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When I shut off the engine ( 17.5 Hp Troy Bilt mower) it of course spins a bit until it comes to a compression stroke then stops. Go to try to start again and it will not go through that compression stroke acting as if the battery was low or starter is weak. If I spin the engine back a bit so that it has a running start coming to the compression stroke it will get passed it and start. New battery and starter. Any ideas?

I would start with checking and adjusting the valve clearance, and if that doesn't fix the issue then most likely would need further checking to determine if the ACR on the camshaft is broken.

gary8241 said:

New battery

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New battery means nothing. Needs to be load tested. Auto parts stores check for free.

gary8241 said:

New battery and starter.

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Save the old starter. Could be good. Take a jump pack and see if the starter spins over.

Agree check valve lash as ILENGINE said.

Number one problem is the valve lash adjustment.

Go to a You Tube site called Teryl fixes all. He is a bit of a clown but has all the info you need about how to adjust the valves.

The next problem could be more serious and the compression relief mechanism is broken or stuck on the camshaft. This would take professional repair knowledge to correct.

Did this get fixed and slaying some grass? OP ghosted us.

slomo said:

Did this get fixed and slaying some grass? OP ghosted us.

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Thaks for the response. Yes, I have no problem there. On advice gained on this site I have adjusted the valves but the problem persists. I guess it is the compression release on the cam. When I start the tractor have been rotating the engine counterclockwise a ways and that allows it to get enough momentum to start.

Hi Gary 8241,

From your description, the compression release mechanism made onto the camshaft has given up. What is worse about the situation is that aftermarket cams and even new Briggs cams are unreliable.

gary8241 said:

Thaks for the response. Yes, I have no problem there. On advice gained on this site I have adjusted the valves but the problem persists. I guess it is the compression release on the cam. When I start the tractor have been rotating the engine counterclockwise a ways and that allows it to get enough momentum to start.

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Before saying 100% for sure the compression release is the issue, I would strongly suggest the following be done:
1) charge and load test battery
2) clean all wire terminals and check for excessive voltage drop
3) check or recheck valves for proper clearance
4) check starter for proper operation
5) pull valve cover and rotate engine and watch for very subtle bump in valves, indicating that the compression release is in tact and working.

Rarely is it the compression release mechanism on camshaft that breaks.