Head Gasket Failure Diagnosis - Misfire code P0300 (P0301, P0302, P0303, P0304, P0305, P0306)

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In this video, we show you how to use a Cylinder Leak Down Tester in conjunction with a Cooling System Pressure Tester on a 3rd generation Toyota 4Runner to verify either a bad head gasket or cracked head. The 5vz-fe engine shown in this video is also used in the 1st generation Tacoma, Tundra and T100 pickup trucks. Cylinder pressure can be lost through several means. It could be getting past worn or cracked piston rings. It could be getting past a worn valve seat or a burnt valve. It could be getting past a bad head gasket into a coolant jacket, oil gallery, or to a neighboring cylinder. It could be escaping through a crack in the head.

Using a cooling system pressure tester in conjunction with a cylinder leak down tester is for when you suspect the integrity of the cylinder has been compromised and cylinder pressure is leaking into a cooling jacket.

Telltale Signs Are:
*Excessive Exhaust Smoke upon a cold start (smoke smells sweet)
*You're losing coolant but there's no obvious leak (engine is consuming the coolant)
*Engine is misfiring

Sean was getting a General Misfire P0300 Check Engine trouble code on his 2002 4runner. You may experience a specific cylinder engine code i.e. P0303 would point to the number 3 cylinder, a P0304 would point to the number 4 cylinder etc.

An alternative method to verifying you have failed head gasket or cracked head allowing combustion pressure to escape into a coolant jacket is by using a Combustion Leak Test Kit. The kit works by detecting the presence of exhaust gases in the engine's cooling system. Here's a link to a kit I own: https://amzn.to/3lQauT8 This kit can verify a head gasket or cracked head issue, but it can't tell you which cylinder is compromised like the method we use in the video does.


HELPFUL TOOLS
If you're looking for other tools not used in this video, check out Timmy's Master Tool List.
https://www.amazon.com/shop/timmythet...

*1/4" and 3/8" Flex Head Ratchet Set - (Great functional ratchets. Flex head with 120 engagement points is a serious game changer) https://amzn.to/2ql8nNA

*5/8” Magnetic Swivel Spark Plug Sockets w/ Extension Set - (Nice magnetic socket set with built-in swivels and extensions of different lengths) https://amzn.to/2HRUmQx

*OTC 5605 Deluxe Compression Tester - (Used to perform an initial compression test of all cylinders) https://amzn.to/2vNRRbu

*OTC 5609 Cylinder Leak Down Tester - (Used with the Harbor Freight 21 gallon air compressor) https://amzn.to/36WrQnb

*Digital Borescope Camera - (Used to view inside the cylinder)
https://amzn.to/2R8NwH0

*Harbor Freight 21 Gallon 175 PSI Air Compressor - (Used with Cylinder Leak Down Tester)
https://www.harborfreight.com/21-gall...

*Cooling System Pressure Tester - (The Matco one I own looks just like this one sold by Harbor Freight. Is it the same quality? Who knows.)
https://www.harborfreight.com/radiato...

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