Excessive Antifreeze Concentrations Can Cause Overheating

All Caterpillar Engines

Most formulated antifreezes contain chemical compounds which rely on water to keep the compounds dissolved. If little or no water is used with antifreeze, the compounds will come out of the solution and build up on hot surfaces. Not only do the deposits result in overheating, but more seriously, they can lead to water pump seal leakage and/or cylinder head cracking.

These compounds will appear as hard, greyish to white deposits, and they may be very smooth or porous. They will normally form on prechambers and the water passages in the cylinder head. See Illustration 1.

Illustration 1. Deposits on prechamber.

These compounds will usually redissolve in water. Follow the “Procedure to Dissolve Deposits”.

Procedure To Dissolve Deposits
1. In order to dissolve these deposits, drain the coolant and fill the cooling system with clear water.

2. Fasten cardboard or light plywood to the radiator on the opposite side of the fan.

3. Start and run the engine at high idle rpm with no load. Allow the temperature of the coolant to increase, but do not exceed 93°C (200°F). The radiator cap is to be set loosely on the filler neck during this operation and load is not to be applied to the engine.

4. After a one hour period, decrease engine speed to low idle. Remove the material blocking the radiator and continue to run the engine at low idle for five minutes.

Illustration 2 shows the same prechamber after 30 minutes. Illustration 3 shows the same prechamber after 60 minutes.

Illustration 2. Prechamber after 30 minutes.

5. Stop the engine, drain and discard this water.

6. Replace the water conditioner filter and element if used. If a water conditioner filter and element are not used, add cooling system conditioner to obtain a 3 to 6% concentration after filling the system.

7. Refill the cooling system to the full mark with a 50/50 mixture of clean antifreeze and water for coolant. Note: If bulk antifreeze or mix is used, obtain a sample in a clear sample bottle and let it stand for 30 minutes. If the antifreeze mix is discolored, has particles floating in it or has a layer of darkish material floating on the surface, the mix should be filtered through a filter media before pouring the mix into the cooling system. Start the engine and top off to the full mark once again.

Illustration 3. Prechamber after 60 minutes.

Coolant mixtures in excess of 50% antifreeze should not be used unless temperatures below -34°C (-30°F) are expected. Increase to 60% antifreeze in this case but as the outside air temperatures start to be consistently above 0°C (32°F), switch back to the 50/50 mixture.

Antifreee concentrations in excess of 63% provide less rather than more freeze protection.

A good practice to follow after operating an engine is to return the engine speed to low idle for 5 minutes before shutting the engine down. This reduces the surface temperature of the prechambers, heads and liners minimizing localized boiling at these areas. This will also reduce the plating effect of the compounds in the coolant.

02. March 2019 by sam
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A New Method To Clean And Polish Engine Valve Stems

A special 6V2033 Flap-type Finishing Brush is now available to clean and polish (make smooth) engine valve stems. Formerly, solvent or vibratory cleaning were used on valve stems.

The 6V2033 Brush is 8″ (203 mm) in diameter and 2″ (51 mm) wide. It is made of a fine grade abrasive that will not damage the valve stems. To operate the brush, you need a bench grinder with a speed of 1800 to 3200 rpm (maximum).

To fit the brush on the grinder, use two 6V2032 Adapters. If the grinder shaft is larger than .50″ (12.7 mm), the holes in the adapters can be made larger. For instructions to use the brush and for information on different methods to clean valves, see Form SEBF8002-01 Guidelines For Reusable Parts-Valves and Valve Springs.


The 6V2033 Brush can be used to clean and polish all Caterpillar inlet and exhaust valve stems.

02. March 2019 by sam
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Improved Engine Design Uses Cylinder Block With Spacer Plate And New Crankshaft Thrust Plates

All 3304 and 3306 Engines Made In The U.S.A.

Description of Change: Several improvements have been made to 3304 and 3306 Engines starting with the serial numbers shown in the chart.

… A new cylinder block uses a spacer plate instead of counterbores for the cylinder liners, and has a number of other changes to increase the strength of the block casting. The spacer plate design is similar to the design used on other Caterpillar engines.

… A new cylinder head is used with the new cylinder block. The new cylinder head has a different design of the oil passage to the valve mechanism. The supply of oil to the valve mechanism now flows through a hollow dowel, which has two O-ring seals to prevent leakage.

… New valve mechanism groups use new rocker shaft assemblies with a new bracket. The new bracket has a passage to permit oil flow from the hollow dowel to the rocker arm shaft. An O-ring seal is installed in the bracket to keep oil out of the area around the head bolt.

