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Thread: MEP-803A Hard cold starting

  1. #21
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    Yes, there is a gasket on the side cover. Many times you can reuse it if it doesn't get damaged or just replace it. You can get an entire LPW4 gasket kit on ebay for under $70 or you will probably pay 1/2 that for just the side gasket from Onan.
    Here is a new relief valve. https://www.ebay.com/itm/Lister-Pett...EAAOSwvWBa80Dc

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  3. #22
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    Ray70
    Thanks so much for the info I finally got parts and replaced relief valve the old one was plugged full of sand or garbage. I just bought a new one for it and put it and fired right up. I took you advice and pulled the push rods out and 5 of them are bent. My questions is what is the best way to find tdc on pistons in tm it say don't install new push rods with pistons at tdc. Thannks again

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    I sit with bloodied knuckles from just trying to get the fuel water separator loosened on my unit. I'm thankful for the wealth of knowledge found here.
    O Lord, won't you buy me a diesel Humvee. My friends all drive Teslas, that won't work for me. Worked hard all my lifetime, no help from the DMV. So Lord, won't you buy me a diesel Humvee.

  5. #24
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    Quote Originally Posted by william54952 View Post
    Ray70
    Thanks so much for the info I finally got parts and replaced relief valve the old one was plugged full of sand or garbage. I just bought a new one for it and put it and fired right up. I took you advice and pulled the push rods out and 5 of them are bent. My questions is what is the best way to find tdc on pistons in tm it say don't install new push rods with pistons at tdc. Thannks again
    If you've already pulled the side cover and just look at the crank. Just turn the crank to the point where all four pistons are in the middle of their stroke.

    Either pistons 1 and 4 will be up and 2 and 3 will be down or vice-versa... Just make sure all the connecting rods are in the same position and you'll be in the middle of a stroke.

    I know all this sounds confusing if you're not an engine guy but I saw that no one has responded so I figured I'd say something.

    I have not had to crack open my 803 so there may be a easier way, possibly a timing mark on the crank pulley.

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    Yes, Joseph is correct you can simply turn the crank so that none of the rod journals are straight up.
    After you tighten the rocker arms back down, leave it for at least an hour before you crank the motor at all.
    The lifters need time to settle down do that your valves don't hit again. Think the TM says to leave "used" lifters for 15 mins. but I always go an hour or more.
    Did you straighten your old push rods or replace them? They get expensive to replace so I reverted to straightening them after replacing a few.

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    I found a place to buy them so I am planning on replacing all 8 of them.
    Is there another way to find tdc as I have put the cover back on the engine.
    Thanks

  10. #27
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    If you didn't already purchase, check Mayi diesel. They have good prices.
    Maybe check the timing cover to see if there is a notch on the pulley and a mark on the cover. If so, just make it so they a somewhat out of alignment.
    You could also pull an injector and stick a wire in the hole to feel the piston moving upward, or you could drop the pushrods in ( without the rockers in place ) and watch for them to move as you rotate the motor to determine where pistons are at, but to tell you the truth, the chances of you installing them with the motor exactly at TDC is slim to none. Even if it was at TDC you still shouldn't have a problem. You could install them and tighten the rocker arm nuts part way, until you feel contact with the valve tip and pushrod, go another 1/2 turn, then wait 15 mins. give another 1/2 turn, wait 15 mins more and tighten them down completely, then give another 15 mins or more before cranking it.
    Turn the motor 1 revolution and let sit another 15 mins.
    Even doing all that is probably being overly cautious and in excess of what the TM says, but should guarantee success regardless of piston position. I've installed plenty and never checked for TDC. You just don't want to dead crank or try to start it immediately after installing them, in case the lifters are still fully expanded.

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  12. #28
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    ok thanks
    I bought them already paid 13.00 each for them.

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