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I have a B&S 16.5 OHV MTD Yardman that will not turn over even though the starter and battery are OK. It will turn to a point and then stops. If I remove the spark plug it turns freely like it should. I know that removes the pressure in the cylinder but I don't know what could cause it to bind under pressure. Help!
Adjust the valves... and go on from there.
http://faqs.custhelp.com/cgi-bin/faq...ted=1101860144
The valves need adjusting. This happened to me yesterday. With the plug removed, the piston at top dead center, and both valves closed, set the gap for the intake valve at .004 in. and the exhaust valve at .006 in.
The engine has a built in compresion release that could be bad. Is there oil in the cylinder and could be causing a "hydraulic lock". Valve adjustment will be irrelevant because on the compression stroke both valves are closed and can not cause MORE compression the compression release holds the intake open a fraction to help crank, maybe adjusting is compensating for a failure .
Check and see if fluid comes out when cranking, clean it out and try again.
Perhaps there is another problem, but I had the exact symptoms. I replaced the battery, checked all wiring, and even took apart the starter and cleaned the brush contacts. When the plug was pulled, the motor would turn over fine. With the plug installed, the starter acted as if it didn't have enough power to turn the motor over. It would get to the compression stroke and bog down. My parts store owner suggested adjusting the valves as I stated in my earlier post. When I checked my valve gap, both valves were gapped around .008 in. I adjusted them to 4 and 6 and my problem was resolved. Perhaps with the gaps too wide, the valves were closing early causing more compression. I can't explain it, but I know it worked for me.
Duh, I guess if the clearence is to wide the compression release would not work.. . I have to say though I have seen A lot of these units and have never experienced an incorrect valve setting creating so much compression it won't crank. I have had manual start engines with incorrect settings kick back on the compression stroke.
Is it possible that when you removed the plug and cranked it, fluid was discharged?
Total waste of time BUT I bet if your clearences were set back to where they were.. . It would crank.
Just because I have not experienced it doesn't mean it can't happen. But pretty damn close.:D
Oh Yea, I have had cams that were broke not allowing any valve travel and the engine still cranked.
Bought a briggs 16 horse I/C ohv engine maybe 2 years ago on a ayp (sears)... lmao, came with the valves mis adjusted and caught on the compression stroke almost every time... could have fixed it myself... sure... but took it back, acted dumb and got a 18.5 intek powered one that had just went on sale that day... for a couple hundred more... :P which was a much better engine...
It happens... valves go out of adjustment just a couple degrees and it will catch.. usually the first thing I recommend when they do catch like that... believe briggs recommends like every year or every other year they are checked and adjusted...
Is it recommended to use a threadlock after adjusting the valves and if so what type is recommended?Quote:
Originally Posted by rsb1122
Wouldn't recommend it unless they keep loosening in a short period.Quote:
Originally Posted by Zormo
This exact problem came to my shop and I spent a lot of time troubleshooting the electrical system and it has nothing to do with it. I cranked up the valve adjustment to .003 on both valves. Spec says .003-.005 on both valves. This might bandaid an older engine with lower compression, but you can't get enuff adjustment with a fairly new engine. Check your oil and if it looks or smells bad it's the compression release mechanism that is built onto the camshaft that failed. Big job just to get at the camshaft so the cheapest way out is if it won't start turn the flywheel over by hand to get past the compression stroke then start it.
Briggs only had a short period of engines with a problem where the compression release was failing. Your problem is probably valve adjustment related.
Can you please give me some idea when this short period was? Or what model/serial#s are affected? Or point me to where I can find out?Quote:
Originally Posted by MOWERMAN2468
Thanks
I have a Murray with a 16.5 hp briggs that I had a problem with it turning over.. In reading the forum I got my answer about adjusting the valves.. I set intake at .004 and exhaust at .006 and it solved the problem. I had replaced the batt. And removed and disassembled the starter and found no problem there.I found as long as it was hot outside in the summer it would start but the first cool morning the nightmare came back. Thanks to all that took the time to enter info about the briggs 16.5 hp and remember adjust your valves every year.. Easy to do!
On b&s 16.5 ohv when you push throttle up fast it gets too much fuel and black smoke comes out muffler and acts like choke on if you ease throttle up it will run OK
Try checking your air filter and or where the air is coming in to the filter.This engine uses a lot of air under load.Try running it with out the filter ONLY FOR A FEW PASSES to see if it helps.. Replace filter if it does.
[QUOTE=deerecrouse;1363555]I have a Murray with a 16.5 hp briggs that I had a problem with it turning over.. In reading the forum I got my answer about adjusting the valves.. I set intake at .004 and exhaust at .006 and it solved the problem. I had replaced the batt. And removed and disassembled the starter and found no problem there.I found as long as it was hot outside in the summer it would start but the first cool morning the nightmare came back. Thanks to all that took the time to enter info about the briggs 16.5 hp and remember adjust your valves every year.. Easy to do
I just wanted to add that a earlier post of my Murray 16.5 hard to start problem. I had the same problem again in early spring and I adjusted the valves again but had the same slow cranking problem. I drained the oil and replaced with a 10w30 oil instead of the 30 wt I had used for years and it worked great.. I think with this high compression engine this lighter oil helped. I have never had a manual with this mower but maybe I had been using the wrong weight all along.. thanks and I hope this helps others because I have been helped by this site..
I have done these adjustments but still does not start!
it the cpmpression release on the cam shaft . Here is the fix . Remove flywheel fan cover on top of engine . Next unplug spark plug wire from plug remove ohv cover on front of engine have a rag ready to soak up any oil that drips out . Rotate engine till you see the the rockers open close determine witch is fuel air and exhaust at this point rotate engine till you see the rockers open and close when the exhaust opens and closes the next thing you'll see is the intake fuel air valve open and close at this point stop right their now your coming in to the compression stroke of the engine ( cam has a compression release built into the cam for the purpose of making easier for the starter to start engine ) other wise it'll burn up the starter slowly bring the piston to tdc ( top dead center on the compression stroke ) using a wooden cooking spoon slide it slowly into the spark plug hole till it bottoms out on the piston rotate engine slowly till the spoon moves up/or out of the spark plug hole when you think your close to tdc rotate it back n forth till you find tdc . Make a mark on the wooden spoon razor works best thin line take spoon out use tape maesure making 1 more line 1/4 of a inch above that frist line stick spoon back inn piston start to travel the piston down till the 1/4 inch line above the frist 1 make sure where you used to make the frist mark is the same place the 2 nd mark is lined up with . Looking at the rockers on the front of the engine you'll see two nuts inside those nuts are a adjustment screw torks heads in most cases losen it turning counterclock wise same on the other rocker . Using a fueler gauge .003to.005 for the intake /.004to.007 for the exhuast . Slide the fueler gauge between the valve stem cap and rocker with the large nut turn it till tightens down on the fueler gauge it just move with lite reissaince now tightin the tork screw in the center of that bolt repeat that on the other valve that is the correct valve last setting on a briggs stratton compression release cam type engine should start right up after that after putting back ohv cover n flywheel fan plug n wire use lock tight on ovh can bolt clean out threads frist before using lock tight that's it have a good 1
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