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post #1 of 18 (permalink) Old 05-22-2020, 09:45 AM Thread Starter
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no vacuum on fuel side of engine - Craftsman rider

Model # is 247.288811.

I get nothing when trying to start. Have spark & fuel. Pressure at plug is 40 psi. I get nothing with starter fluid. Not even a pop.

Checked vacuum after removing intake manifold and there is NOTHING. Tested with the palm of my hand when cranking starter. I mean there is nothing. I had to check it myself after my son said there was nothing last night and I saw 40 psi at the spark plug hole this morning. No vacuum! Intake manifold removed for test.

Something must be up with the intake valve. Our next step is to take the motor apart.

Has anybody seen some psi at the plug and no vacuum at the intake? If so, what was wrong?

Thanks.
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post #2 of 18 (permalink) Old 05-22-2020, 03:53 PM
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Is this an "Overhead Valve" Engine?
Which Manufacturer?
Engine Model Number?
You may have a "Stuck" Intake Valve, Dislodged Valve Seat, Worn Camshaft, or be in DESPERATE NEED OF A VALVE ADJUSTMENT( OHV)...
Could you respond with a picture of the Model Number and Manufacturer Tag/Label please.
-This will help "us" help you.

Take care,
-Thomas (12)
Port Orchard, Washington
(Just West of Seattle)

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post #3 of 18 (permalink) Old 05-23-2020, 07:43 AM Thread Starter
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It is a Briggs & Stratton, OHV. Tag attached.
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post #4 of 18 (permalink) Old 05-23-2020, 07:51 AM Thread Starter
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Quote:
Originally Posted by skagentk View Post
...You may have a "Stuck" Intake Valve, Dislodged Valve Seat, Worn Camshaft, or be in DESPERATE NEED OF A VALVE ADJUSTMENT( OHV)...
Yeah, suspected something like that. We're going in.
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post #5 of 18 (permalink) Old 05-23-2020, 05:25 PM
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Quote:
Originally Posted by Joe Kuhn View Post
Yeah, suspected something like that. We're going in.
thereis no "going in", just pull the valve cover off and set the clearances. to do this remove spark plug and rotate engine by hand until one valve opens (pushes the valve all the way in) and then you set the other valve, then rotate until that valve opens and set the other valve. when one valve is pushed all the way in you know the other is in the correct position to set the gap

set the intake (aluminum push rod) is set to 0.004 and set the exhaust (steel push rod) is set to 0.006

then everything will be working fine again.



things to watch for:

make sure the valve stems still have the little caps on them behind the rocker arms

make sure the bolt for the adjuster hasnt backed out of the head

make sure both valves and valve springs sit at the same level when not being compressed, if one seems shorter then look close to be sure the valve guide hasnt backed out of the head and if thats ok, then pull the head to see if the valve seat has come loose from the head
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post #6 of 18 (permalink) Old 05-23-2020, 10:33 PM Thread Starter
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Both rocker arms were completely loose with the one on the bottom pointing down as shown in the picture when we took the valve cover off. The exhaust push rod (top) moves some when we turn the engine with the spark plug out. The intake push rod is bent and does not move at all.

Drained the engine oil and it doesn't have any metal in it.

I'll need to clear some bench space for this one.
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post #7 of 18 (permalink) Old 05-24-2020, 05:15 AM
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Is the intake valve stuck. I have a Vanguard that both intake valves stuck and bent the push rods. I got the valves freed up with PB Blaster, replaced the intake push rods and ran it with a healthy dose of Seafoam in the gas. That was a few years ago and it's still running. It would be an easy thing to check before you do any more disassembly. I don't see how a valve seat would bend the rod, don't know about the guide. If you need a head there should be plenty around with all the blown Inteks.
Cannon
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post #8 of 18 (permalink) Old 05-24-2020, 10:33 AM
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Quote:
Originally Posted by Joe Kuhn View Post
Both rocker arms were completely loose with the one on the bottom pointing down as shown in the picture when we took the valve cover off. The exhaust push rod (top) moves some when we turn the engine with the spark plug out. The intake push rod is bent and does not move at all.

Drained the engine oil and it doesn't have any metal in it.

I'll need to clear some bench space for this one.
no no no, you still dont need to open the engine. all this is repairable from inside the valve cover. why are you so ready to pull and take apart the engine?

what about the cap on the valve stem? was it still there? you cant set the rocker directly on the end of the valve stem, it needs that tiny cap on it, so make sure of that.

the bent push rod needs replacing, obviously, but it sits in a small divot in there so its most likely slipped out of it. as you replace the push rod you can feel when it goes into the seat and then the rod will move as you turn the engine again.

this is great news for you and a pretty easy fix
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Last edited by keakar; 05-24-2020 at 10:39 AM.
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post #9 of 18 (permalink) Old 05-24-2020, 11:41 AM Thread Starter
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no no no, you still dont need to open the engine. all this is repairable from inside the valve cover. why are you so ready to pull and take apart the engine?

what about the cap on the valve stem? was it still there? you cant set the rocker directly on the end of the valve stem, it needs that tiny cap on it, so make sure of that.

the bent push rod needs replacing, obviously, but it sits in a small divot in there so its most likely slipped out of it. as you replace the push rod you can feel when it goes into the seat and then the rod will move as you turn the engine again. You can see it behind the rocker arms in my first picture. You can also see one of the caps in the lower left. Hah!

this is great news for you and a pretty easy fix
We're ready to pull the engine and tear it down because the intake valve push rod doesn't move at all. We'll straighten it and see if it will move with a turn of the system. Will replace it in the end, but I'd like proof that this rod will move. Thanks for your explanation. We're NOT taking this engine off the mower because of your insightful help. Thanks!

Looked further for the caps and found them sitting at the bottom in some oil. Here they are with the aluminum push rod that's bent and a piece of plastic from the push rod 'guide'. Might replace that black guide as well. You can see it in my last picture above, behind the rocker arms. You can also see the one cap sitting in oil and full of oil on the lower left. Didn't look far enough.

Thanks again for the help!
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Last edited by Joe Kuhn; 05-24-2020 at 12:00 PM.
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post #10 of 18 (permalink) Old 05-24-2020, 03:07 PM
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We're ready to pull the engine and tear it down because the intake valve push rod doesn't move at all. We'll straighten it and see if it will move with a turn of the system. Will replace it in the end, but I'd like proof that this rod will move. Thanks for your explanation. We're NOT taking this engine off the mower because of your insightful help. Thanks!

Looked further for the caps and found them sitting at the bottom in some oil. Here they are with the aluminum push rod that's bent and a piece of plastic from the push rod 'guide'. Might replace that black guide as well. You can see it in my last picture above, behind the rocker arms. You can also see the one cap sitting in oil and full of oil on the lower left. Didn't look far enough.

Thanks again for the help!
the push rod is a 2 part system, it has tappets that ride on the came lobes and a short shaft that sticks through the engine block so from the valve cover opening shine a light in there and you will see the little divot for the push rod to sit in.

for now, just to confirm everything is working, you can use the good push rod and hold it in place and then turn the engine flywheel by hand to see it move.

its "nearly" unheard off for a cam lobe going out unless you never change the oil. this is what the exploded view of the push rod setup looks like.
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File Type: gif push rod.gif (5.6 KB, 1 views)
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Last edited by keakar; 05-24-2020 at 03:16 PM.
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