Tight engine

Greetings from a new user. The grandchildren gave me an older mower to fix. B&S 1 cyl vertical 17 hp. I have had it apart twice, actually had it running once and now it is back to the original problem after I installed a new intake valve (because of some spitting out the carb when running- the valve did have a defective seat ).

The engine turns fairly freely with the plug removed. With plug installed , it is tight on compression (maybe too tight ) but then gets equally tight about 1/2 way down on the power stroke. On the last assembly, the crank only turned freely, then the crank and cam turned freely, then the crank and cam and valves turned freely until the plug was installed. The started seems OK, but would not get over TDC

Another clue. The original problem was a broken intake push rod. Broken end never found.

Any help would be appreciated. David

Post engine numbers: model xxxxxx, type xxxx, trim xx, you need to find broken end of intake push rod, thanks.

IF the broken end of the push rod is not in the valve area then it is in the crankcase.

"On the last assembly, the crank only turned freely, then the crank and cam turned freely, then the crank and cam and valves turned freely until the plug was installed"

What are you dis-assembling assembling that you would not find the push rod and yet affects the crankshaft/camshaft turning? Doesn't figure. It is possible that the compression release is not working OR that you are not adjusting the valves properly. Also, check the height of the valve guides, they should not extend more than 1/8 inch above the head casting, intake guide may have slipped up causing the push rod to break.

I can send you a Service Manual for your engine at address below IF you like. Put address in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

Thanks.. The push rod was broken when I first got the engine so I don't know about valve adjustment.

I paid little attention to the compression release when investigating. All I saw was a little flipper at the valve cam which seemed to have a spring and moved freely. I do not sense any effect of compression release when turning the engine manually.

I am mostly concerned as to cause of hard turning in middle of compression downstroke - something major bent ? Incidentally the inside of the engine was clean with no obvious excessive wear.

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

IF the broken end of the push rod is not in the valve area then it is in the crankcase.

"On the last assembly, the crank only turned freely, then the crank and cam turned freely, then the crank and cam and valves turned freely until the plug was installed"

What are you dis-assembling assembling that you would not find the push rod and yet affects the crankshaft/camshaft turning? Doesn't figure. It is possible that the compression release is not working OR that you are not adjusting the valves properly. Also, check the height of the valve guides, they should not extend more than 1/8 inch above the head casting, intake guide may have slipped up causing the push rod to break.

I can send you a Service Manual for your engine at address below IF you like. Put address in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com[/QUOTE]

Thanks. I am just trying to lay out the whole story and looking for possible causes. I suspect something like a bent crankshaft but don't want to trash the engine if not necessary. I can turn the engine thru the full cycle by using my hand on the flywheel screen, but it is hard coming up on compression and again half way down on the compression stroke. There is no 'shove' from compression after TDC. There is a feel of snapping over center (somewhere) on the downstroke.

As said before, the engine ran fairly well before I removed the head and replaced the valve. l Hope someone has had a similar problem and got a good diagnosis ( if not a fix ).

You were asked back up the line to post the model number of the engine. To know what engine we are talking about we need this information. I am GUESSING it is a 31 series engine. Either you want help or you don't. I offered a Service Manual. I never heard of a 31 series engine with a bent crankshaft.

Walt Conner

Thanks. I do appreciate the help !! I am running in slow motion and wonder about giving up on this engine. The engine label is gone. The MTD label shows tractor model 13AD673g131 which leads to a manual which shows various B&S Series 28 engines. Hope thee is a photo attached I am thinking I can get adequate service manual info from the internet. Guess I am willing to do one more teardown if it sounds productive.

davidhorneys said:

Thanks. I do appreciate the help !! I am running in slow motion and wonder about giving up on this engine. The engine label is gone. The MTD label shows tractor model 13AD673g131 which leads to a manual which shows various B&S Series 28 engines. Hope thee is a photo attached I am thinking I can get adequate service manual info from the internet. Guess I am willing to do one more teardown if it sounds productive.

Click to expand...

Model number should be stamped into the valve cover. I can not send you a service Manual here, you have to use address above IF you want me to send one.

Walt Conner