… Because the new cylinder block has no openings in the side, a new covers group has less covers, gaskets and bolts.

… Water seals are used with the new spacer plate. These seals are similar to those used on other spacer plate engines, but are orange in color for identification. (Some of the seals first used were gray).

… The crankshaft is not changed, but new thrust plates are used with the new cylinder block. The new thrust plates are thicker and have a tab (ear) to prevent wrong installation, which has caused damage to some engines. Since the cylinder block is machined for the thrust plate thickness and tabs, only the new thrust plates can be used with the new block. Thrust plates are available to permit installation of earlier, wide journal crankshafts in the new cylinder block. See the chart “Thrust Plate Application”.

Adaptable To: All earlier engines when the necessary parts are used together, as shown in the parts chart. The new cylinder head is adaptable to the former cylinder block, but the former cylinder head is not adaptable to the new cylinder block.

02. March 2019 by sam
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Why Engines Are Damaged By Fuel Sulfur

In the past 30 years, fuel sulfur wear in engines has been minimized through the use of correct lubricants, adherence to the correct oil change intervals, and the efforts of the fuel refiners. Recently, we have been receiving reports that fuel sulfur wear is increasing. Many of today’s servicemen and machine operators are not familiar with this type of wear. This article answers some of the questions most frequently asked by engine owners, operators and service personnel.

1. What causes fuel sulfur wear?

Fuel sulfur wear is caused by the corrosive effect of sulfuric acid formed from combustion gases. An explanation of this corrosive wear appears in the February 5, 1979 Service Magazine. (March 7, 1979 Engine News.)

2. How do you recognize fuel sulfur wear?

It causes severe ring and liner wear, plus wear in the exhaust valve guides. Unlike abrasive wear, there will be little or no crankshaft wear. Bearing damage can result from foreign material bypassing the soot-filled oil filters. In very bad cases the bearing surface could show pits.

3. How can fuel sulfur wear be eliminated?

It probably never will be. As long as crude oils contain sulfur, this type of wear can be a problem. But, if you must use high sulfur fuel (and, there will be times and areas where its use cannot be avoided) engine damage can be minimized:

First, through the use of the correct lubricant to protect and clean engine parts. Caterpillar recommends the use of CD quality oil.

Second, by more frequent oil changes. For 30 years Caterpillar has recommended that the oil be changed at ONE-HALF NORMAL OIL CHANGE INTERVALS whenever the sulfur content in the fuel is between .4% and 1%.

4. How can we know we have a CD oil?

Oil quality and type have to be assured by the oil supplier. You can obtain the suppliers’ brand names for CD oil by using Caterpillar Form GEG05044-02, which lists the various oil brands and their quality.

5. Why is there more wear due to sulfur in the past 2 years?

There are several causes:

A. Diesel fuel standards in most countries have always permitted 1% fuel sulfur. However, in the past, fuel suppliers have provided a product under this limit. Now, it is doubtful whether refiners can continue to supply lower sulfur fuel while sulfur increases in the crude supply. Many are now supplying fuel containing almost 1% sulfur.
B. Many users have neglected to change oil according to our recommendations. They had little trouble as long as fuel sulfur was near .6%. Now, with fuel sulfur between .8% and 1.1%, they are experiencing considerable trouble.
C. U.S. and European contractors are moving into jobs in areas with lower quality fuels. Until maintenance practices (such as oil changes) are adjustd to local conditions, heavy wear occurs.
D. If high sulfur fuel is used in an engine with high oil consumption, you may get by with no problems if the shorter change intervals are not used because the continued additions of new oil keep the existing oil in good condition. If a rebuilt engine or a new machine is used with the same extended oil change intervals, problems will result. The new or rebuilt engine will not require much oil addition. This allows the oil condition to deteriorate seriously with the extended change intervals.

6. Why is there so much difference between .5% fuel sulfur and 1.0% fuel sulfur?

Wear is caused by sulfuric acid. The formation of sulfuric acid depends on condensation of sulfur trioxide gas. The condensation point (dew point) varies with the sulfur percentage.

At .4% to .5% sulfur range most of the sulfur trioxide passes out of the engine as gas. As sulfur percentage increases, the dew point becomes higher than engine operating temperature so more acid condenses. Therefore, it is most important to keep the engine cooling system temperature as high as possible and not less than 165°F (75°C).

