C7.1 Marine Engine Caterpillar

Remember that temperature and pressure work together. When a diagnosis is made of a cooling system problem, temperature and pressure must be checked. Cooling system pressure will have an effect on the cooling system temperature. For an example, refer to Illustration 1. This will show the effect of pressure on the boiling point (steam) of water. This will also show the effect of height above sea level.

Illustration 1	g00286266
Cooling system pressure at specific altitudes and boiling points of water

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Personal injury can result from hot coolant. Any contact with hot coolant or with steam can cause severe burns. Allow cooling system components to cool before the cooling system is drained.

The coolant level must be to the correct level to check the coolant system. The engine must be cold and the engine must not be running.

After the engine is cool, loosen the pressure cap to relieve the pressure out of the cooling system. Then remove the pressure cap.

As a guide, the header tank has a raised lobe inside visible from the neck, which the coolant should not be above.

Test Tools For The Cooling System

Table 1

Required Tools
Part Number	Part Name	Qty
4C-6500	Digital Thermometer	1
8T-2700	Blowby/Air Flow Indicator	1
9U-7400	Multitach Tool Group	1
9S-8140	Pressurizing Pump	1

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Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts. When working on an engine that is running, avoid contact with hot parts and rotating parts.

Illustration 2	g00876179
4C-6500 Digital Thermometer

The 4C-6500 Digital Thermometer is used in the diagnosis of problems that cause overheating or overcooling in the engine. This tool can be used to check the temperature in several areas of the cooling system. The testing procedure is in Tool Operating Manual, NEHS0554.

Illustration 3	g00286369
9S-8140 Pressurizing Pump

The 9S-8140 Pressurizing Pump is used to test the filler caps. This pressurizing pump is also used to pressure test the cooling system for leaks.

Checking the Filler Cap

Table 2

Required Tools
Part Number	Part Name	Qty
9S-8140	Pressurizing Pump	1

One cause for a pressure loss in the cooling system can be a faulty seal on the filler cap.

Illustration 4	g06019479
(1) Sealing surface between the filler cap and header tank.

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Personal injury can result from hot coolant. Any contact with hot coolant or with steam can cause severe burns. Allow cooling system components to cool before the cooling system is drained.

To check for the amount of pressure that opens the filler cap, use the following procedure:

1. After the engine cools, carefully loosen the filler cap. Slowly release the pressure from the cooling system. Then, remove the filler cap.

2. Inspect the pressure cap carefully. Look for damage to the seal. Look for damage to the surface that seals. Remove any debris on the cap, the seal, or the sealing surface.

   Carefully inspect the filler cap. Look for any damage to the seals and to the sealing surface. Inspect the following components for any foreign substances:

   • Filler cap

   • Seal

   • Surface for seal

   Remove any deposits that are found on these items, and remove any material that is found on these items.

3. Install the pressure cap on the 9S-8140 Pressurizing Pump.

4. Observe the exact pressure that opens the filler cap.

5. Compare the pressure to the pressure rating that is found on the top of the filler cap.

6. If the filler cap is damaged, replace the filler cap.

Testing The Cooling System For Leaks

Table 3

Required Tools
Part Number	Part Name	Qty
9S-8140	Pressurizing Pump	1

Use the following procedure to test the cooling system for leaks.

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Personal injury can result from hot coolant. Any contact with hot coolant or with steam can cause severe burns. Allow cooling system components to cool before the cooling system is drained.

1. When the engine has cooled, loosen the filler cap to the first stop. Allow the pressure to release from the cooling system. Then remove the filler cap.

2. Put the 9S-8140 Pressurizing Pump onto the cooling system.

3. Use the pressurizing pump to increase the pressure to an amount of 20 kPa (3 psi) more than the operating pressure of the filler cap.

4. Check all connections and hoses of the cooling system for leaks.

   The cooling system does not have leakage if all the following conditions exist:

   • You do NOT observe any leakage after five minutes.

   • The dial indicator remains constant beyond five minutes.

   The inside of the cooling system has leakage only if the following conditions exist:

   • The reading on the gauge goes down.

   • You do NOT observe any outside leakage.

   Make any repairs, as required.