I think my shop sees more older and high-mileage vehicles than most. Within the past few months, I have seen more internal engine problems and failures than usual.
Maybe it's the extended life, coolant/antifreeze being used, or due to the quality of the metal; or it's the use of dissimilar metals; or maybe it´s just my imagination.
If your shop performs services such as emission repairs, drivability diagnostics and tune-ups, it still is important that you have a competent understanding of how to test and diagnose internal engine problems. Let me cite an example of what can happen.
A vehicle that is 8 years old with 105,000 miles on it comes into your shop and is running a little rough. The malfunction indicator light is on, so your technician checks it out and pulls codes from the computer that indicate a misfire. He then determines that the spark plugs are original, the wires are arcing and are leaving burn marks in the metal, and the air filter is dirty.
The fuel filter also looks to be original. The coolant/antifreeze looks rusty and has low pH, indicating high acidic levels. The service manager takes the technician's findings, contacts the customer to sell the needed services and secures the job.
All the work is performed and then—BAM. When the vehicle is started, it still runs rough, the engine light returns, and the same misfire codes return. Now everyone is looking at each other saying, “What did we do wrong?”
Surely, a vehicle with original wires and spark plugs at over 100,000 miles should have them replaced if the engine is misfiring, right? Well, yes, assuming the engine is sound internally. So what should a shop do prior to performing such repairs?
First and foremost, never assume anything. Even when a vehicle is in obvious need of repairs such as spark plugs or wires, we must perform pre-repair diagnostic checks, as well as perform checks during the repairs, and, in many cases, following the services performed.
Let's realize that a majority of the vehicles today have spark plugs whose service life is 100,000 miles or longer. Depending on how a vehicle is maintained and driven, it would not be unusual to see head gasket failures or severe engine wear at the same mileage. Let's start with some basic checks.
If the oil is found to be low a quart or two, you know the oil level is not being properly maintained between changes. Most customers are not checking their oil between changes, and in an engine with high mileage, it would not be unusual for the engine to consume oil.
So correct the oil level. Check for excessive engine blow-by (a good indication of cylinder, piston and ring wear).
Additionally, check the coolant/antifreeze level. Engines that consume coolant/antifreeze but have no obvious leaks are often in the early stages of a head gasket failure.
When you check coolant/antifreeze, test the acidity level and keep in mind that coolant/antifreeze has permanent protection for boil-over.
However, over time, coolant/antifreeze will become acidic and high acidity levels will corrode metals in the cooling system, particularly the head gasket.
If a car is using coolant/antifreeze or is found low in coolant/antifreeze, I recommend a block/dye test, which detects combustible gases within the cooling system.
A positive test result characteristically indicates a failure in the head gasket or a cracked head.
Another test prior to major repairs would be a vacuum test. This may expose a weakness in the engine's integrity. A uniform pulse is what you want to see during this test. This is very helpful and simple to do on many engines but can be quite tricky on others.
All of this could take a substantial amount of time depending on the year, make, model and engine configuration. It is a small price to pay compared to performing services on an engine that needs extensive internal repairs. All the external parts in the world will not make it run correctly.
Bob Richey is owner-operator of Richey Inc./Goodyear Tire Center in Bellevue, Pa. This article, which first appeared in the Tire Dealers Association of Western Pennsylvania's newsletter, has been edited for length and clarity and is used by permission.