The wear caused by sulfur, therefore, does not follow a straight line variation. Wear when using fuel with 1% sulfur is at least four times as severe as .5% sulfur.

7. How do I determine the fuel sulfur percentage in fuels available in our service area?

Ask the fuel supplier. He should get this information for you. Use Caterpillar Form SEHS7067 which lists fuel standards and see if any apply to your area. If none of the standards apply, assume you are using 1% fuel sulfur Or, contact the refineries. If possible, have a private laboratory make a test for fuel sulfur. Use test procedures ASTM D1552, D1266, or D129. Fuel sulfur cannot be measured with litmus paper or any simple process.

8. Why are some engines affected much more severely than others?

The ratio of oil sump capacity to horsepower cannot be kept constant for all machines.

For example, the D6D Tractor uses the Caterpillar 3306 Engine with a turbocharger. Thus, the Cat standard oil change interval of 250 hours for turbocharged engines is recommended, even though the engine is set for 140 HP. This engine in the similar 3306 Industrial version can have an approved setting of 250 HP, but uses the same oil pan (sump) and the oil change interval is also 250 hours. When the oil pan is designed for 250 HP and the same pan size is used on the same engine at 140 HP, the engine with the low HP setting will consume considerably less fuel, and therefore considerably less sulfur, than the same engine with the higher HP setting.

It is not possible to select the optimum oil change interval for all applications. We recommend the standard, easy-to-remember oil change intervals of 250 hours for turbocharged engines and 500 hours for naturally aspirated engines. However, it is important to remember that all engines will not respond similarly to the longer oil change intervals when high sulfur fuels are used.

9. Why is the fuel sulfur problem not universal?

The United States and Canada have always removed fuel sulfur. Most Japanese users burn kerosene. Scandanavian countries have supplied .5% sulfur fuel. Now, many countries in Europe are specifying that fuel for land use can only have .5% sulfur. Therefore, these areas have a minimum of potential for trouble with land-based equipment. At sea, all areas could be a problem since land-based standards do not apply to seaports.

10. Do some types of engine applications experience more difficulty than others?

Not really, but the engines in fishing and railroad service usually have longer oil change intervals than other types of service. The fishing industry tends to change oil at the end of each trip. Railroads follow mileage or date change periods. Neither method may relate the change period to the actual oil condition. These applications also idle the engine for long periods, so lower engine temperatures can add to their problem.

11. Can we monitor oil condition?

Yes. Use ASTM procedure D664 to monitor the Total Base Number (TBN). It should not be less than one. Change oil with TBN 1 to 2. Dealers equipped with infrared oil analysis equipment can monitor percent of sulfur in the used oil. If ASTM procedure D2896 is used, a TBN of 3 must be used as the condemning minumum since there is a difference in readout between ASTM D6643 and ASTM D2896. These numbers are applicable for fuel sulfur up to 1%.

12. What is Total Base Number?

It is a measure of the alkalinity of the oil. The alkalinity tends to neutralize the acid products from the fuel sulfur. If the TBN value reaches zero, a strong acid number (SAN) occurs and the attack is very severe.

13. Do new oils have a Total Base Number?

Yes, new CD oils will have a TBN value generally between 7 and 15.

14. Are there other oils that might be used to combat fuel sulfur?

The marine industry has used special marine oils. At this time we do not have experience with these oils. Also, when high TBN marine oil is used with low sulfur, ring stickage occurs. The marine oils do not follow the automotive CD classification system, so until we know more we cannot make a general recommendation.

We hope you find this series of questions and answers informative and see that this information reaches personnel responsible for engine maintenance. It is necessary for all concerned to adjust oil change intervals to the fuel quality being used since there is no improvement in fuel quality likely at this time.

If severe wear is encountered, high fuel sulfur, oil change intervals that are too long, or cooling system temperatures that are too low can be suspected. However, there are other causes for engine wear, so a complete investigation should include the following considerations:

1. Abrasive wear. Look for presence of silicon in oil analysis, dust in inlet manifold, or sand particles in oil pan.
2. Freon gas. Where engines are used to power a refrigerant compressor or in a room with refrigeration equipment, look for freon gas leaks. Freon entering an engine through the air cleaner causes extreme wear.
3. Exhaust gas recirculation. Check on engine installations to be sure exhaust gases are not reentering the engine through the air inlet. Recirculating exhaust gas can cause oil deterioration and corrosion of the inlet manifold. Corrosion particles will then enter the engine.
4. Excessive cooling. More and more diesel engines have a water cooled aftercooler between the turbocharger and inlet manifold to cool the compressed air. When the aftercooler is cooled independently from the engine jacket cooling system, be sure the temperature of the water that leaves the aftercooler is above the dew point of the ambient air. Use a drain valve on the inlet manifold or elbow to periodically drain water which can accumulate while idling. The larger Caterpillar marine engines are equipped with these drain valves.
5. Water leaks inside air aftercoolers. This permits water to enter the engine and increases corrosion and wear.
6. High temperature of air entering engine.
7. Engine overloading or higher than rated engine power settings.

