Blown Head Gasket Scam Tutorial for Non-Mechanics Part 2
THE NEXT STEP IN PROTECTING YOURSELF FROM A HEAD GASKET SCAM
Now that we’ve gone over the fundamentals of what a blown head gasket is so that you can be adequately informed enough to avoid an expensive head gasket scam, here is another video by the same mechanic from the Pete’s Garage YouTube channel that provides a little added instruction on not just observational, but actual leakage tests mechanics use to accurately diagnose a blown head gasket.
Leakage Tests---There are two types of leakage tests: (1) A type referred to as a “cylinder compression test” that measures the actual compression pressure in a cylinder that indicates whether your cylinder is air-tight enough compared to normal engine specifications. (2) A type referred to as a “leak-down cylinder test” that indicates the rate of air compression loss within a cylinder.
What These Tests Tell You---Firstly, it is important to understand two things: (1) cylinders are not 100% airtight. (2) Leakage from either of the two tests do not always indicate a blown head gasket. There are other ways compressed air can leak from cylinder such as:
• Worn piston rings
• A hole or crack in the piston head or piston skirt
• A crack in the cylinder head or in the block.
• Worn intake or exhaust valve seats or leaky valve faces
Furthermore, you can always expect some level of leakage from these tests---just like your car tires normally leak some air slowly over time because it is not a truly air-tight system. It’s just that it needs to be determined if the leakage is more than would normally be expected based on your engine specs and the age of the engine due to wear; and, where the leakage is coming from so that you will know if this is due to a broken engine component.
While the cylinder compression test can indicate whether or not there is leakage occurring, it is the “leak down cylinder test” that can help identify where the leak might be occurring with respect to the valves, the pistons, or an actual blown head gasket. If the leak is coming from the valves, then it requires a different repair than if the problem lay in the head gasket. If the leak is from a crack in the block, then you will need to consider your options very carefully to either replace the block, or junk the vehicle before putting any serious repair money into it.
One More Important Scam Warning Point---In the video, Pete warns about mechanics coming to you with a blown head gasket diagnosis and telling you that not only do you need a new head gasket installed, but also the surface of the cylinder heads to be resurfaced---which is an expensive and not always a necessary procedure.
While most car owners cannot be expected to tell whether the surface really does need to be resurfaced or not, the owner can question the mechanic on how they’ve determined that the head surface is off by too much for the gasket to compensate for, and what his measurements say supporting this. With this diagnosis, it is a good idea to get a second opinion. If it really is a problem, the mechanic should not balk at letting someone else confirm his measurements.
That said, here is the video in its entirely that will go over all of this in more detail and with visual demonstration.
Avoid Getting Ripped Off - Testing For a Blown Head Gasket, Leak Down Test, Warning Signs
For additional used car articles related to the topic, be sure to check out the following linked articles “Save Thousands Yearly in Scam Car Repairs and Maintenance With This Guide; and, “A Dealership Horror Story That Could Happen To You.”
Timothy Boyer is Torque News automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on Twitter at @TimBoyerWrites for daily automotive-related news.