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Hot!Intek 25 hp 44S9

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labans
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2019/08/31 12:16:01 (permalink)
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Intek 25 hp 44S9

I looked engine up on the Briggs site and came up with the number in this email title. The engine is clearly marked as a 25 hp Briggs Intek;
 
 
The problem:
New purchase; first time with any riding lawnmower---a newbie.
Engine says 384 hours.  Installed new plugs and battery and cranked it over.  Every other revolution it compresses through the carburetor. Compression checks at 150 per cylinder. With plugs out, cranking engine sounds quite normal. Put in right side plug and it compresses normally on one cylinder. Put left side plug in and it compresses quite loudly out of the carburetor as above.
I think on an automotive engine I would immediately suspect a burnt exhaust valve to be the culprit.  But reading up a little it seems that these engines might have a compression release so since I don’t know and do not have the factory engine service manual, I thought I would ask for some help before I open it up. 
Checking other items, the oil is clean and has no contamination, the plugs both show normal, equal carbon burn and there are no oil leaks.
I have to admit that I have not tried to start it because of the horrendous compression coming up from the carb every other stroke.
I would truly appreciate any help.
 

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    AVB
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    Re: Intek 25 hp 44S9 2019/08/31 12:54:09 (permalink)
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    First your compression readings are way too high for an engine with ACR on the camshaft. It should be closer to 70 psi. The side that sending compression though the carburetor sounds like it has dropped the exhaust valve push rod.
     
    Before going any further cranking pull both valve covers and check the valve clearances. I suspect you will find them quite opened up and maybe even a dropped or bent push rod. If the push rod is bent then one or more of the valve guide have moved causing bottoming out the rocker arm. If this is the case then new head(s) are needed.
     
    Valve clearances are as follows: IN /EX .004"-.006". Must be adjust either 1/4" pass TDC compression on each cylinder or individually. If the compression reading are still high then the ACR has failed which mean camshaft replacement.
    post edited by AVB - 2019/08/31 12:55:50
    labans
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    Re: Intek 25 hp 44S9 2019/08/31 13:27:14 (permalink)
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    Thank you so much for the focus. I will post the results once completed.
    labans
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    Re: Intek 25 hp 44S9 2019/08/31 14:02:26 (permalink)
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    Well you nailed it.  Removed left side valve cover and discovered NO push rod for the exhaust valve (???WTF???) and a bent pushrod for the intake. I presume the intake is the aluminum one. Of course I have no indications as to why this is the situation so I don't know if there is further damage.
    Can you share with me how to buy the correct push rods? I don't yet know how to run down the parts as the Briggs site is totally user-friendless!
     
    AVB
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    Re: Intek 25 hp 44S9 2019/08/31 18:25:22 (permalink)
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    On one of the valve covers should be engraved the model-type-factory codes along with the date code, If you post those I can look up the push rod part numbers. Also look inside the springs on the head with push rod bent to see the valve guides and compare them to the other head. You probably will find they have moved out which would explain the bent push rod. Also you need to find the missing push rod as it is inside the engine and hopefully didn't do any internal damage.
    post edited by AVB - 2019/08/31 19:18:01
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