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2023/07/01 17:00:42
just4fn

briggs and Stratton 17.5 intek has a snap when I turn engine

I found I have a flat cam in my Briggs and Stratton 17.5 intek engine.  I got an oem camshaft with lifters.  The new cam shaft has the slot for the oil pump which the old one did not.  I don't think that would make a difference but maybe you guys can let me know.  Anyways.  I got it all together and adjusted the valves on the bench. When I turn it over by hand the intake opens and when it shuts,  I get a snap in the engine.  If I take the oil sump back off,  it doesn't do it.  If I remove the push rod from the intake it doesn't do it.  What is going on do you think?  My experience with this engine is 0 out of 10. Maybe the counter balance is hitting the side because it's positioned standing up instead for laying down?  Thanks for the help!!!!!  I was just thinking,  maybe it's the pressure relief setup on the camshaft?  If so,  Why would I hear a snap?
18 comments Leave a comment
SRTsFZ6
W/O the slot in the cam, what was turning your oil pump?  
 
Did you set valve clearances with the side cover(sump) on?  
What gaps?
 
I'm not sure what a "snap" is in regards to and engine. Can you elaborate or better yet a You Tube video?
 
Your sure the cam is timed correctly to the crank, IE intake valve isn't hitting the piston?
You may try loosening that cam fully(case still assembled), and see if there's any difference..
 
.
2023/07/02 08:05:44
just4fn
thanks for all the suggestion and reply!  I am now 100% sure it is the pressure relief mechanism on the cam shaft.  I can go back and forth with the crank and can see it snap closed.  I have my intake at .004 and exhaust at .006.  The cam is lined up with the 2 dots with the crank.  I don't have an oil pump.  It just slings oil with the crank.  No oil filter. Is there a solution or do I just put it on the mower and hope for the best? Thanks!
 
How do I loosen the cam with the case assembled? 
2023/07/02 09:47:50
SRTsFZ6
Can you post your full model #? 
 
When I referred to loosening the valve, I meant to loosen the adjuster screw in the head so the valve wouldn't open.  
 
There should be a compression release on the cam, is that (circled below) what your referring to?
 
 
2023/07/02 20:35:17
just4fn
Yes, the compression release is what is making the snapping noise.  Is this normal?  It took about 6 months to get the oem cam.  I don't want to get another one just to test.  I may go with aftermarket just to test and see if it still makes the noise.  I've heard they are not very reliable. 
 
model  31c707-0154-E1
type-  00154E1
code  030514ZD
 
2023/07/02 20:40:24
SRTsFZ6
Tks for the model #.    Yep, you have a splash only oiling system (no pump).
 
For cranking or at rest, the weight is pulled in with springs(as you know) activating the compression release.
 
Once started, the weight swings out disabling the CR.
 
As for the "snap" noise, I can't hear mine. 
 
The aftermarket cams are reportedly, not so good.
I guess ok for testing. 
 
I suspect that noise your hearing is something else, possibly the loose/large balancer weight, etc.
 
Can the sound be heard if posted on say You Tube?
 
.
 
 
 
 
 
2023/07/03 07:40:55
just4fn
Maybe but I need 3 arms.  I will try.  Does this engine rotate clockwise or counter clockwise when running?  I assume it runs clockwise. I can see the mechanism snap when I turn it.  Thanks for the help!  
2023/07/03 20:58:41
SRTsFZ6
The engine turns clockwise looking at the flywheel /pull starter side.
 
How can you see the CR, it's buried inside the engine(when assembled)?
 
Are you talking about it making noise when not installed? Weight snapping back when in when pulled out by hand?
 
.
2023/07/04 08:23:42
just4fn
I have the engine out and the sump cover off.  It snaps when I turn the engine over by hand on the bench by tuning the flywheel.  I noticed it when I was adjusting the valves getting it to top dead center. I had it all together adjusting the valves and that's when I heard the snapping noise.  I said what is that noise?  I took the sump cover back off to investigate and that's when I can see the cr snapping and making the noise after the intake valve starts to close.  Maybe it wont make the noise when it's running and compression?  Right now I have the plug out so I can turn it. 
2023/07/04 10:26:14
just4fn
I think I am just going to put it together because there are no adjustments or anything that is wrong. I'll report back on how it runs.  Maybe do it this weekend if the gasket shows up.  Thanks for the help. 
2023/07/05 11:21:16
SRTsFZ6
Well it is spring loaded so I suspect that's what your hearing. 
I never paid any attention to it. Mine was good, just re-assembled like you are...
 
You won't hear it on start up.  
 
Also, make sure when you adjust the valves that one is open when adjusting the other.
You definitly don't want the CR activating when adjusting..
 
As I recall, Brigg's wants your piston about 1/2" past TDC on the compression stroke when adjusting valves..  Again, as long as one's closed, it'd be fine..
 
. 
2023/07/05 19:33:00
just4fn
According to the tech on Youtube.  You rotate the engine until the intake opens then bring the piston up to the top- with something in the spark plug hole and go 1/4 inch past tdc.  Fingers crossed. 
2023/07/05 21:40:44
SRTsFZ6
Any updates?
2023/07/08 19:21:16
just4fn
No updates yet unfortunately. I'm waiting on the sump gasket.  Nobody has one in stock. Should be here by the end of next week. 
2023/07/08 22:00:52
just4fn
Ok!  I finally got my gaskets.  I'm also changing the head gasket.  I'm about ready to pull my hair out.  My last step is putting on the sump pan.  It will not go on the last 1/4 inch.  I had it on before a couple of times.  It almost feels like the cam is not going into the hole of the sump pan.  I've tried for about an hour and getting tired of it.  What am I doing wrong?  I want to start this thing to see if my tick is gone but it wont let me.  I'm 99% sure it's not the pins but still could be because it drops over the pins but no further.  Thanks for the help!
 
video here:  https://www.youtube.com/shorts/ricJmT1rJCs
 
 
 
 
 
 
2023/07/21 19:54:24
just4fn
Ok,  I rested and waited until after dinner and 2nd try it went together.  WTF???  I will report back next Friday if it runs!
2023/07/22 00:37:44
just4fn
I got the engine installed and started it!  It seems to run perfect.  No more bogging down due to a flat cam.  I just need to adjust the low idle.  Can someone point me in the direction of the idle  screw? Thank you for all of the help!
2023/07/28 19:37:23
SRTsFZ6
You have throttle plate on the carb, closest to the engine and a choke plate, closest to the air filter.
 
There's a screw with a spring around it that touches the throttle "lever" atop the carb. 
Turn it in, clockwise, to raise the idle...
 
.
2023/07/28 20:56:59
just4fn
All done and ready to mow!  idle is adjusted, tire pressure checked, oil checked, washed.  Done
2023/07/31 16:36:03

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