Marinucci: Leak diagnosis demands precautions, patience

Successful leak diagnosis may demand more patience and attention to detail than harried service personnel realize. Here are some practical tips borne of experience.

Troubleshooting automotive leaks such as oil, coolant, transmission fluid and refrigerant sometimes frustrate well-meaning service personnel — including sales professionals as well as technicians.

Feeling pressured to hustle a repair job through the bays in record time is not — and never has been — a solid foundation for successful diagnosis and repair. And this certainly applies to leak detection on a variety of automotive systems.

What's more, leak detection is unpopular with some techs simply because it's been a stressful, frustrating exercise on previous jobs. Some techs tell me that they welcome a leak check assignment like they welcome a skin rash.

However, when I politely press these techs for more information, the most-meaningful detail they provide is that the motorist — and, in turn, the service writer — expected a miracle. Basically, they wanted instant answers.

The fact is that troubleshooting leaks simply may require more patience than anyone in the customer lounge or at the service counter expected.

For example, the location and nature of a leak may spread liquid over a relatively large area. The most time-efficient step here may be to rinse off the work area with something such as brake cleaner or soap and water. Then run the engine again and recheck the area.

I don't know how many Tire Business readers have chased the source of leaks, but my experience has been that the initial clean-operation may be vital.

Without it, I can't confidently tell if the leak originated above or below a particular gasket or component.

What's more, the path that the leaking fluid travels may fool you.

Suppose the leak is an oil-based fluid such as engine oil, transmission fluid or power-steering fluid; imagine that the tech has rinsed off the work area. Sometimes, dusting the area with baby powder or aerosol foot powder quickly highlights the leak source.

The tech must run the engine again and possibly include a road test, but the effectiveness of this old-time powder trick may pleasantly surprise everyone at your tire dealership or service shop.

Beware, though, because the car owner may have to drive the vehicle for some period of time before the leak reappears. This may happen whether you have dusted the outside of the engine with powder or put a leak-detection dye inside it.

During my travels, I have observed that leak-detection dye has become increasingly popular among techs in all kinds of service facilities. A competent tech equipped with a high-quality dye test kit can do first-rate leak detection — period. Personally, I also have had great results with leak-detection dye.

However, some techs may waste time troubleshooting leaks for an unexpected reason: Dye residue from a previous leak repair is confusing the diagnosis.

Let me recap the dye technique in case some readers aren't familiar with it. Dye contains material that will fluoresce when a tech shines an ultraviolet (UV) light on it.

Suppose engine oil carries some leak-detection dye out through a leaking gasket. Then a tech shines an appropriate UV light onto the work area, energizing or activating the dye.

Depending upon the brand of dye and the system you are testing, the dye will appear as a distinctive color.

For example, the activated dye may look green, lime green, yellow-brown, etc., but typically the dye contrasts itself vividly against the area adjacent to a leak.

Following a leak repair, thoroughly rinsing off dye residue is shop policy in some — but not all — service shops and tire dealerships.

Therefore, dye residue from a previous diagnosis may "fluoresce," creating a false positive result when one of your techs searches for a leak.

For your information, some techs rinse off residue with a cleaner made by the dye manufacturer; others clean up with common, aerosol brake cleaner.

Coach service salespeople to collect as much vehicle history as possible. Suppose a motorist asks you to investigate a leak of some kind. If that's the case, ask if any leak repairs were made in the past.

Then inquire about the potential use of leak-detection dyes on the vehicle. For all you know, that motorist may remember such a detail — or have that information on a work order stowed in a vehicle repair file at home.

On the other hand, a car owner may be wholly unaware of the vehicle's history.

Remember that some service managers build extra time into a leak diagnosis for an initial inspection with a UV light. For one thing, try to rinse off the work area — and any dye residue — as well as practically possible.

Then proceed with caution when using dye on the diagnosis at hand.