Quick Way to Check for Leaky Intake & Exhaust Valves Causing Misfires

This compression tester set is a great tool for performing this test Here-
In this video I show how a simple tool can be used to easily determine where the compression loss is.

[MrGoldman]

I would like to tell you that every time I watch the most wonderful content, I learn something new in a scientific way, mixed with the great experience that you share with your followers from all over the world. Thank you for everything you provide.

[Ashroyer]

Not a Ford guy, but this guy is worth watching. Respect.

[eldadisrael]

Very helpful. I have a 1991 Ford F150 5.0 and there is definately compression exhaust blowback and compression issues. This video explains a lot.

[tinkerwest]

Probably best not to rap on any valve until AFTER initial leak-down test because you may inadvertently correct the issue before diagnosing and are left dumbfounded as to the problem...

[stuckinmygarage]

This method forces you to see and hear your valve operation as well as the rings condition. U may have even misadjusted your rockers and u get to check/feel. I like.

[mccaffery]

That was a GREAT explanation on how to test for bad valves. Thanks!

[spelunkerd]

Interesting work flow, I guess it helps to have an engine that has easy access to valve covers. You already knew this engine needed more work so it was not wasted effort. It would be worth knowing about a bad spring by having the cover off, even in an engine that isn't worth the expense of a full head gasket repair. I know what you mean, it's often easier to watch rockers to decide what part of the cycle each cylinder is on. By removing rockers you delete that part of the equation, and with all valves closed the engine won't be so willing to spin with the compressed air. Also flow through the head gasket to an adjacent cylinder would be less likely to find an open valve. That said, maybe you want to demonstrate head gasket flow between cylinders before pulling the head. Good point, the leak down confirms air flow but doesn't take you much farther, and it's an extra step.

[Orefamilylawncare]

I love how so many "shops" will throw parts at a vehicle with little understanding of diagnostics. The former tech in me asks myself how the hell did they miss this🤦 then again im not a heart surgeon so i cant throw too much shade. Good diagnosis on your part 👍

[martystevens]

Make sure you have the special Ford tools! Like valve spring compressor and lifter bleed-down wrench. OTC has it also Rotunda. Kent-Moore has tools for other cars.

[bartfox]

Did i hear correct ? If air comes out another plug hole its from a leaking head gasket . Did i hear that right ? Or did i miss something ? Thanks for the videos ! They are very informative and well done !

[thomasv]

in this scenario, would the misfire on power balance greatly lessen when driving? I have a miss, not a dead miss, at idle on cylinder 2 on my 5.4 3v, but it dissapears during driving conditions, except at idle. Have ruled out all my secondary ignition stuff, and also smoke tested and vac gauged for vacuum leaks. The engine is newly rebuilt with new heads, but I'm thinking it has to be a valve issue on that cylinder, unless there is unmetered air getting in there somehow.

[misterbulger]

Suspecting this on my 2v 4.6 mustang... coil packs didnt solve the noise. I'll try listening to the cranking. The exhaust occasionally smells a bit so not ruling out a hanging injector... but I'll have to pull the valve cover off and get a better look. It's hard to tell which head to look at tho.

[markmartines]

So did you put a new head on it? What was the fix?

[XORBob]

Great video -- however, I don't know your final diagnosis. I guess this means a bad ring or piston? Air is leaking by into the crankcase and you are hearing it through the PCV line.??

[hunterm.]

So doing it this way it’s kind of like a reverse compression test just a lot more work but a lot more effective lol this test you’ll find whether it’s a intake or exhaust valve

[kacywheatley]

Hi there. You probably won't get this in time, but thought I woild give it a shot. Seems like you know exactly what you're talking about. I am going today at 5 pm to look at a Ford f150. The guy says he thinks there is a valve problem. He has replaced sparkplug and he says its still running ruff. I won't know till tomorrow. He has agreed to allow me to take it for an inspection. Do you know of someone reliable in Thornton Colorado? Thank you so much! I subscribed, because I think I will learn a lot from you. Thanks Again!!!

[fastlife]

This might be a dumb question but do you look up the torque spec for those rockers arms to go back on or it doesn't matter because it has a valve leak either way?

[jjdavila]

I lapped the valves on both the rear and front cylinder banks. My problem is that the front cylinder bank has 3 leaky intake valves. I’ve re-lapped them and eventually replaced them. However, they are still leaking. I’ve hit the top with a mallet so that they seat correctly but no luck. Would this be due to the valve springs? The valve seats?

[karimali]

Any recommendations on a budget scan tool?

I've been maintaining my 2010 f150 myself (5.4 3v) and would love to hear your thoughts on a budget scan tool

[douglasrowden]

when checking for leaky valves with shop air does each cylinder being tested need to be on top dead center on compression stroke