I have trouble with my lawnmower engine turning over just to the compression stroke,somebody said that it might be mcr,or machanical compression release... I have to take out comshaft.how thanks james

Hi,
If this is an OHV Intek, then there are a bunch of improperly heat-treated camshafts out there. Most failed earlier, but you may want to contact you dealer, or Briggs. Abunch had the intake lobe wear prematurely and they may do something for you. Never be afraid to contact manufacturers with complaints as they will not seek you out but will listen!
If further info needed, post and I will walk you through it, ad infnitum.
Peace.
Clarke

crigby thanks for answering my problem, I had a lot of advice on what to do but still not satisfied... here it is I have a 17hp b&s ohv # 313777 type 0135-e1,code 011030ze.. it will not go past the comp. stroke. With out the spark plug OK,turns over fast.got new battery,new solenoid.had starter tested by shop,they said its OK.need some instructions on how to remove the camshaft with out doing any damage. Is the compression release sys. On the drive gear,and how does it hold or push the valve up. I set the valves at intake .004 and the ext at .006. Still the same... checked the valve movement on the intake,seems OK,if you need more please let me know,I talked to a very good source about it. Thanks davie1973

Hi,
Okay, sounds like a bad cam. ACR is a spring loaded piece just inboard of the gear. I have seen the spring break and do what you describe, but I have seen and improperly heat-treated intake lobe more often. An easy check is to take off the valve cover and manually turn the engine over in a clockwise direction(plug removed) and watch the movement of the rocker arms. If the intake arm moves just slightly compared to the movement of the exhaust arm. Then it is the heat-treating. Either way if requires a replacement.
First remove the deck belt and engine sheave retaing bolt(probably 5/8".) You can be draining the oil at the same time as you do the early steps. Disconnect starter wire, othe electical connectors and fuel hose. Lock the park brake to remove tension from the motion drive belt. Remove the engine mount bolts(probably 4) and the front ones likely hold the belt guide(s) plate. You should be able to ease the motion belt off the upper sheave and ease the sheave off. Lift the engine up and off(I usually remove the hood and use the frame as my "workbench") and invert it. Oh, turn the engine over to TDC on compression stroke before inverting. Remove the bolts that secure the sump.
By the way you will want to have a 692226 gasket, a 790340 cam and two qts. of 30W oil before starting. Do not get surprised if part numbers change.
No tap the sump loose so that it can be lifted up and off(taking care not to allow the keyway on the crank to touch the seal - it will cut it.) Then you should be looking at the cam gear and crank. If you got the engine at TDC, you should see the marks on the gears aligning with each other and a bit of a wiggle of the cam and its should lift up and out. The remove the tappet(the cam should come with new ones) abd replace them. Insert new cam with marks aligned(should be a tooth with a dot on crank and a space marked between two teeth on the cam.) Clean gasket surfaces on sump and block and lay the new gasket in place. There are two alignment pins pressed in place on the block to hold it in place.
Ease the sump the crank(again being mindful of the seal and keyway - there should be plenty of room as the crank step down in size on the outside of most of the engine.) Put the screws back in that hold on the sump and torque to 165 in.lb.
Now flip the engine back over and into place(there are usually places in the paint that will tip you off - wear patterns.) Put in the two rear bolts to hold the engine in place and snug them. Next slip on the engine sheave, snug the sheave bolt and get the motion belt into its sheave. Release the park brake to tension the belt and put the guide plate and and bolts back in the front of the engine(should be marked in the paint as to which holes are correct - usually two or three choices on each side.) Tighten all bolts. Add oil to full mark(about 1 and 1/2 qts.)
Adjust valves to a snug 0.005" and turn engine over by hand to inspect proper opening and closing. Recheck clearances at least once, I do about three times. If one or both does not move, the push rod is not in the tappet. Correct and adjust as necessary.
Put deck belt back in lower engine sheave. Connect fuel hose and electrical connectors. Put in plug and connect wire. Should be ready to fire up!
Hope that helps.
Peace,
Clarke