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Thread: Can valve springs age? Lifter issues...

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    Guest Christian's Avatar
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    Can valve springs age? Lifter issues...

    Hi

    I‘m resurrecting my S13 (and this account ^^) and face weird problems related to lifters and open valves.

    I have confirmed the valves are never completely shut by putting one cylinder on TDC and using an adapter in the spark plug hole to blow compressed air in there. Air hissed out on the intake side, so the valves are not 100% shut. I loosened the camshaft to allow the valve spring to relax and bingo - the cylinder is tight.

    Now I can only imagine the lifters are pumped up too high (I used genuine brand new Nissan ones) and keep the valves from completely closing.
    AFAIK they should bleed some oil when pressurized, so I turned the engine until the cam lobes pushed the valves completely open and left it for 2 days - nothing changed.

    Is it possible valve springs get weaker with age and dont manage to squeeze the too high lifters to the correct height? The engine started to do this some years back and got gradually worse. Now it was rebuilt, but is still doing the same - thats why I changed the lifters.

    This is happening on 3 cylinders by the way...

    Cheers
    Christian

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    What do the valve heads look like? There was a bad batch of inlet valves that wear and then leak.

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    Guest Christian's Avatar
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    When the engine was apart everything looked quite tidy. I always used Castrol 10W60.

    The thing is...
    The engine was developing this over the years. Starting with low compression on one cylinder during startup and after a few seconds it ran like a charm.
    Then it gradually got worse and it took longer and longer until all cylinders were firing.

    I expected it to be OK after the engine rebuild, but it seems the new lifters are pumped up too high since the cylinder is sealed once the camshaft is removed and the valve springs are able to relax some more.
    That's why I'm asking about too weak springs.
    AFAIK the lifters should slowly bleed down when pressurized, but even 2 days of full valve spring pressure hasn't moved it a bit. (being a new lifter mind you)

    Cheers
    Christian

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    Dorset & Hants Rep pointz's Avatar
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    Cylinder will never be completely sealed due to blowby.

    How have you determined it's leaking past valves?

    I'm with skyshack that I also suspect it's a valve issue too.

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    Guest Christian's Avatar
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    The engine was rebuilt, so in theory valve seats should be ok, if the builder did a decent job.

    Compression test was extremely low apart from one cylinder - that one was on 12,5 bar which is around 180 PSI.
    Air was hissing past the valves when blowing into the cylinder with compressed air.
    This stopped when loosening the camshaft bolts and removing the camshaft, so the valve seats should be ok.
    In consequence the valves have to still be open even though the cam lobe is on its lowest part and the valves should be closed.

    Yesterday I made some measurements. It could be due to the 2 rebuilds (and regrinds of valve seats and valve heads) the valve stems are sicking out too far towards the camshaft.
    It seems, if I measured accurately, the hydro tappets are completely bottomed out (compressed as much as mechanically possible) and the valves are still opened slightly.
    There is not enough space between the valve stem and the cam lobes to accomodate a bottomed out tappet. About 0,5mm missing on 3 cylinders, which would also fit to one cylinder being perfectly fine (as new, 12,5 bar compression) and 3 being way out.
    The tappets have also been taken out of the engine and checked for free movement of the piston inside - they seem fine as expected being brand new.

    I think the only way to fix this would be to regrind the camshafts to a smaller base circle.
    Does that make any sense?

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    Did the person who did the head work resize the valve length after recutting valve seats and lapping the valves in? If you take off too much material the valve stem will be too long in relation to the valve seat, meaning it does not seal correctly.
    This is solved by removing material from the valve stem, not by regrinding cams!

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    Guest Christian's Avatar
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    I‘m not sure about that, and considering the situation I‘d assume no.
    He didn‘t know it was the 2nd rebuild, so maybe he didn‘t pay attention?

    But since the engine is installed I guess it would be easiest to regrind the camshaft, wouldn‘t it?
    Taking the engine out to shave a bit off the valve stems seems a bit like overkill.

  8. #8
    Dorset & Hants Rep pointz's Avatar
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    Or take it back to whoever built it and tell them to sort it!

