General Boards > Technical Support
Cummins lift pump leaking
Joel Ashley:
Here's a tidbit about lubricity from Wikipedia:
Sulfur is not a lubricant in of itself, but it can combine with the nickel content in many metal alloys to form a low melting point eutectic alloy that can increase lubricity. The process used to reduce the sulfur also reduces the fuel's lubricating properties. Lubricity is a measure of the fuel's ability to lubricate and protect the various parts of the engine's fuel injection system from wear. The processing required to reduce sulfur to 15 ppm also removes naturally-occurring lubricity agents in diesel fuel. To manage this change ASTM International (formerly the American Society for Testing and Materials) adopted the lubricity specification defined in ASTM D975 for all diesel fuels and this standard went into effect January 1, 2005.[8]
The refining process that removes the sulfur also reduces the aromatic content and density of the fuel, resulting in a minor decrease in the energy content, by about 1%. This decrease in energy content may result in slightly reduced peak power and fuel economy.
The transition to ULSD is not without substantial costs. The US Government has estimated that pump prices for diesel fuel will increase between $.05 and $.25 per gallon as a result of the transition. And, according to the American Petroleum Institute, the domestic refining industry has invested over $8 Billion to comply with the new regulations.
ULSD will run in any engine designed for the ASTM D-975 diesel fuels.
It is, however, known to cause some seals to shrink (Source: Chevron paper) and may cause fuel pump failures in Volkswagen TDI engines used in pre-2009 models. TDI engines from 2009 and on are designed to use ULSD exclusively; biodiesel blends are reported to prevent that failure (Source: HRCCC.org Biodiesel Best Management Practices).
Additives added make up for any lost lubricity. However, apparently some seal shrinkage unrelated to lubricity can occur, which may be the Cummins pump situation.
Jack Whitmill:
We have a Cummins 350 and had a SLIGHT diesel leak under the lift pump about a year and 9,000 miles ago. Difficult but got in there and tightened every bolt I could find on the lift pump. No more leak. Coach has run both LSD & ULSD in our travels (70,000 miles). We know of an '02 Patriot, '03 Monterrey, and 3 '04 Monterreys that have Cummins so they have been putting them in for a while. Probably depends on what is available. In some years and models you could get either Cummins or CAT as an option.
Richard And Babs Ames:
Cummins was an option one year I know of in the Patriot the Cat C9 was standard and the Cummins was a $4000 plus option. Do not know how many were built.
David Rudisill:
--- Quote from: Bill Sprague ---After we owned our Beaver for awhile I was shocked to learn it was supposed to have a Cat! We have a Cummins and the lift pump seal did develop a leak after running about 3,000 gallows of old diesel followed by about 2,000 gallons of ULSD. We were in the Maritimes of eastern Canada. Went to the nearest truck shop with a Cummins sign. Cummins would not honor the warrantly unless the shop replaced the whole assembly. The shop thought that changing the seal would fix it. Cummins sent the new assembly, including pump and mounting bracket. It was in a difficult location and took the shop about 5 hours to get the old one out and the new one it. Cummins paid the entire bill. I suspect Cummins wanted it back as a unit to analize the failure. I'm pretty sure that most of it is history. ULSD has been all you can get for long enough that any seals scheduled to fail would have by now.
Does anybody know why 2004 Montereys didn't get a CAT? What other years and models were deprived of their heritage?
--- End quote ---
The early '04 Montereys like yours and mine had Cummins. They switched to Cat later in the model year.
The leaking lift pump was replaced in ours under the Cummins warranty a couple years ago.
George Harwell:
Have heard rumors about the lift pump leaking due to the ultra low sulfur diesel for several months but did not really pay much attention as there was no dripping on the ground. My neighbor has an 03 Country Coach and found it was leaking so I slid under and discovered the bad news also. The pump is located above the starter on my ISC 350 and not easily accessable so I removed the starter to make things easier. We managed to change the Country Coach ISC 370 without removing the starter but it wasn't easy. Takes 2 people to get this done. One in the bedroom to remove the 3 bolts and the other holding the pump underneath. We also changed the gasket on a neighbors 04 Travel Supreme and it was the most difficult of all. My neighbor and I have retired after doing 3 coaches unless I have a change of heart. This problem appears to be confined to 04 coaches down with the cummins engine but newer units should be checked.I got my gasket at Cummins in Orlando but you should be able to find it at any Cummins shop.
Gasket part number: 4928511 $6.41
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