommend that you unscrew the “T” fitting, let the cap drop to the bottom of the cooling jacket, re-install the “T”, and then press on to enjoy the rest of your season. In the meantime, having all the incoming water directed toward the center of the block is not likely to create any ill effects for this short period of time. The side plate can be removed later as a winter project. – Updated: November 13, 2003

It appears that the total flow of water through your cooling system has greatly reduced.

When the total flow of cooling water reduces, in addition to the engine overheating, the water sometimes turns to steam when it enters the hot section of the exhaust system. A normal amount of water will overcome the temperature gradient and keep the exhaust piping cool in the immediate area where the water enters the system; small flows will not be able to cool the exhaust enough to prevent steam.

Things that can cause low flow include the water pump itself, a restriction in the discharge of the pump or a restriction in the area of the rear fitting on the manifold. In general, you’re looking for a restriction in any location where total flow would be affected.

A bad thermostat could cause overheating, by not allowing enough cooling water to go through the block and the head. However, a faulty thermostat would not affect total flow, since water would still be free to bypass over the top of the thermostat and leave through the exhaust system (assuming that there were no restrictions to total flow). – Updated: November 13, 2003

I don’t believe that your steam is caused by a crack in the head or a defective gasket. In these cases, the water would first go through your combustion chambers, and you would surely be reporting on poor running of the engine. However, you could have developed a small crack in your manifold water jacket.

If you really are ingesting a small amount of water in through the manifold, it will be rather serious, since it will cause a very thick caramelized brown goo to form on the stems of intake valves and cause them to stick rather soon.

In terms of other possibilities, are you sure that what you’re seeing is steam? In the early part of the season, it is rather common within our northern operation locations for people to report a “vapor” coming out with the exhaust on their boats. This is simply a matter of warm moist air cooling and condensing behind the boat. The problem goes away as soon as the weather warms up a bit.

It would also be important to observe whether or not the steam persists from the first time you start up the engine, or if it only starts after the engine is fully warmed up. If the steam only starts after the engine is fully warmed up, your cooling water flow may have reduced somewhat and is no longer sufficient to keep the hot section of the exhaust system cool where the engine cooling water enters the system, and a small amount of steam may be developing right in the hot section itself. – Updated: November 4, 2003

We have had good results with any general purpose grease that lists marine service (and/or that it is suitable for wheel bearings on boat trailers) in its application guide on the outside of the can.

Grease of this description is available in most local auto parts stores. – Updated: November 4, 2003

You might try putting a little more restriction in the bypass loop. This is the hose running from the “T” fitting in the middle of the water jacket side plate to the inlet of the thermostat housing.

You could try simply crushing the hose a bit using a pair of visegrips to see if it helps. If it does, you could plumb a small ball valve in that loop for a more permanent fix. – Updated: November 4, 2003

There have never been any zinc locations identified by the factory for the Atomic 4. All of the water-jacketed castings were made using a corrosion-resistant alloy that has worked rather well, and which explains why so many of these engines are still around. We have rebuilt engines that have been sea water cooled for over thirty years which had little or no corrosive damage. 

I don’t want to overstate this position, but we find somewhat more corrosion on the very latest engines, which may indicate that the quality control of the alloy may have slipped a bit in the later years. Whenever we do see a lot of corrosion on an engine, we believe that it has a lot to do with whether or not the boat itself was in what is sometimes refered to as a “hot marina”. In general, the same kinds of things that cause thru-hulls, prop shafts, prop struts, etc. to corrode can affect the engine as well. – Updated: November 4, 2003

Engine “overcooling” is usually caused by one of three conditions: 1)water is getting through the thermostat (check for defective thermostat), 2) water is somehow getting around the thermostat (check for deep corrosion on the surface of the head, where the thermostat seats, or on the base of the thermostat housing), or 3) The indicating system is defective. 

Sometimes, overcooling is the unintended consequence of adding too much restriction in the bypass loop, which may have been added (ironically) to cure an overheating problem. Excessive restriction in the bypass loop can overpower the thermostat (forcing water through or around it) even in engines with fairly normal thermostats. 

In these cases, you simply have to reduce the amount of restriction in the bypass loop until the thermostat can regulate temperature normally. – Updated: December 11, 2003

As engines age and cooling passages in the block and head become less than perfectly open (even after flushing), it becomes just as easy for water to flow up through the bypass loop as to flow through the engine. At this point, temperatures may tend to creep up, sometimes as high as 180 degrees. 

At 180 degrees, the normal 140 degree thermostat is fully open and mechanically restricts the flow of bypass water entering through the top of the thermostat housing. In cases where cooling systems are reasonably well maintained, temperatures can be brought down closer to the thermostat’s range by installing a partial restriction in the by-pass loop. – Updated: November 4, 2003

There are three general causes of overheating in late model engines: 1) a restriction somewhere in the system (by far the most common cause), 2) a dirty or malfunctioning thermostat, or 3) a malfunctioning water pump. 

In terms of restrictions, if you have just acquired an engine that appears to have had little or no preventative maintenance performed on its cooling system, the restriction could be partially blocked water jackets in the block, head, or manifold. In this case, a good flushing is in order. 

If the engine has been cooling satisfactorily for several years, the restriction is more likely on the order of seaweed in the raw water intake, or a small piece of water pump impeller lodged somewhere in the system, frequently in one of the elbows on the pump itself. These pieces of impeller can be from a failure that happened several years earlier, and they are particularly frustrating in troubleshooting efforts. They can flop around in an elbow so that for a while they will let water pass quite normally, and then (without warning) they can as easily flop closed and cause a rapid overheating condition. 

