Water Testing Cylinder Heads to Diagnose Compression Issues

In this video I show you how to water and air pressure test your cylinder heads for valve seating issues right on your bench. Be sure to blow out the excess water and spray WD-40 onto valve stems after testing.

[vettepurist]

One of the better videos on this technic I’ve seen here on YouTube! Nicely done.

[DaveW_googleplus]

This really helped me confirm the problem I suspected with my exhaust valve. I tried another method, but there were no results. I watched this video then ran out and tried it on my cylinder head immediately. Sure enough, the test confirmed the valves were leaking on the cylinder that had low compression!

[MIkhailCruverov]

Old guy told me to do this a year ago and wanted to verify how to do it. Pretty much as I expected. Very easy. Thanks.

[bobstout]

Excellent demo! I'm buying some used 454 heads and this is the perfect test to try before I buy! Thanks!

[jimzivny]

Water works ok, I've found alcohol or unleaded gas is thinner and has less surface tension, it will flow through spaces water will not. Just a thought

[radmansa]

Wow! I definitely learnt something new, I am working on my 1.6 CVH motor this weekend and will do this test on the head. I have an efi head that I am fitting on my carb cvh unit to convert from carb to efi, Thanks for sharing

[Chris-iwup]

you are a genius with this test. I'm just curious how many bars were able to be pulled out with such leaks.?

[randyscrafts]

Nice. Never thought of doing it this I'm just a weekend mechanic, at best.

[BulliKid]

Is that signs of bad seat or bent valve not closing?

[MrJerrysaxx]

Since the pressure required to force leakage past a minuscule gap is usually only obtained under full piston compression, the water/ petrol leak test is only conclusive if the valve seats are properly wrecked. How do I know? Following piston collisions on inlet valves on an Alfa 105 engineI can report the liquids revealed nothing, apparently no leaks. My head guy said swap all the valves, especially the inlets. Sure enough, there was evidence of carbon tracking past the seats on the swapped inlet valves. Remember, the piston pressure will be around 150psi, not atmospheric pressure.

[martystevens]

When you hit those springs, I started to hear a song!

[christanehrhart]

What are the next steps to take if you determine your valves are leaking?

[ajdoti]

How do you dry the port out after if there is no leaks and your putting it back on the block?

[Defundemorats]

What running condition was that head causing a rough idle or complete misfire backfire through intake etc? It is my assumption that many valves leak but I cannot determine when too much is too much

[vitamin_si]

Could leaks on those cause my coolant to bubble and my car to overheat?

[himeedajew]

Very insightful vid. I just dont understand a) why not do the light test 1st. Takes seconds vs this way. And 2nd why would you use water over wd, diesel, or gas? Water is much thicker than petrol....light test then petrol test in my opinion.

[wyattandwill]

Worst case scenario and the heads need more work than resurfacing, hope my local machine shop will cost less to restore them than it would be to buy new heads. However, I saw something about how certain types of heads can't be resurfaced if they're damaged in a certain way.

[dannypalmer]

Seems the leak is always near the hot plug? 😮

[Clamjammer]

Hey man I have a question for you!! I just diagnosed my crown Victoria misfire! Cylinder 4 on this 2v 4.6 my cam follower fell off ! Why would this happen ? I was able to reinstall it with a flathead screwdriver, no problem. I then checked compression on this cylinder and while the other cylinders tested at190-200psi and held there well. This cylinder (4)only got to 90 psi. A wet test brought it up to 190psi. A friend says”yep, bad rings needs a rebuild”. I dont believe it. The car has 40k miles on it. Should I be lookin for something else ? I’m a bit of a novice with auto repairs. With the cylinder on the compression stroke(not top dead center) I shot air into the spark plug well and can feel it freely leaking out of the intake port(I have the intake removed-another issue). Am I missing something ? Should the head be removed? This is my daily driver and only vehicle and I need it running by the time this quarantine crap is over. I also had a coolant leaking internally in the intake manifold. It’s possible it was pulling coolant into this cylinder, even tho cylinder8 was right next to the leaking culprit

[kelvinleong]

Will the cylinders head leak effect oil pressure