valve leaking maybe bad springs

[cpdtwo]

I have a Yanmar 1500d
valves a leaking and I think I may have weak sprongs. Doe any one know the valve free lenth and what the min. is. have a book but it just happens to be on a page my dog chewed up(just like hoework in school) it would be found on page 17. the valves on the other Yanmar are different but it may give me an idea of what mine should be.

 

[DieselPower]

If your valve tips are worn I doubt they will cause a leakage problem. If they are to short (from wear) then they will be out of adjustment and not opening far enough or the opposite of not closing all the way. Have you checked valve adjustment yet? Do the rockers or valve tips look pitted or is metal spalling off?

If your measuring valve length I assume you have the head off already. What do the valve seat's look like?

 

[cpdtwo]

the seats are good. did a flow check using water poured into intake and exust with both there was seepage from the valves. redid the homming on them as i had them out . valves would adjust but seems to not be closing fully

 

[DieselPower]

Sounds like either the seats are severly worn/recesed or the springs are bad or broken and are not providing enough clamping force. I highly doubt it's valve length, I have never seen a valve get longer before.

 

[cpdtwo]

not looking for valve lenth looking for valve spring lenth, the spring lenth is how you tell if it is weak, mine are 3.5" need to know what it say in book

 

[normde2001]

not looking for valve lenth looking for valve spring lenth, the spring lenth is how you tell if it is weak, mine are 3.5" need to know what it say in book

You originally said valve length, but I knew you meant spring length. Don't have the info though.

 

[kenmac]

you could have machine shop check the valve seats .I guess you would need to know valve spring tension for your mod. engine.

 

[cpdtwo]

need to know what the valve spring lenth is because that is what gives you the tension on the valves. could go get springs if I can find the lenth of the springs.

 

[normde2001]

need to know what the valve spring lenth is because that is what gives you the tension on the valves. could go get springs if I can find the lenth of the springs.

Just knowing the spring length won't help you get the correct springs, only tell you if yours have compressed. If in doubt, why not just order a new set of springs for your engine.

 

[DieselPower]

You can not test valve springs by measuring free length. They need to be tested on a valve spring test stand that measures spring resistance at the compressed height.

 

[mark777]

You can not test valve springs by measuring free length. They need to be tested on a valve spring test stand that measures spring resistance at the compressed height.

Exactly!

I must be missing something here...I've done a few Yanmar heads and have never encountered weak springs. I can compress the valve assembly and spring with the palm of my hand after they're assembled. There isn't a radical, or high lift cam, nor high RPM's to cause valve float. Even bent push rods would have the opposite effect of allowing valves to stay open...seems to be one of a few choices. Cracked head/seat, porosity on valve face or seat or a poor grind match between valve faces and seats. All of which would fail a liquid leak through test.

I guess I'm not understanding what's happening.