Holden 308 V8





Results 1 to 13 of 13

Thread: Holden 308 V8

  1. #1
    Join Date
    Feb 2017
    Location
    Pietermaritzburg
    Age
    48
    Posts
    60
    Thanked: 1

    Default Holden 308 V8

    Hi guys

    I have a Holden 308 V8 motor on my 72 El Camino. Motor runs well except that it smokes a bit from cold startup. Drive for 5 minutes and smoke is gone.

    I am certain it is the valve stem leaking. I have replaced the seals which are the little O ring type and no luck. There must be wear on the guides which would mean installing K Liners which I am not ready to do, Hoping I can get away with a quick and on budget repair. I have heard of people using the umbrella type seals instead on these motors. Some say the Ford seals but i am not sure which Ford motor.

    Can anyone shed some light on which seals I can use. The valve stem is 8.5mm, the guide boss 14.5mm and the inside diameter of the spring is 20.5.

    Would appreciate any advice.

    Thanks
    Kavesh

  2. #2
    Join Date
    Feb 2017
    Location
    Pietermaritzburg
    Age
    48
    Posts
    60
    Thanked: 1

    Default Re: Holden 308 V8

    I had a leakdown test performed on the motor. This test was done on a cold motor.

    There was a leakage of between 15-20% between on the 8 cylinders.

    On all 8 cylinders air hissed out the oil filler cap. There was no leakage at the carb or exhaust, with each test done with the cylinder at TDC.

    The guys that did the test said that he believes that it is the rings that are worn.

    I have been doing some research and it seems that if the valve stem/guide is worn air will escape at the oil cap.

    If its the rings one would hear the air hissing at the dipstick tube. Sadly he did not remove the dipstick during this test.

    Also there were no bubbles coming from the open radiator cap, so that suggests the head gasket is good.

    I also learnt through my research is that he did not put enough pressure into the plughole. He only used 10psi. How much would this affect the results to give an indication of where the problem is.

    I would really appreciate your advice guys.
    Thanks

  3. #3
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,887
    Thanked: 14240

    Default Re: Holden 308 V8

    Either worn/carboned rings or burned/carboned valves.

    Symptoms say rings.

    Valve stems won't have an effect on compression if the valves are seating properly.

    I suppose you only drive it short distances?

    When last did you do a nice long highway run?
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  4. #4
    Join Date
    Feb 2017
    Location
    Pietermaritzburg
    Age
    48
    Posts
    60
    Thanked: 1

    Default Re: Holden 308 V8

    Quote Originally Posted by jelo View Post
    Either worn/carboned rings or burned/carboned valves.

    Symptoms say rings.

    Valve stems won't have an effect on compression if the valves are seating properly.

    I suppose you only drive it short distances?

    When last did you do a nice long highway run?
    It really has not had a long drive.
    Before lockdown I would normally do a 30 to 40 km drive on a Sunday morning on the highway.
    Once the initial smoke clears up it would only give a puff of smoke when taking off from a stop.
    Previous compression test was all consistent and good readings. I am actually going to redo the compression test on a cold and then warm engine. Will do a wet test after the dry, just to see if there is any significant change in readings.
    I have also read that if the oil does not get black and dirty looking quick after an oil change that would also be good. My oil was changed last year sometime and still looks reasonably clean. Definitely not black.

    Just trying to figure out where to repair and not waste money on something that does not need to be fixed.

  5. #5
    Join Date
    Nov 2007
    Location
    Kathu
    Age
    59
    Posts
    9,373
    Thanked: 2900

    Default Re: Holden 308 V8

    Check your PVC valve. Known problem on the 308
    It is not what you buy its what you build.

  6. #6
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,887
    Thanked: 14240

    Default Re: Holden 308 V8

    How to test for oil rings:

    find a LONG downhill (any of the long downhills on the N3 will work), get up to a decent speed (100-120) and then let the engine run against compression with no foot on the throttle
    at the bottom of the hill, hit the throttle while watching the rear view mirror

    a cloud of smoke is almost certainly worn rings
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  7. #7
    Join Date
    Feb 2017
    Location
    Pietermaritzburg
    Age
    48
    Posts
    60
    Thanked: 1

    Default Re: Holden 308 V8

    Quote Originally Posted by grips View Post
    Check your PVC valve. Known problem on the 308
    PCV is new. However, its not plugged into vacuum as it was sucking oil in and making it smoke alot more.

    As a trade off I found valve covers with oil filler breather caps. Now I have 3 oil filler breather caps, with the third on the timing cover riser, which is the original position.

  8. #8
    Join Date
    Feb 2017
    Location
    Pietermaritzburg
    Age
    48
    Posts
    60
    Thanked: 1

    Default Re: Holden 308 V8

    Quote Originally Posted by jelo View Post
    How to test for oil rings:

    find a LONG downhill (any of the long downhills on the N3 will work), get up to a decent speed (100-120) and then let the engine run against compression with no foot on the throttle
    at the bottom of the hill, hit the throttle while watching the rear view mirror

    a cloud of smoke is almost certainly worn rings
    I will try this, I assume you want me to heavy foot it at the bottom of the hill?

    Btw all the plugs look in decent condition, light tan

  9. #9
    Join Date
    Nov 2007
    Location
    Kathu
    Age
    59
    Posts
    9,373
    Thanked: 2900

    Default Re: Holden 308 V8

    What oil do you run the 308 on ?

    Try Delo 400.
    Last edited by grips; 2020/06/24 at 01:28 PM.
    It is not what you buy its what you build.

  10. #10
    Join Date
    Feb 2017
    Location
    Pietermaritzburg
    Age
    48
    Posts
    60
    Thanked: 1

    Default Re: Holden 308 V8

    Quote Originally Posted by grips View Post
    What oil do you run the 308 on ?

    Try Delo 400.

    Shell Helix 25w60

  11. #11
    Join Date
    Nov 2007
    Location
    Kathu
    Age
    59
    Posts
    9,373
    Thanked: 2900

    Default Re: Holden 308 V8

    Delo 400 with its additives is about the only oil left to run in old v8 engines. We have three Yank v8`s in the family.
    Many km`s covered on them. All of them on Delo 400.

    Had the same problem with Helix on a v6 many moons ago. Changed oil brand and the smoke were gone.
    Last edited by grips; 2020/06/24 at 01:57 PM.
    It is not what you buy its what you build.

  12. #12
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,887
    Thanked: 14240

    Default Re: Holden 308 V8

    Quote Originally Posted by grips View Post
    What oil do you run the 308 on ?

    Try Delo 400.
    I agree. Dump the Helix.
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  13. The Following User Says Thank You to jelo For This Useful Post:


  14. #13
    Join Date
    Feb 2017
    Location
    Pietermaritzburg
    Age
    48
    Posts
    60
    Thanked: 1

    Default Re: Holden 308 V8

    Just an update on this

    I took her for a highway run up and down hills as mentioned above and did not get big puff of smoke at the bottom of hill when resumed heavy foot.

    I performed a cold compression test and had fairly close readings between all 8 cylinders, low of 100psi and a high of 115psi

    Then I performed a hot compression test and the results went up. Lowest reading was 118psi and a high of 125psi.

    On the warm engine I then did a wet test and the readings did not change, only 2 cylinders had a marginal drop in reading, about 5psi.

    What do you guys make of the compression test results.

    I am putting off changing the oil incase I am having to strip all or part of the engine

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •