Cummings Diesel

Is it a Itasca Horizon 40KD?

May have disc breaks, dual pane Windows, power cord real if it is.

All things being equal on he condition of the coach, go with the ISL400.

If still looking, and wanting to compare this coach with the ISL400 to another one. Try to determine which ISL400 is in the 04 model. It could be the older, and very mature, CAPS era ISL. Or, it could be then newer Common Rail with VGT ISL. The newer Common Rail would be a nicer engine to have, especially if it coms with an Exhaust Brake vs Jake Compression (The ISL vs the ISC, can be found with Jake Compression 2 Stage brake assist. While most of them come with a Exhaust Brake assist.)
The Common Rail and Variable Compression Turbo (VGT) has a more usable HP/Torque curve, and in many applications, you get added Braking HP via the Vanes closing up in the VGT providing more back pressure to help the Exhaust Brake. (I may not have described that accurately, but the VGT does provide a bit more Braking HP, as I understand it.)

And as always, coach layout and overall condition, usually trumps the specifics of the engine:)!

Best of luck to you,
Smitty

CAPS can be a pain in the tail. Pain. I can not tell you how many caps pumps I replaced while working for Cummins. But I had nightmares about them.

CAPS pumps are a pain in a truck chassis and a REAL pain in a DP

I have never met a DP owner who said he has too much HP. Get the extra HP and relax.

Go with the 400 hp version

I've read many various opinions on CAPS era engines. My conclusion was that many were damaged in the early years after the **** to ULSD from Diesel 2, due to lower lubrication. And while todays ULSD is advertised to meet all lubrication needs, and does for sure for engines designed to run on ULSD. My own opinion is that adding a lubricant additive, I use XPD, to each tank - is cheap insurance.

My second concussion, after talking to real nice veteran mechanic of diesels, is that CAPS do not handle fuel starvation well. The fuel both lubricates and cools the CAPS. A filter system that is partially clogged, can restrict adequate flow to the CAPS. Also at engine first start up, a failing or leaking lift pump, can also send a smaller supply of fuel then is needed by the CAPS.

Keeping filters clean (Sure right to do so on all engines!), either keeping the Lift Pump healthy/or/bypassing it and adding an aftermarket fuel pump (We have the FASS pump only, not the additive fuel filters, as I felt CC had good quality filters to start with.), and also adding a Lubrication additive to each tank - provides your best chance of keeping a CAPS up and running for a longer life.

And note my first post, suggesting that the non CAPS era ISL Common Rail with VGT was I felt a positive for a coach:)! So sure not arguing that CAPS era engines are not as easy to maintain as the CMR's.

Opinions vary, best to all,
Smitty

I do not see on your OP what year the coach is, but between 10/17/2005 and April/ 18/2006 their was a recall on ISL Cummins engines. Serial numbers range from 46543077 to 46603939 the connecting rod contains a machining defect in the wrist pin bushing of the rod that could cause seizure of the piston pin. This could lead to engine failure with the possibility of the rod rupturing the block.

Make sure you do not get stuck with one of these engines, because as I remember Cummins really did not tear the engine up to make sure the wrist pin was not defective, instead they just added a warning light that would tell you if the engine was about to blow up.

If the 400hp has the side radiator I would definitely go with it and pay the extra dollars

I have the ISL 370 HP in a 41 foot Dutch Star with four slides, usually at maximum weight, pulling a Jeep, and I go anywhere, on any grade with it, and get 8 mpg with it in good conditions. I may be heavier than the coach you are looking at with the 350. You could probably be fine with the 350. But, like others, why not go a bit larger unless information on mpg etc. is very negative on the 400.