My lawn mower will not start, it has spark but 0 compression.

The timing chain has slipped a few link and is out of sync. This happens with a loose chain. Replace chain and re- align with the timing marks

Hi there:

Rocker Arms & Pushrods

Removal & Installation

3.1L & 3.4L Engines
Left Side

1. Before servicing the vehicle, refer to the precautions section.
2. Drain the cooling system to a level below the coolant pipe on the front of the engine.
3. Remove or disconnect the following:
   NOTEKeep the pushrods in order. Intake pushrods are 5 3 / 4 inches long and exhaust pushrods are 6 inches long.
   
   
   Negative battery cableSpark plug wiresHeater bypass pipePositive Crankcase Ventilation (PCV) valve and hoseRocker arm cover
   
   
   Rocker arms and pushrods
   

To install:

1. Lubricate all the valvetrain components with engine oil.
2. Install or connect the following:
   
   Pushrods and the rocker arms. Torque the bolts to 24 ft. lbs. (32 Nm).Rocker arm cover using a new gasket. Torque the rocker cover bolts to 89 inch lbs. (10 Nm).PCV valve and hoseHeater bypass pipe. Torque the screw at the water pump to 106 inch lbs. (12 Nm), the bolt at the cylinder head corner to 18 ft. lbs. (25 Nm) and the nut to 18 ft. lbs. (25 Nm).Spark plug wiresNegative battery cable
   
3. Refill the cooling system.
4. Start the vehicle and verify no leaks.

Right Side

1. Before servicing the vehicle, refer to the precautions section.
2. Remove or disconnect the following:
   NOTEKeep the pushrods in order. Intake pushrods are 5 3 / 4 inches long and exhaust pushrods are 6 inches long.
   
   
   Negative battery cableAlternator bracket on 2005 modelsSpark plug wires from the spark plugs and the upper intake plenum wire retainerPower brake booster vacuum pipe from the intake plenumAccessory drive beltAlternator, if necessaryIgnition coil assembly and Evaporative Emissions (EVAP) canister purge solenoid as an assemblyRocker arm cover
   
   
   Rocker arms and pushrods
   

To install:

1. Lubricate all the valvetrain components with engine oil.
2. Install or connect the following:
   
   Pushrods and the rocker arms. Torque the bolts to 24 ft. lbs. (32 Nm) plus an additional 30 degree turn.Rocker arm cover using a new gasket. Torque the rocker cover bolts to 89 inch lbs. (10 Nm).Ignition coil and EVAP solenoid assemblyAlternator, if removed. Torque the bolts to 37 ft. lbs. (50 Nm).Accessory drive beltPower brake booster vacuum pipe to the plenumSpark plug wiresNegative battery cable
   
3. Start the vehicle and verify no leaks.

Hope this helps.

A broken pushrod can indicate an engine with out of sync valve timing. It may be that a piston slapped an open valve snapping the pushrod...neither one is good, you may need to tear this one down.

The easiest way to install the pushrods is to bring the piston of one cylinder to top dead center on the compression stroke. This means the piston is at the top of its travel in one cylinder with BOTH lifters down in the tappet blocks. Use an ordinary plastic drinking straw, nothing else, to check the position of the piston with. The plastic drinking straw will not damage the piston nor break off and drop into the cylinder while checking the piston position.

Raise the rear wheel of the bike off the ground and secure it so that the bike will not fall over. Shift the transmission into high gear. Remove the spark plugs. Take the original pushrods out of the engine.

Begin by putting your finger over the front spark plug hole and turn the rear wheel slowly in it's normal direction of rotation until you feel compression blow your finger off the spark plug hole. Then, insert the drinking straw into the plug hole down to the piston. Continue turning the rear wheel while monitoring the movement of the piston. When the straw comes all the way to the top, stops, and starts to move back down ever so slightly, you are at or just barely past top dead center. Put the appropiate pushrod tube seals in the heads and the tappet blocks. Check to see if all four pushrods are the same length. If two of the pushrods are longer than the other two, the long ones are the exhaust pushrods. Assemble a pushrod and it's tube and insert it into either the intake or exhaust position. Turn the adjuster outwards making the pushrod longer until it seats in the rocker arm socket at the top and the tappet socket at the bottom and you can no longer turn the adjuster with your fingers. Take the appropiate size wrenches and lenghten the pushrod by three or four more full turns (18-24 flats). This is not critical as the tappets are hydraulic and have approximatelky 0.150" travel in them. Lock the locknut on the adjuster and then procede to install the other pushrod on that cylinder. DO NOT TURN THE ENGINE OVER UNTIL THE TAPPETS BLEED DOWN AND YOU CAN AGAIN TURN BOTH PUSHRODS WITH YOUR FINGERS. Once the tappets bleed down and you can spin the pushrods you just installed with your fingers, rotate the engine until the piston in the other cylinder is at top dead center on the compression stroke. Install the pushrods in that cylinder in the same manner as you did in the first cylinder. Refer to Page 17 of the PDF file that you can download at this site for instructions.
http://www.andrewsproducts.com/Downloads/andrews_motorcycle07.pdf

Good Luck
steve

or you getting the right fuel pressure? check fluid filter, check pressure regulator, check spark plugs to see if they are soaking wet if they or wet take them all out and pull fuel pump relay out turn engine over and blow all gas out the plug holes. install plugs and relay and try start again , check engine compression, check coolant senor ,check cam sensor

I think one of the intake valves, or a valve pushrod, is bent or warped. When the engine heats up, the metal expands and the valve starts sticking open. That would cause compression to be lost in one cylinder, reducing available power so things drag when you engage the blades. This would also causes air/fuel to be blown back through the intake. I think you'll need to take it to a small engine mechanic. Good luck! Please rate my solution if helpful, thanks.

exhaust valve and pushrod should be darker , pushrod due to heat , and the valve due to heat and carbon

I find my 2148 runs much happier on the medium grade shell than on the cheaper gas. I did have a nasty POW, which resulted in bent pushrods, or perhaps the bent pushrods caused the POW. After replacing the pushrods, and adjusting same, the backfiring stopped altogether. knock on wood. The 21 is a B&S engine which has a propensity to the bent pushrods. Fortunately for me, my neighbor is a wiz at those fine adjustments.

Intake is aluminum, exhaust is steel. Set valves 1/4" past top dead center on compression stroke (both valves closed), intake (bottom) .003-.005, exhaust .005-.007

try putting in 1/2 once of oil in #2and#5 turn engine over for 2 seconds then hook up the compression gauge and check compression if there is then the cylinders got wash out if compression doesnt come up you have broke the spring or bent the valve.