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Briggs-Fan
Briggs-Fan, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1198
Experience:  over 15 years experience in small engine repair, multiple certifications
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I have a &S 18HP Intek OHV engine on an older Craftsman

Customer Question

I have a B&S 18HP Intek OHV engine on an older Craftsman LT1000 riding mower, that stalls frequently after running the engine for four or five minutes. A friend says he thinks it might need rings, but I'm wondering what troubleshooting / diagnostic steps I might take to be sure before I commit my time to doing a rebuild?
Submitted: 3 months ago.
Category: Small Engine
Expert:  Briggs-Fan replied 3 months ago.

Hi my name is ***** ***** welcome to Just Answer. There's a few things that could cause this , it could be a loss of compression, loss of spark , loss of fuel as well . Does it start right back up ? . Have you tried removing the gas cap to make sure it's not a faulty cap that isn't ventilating correctly ?

Customer: replied 3 months ago.
It starts again, but not immediately. 20 - 30 seconds, and then it starts fine, but will only run for a couple of minutes before it stalls again. It's definitely not a spark problem, and it seems to be getting fuel just fine...I bought a new fuel cap a few weeks ago. Sometimes (but not always) when I restart it there will be some blue smoke, like oil is getting into the combustion chamber. As I understand it, these engines have three fairly common issues as they get older: leaking head gasket, leaking valve seal, and worn rings. I don't see any oil spatter that would indicate a leaking head gasket, so I'm thinking it's more likely a bad valve seal or I need new rings, but I'm not really sure how to confirm that it's one or the other. I suppose it might even be both? Looking for the best way to nail down the problem.
Customer: replied 3 months ago.
I'm certainly open to investigating other possibilities...anything that narrows it down to the right solution.
Expert:  Briggs-Fan replied 3 months ago.
If you could get a compression tester you can test the compression before starting it and right after it dies , being a higher hp engine it should have 100 to 120 psi compression . If it has that starating but has 60 after it dies then you know your losing compression
Customer: replied 3 months ago.
I'll try that this coming weekend...I think one of my friends has a compression tester. Will follow up with you afterward.
Expert:  Briggs-Fan replied 3 months ago.
Sounds great , I look forward to hearing from you
Expert:  Briggs-Fan replied 3 months ago.

Hi just wondering if you had a chance to test the compression

Customer: replied 3 months ago.
Checked compression over the weekend. 120 psi cold, ran until stall and then checked again and found 110 psi, so it doesn't really seem like enough compression loss to point to worn rings, does it? Maybe a bad valve seal, or something else? What would you suggest for next steps?
Expert:  Briggs-Fan replied 3 months ago.

It could be a valve issue , it's only losing 10 psi, could even need a valve adjustment

Expert:  Briggs-Fan replied 3 months ago.

A leak down test will show where your losing compression