Just got my head back from port/polish and valve job. I'm a little concerned about the valve seals even though all of the chambers passed the vacuum test. If I shine a flashlight from under the head around each valve, I can see cracks of light when looking inside the chambers. If I put a few drops of water inside the chamber, the water very slowly starts to leak through after a few minutes (see pic). If I shoot compressed air around the edges of the valve, I can get the drops of water to bubble (see vid). Is this normal? I expected the valve seals to be air tight. I never performed these tests on the head prior to getting the work done.

So I lapped one of the valves with fine lapping compound and re-tested. No water leak now and the bubbling has reduced. I took the head back to the shop (which by the way deals with a lot of high profile Hondas) where I saw them vacuum test the head with my own eyes. So why do my tests fail? I realize the compressed air test is trying to force a lot more psi through. Should I lap all of the valves? The shop said the head material is hard enough that lapping wouldn't do much. They suggested to run it as is and don't think I should be concerned.

I just don't want to sacrifice any compression, it's an all motor setup, I need all the compression I can get!! Any advice would be helpful..

Pic
http://dmostudio.com/Temp/waterleak.jpg

Video
http://dmostudio.com/Temp/airwatertest.mpg

 

Seats pound in. Some people say they do, some people say they dont. If you do a leakdown test on a head with a fresh VJ that has never been run, it will show higher leakage numbers the first time than it will after a few heat cycles.

 

thanks for the rely, just trying to get some second opinions and thoughts before i install the head. if anyone else has a comment, please post it. thanks!

 

Do you know the seat width that the shop used on your particular VJ?

 

A quick lapping wont hurt, just clean it up real good, the spring tension should be enough to seal the seats.

 

With the proper machine, a good mechanic, and good angles, valves should have no problem seating, most of the time.

imo that’s a lot of bubbles. Do another water test on all the valves but this time use rubbing alcohol instead of water (water may corrode). Also, color the combustion chamber with a dark sharpie marker. This way you don’t have to sit and wait for the leak. Just pour in the alcohol and let it sit for an hour or two. If there’s a leak, the alcohol will erase/smudge the sharpie markings.

I would recommend a light lap on every leak that you find.

Btw, your shop was right when they said the material of the seats in the head was hard but it is not that diamond hard that a lap wouldn’t scratch the surface. I lapped with toothpaste once and had success. Good luck.

 

The seats are very thin now. I'd say about half the width of the stock seats (I'm checking with the shop for specifics). Also, the valves and seats are very smooth after the machining as expected. Lapping roughened up the one seat a bit which eliminated the light shining through and the water leak test. Am I just being paranoid? After all, all of the chambers passed the vacuum test..

 

I worked for 8 years as a cylinder head machinist. Once you expose that head to the heat and pressures of a running condition, the valves will seat themselves on the seats making a better seal than the one you are seeing now. Lapping those valves with fine lapping compound wont hurt if you want some peace of mind, just make sure you clean all the lapping compound out before final assembly.

 

I had the exact same problem.
Had a valve job done from a very reputable shop. Received it and decided to just double check some of the work. Poured some washer fluid in the ports and it slowly drizzled out past the valves. They told me to run it and there shouldnt be a problem.
I took their word for it and it ran fine. Later I did a leakdown test and there was virtually no leakage...So I think youll be ok also

 

thanks PyroProblem and soaringchimp, i went ahead and installed the head. haven't started the car yet but i'm starting to feel a lot better about it. 10s all motor, here i come..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16b18 &raquo;</TD></TR><TR><TD CLASS="quote">thanks PyroProblem and soaringchimp, i went ahead and installed the head. haven't started the car yet but i'm starting to feel a lot better about it. 10s all motor, here i come.. </TD></TR></TABLE>

What, no love for me? I posted the same thing as they did, only 9 minutes after you made this original post.

Oh well.

 

thanks Combustion Contraption!!

 

Just posting some love for combustion contraption as well