| Auto Cooling-System Repair -- Visual Inspection and Pressure Test |
From "Weekend Mechanic"
episode WKM-102 |
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In this episode, DIY Weekend Mechanic Bruce Bonebrake shows how to diagnose problems with your car's cooling system, repair a faulty water pump and radiator, and perform a general overhaul -- replacing worn belts, hoses, thermostat, etc. The problem: Our project vehicle, a late-model work pickup exhibits overheating during operation. After the truck has been running for a while, the needle on the temperature gauge slowly creeps up toward the red zone. When the truck is in the garage, coolant is found to be slowly leaking out onto garage floor. Note: If an engine is allowed to run without coolant, it will overheat severely and can cause permanent or irreparable damage. Metal parts can actually fuse together, and ultimately ruin the engine. If your vehicle begins to overheat, pull over and allow the engine to cool down. Once the engine has cooled, check to be sure you have water and coolant in your system.
DIY Difficulty Rating for Repair: A thorough check and straightforward repair to the cooling system should take about a day and a half. We give it a difficulty rating of 2 on a 5-point intermediate-level scale. In our demonstration, the repair took about 9 hours over a period of two days. Project time may vary considerably depending on make, model and specific parts being repaired.
Important: Included below are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. Always consult your vehicle's service manual when undertaking significant automotive repairs.
In addition to standard auto-mechanic's tools, some of the specialty tools that will be needed for this project include cooling-system pressure tester, replacement coolant and drain pan.
Visual Inspection of Cooling System
- The initial phase of this project is a visual inspection under the hood. Look for any obvious leaks and check the condition of the drive belt and hoses. In our inspection, a leak was identified by coolant pooling on the garage floor. Also, hoses were found to be in worn condition, and one was almost completely collapsed (figure A).
- Visually inspect the radiator -- the heart of the cooling system that serves to dissipate the heat generated by the engine. Making certain that the engine is completely cool, remove the cap (figure B) and check inside the neck of the radiator for the presence of rust and debris.
- In our demonstration, the radiator was found to be in poor condition, and rust was visible inside. Rather than attempt a radiator repair, it was deemed more practical to simply replace the radiator with a new one. The radiator cap will be replaced at the same time.
- Check the coolant recovery tank (figure C) for leaks and for the condition of the coolant. Again, coolant that is brown or rusty looking indicates a cooling system in need of service.
- Our visual inspection also revealed a visible leak on a weep hole at the water pump. Weep holes are purposely built into the water pump as an alert to internal failure. This indicated that the water pump should be replaced also.
- The drive belt that runs the water pump was also inspected for tightness and condition (figure D).
- The visual inspection indicated that repair of this cooling system should include replacement of the radiator, water pump, hoses, radiator cap, belt and coolant.
Pressure Test
Before beginning the repairs, conduct a pressure test to ensure that there are no additional leaks that were overlooked in the visual inspection. - A pressure-tester can be purchased from an auto center for around $35.
- The pressure tester has an adapter on the end of the hose that connects to the radiator in the same place as the radiator cap (figure E). Install the cap and tighten it down securely.
- The pressure tester has a gauge (figure F) with color bands indicating the pressure levels that are appropriate for specific vehicles and cooling systems. Your radiator cap should indicate the appropriate pressure for your system. You can also get this information from your vehicle's owners or service manual.
- Our project vehicle had a 13-pound system, indicated by the blue bar on the gauge.
- With the tester connected, increase the pressure to the cooling system -- using the hand pump -- until the needle on the gauge reaches the appropriate bar.
- Leave the tester on the system, and check it in about 5 minutes. If the system is sealed properly, it should hold pressure, and the needle will not drop significantly. If the system has a leak -- as ours did -- the needle will quickly drop down out of the acceptable range (figure G).
- With pressure applied using the pressure tester, an additional leak was identified in the area of the bypass hose that hooks to the water pump (shown in figure H at the tip of the screwdriver).
In the segment that follows, the faulty water pump is removed and inspected.
RESOURCES :
The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books
How Cars Work
Author: Tom Newton
ISBN: 0966862309
Publisher: Black Apple Press
Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896
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