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    Quote Originally Posted by Christian View Post
    I‘m not sure about that, and considering the situation I‘d assume no.
    He didn‘t know it was the 2nd rebuild, so maybe he didn‘t pay attention?

    But since the engine is installed I guess it would be easiest to regrind the camshaft, wouldn‘t it?
    Taking the engine out to shave a bit off the valve stems seems a bit like overkill.
    It being the 2nd rebuild should make no odds, it's something he should have done in the head machining process so him not paying attention would mean he's ****ed up and should rectify it.

    You can't just regrind a camshaft either, it's not that easy due to the fact they're hardened, so please forget that bodge

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    Guest Christian's Avatar
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    I agree with you saying the builder should fix it. This would be the normal, sensible procedure.

    But...
    1, The rebuild was done 3/4 years ago and I just didn't find the time/energy to put the engine back in the car until now.
    So the normal 6 months guarantee are gone by, it would be at least an argument with them, at worst I'd have to take legal advice.
    2, I'd have to take the engine out again which I'm not really prepared to do.
    I don't have a workshop at hand so it's always kind of hard finding a place and stressful to complete the job in time.

    I have read there are companys who reharden the camshafts after the grind.
    On the up side the 174000km camshafts would be resurfaced after this.
    Do you think this would really be that bad?

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    You need to get the valve measured for new shims that go on top of the valve, I reckon. Grinding the valves is the way to go when it's first being assembled, but once it's all together, changing the shims is way easier. Any competent engine builder should know how to do this.

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    Dorset & Hants Rep pointz's Avatar
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    Quote Originally Posted by Mike41288 View Post
    You need to get the valve measured for new shims that go on top of the valve, I reckon. Grinding the valves is the way to go when it's first being assembled, but once it's all together, changing the shims is way easier. Any competent engine builder should know how to do this.

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    This is a very good point.

    There are shims under the valve springs


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    The shims I'm talking about sit on top of the valves and are what the rocker arms push on. But if the washers aren't under the springs, I can imagine that'll make the situation worse

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  14. #14
    Dorset & Hants Rep pointz's Avatar
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    Quote Originally Posted by Mike41288 View Post
    The shims I'm talking about sit on top of the valves and are what the rocker arms push on. But if the washers aren't under the springs, I can imagine that'll make the situation worse

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    You thinking sr20?

    Ca has the shims under valve spring or am I confused lol

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    Yeah, I think you mean SR20.
    CA has got no rocker arms.

    Changing shims under the springs won‘t change the length of the valve stem, would it?
    Just change spring pressure.

    BTW thanks for all the inputs as this is more or less a terminal question, if I can get it to run again or not.

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    My bad, was replying from my phone which only shows the "s1" part so assumed wrongly

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    I didn't realise the engine was built so long ago. What engine are we talking about as I'm now confused.

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    Well it‘s a bit my own fault, but I took the engine to the builder last year and had so much to do at work that the engine got stored away for some time.
    Now I found time/energy to install it, and face these issues.
    At first I thought the lifters are faulty, but now after changing them and finding out about the clearance issue... I‘m a bit at a loss what to do.

    Engine out again is... pffff, well doable but I‘d have to buy yet another metal head gasket, invest all the labour...
    That‘s why I came up with the cam regrind idea.

  19. #19
    Dorset & Hants Rep pointz's Avatar
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    Quote Originally Posted by Christian View Post
    Well it‘s a bit my own fault, but I took the engine to the builder last year and had so much to do at work that the engine got stored away for some time.
    Now I found time/energy to install it, and face these issues.
    At first I thought the lifters are faulty, but now after changing them and finding out about the clearance issue... I‘m a bit at a loss what to do.

    Engine out again is... pffff, well doable but I‘d have to buy yet another metal head gasket, invest all the labour...
    That‘s why I came up with the cam regrind idea.
    Why would you have to buy a new gasket metal head gaskets are reusable

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    Guest Christian's Avatar
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    Really? I thought there is some rubber coating that gets ripped apart.

    At least thats what I remember the old HKS gasket to be like?? But thats long ago, so maybe memory is a bit off.

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