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2002/3 ISL-400 repairs & mileage


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Any major repair issues from you fellow ISL 400 users?  94,000 miles so far and rear main performed at 78,000.  Looking to benchmark a budget.

annual PM performed - engine sees under 6000 miles/year since I’ve owned it.

best mileage is 7.4/glln (avg 6.7) per trip tech.  How about you?

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If an 04 counts.... I have done the high pressure fuel pump, doing the oil pan gasket, have redone the alternator, new water pump, and replaced a transmission line as it got a hole rubbed in it.  Other than that mostly basic maintenance.. It has been a solid unit with 125k on it. 

 

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Ours is an 04 Dynasty with the ISL 400. Just had an exhaust manifold replaced...do mostly my own work on it...no problems with it other than belts and idler pulley... 94K. mileage? Don't really care about it...in my opinion,  you either run with the big dogs or you sit on the porch 😉

Edited by ktloah
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Surprised to hear about the rear main.   When we sold our 03 Dynasty last year it had 160k+ if I recall... was talking to the mech about valve lash... don't know when that is due.  What I remember... watch fuel leaks, they can mess up wiring long-term... Don't let anyone who doesn't know what they're doing touch injector lines; that includes C.   Get a mech who looks you in the eye when he talks to you.  That's not ISL specific.  🙂

Enjoy, you seem to have a great coach.

I see you're in the ballpark with MPG.  🙂

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Since not all of us want to run with the big dogs I too am concerned.  I have an 07 400isl in my Diplomat.  Radiator, serpentine belt, hoses, exhaust leak, general maintenance. The house sucks but mechanically and drive train really reliable.  Hope that helps. 

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2008 ISL 400 new to me.  40K miles.  I do all my own maintenance.   Getting right at 7 mpg.  Funny tale,  The first time I topped it off to check mileage, I fueled it where it sits.  I fueled from my work truck slip tank.  What I didn't think about, was that the coach was listing to port ever so slightly.  I brimmed it, when I put 500 miles on it and filled it again at a truck stop, it only took 50 gal.    For a minute I was thinking WOW 10 MPG for a 40,000 tag axle rig?  But subsequent fill ups showed me the error of my ways.....

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10 hours ago, CapnDean said:

2008 ISL 400 new to me.  40K miles.  I do all my own maintenance.   Getting right at 7 mpg.  Funny tale,  The first time I topped it off to check mileage, I fueled it where it sits.  I fueled from my work truck slip tank.  What I didn't think about, was that the coach was listing to port ever so slightly.  I brimmed it, when I put 500 miles on it and filled it again at a truck stop, it only took 50 gal.    For a minute I was thinking WOW 10 MPG for a 40,000 tag axle rig?  But subsequent fill ups showed me the error of my ways.....

ISL-400 with 116,000 miles and the only thing we have done is replace the exhaust manifold gaskets and the tail pipe after the muffler. I was also surprised to see the rear main bearing replacement at only 70,000 miles. What is going on with that? The ISL is a 1,000,000 mile engine before requiring overhaul.

CapnDean, you can get the same mileage variation between fill ups at a Sam's Club versus a truck stop. We have found that using the automobile diesel pumps at Sam's Club lets us get a lot more fuel in the tank. I attribute this to the slower fuel flow that results in almost no foam in the tank.

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