Tech Tip #75: Overcoming Cam Problems in GM 4.3 V6 Vortec Industrial Engine

Dr. Diesel
Written by Dr. Diesel

How to get around a few troublesome issues

This Tech Tip discusses a weakness in GM 4.3 V6 Vortec industrial engine camshafts and related components under certain conditions and recommends a retrofit kit.

The GM 4.3 V6 Vortec industrial engine is a rugged engine that has been used in a variety of applications. See Foley Tech Tip #43 for tips on how to identify which GM 4.3 V6 you are working on. This is important if you wish to order the correct overhaul parts or to exchange it for a new or reman engine. (Note: pricing on new 4.3 V6’s is so low that rebuilding a GM 4.3 V6 industrial is often not cost effective.)

We have noticed problems with the roller camshafts on the GM 4.3 V6 Vortec industrial engine if the GM V6 is used in a low RPM, constant speed application. This includes applications such as constant speed 1800 RPM generators, oil well pumping units, or in an application such as a forklift or wood chipper where the engine idles for long periods of time at very low RPMs. Under low RPM conditions, the roller cam in the GM 4.3 V6 Vortec doesn’t get enough lubrication from the oiling system and soon fails. The solution for this problem is to swap out the roller cam for the older style, flat tappet camshaft and related components.

Foley Engines markets a complete kit to do this. This kit includes a reground flat tappet camshaft with the base circle reduced by .060, new flat tappets, new push rods, and a brass bushing to replace the front cam bearing. The kit installs easily. The new bushing presses in using the cam retaining plate as a guide and the rest of the parts install quickly.

When you install the new cam, we strongly suggest that you use camshaft assembly lubricant (molybdenum disulfide) and petroleum-based oil, not synthetic, for the initial break in of the cam and lifters. See our Tech Tip #25, Break In Lubricant, Not Synthetic for more information on break in oils. At the first oil change, change the oil filter to remove any residual cam assembly lubricant which can easily clog an oil filter. Then switch to a high quality synthetic oil. If the engine is not in regular use such as in a standby generator application, we recommend a 50/50 mix of synthetic and petroleum based oil to avoid dry starts. See our Tech Tip #1, Blend the Oil for a discussion of the benefits of petroleum based oil in preventing dry starts.

Dr. Diesel
Written by Dr. Diesel
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