Bottom Line
Maintenance Q&A
High heat and starter stress

Paul Abelson
Senior Technical Editor

Question: I have a 2004 Mack Vision with the 460 hp motor. This is my first Bulldog. I have less than 100,000 miles. I just threw my second fan belt, one of those long ones. The dealer who sold me the replacement told me to have the tensioner replaced too. It was under warranty, so that’s not the problem, but why is all this happening so soon?

Answer: This is a very timely question. At the recent annual meeting of the Technology and Maintenance Council, the cab and controls study group had a technical session on underhood temperatures. One of the first slides was of a serpentine belt with most of its v-grooves worn away, or more accurately, broken off. 

Above 230 degrees, many polymers and rubbers start to dry and deteriorate. The new 2002 emission engines generate tremendous heat. For example, power steering fluid that used to be about 150 degrees in the reservoir has been measured above 250 degrees. Old style greases cook out or leak past seals that have broken down from heat. Both your problems are due to excessive underhood heat.

Here are a few suggestions that came out of the TMC meeting for those operating the new emissions-controlled engines:

  • Make sure your engine compartment can handle high temperatures – use high temperature fluids, greases and seals; 
  • Check with your engine and truck builder for the latest technical bulletins about temperature problems; 
  • Make sure debris or bugs don’t restrict air flowing through the radiator; charge air cooler and oil coolers; 
  • Consider adding louvers or vents to allow underhood air to escape. Be careful where you place them. If they’re in a high- pressure area, near the windshield or external air cleaners for example, they could force air back in and restrict flow instead of helping it.

Question: I have a 2003 Peterbilt. The Delco starter on the ISX Cummins broke after about 110,000 miles. This is much quicker than the Series 60 starters on my last truck. Why? What can I do?

Answer: According to the cranking curves supplied by Delco, the ISX is harder to crank than your old Series 60, especially in cold weather. This past winter made the situation worse. 

Delco’s 39MT starter came on many Petes. The 42MT is a heavier duty starter. You could upgrade. It has solved starter life problems for several fleets I know of. But the problem may not be in the starter. The electrical system can contribute to poor cranking performance and eventual starter burnout.

Anything that reduces the current to the starter makes the motor work harder. Check starter wiring and your batteries. Batteries should always be checked under a load. Just checking voltage across the terminals tells almost nothing about cranking power.

Once you have determined that your battery has sufficient power, check the cables from the battery to the starter. Make sure that they are large enough and that the insulation hasn’t been compromised by rubbing or chaffing. That could allow corrosion inside the cables. That increases resistance and cuts available power.

Check terminal ends and grounds for tightness and corrosion. Make sure terminals are firmly attached to the wire, not the insulation. If there is looseness, tighten. If there is corrosion, clean with a paste of water and baking soda, then flush and dry. If you’re buying a rebuilt starter, consider a factory remanufactured one unless you are familiar with and confident in the rebuilder. Remanufactured units are more consistently reliable and durable than rebuilt models.

Maintenance questions?
You can write to Paul Abelson, senior technical editor, in care of Land Line Magazine, PO Box 1000, 1 NW OOIDA Drive, Grain Valley, MO 64029; or you can fax questions to (630) 983-7678; or e-mail them to Please mark your message Attention Maintenance Q&A. Although we won’t be able to publish an answer to all questions in Land Line, we will answer as many as possible.