alright...if im buying a head...whether D16z6 or B18b....how would i know if the head is good.....and how can you tell a valve is bent???....

if the camshaft is removed and the valves seat well....is that part of it??....thanks...

im a NEWB

 

One simple way to check for proper valve seating is to flip the head over and fill the combustion chamber with water. No leaks=probably good, leak=bad valve. In this case it is easiest to check them with the cams out since all the valves will be closed.

 

i know when the camshaft is out...the valves shut...so i should flip it over and pour some water....and if the water leaks through the valves...tthere bent????

 

Yup. If water will leak out then combustion pressure will definately leak out. If it does not leak water out, it does not guarantee they are perfect, but they are pretty good at least. It's a pretty good, simple, free test.

I suppose you could also pour water into the ports and look for it to leak out. Either way, dry it out well afterward to make sure nothing rusts up. A little WD-40 sprayed out later will help displace water and prevent rust.

I would also look in the ports and check the valve stems and the backside of the valves. Bad seals will leave oil deposites baked on the valve heads. A bent valve can also have odd looking wear marks on the stem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mohudsolo &raquo;</TD></TR><TR><TD CLASS="quote">One simple way to check for proper valve seating is to flip the head over and fill the combustion chamber with water. No leaks=probably good, leak=bad valve. In this case it is easiest to check them with the cams out since all the valves will be closed.</TD></TR></TABLE>


I would not use this advice as a test to look for bent valvesi t is not realiable. Because, a slight run out on the seat or valves can let water leak through. And, if the valve spring tension is weak or carbon on the seat or valves can give a false reading. I would have a local machine shop vaccuum test the integrity of the valves. The machine shop generally charge $30-$50 for the service and get the seller to pay for it.

 

I have to disagree about the test not working reliably. If the springs are weak enough or the valves have that much runout, that it will not retain 3/8" of water, then compression was blowing through really nicely when it ran last. That will ruin the valve and seat. Either way, if water can run through, at the least the head needs a valve job. I assumed the person asking the questions wanted a head that could be bolted up without additional work.

No this is not a perfect test, but it will weed out questionable heads for no cost and a few minutes work with a water bottle. It will work at a swapmeet or junkyard. If practical, I also recommend a machine shop. Unless I knew it was from a low mileage motor and took it off myself, I would probably have a valve job done anyway because I hate doing the same job twice. But that's me.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mohudsolo &raquo;</TD></TR><TR><TD CLASS="quote">I have to disagree about the test not working reliably. If the springs are weak enough or the valves have that much runout, that it will not retain 3/8" of water, then compression was blowing through really nicely when it ran last. That will ruin the valve and seat. Either way, if water can run through, at the least the head needs a valve job. I assumed the person asking the questions wanted a head that could be bolted up without additional work.

No this is not a perfect test, but it will weed out questionable heads for no cost and a few minutes work with a water bottle. It will work at a swapmeet or junkyard. If practical, I also recommend a machine shop. Unless I knew it was from a low mileage motor and took it off myself, I would probably have a valve job done anyway because I hate doing the same job twice. But that's me.</TD></TR></TABLE>

Well....it sounds like you got it all figured out. I guess all machine shop should use this method rather than investing on a machine that is worthless when they can use the water method test for bent valves. Within the 8 years as a tech and build motors, I could have just used your method and not spend customers money on machine shop fee's; and, I quess I did not need a dial indicator to check valve out run and seat . Next time, I'll just use that water method I guess.

 

Do you bring a machine shop to a swap meet or when checking out something being sold by the friend of a friend? Which pocket do you carry it in? Maybe bring a magnaflux machine to check cranks and an x-ray machine to check the head for cracks in the other pocket.

Of course a machine shop is the best way to check. It is not always possible. He was looking for a simple way to avoid buying crap, I gave him one. No it's not perfect. Have a nice day, go your way, I'll go mine.