5 Auto Shops Fail To Diagnose Problem. Then The 6th Mechanic Pulls Out A Dollar And Solves It Instantly: 'Old School Trick'

'My dad taught me this.'

Five Auto Shops Fail To Diagnose Problem

Photo by: Unsplash.com

Mustafa Gatollari

By: Mustafa Gatollari

Feb 9, at 2:00pm ET

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An automotive technician with 30 years of experience was able to successfully diagnose an issue with an owner’s vehicle. And while multiple other shops were stumped by the issue, this talented repair expert was able to Sherlock Holmes the situation; all they needed was a single dollar bill to do it.

The TikTok account Expert Mechanic Tricks (@expertmechanictricks) posted a viral video showcasing a simple yet effective method.

The clip begins with a recording of a car’s muffler sputtering exhaust fumes as the tech holds up a U.S. dollar bill to its back. Upon doing so, the bill begins to curl backwards. Once it’s been rolled, the auto tech then turns the bill upside down and holds it to the muffler before the clip comes to a close.

In a text overlay for the video, the social media account states that this rudimentary hack succeeded where five other auto technicians failed: "Would you think it was crazy if your mechanic walked up and pulled a dollar out of his pocket and diagnosed your car after five other shops couldn’t?"

What Is The ‘Dollar Bill’ Test?

Folks in the comments section of this TikTok expressed their familiarity with this technique. One person penned that this is a quick way to determine if a vehicle may have a "burnt exhaust valve."

Further down in the thread, the Expert Mechanic Tricks’ TikTok account confirmed there was indeed an issue with the vehicle. The reply to its own clip indicates the vehicle has "dirty engine valves from running cheap gas." Additionally, to clarify this point, the video’s creator showed a photo of two valves. One is caked over with a crusty, black substance. The other appears to have only some soot on it.

There have been others who’ve opined about the efficacy of the dollar bill test in order to determine if there’s an issue with your vehicle’s engine valves.

Reddit users in the r/AskMechanics sub replied to a car flipper who saw someone performing this trick on a vehicle they were selling. OP was curious about what such a seemingly random test would accomplish, and other users explained why a potential car buyer would use this tactic.

One person shared a YouTube link, noting that the dollar bill test is a good way to determine whether a vehicle has "sticky valves." While a sheet of paper is used in this video instead of a dollar bill, the logic behind the assessment and what it determines is the same. In a video caption, the YouTuber Wayne M. writes that "sticky engine valves are caused by the build-up of gunk in the engine over time." Furthermore, this prevents the valve from being "able to slide in and out easily when the camshaft pushes on the valve stem," he writes.

Grimy, Lumpy Valve Stems

The same YouTube user also states that this excessive buildup can inhibit the quality of your car’s ride. If a car’s engine valves aren’t functioning properly, this could result in a loss of power in the vehicle. Moreover, your vehicle’s gas mileage may suffer, and it may experience rough idling that becomes more noticeable when you’re resting at a stoplight or parked with the engine keyed on.

Automotive enthusiast Matt Payne, who regularly uploads content to help folks diagnose and fix issues with their cars, also discussed the dollar bill test. Like others, Payne says that this evaluation can determine whether or not a car’s "head gasket or a valve/valve seal" is malfunctioning.

If it isn’t, then the exhaust blowing out from the back of the car will keep the bill "pushed away from the end of the exhaust." Conversely, if there is something wrong with these aforementioned components, then the muffler will more than likely pull "the dollar bill towards the exhaust" with a "sucking force," Payne writes. In his video, Payne performs the test, and the dollar bill intermittently gets brought into the muffler of a vehicle that’s been turned on.

He goes on to state that if people get the same result as in his clip, they should perform an engine compression test.

How Do You Fix Sticky Valves in a Car?

If you’ve performed the dollar bill test or otherwise confirmed that your car’s engine valves may be coated with grime, there are several ways to fix this issue. The effectiveness of these solutions will depend on the condition of your valves. As expounded upon in this Just Answer post, using upper cylinder lubricants and fuel treatments, like Marvel Mystery Oil and Lucas Oil, can help to keep one’s engine clean.

However, if dirty valve heads and carbon or gunk buildup inside an engine go unaddressed for an extended period, these products may not resolve the issue. This Sacramento, California-based auto repair shop states that, over time, poor engine performance, increased exhaust emissions, and engine misfires from dirty valve heads can cause long-term engine damage. To minimize the risk of these issues, the business urges customers to regularly maintain their vehicles.

What do you think?

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Using "quality fuel" and fuel cleaning products and additives, along with driving a car at "optimal operating temperature," can go a long way in promoting engine health, the mechanic shop writes.

Motor1 has reached out to Expert Mechanic Tricks via TikTok direct message for further comment. We will update this story if they respond.

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