Tech Stuff

Changing a camshaft in the GM LS engine

When servicing the camshaft on an LS engine, there’s no need to remove the intake manifold or top engine cover, but you will need to disassemble the front of the engine and remove the oil pan.
<p>When servicing the camshaft on an LS engine, there&rsquo;s no need to remove the intake manifold or top engine cover, but you will need to disassemble the front of the engine and remove the oil pan.</p>

Servicing a camshaft in any overhead-valve engine requires a degree of disassembly, but in the case of GM’s LS-series of engines, the task is a bit less tedious, since there is no need to remove the intake manifold, upper engine cover or lifters. Here we’ll explain the process.

1. Remove both valve covers.

2. Remove all rocker arms.

3. Remove the following components:

 • Water pump

 • Crankshaft pulley

 • Oil filter

 • Oil pan

 • Front engine cover (timing cover)

 • Oil pickup tube/screen assembly

 • Oil pump

 • Oil pump drive gear (slides off of the crank snout)

As this example of a bare LS block shows, there’s no access to the lifters at the top valley. The lifters are located in the upper deck areas of the block and are held captive by the cylinder head. When removing or installing a cam, there’s no need to remove the heads either.
<p>As this example of a bare LS block shows, there&rsquo;s no access to the lifters at the top valley. The lifters are located in the upper deck areas of the block and are held captive by the cylinder head. When removing or installing a cam, there&rsquo;s no need to remove the heads either.</p>

4. Rotate the crankshaft two full turns (360 degrees), and position the crank gear and cam sprocket dots (cam gear dot at 6-o’clock and crank gear dot at 12-o’clock). Once positioned, DO NOT rotate the crankshaft at any time during the process. (By rotating the crank two full turns, this causes the camshaft lobes to push the lifters up into the plastic lifter buckets. With no valve spring pressure, since the rockers have been removed, the lifters will “snug” into the lifter buckets, holding the lifters up and away from the camshaft, allowing a clear path for camshaft removal without the need to remove the lifters. Note that in order to remove the lifters, the cylinder heads must be removed. This feature (lifters secured in the buckets) avoids the need to remove the heads). There is no need to remove the intake manifold or the upper engine cover plate. There is no access to the lifters at the top valley, and there’s no need to remove the lifters anyway.

This view shows the timing setup (with pulley, water pump, front cover and oil pump removed). Depending on the version of the oil pump drive gear, this might incorporate the crank gear or it may be a separate gear.
<p>This view shows the timing setup (with pulley, water pump, front cover and oil pump removed). Depending on the version of the oil pump drive gear, this might incorporate the crank gear or it may be a separate gear.</p>

5. Remove the camshaft sprocket and timing chain.

6. Remove the camshaft retaining plate.

Post a comment
 

Comments (6)

 

Post a Comment

Submit
Subscribe Today

Subscribe to Auto Service Professional

Sign up for a FREE subscription to Auto Service Professional magazine

Subscribe