Exhaust and Intake Pushrods, on G.M. 3.1 and 3.4 engines are different lengths.
Quite often I am seeing, bent pushrods and valves, when they are mixed up.
Consequently, Exhaust pushrods on G.M. 3.1 and 3.4 engines, are longer than their intake counterparts.
As a result, it’s critical to reinstall, the correct length pushrods, in the correct place.
The most common reason to remove the them, is to repair leaky intake manifold gaskets.
Consequently, this is the most common problem on these engines. Some have blamed the problem on, GM’s Dex-Cool antifreeze. But, the real problem, has been the intake manifold gaskets, on many engines. The original equipment gaskets, have a plastic carrier and soft sealing beads, around the coolant and intake ports. Over time, the plastic carrier and seals soften and deform, causing the gasket to lose its seal.
As a result, coolant then starts to leak, down into the lifter valley and crankcase. Eventually, the loss of coolant, causes the engine to overheat, which may cause additional damage. Eventually, leading to a cracked cylinder head or crushed head gasket. The leakage problem, can occur in as little as 60,000 miles on some engines. So, the higher the mileage, the more likely the intake manifold gaskets, are going to leak coolant.
Coolant leakage can be diagnosed, by checking the oil dipstick or by pressure testing the cooling system.
SO, IF THE OIL LOOKS MILKY OR FOAMY, IT PROBABLY HAS COOLANT IN IT !!
If an internal coolant leak is indicated; the fix is to pull the intake manifold and replace, both intake manifold gaskets. Several aftermarket gaskets, offer design and material improvements over the (OEM) gasket. As a result, providing a longer lasting trouble-free seal.
I also recommend using a pushrod removal tool. As, stripped rocker bolts, are common, while doing this repair.
The removal tool is for, the newer 3.5L and 3.6L GM engines. But, also works on GM V6 2.8L, 3.1L and 3.4L.
It helps you quickly remove pushrods, so you can replace the intake gasket. So, there is no need to loosen and retighten the rocker arm. The tool pivots the rocker arm, to compress the valve spring and free the pushrod for removal.
The Exhaust and Intake Pushrod on G.M. 3.1 and 3.4 engines are different lengths.
- The intake valve pushrod measure 144 mm (5.75 in) long.
- Exhaust valve pushrod measure 152.5 mm (6.0 in) long.
So, how do you commit to memory which pushrod goes where?
It’s easy if you remember this short phrase… “It’s been a long, exhausting day.”