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  1. #1
    Registered jbrauer's Avatar
    My Boats:
    2003 Spectre 36' Poker Run
    Join Date
    Sep 2001
    Nashville, TN

    Question Checking valve springs on HP500 - How?

    I understand that the valve springs on early HP500 carb motors have a tendency to break. My motors have about 200 hours on them. They run great, but I want to check the springs before the season gets rolling. I'm hoping someone on OSO can answer some questions.

    Do they need to be inspected now? Will a broken spring cause a major failer in the motor? Which springs are the ones that fail most often inner or outer? What's the best and easiest way to check them? Can it be done without removing the rockers and valve springs themselves?

    Lot's of questions - looking for a few good answers. Any help is appreciated!!!!

    Thanks, Jeff

  2. #2
    Registered formula31's Avatar
    My Boats:
    1988 Cruisers 2800 Rogue
    Join Date
    Mar 2001
    You need to get a hold of Scott.

  3. #3
    Charter Member #30 Charter Member Scott's Avatar
    My Boats:
    PQ 38 Avenger
    Join Date
    Oct 2000
    My motors are from early 1998. The serial # is OL000100 and 400. If you look them up on mercruiser parts you will find a * showing the spring part # has been changed. I am not sure when they started using the correct springs. Mercruiser will not admit they were wrong they will give you a story that is believable but totaly false. On the other hand Crane will tell you that they were a problem and thats why they now have a new design and part number.

    The Crane cam # for your motor is 169611 if you go to there web site and punch up the cam card you will find that the spring that is now recommended is part # 99896. The closed seat pressure is 132. My old springs were measured at 180+ pounds!!!!!

    I have two motors with junk valve tranes because of this. Last year I had a lifter explode and take out a cam and throw metal around my motor. Now I am rebuilding both from the block up (I want both motors to be the same) I should NOT be doing this at 160 hours.

    All of the info are facts gathered from the manafactures and my own findings. Have fun !!!

    Do some research and find out when your motors were built and what springs they used. If they are wrong the easy fix would be compressed air in the cylinder one at a time pull and change springs. Don't worry if they are broken or not . If they are the old style you should change them regardless. The closed seat pressure is way too high. Scott
    I have Steps & Bubbles!

  4. #4
    Charter Member #1055/Moderator Charter Member GO4BROKE's Avatar
    My Boats:
    Sonic 386
    Join Date
    Feb 2001
    I  Voted
    There are many checks for valve springs, installed height,seat pressure, open pressure, coil bind, cracks, etc.,etc., but the best way to check them if you are unsure of them is to inspect the way they look in the trash can, I'm sure they will look good there, then install new from Crane as Scott recommended. Cheap insurance!

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