02. March 2019 by sam
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Fuel Sulfur-Your Diesel’s Silent Enemy

The problem of wear caused by sulfur in diesel fuel is serious. At this time, there are confirmed reports of increasing amounts of sulfur in today’s crude oils, particularly outside the United States and Canada and in coastal areas. Equipment users can expect to experience this wear at one time or another in the future.

A new full-color brochure entitled “Fuel Sulfur–Your Diesel’s Silent Enemy,” Form SEBD0526, is available to help users reduce fuel sulfur damage to their diesel engines. The brochure tells what fuel sulfur wear is and why it is on the increase. It also describes the symptoms of fuel sulfur damage and tells what can be done to keep engine damage to a minimum.

02. March 2019 by sam
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Vacuum Tester Checks For Leaks Between Valve Face and Seat

The FT1741 Vacuum Tester can be used to check for leaks between the valve face and the seat on cylinder heads.

The vacuum tester can be used after the valves and seats are ground and the valve springs are assembled. To use the tester attach the correct adapter to the vacuum pump handle. With the vacuum pump on, place the adapter over the valve. Make sure that the adapter seal is in full contact with the combustion surface of the cylinder head. If the gauge shows less than 68 kPa (20 inches Hg) vacuum, the seal is not good. Tap the stem of the valve with a soft tip hammer and test again. If the gauge shows a wrong reading a second time regrind the valve face and seat.

The FT1741 Vacuum Tester can be used to check all cylinder heads.

02. March 2019 by sam
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Check For Interference Between Water Temperature Regulator And Cylinder Head Bore

3300 Series Engines

Reports indicate that some 3300 Series Engines with 7N208 Water Temperature Regulators have experienced overcooling or cooling system pressure surges. In many cases this problem is caused by interference between the water temperature regulator guide tabs and the bore in the cylinder head. Interference occurs when the guide tabs are bent outward. When the guide tabs are bent slightly inward, there is no chance of the interference between the tabs and the cylinder head.

Location of guide tabs on 7N208 Water Temperature Regulator.

02. March 2019 by sam
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3300 Engine Front Single Lip Silicone Rubber (5S6296) Crankshaft Seal Group

Illustration 3 shows a seal with a single silicone rubber sealing lip.

02. March 2019 by sam
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3300 Engine Rear (4W452) Hydrodynamic Crankshaft Seal Group

This seal has hydrodynamic grooves in its sealing lip (see Illustration 1). These grooves move lubrication oil back into the engine crankcase as the crankshaft turns. There is an additional lip without grooves on the flywheel side of the seal. This lip acts like a dust lip to prevent small particles or debris from contacting the inner seal lip. The seal offers more durability than the former silicone rubber lip seal group. The 4W452 Crankshaft Seal Group is a direct replacement for the former 1N3216 Crankshaft Seal Group.

Illustration 1. Cross section of hydrodynamic seal.

The 3300 Family of engines have an oil shelf on the flywheel housing and an oil slinger on the flywheel. When the flywheel housings are partially wet with oil, the single lip crankshaft seal is used. The oil shelf and oil slinger “throw” the oil away from the seal area. See Illustration 2.

Illustration 2. 3300 Rear crankshaft area.

02. March 2019 by sam
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Three different designs of 7S3161 Valve Lifter.

There has been some customer concern regarding the use of Remanufactured exhaust valves with Remanufactured cylinder heads in certain applications. The decision to use NEW exhaust valves in Remanufactured cylinder heads will enable the customer to choose Remanufactured cylinder head groups with greater confidence. This will provide the customer with the maximum exhaust valve life expected from a quality Remanufactured product.

Since September 1, 1990, all Caterpillar Remanufactured cylinder heads have been assembled with NEW exhaust valves. The cylinder head part numbers will NOT change. Date codes of 9/90 and later will identify those heads with the new exhaust valves. The date code is stamped near the remanufactured part number on the cylinder head.

Date Updated -08/10/1990

02. March 2019 by sam
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