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Can valve float cause low compression?

Discussion in 'HYBRID -> EG-EK / DC' started by Teambypass, Mar 1, 2004.

  1. Teambypass

    Teambypass Senior Member

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    I have a jdm 98 GSR B18c. 1st and 2nd piston both have 130 when I do the compression test. 3th and 4th both have 120. I used to shift at 8500K a few times. Could a valve float cause low compression? I check head gasket and its good. NO oil leaks, no bad smokes. Any idea. thanks
     
  2. UDT

    UDT Senior Member

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    Well it seems to me there could be some bleed of if something got bent a little. But i dont know how likely that is. Why the compression test all of a sudden? Did you have some losss of power or some thing that led up to the compression test? I would try and get a leak down test done to.
     
  3. MikeBergy

    MikeBergy Blah blah blah....

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    If you floated a valve, the only way it would make a difference on a compression test would be if you floated the valves, and they in turn were bent up because the piston ran into them. Have your valve seats and piston rings replaced if there is nothing wrong with your valves. Those are the only important sources for compression loss. Good luck. A valve job is like 250, providing your head is off, and new rings and honing the block will be another 350 or so.
     
  4. E_SolSi

    E_SolSi Member of the 20 nut club Moderator VIP

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    valves ONLY float at high RPMs (basicly the cam is spinning too fast for the spring to be able to hold the valve against it... so the valve loses contact with the cam, ie: floats)

    now when a valve floats, bad shit can happen like bent/broken valves, damaged pistons, entire engine blown to shit, etc..... sometimes nothing at all happens

    your compression numbers really dont look bad
    maybe clean up/replace the valve seals :shrug:
     
  5. whiteLS

    whiteLS Senior Member

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    if your valves float and hit the piston then your probley gonna bend a valve.

    try a leakdown test if you hear air out the intake then bad intake valves. and etc..
    for air out the exhaust
     
  6. UDT

    UDT Senior Member

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    :werd: thats why i ask what led up to this test.
     
  7. xj0hnx

    xj0hnx I wanna be sedated VIP

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    If they were say 130 in one and two, and say 50 in the other two, then you'd have problems, but those are close enough together that you're probably ok.
     
  8. Teambypass

    Teambypass Senior Member

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    Thanks guys. I appreciate the info. a valve job here is $200 and I will take the head off. What lead to the compression test is that I had a loud noise comming from the mid low section end of the motor. at first, I thought I might have a tranny problem, but shifting between gears are flawless and smooth with no griding. So, I firgure out its not the tranny. and after the noise problem, my car would slow down when driving, like no fuel comming through the injectors. I replace the prelude injectors and put RC 310 on, the noise went away. now I am running very rich. I dont know what do you guys call this noise, but when you run very rich, the fuel that remain unburn poping through the exhaust and make this ugly sound. putting the RC 310 fixed the injectors problem but Im running rich now and its better than running lean. I guess if I bend some valves, I would have to replace them. Anyway, HOW DO YOU DO A LEAK DOWN TEST??? I HAVE THE HAYEN MANUAL BOOK AND WILL CHECK ON THAT BUT IN THE MEAN TIME, IT WOULD BE NICE FOR SOME TO TELL ME HOW. THANKS
     
  9. Teambypass

    Teambypass Senior Member

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    one more question. If in fact, I have some bend valves or bend pistons and since I already have the skunk2 camshafts, prings, retainers, I think it would be easier to just replace the pistons while I have the head off. what do you guys recommend for pistons, I read about Toda pistons on their site and they have the same wall and piston clearance as the stock OEM and their pitons ratio was like 11 something with stock head gasket. I also check JE pistons and their ratio was like 12 something. I could afford the pistons but what is the cost of labor? would both of this brand of pistons have the proper clearance or do I have to do something else to make sure that the pistons are not gonna hit the valves? thanks

    This is not related to this post, but do you guys know a member from this site by the name 1HOTCRX? he have a brand new skunk2 camshafts, springs, retainers, cam gears for sale and I will drive 20 hrs to pick them up for my brother civic on spring break. do you guys know if he is legit? the reason I want to pick them up myself is because I want to see the items myself and I need a break from overload course as well. hit me back.
     
  10. xj0hnx

    xj0hnx I wanna be sedated VIP

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    If you can drive to him, call it a road trip and mke a few days of it. Better safe than sorry. worth it to not gte ripped for a G+.
     
  11. Teambypass

    Teambypass Senior Member

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    I definately drive to him if the items are new as he stated. I saw the pics and they seem to be in plastic bags so I assume they are new. I will have to wait for his answers.
     
  12. MikeBergy

    MikeBergy Blah blah blah....

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    Buy A leakdown tester, or build one yourself, that is what I did. They go for a bout 60-80 bucks in the catalogs, I made mine for about 20, and it didn't require welding, pretty basic. You'll need an air compressor capable of holding 100+ psi. Screw the tester into the first cylinder you want to test, set the piston at tdc, and make sure the piston is at tdc, or else it will move when you turn on the air. Turn on the air, and if it is holding 95-100 psi, at least I think those are the numbers, you should be okay. It's been a while since I did the test. Do this for all the cylinders. If you get those readings for all the cylinders, you should be good. My cylinders were only hold like 60 psi or less, so no car for me right now. BTW, this test will only tell you you have compression leaks, not where. And to correct E_SolSi, you would replace valve seats to restore compression. You replace valve seals if you are burning oil. Seals have nothing to do with compression. Reading up on some of E's posts, I'm figuring it was prolly just a typo. Hope this helps
     
  13. Teambypass

    Teambypass Senior Member

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    Thanks for all the helps. Some of you think that those numbers are not that bad for compression test since they are very closed together and I think maybe you guys probably right. What concern me is that, when I did the compression test, my cousin also checked his B16a t3/t4 turbo charge. He got cd thick head gasket with block guard and his compression still read 150 to 160. Since my car is all motor, the number should be higher than that. I will do the leak down test and see what happen.
     
  14. dohch22a4

    dohch22a4 Senior Member

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    Wow... I must have awesome compression if those numbers are that fucking low. I have the same motor and I read 240 on cylinders 1, 3 and 4, and 239 on number 2.
     
  15. Teambypass

    Teambypass Senior Member

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    Those numbers are exactly my concern. For this motor the nominal compression is 270 and minimal is 135 with variation of 15%. these mumbers are too low for an all-motor. that's why i asked you guys for help and suggestions.
     
  16. dohch22a4

    dohch22a4 Senior Member

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    You may have partially blown rings for some reason. Either that or all of your valves are pretty bent up.
     
  17. Teambypass

    Teambypass Senior Member

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    thanks Dohch22, and please check my other post for pistons but I will ask here too. since I already have everything that I need except valves, and I will take off the head and pay for a valve job I think I might as well upgrade my pistons, any recommandation for pistons??? keep in mind, I dont dont know how to clay and do the pistons to wall or valve clearance. any after market pistons that can be drop in without problem of pistons hitting the valves??? I want high compression, as high as it could get without pistons hitting valves. thanks
     
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