In the case of thermostats, they usually simply need to be cleaned. We recommend soaking them in vinegar for a day or two, or diluted household muriatic acid (half water and half acid). To have the best chance of avoiding trouble, thermostats in raw water cooled engines should be cleaned every year or two. 

As a general troubleshooting procedure, it is useful to evaluate the amount of water leaving the boat through the exhaust system during the actual overheating condition. If the flow of water out of the back of the boat is relatively normal, the water pump is clearly working, and water is passing normally through the bypass loop, the manifold and the exhaust system itself. In this case, you can limit your focus to potential restrictions that would prevent water from flowing through the block and head, such as a blockage in the “T” fitting in the water jacket side plate or a stuck thermostat. 

If overheating is accompanied by reduced flow out the back of the boat, you will have to extend your investigation to include water pump failures and restrictions that would affect total flow. These restrictions include blockage of the raw water intake fitting, pieces of impeller in the discharge elbow of the water pump, blockage in the rear fitting of the manifold, etc. – Updated: November 4, 2003

As engines age and cooling passages in the block and head become less than perfectly open (even after flushing), it becomes just as easy for water to flow up through the bypass loop as to flow through the engine. At this point, temperatures will creep up to approximately 180 degrees. At 180 degrees, the normal 140 degree thermostat is fully open and mechanically restricts the flow of by-pass water entering through the top of the thermostat housing. In cases where cooling systems are reasonably well maintained, temperatures can be brought down closer to the thermostat’s range by installing a partial restriction in the bypass loop. 

Universal recognized that, except in very new engines, the bypass type of system did not provide very positive control between the time the thermostat began to open (at 140 degrees), and the time that is was fully open (at 180 degrees). An early service bulletin suggested that the hose barb of the brass elbow in the inlet to the thermostat housing be filled with lead and then opened up by drilling an 1/8” hole through the lead. In our judgment, this procedure causes a bit too much restriction. There are other ways to put a restriction in the bypass loop. Some folks install a small ball valve in the loop which gives an element of control to the restriction. 

Moyer Marine markets a bypass restriction kit which uses a spring loaded check valve to create a nominal 2 to 3 PSI back pressure. This amount of restriction causes a slight preferential flow through the block as the thermostat begins to open to maintain temperature more toward the lower end of the thermostat’s range. 

When designing a restriction for the bypass loop, it does not pay to get greedy. Too much restriction will force water past the thermostat and result in “over-cooling” and carbon buildup will be somewhat accelerated. – Updated: November 4, 2003

In short, without a thermostat to control the flow, all water from the water pump is free to pass through the block and head to cool (or overcool) the engine. However, it is also free to bypass the “T” fitting on the water jacket side plate, go directly through the thermostat housing, directly to the manifold and out through the exhaust system (without cooling the engine at all)! 

In cases where engine temperature is quite normal without a thermostat, it simply means that (purely by coincidence) the head loss between going through the engine versus going through the bypass loop balances out so that the ideal amount of water is taking the path through the block and head rather than bypassing. It is just as common, however, for engines to run too cool, or, in other cases, to run too hot. 

It really is better to use a thermostat in the Atomic 4, and to keep it clean by soaking it in vinegar every season. – Updated: November 4, 2003

Like all internal combustion engines, the Atomic 4 would like to run around 180 degrees. However, the designers were concerned about salt precipitating out of sea water at temperatures much above 150 degrees, so they installed a thermostat rated at 140 degrees, which in most areas will maintain an operating temperature between 150 and 160 degrees (depending on outside water temperature). 

Several years ago, Westerbeke came out with a 180 degree thermostat for people operating in fresh water areas or for engines with fresh water cooling systems installed, particularly in cooler climates (like the Great Lakes, Lake Champlain, etc.). In our experience, the 180 degree thermostats create a few problems in warmer waters where just a small amount of fluctuation in operating conditions can cause temperatures to overshoot into the 200 degree range. Effects of running in the cool range (95 to 100 degrees) include increased carbon buildup on valves and rings. Eventually, both the valves and rings can stick, and compression will suffer. Of the two effects of running too cool, sticky rings are the more difficult to cure. – Updated: November 4, 2003

This re-plumbing scenario works well for increasing the water temperature reaching a hot water heater. As you sort through the steps, you’ll see that the main change involves intercepting the water for the hot water heater as it comes out of the thermostat housing (where it has just been heated by the block and the head), and redirecting the cool bypassing water from the “T” fitting in the center of the water jacket side plate directly to the front fitting on the manifold.

ALTERNATE PLUMBING FOR HOT WATER HEATERS IN LATE MODEL ENGINES:

1) Remove the bypass hose between the “T” fitting in the center of the water jacket side plate and the inlet to the thermostat housing.

2) Install a 3/8″ pipe plug in the inlet to the thermostat housing.

3) Remove the short hose between the thermostat housing and the inlet to the manifold. 

4) Connect a hose from the outlet of the thermostat housing all the way to the inlet of your water heating device.

5) Remove the 90 degree elbow from the front of the manifold, and install a “T” fitting in its place.

6) Connect the return hose from your water heating device to one side of the new “T” fitting in front of your manifold (it doesn’t really matter which leg of the “T” you use in this step).

7) Connect a hose between the outlet of the “T” fitting in the center of the water jacket side plate and the unused leg of the new “T” in front of the manifold.

8) Install a ball valve somewhere in the hose installed in (7) above.

The valve in this new bypass loop should be closed down just enough to provide a small amount of back pressure downstream from the “T” fitting in the center of the water jacket side plate. This back pressure will provide enough preferential flow through the block and head to enable the thermostat to maintain your original temperature. Care should be taken to not close the bypass valve too far, as this will cause overcooling of the engine. – Updated: January 20, 2004