Compression and Leak Down Testing an Engine with Suspected Internal Mechanical Issues

In this video I show you the basics and idea behind doing a compression test and a cylinder leak down test on an engine with suspected internal mechanical issues causing a loss of compression in one or more cylinders. These tests help in finding the most likely cause of loss of compression like a bad head gasket, warped cylinder head, cracked cylinder head or cracked block. The leak down test can more accurately tell you how much compression you are loosing and whether you have leaking or damaged exhaust or intake valves.

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Disclaimer:
Due to factors beyond the control of Ratchetsand Wrenches, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. Ratchetsand Wrenches assumes no liability for any property or personal damage that may arise from doing a repair on your vehicle after watching any of my repair video's. Due to factors beyond the control of Ratchetsand Wrenches, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Again Any injury, damage or loss that may result from improper use of tools, equipment, or the information contained in this video is the sole responsibility of the user and not Ratchetsand Wrenches.

[ja.g]

I love how you show that you don't need a leak down tester to do a leak down test you can use a simple hose from a compression tester. Amazing! Wish you would come back to YouTube and do some more videos your explanations are always one of the best!

[donovanlucibello]

A very methodical and thorough explanation - thank you for taking the time to share this!

[stuzman]

Good video in showing the compression and leak-down methods. Just wanted to point out a small error. On a four cylinder engine, you would turn the crank 180 degrees between each cylinder, not 90. It's easy to tell how many degrees to turn. For a four stroke engine, it takes two complete turns, (720 degrees) of the crank for all cylinders to fire, doesn't matter how many cylinders. So you would divide 720 degrees by the number of cylinders. In your case, that would be 720/4 = 180 degrees of the crank to bring each cylinder up to TDC. And for one example on an eight cylinder engine, it would be 720/8 = 90 degrees. Keep up the good work!

[blinkskaterkc]

Thanks for the vid! I have a combustion gas tester that works well for testing head gasket leaks. Just changes the color of a liquid when combustion gases are present in coolant reservoir. i'm sure you've seen that too. Also, your advice on the iac valve was spot on. Replaced it and that was the fix.

[markcc]

Thanks a lot for making this video. I've done this at school. You explain it very well than what our instructor did🤣

[MrSupernova]

Exactly what I was looking for! Now to decide if I want to buy these specialized tools and put myself in the position to potentially replace a head gasket. Thanks!!

[ecmjr]

9:07 -- This is why I love your videos (and your videos are very help too).

[grasshopper]

You are the best youtube mechanic, period.

[jhuntosgarage]

Had the same problem with my '06 HHR, turned out to be the block. Can't complain after 200, 000 miles. Thanks for sharing.

[oljames]

..Very, Very Good information!! my son poured 10 gallons of water in an old beater Ford Ranger he had once and asked me what could it be?? Yep, blew the head gasket & warped the head. He scraped it & bought a 95' Honda, it's still running after 10 years...

[utbemo]

Recently subscribed and gotta say I love the videos! To everyone saying that he lost a subscriber, know that this stuff isn't easy, and that he doesn't have to do it if he didn't want to; but this takes time and money and patreon helps him put these videos out. I'm bummed as well that there are patreon exclusive videos, but I'm still glad there's other videos that he releases to the general public!

Thanks for all of your hard work. You have gained another subscriber :)

[SkyNines]

Thanks for the awesome video. I wish I had the money to spare to watch the head gasket job get done on this car. I'll figure something out.

And being a GM engine, I am not at all surprised the head gasket or intake gaskets have failed. Seems to be a running problem with their engines.

[mattmgarza]

LOL----this video is not car specific yet this is the exact engine I'm going to do this test on. That tells me head gasket issues are probably pretty common on this piece of junk. Great video!

[ChrisBrowning]

great video you did a good job of showing how to use the tools

[train]

Absolutely superb sir.thanku.this has helped me loads.stephen from the uk.
Keep up the brilliant work sir

[Gauravkumar-wrwf]

thank you for sharing your time and information..

[donald]

Great Video on checking for blown head gasket. I had same problem on my olds but was the head, due to idot lights that failed to come on.Know I-have Head temp gauge in my car to keep close eye on engine temp.But hey In that Video lets try Camera in the Cyl to see what's going on may save lot time and maybe see the problem also. Thanks From Donald

[ernestdzakobo]

I was thought not to remove all the plugs before running the compression test. Can you kindly explain why you have to remove all the plugs before the test. Will the test results not be affected if all the plugs are removed before running the test on each cylinder?

[PeterHernandez-lgeh]

Have a po302 on my 2006 Subaru sti. Currently troubleshooting

[bobinhouston]

Excellent video! Appreciate it and of great help as I tackle a ‘67 VW bug.