275ISBs in Diesel Pushers

My 340 hp isb is great. The weight to power ratio is good. You are in 3rd gear going up hills out west but you can not hear the 2700 +/- rpms as it is in the back. Only a little over 32k miles so far.

I have a 2000 kountry star with 93000 miles. not a rocket ship but gets great mpg. mine had a 53 block which was replace by cummins under warranty. Have had no other issues with the engine,replaced my lift pump as a precaution.I am waiting for the vp44 to quit someday but until then all is good. more power would be nice but I will take the fuel economy .

VP44s fail almost always from low lift pump pressure.

The lift pump fails and then the diaphragm has to work harder to pull fuel, thus damaging the diaphragm pump. The reduced fuel flow though the VP44 then causes all the other problems.... increased temp, mechanical wear, and electrical failure.

The best upgrade to any VP44 ISB is any form of lift pump failure detection. I have a gauge with idiot light/ buzzer on the filter output, so that any reduction in pressure/flow will be obvious.

As for the 275, it's not a rocket, but is more than adequate and gets great mpg to boot.

Les

Passin Thru wrote:
Bosch fuel pumps are notoriusly unreliable. Chevy used them in their V8 Diesel which was a gas engine block, (Duramax is made by Isuzu) and they might last 50 K mi.

The Chev/GM 6.2L v8 series had a Stanadyne DB2 pump, similar to the old Roosa Master. They were good pumps, I got 110k, 120k out of the two I changed out. Considering they were less than $500 for a rebuild, I thought them a deal. Completely mechanical pump.

VP44 pumps had mechanical failures of rotor design tolerance imperfections, diaphragm faliures, lift pump caused low pressure, and some electrical issues, heat being an issue causing failure of the electronics. Sort of similar to a DB4 Stanadyne used in GM's. Different beast.

I had my Bosch replaced - with another rebuilt Bosch - I believe that was the only option, I guess 'once a Bosch always a Bosch". Cummins was very direct in explaining the problems with this part. REbuilt was around $1200, + labor. My coach is an '02.

Did they ever change from the Bosch fuel pumps??
How can one determine if the flock is the #53 block. Were there certain numbers for the engine or years that was listed as build date for those blocks?

A couple of sources indicated cracked manifolds at around the 100,000 mile mark. Any one past that mileage, in their truck or MH? Thanks

The biggest problem with most 275 hp 5.9's were the dreaded #53 block that was cast in Brazil and had a problem with cracking. A very expensive problem.

Bosch fuel pumps are notoriusly unreliable. Chevy used them in their V8 Diesel which was a gas engine block, (Duramax is made by Isuzu) and they might last 50 K mi.

I had a 2000 Discovery with the 275 version. In 2001 FW offered a 300 in the discovery. If the manifold is broken you will hear it. If you're not sure get it inspected! The ISB is known for great fuel economy. No problems in 50k miles in 2 1/2 years.

Dave

I have the 5.9 ISB 300 hp. I am a fulltimer, the engine is adequate - not the fastest up the hill, but decent 10mpg - that's a good tradeoff, IMO. I did have to replace the fuel pump, it is the Bosch (sp) vp44 - if I remember right. It is prone to problems, from what I was told by Cummins. BTW, I have over 95k miles on my ISB.