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klcdenver · 01-04-2022, 06:03 PM

I have a 400ISL in a 2007 Monaco Diplomat. I want to install a circulating water heater. Need to now where the inlet and outlet's are located and which is inlet. I found one hose at the back of the engine (opposite of cooling fan) but don't know if inlet or outlet. A drawing or sketch would be great. Cannot find one and Cummins Quick Serve just says go to a shop. Lazy _______

Thanks,

Kenneth

Bruce Anthon · 01-04-2022, 11:11 PM

On my 2003 Alpine ISL 400 DP the return from the heater core is plumbed to the back of the engine. The outlet to the core comes off the front of the engine near the oil cooler / water pump area on the driver’s side.

ok-rver · 01-06-2022, 09:56 AM

we have a 2004 ISC, similar to the ISL. Side radiator so I have good access to engine. I have been looking at heater lines to try and get more heat from my dash air. I replaced my water pump recently. With the pump removed, I saw in the suction cavity behind the pump, below the alternator and above the radiator return are two ports/fittings with heater hoses, driver side on a pusher. one is connected thru the SCA filter. both go forward and cross over to the passenger frame rail. On the no. 6 cylinder end of the block, front because reverse mounted engine, are two 90 degree fittings with heater hoses that are routed to the passenger frame rail and toward the front of the MH. One is above the head gasket and one below. A couple of days ago, I started my engine and warmed up to 140 deg. I used a thermal gun and my hands to try and determine where the hoses went. two go all the way to the front of the MH. Two get lost in all the wiring above my rear air tank. I have not been able to come up with a need for the loop that disappears at the rear air tank. Temperature of the water at a manual steel heater valve at the heater core is only 105-110 deg.
The two fittings at the #6 cylinder end can be used for an engine mounted charge cooler. These have full water pressure from the circulation pump per a Cummins video but there is a bit of differential pressure across the head gasket. The two at the water pump suction will have less pressure and are probably the return. I have not checked the temp of the hoses at the block but that is in the works. The SCA filter did read about 120 deg so water is going thru it.
I changed my water pump to get the new style impeller which has better pressure/circulation and there did seem to be a little more warmth from the dash heater when I drove it to the shop a couple of days ago. One of the lines that runs to the front heater core has foam insulation on about 20 ft of length above my storage compartments. You would hope Holiday Rambler put the foam on the line going TO the heater core, I will be confirming that in the future.
I have been exchanging email with Webastco pumps to see if a circuit pump will handle engine coolant temperatures. I would like to increase the circulation to the heater core.
Hope this helps with your search.

klcdenver · 01-07-2022, 05:40 AM

Thanks ok-rver. I am going to mount one with y connections on the hoses coming of the back by #6 cylinder. My heater is super hot of front. The ducting to the feet is just poor. I run mine on floor and dash but angle the dash vents down and this helps. My heat is not very good until the engine temp coolant reaches the 186 degrees where the thermostat starts working. I have a newer engine and cannot find a SCA filter.
On my previous MH it was mounted on driver side of the block. Where is your SCA filter mounted.

Bruce Anthon · 01-07-2022, 06:38 AM

Cummins ISL engines 2004-5 and newer, do not have a water filter. SCA needs to be added manually.

ok-rver · 01-07-2022, 04:56 PM

Bruce listed a cut off year for Cummins not having a filter. my 2004 is mounted on the upper frame rail engine compartment on the driver side. It is about even with the top of the engine. Behind my air filter but visible.

mid-20s in Tulsa today. We leave for the Gulf Coast early next week and I finished a FASS pump install yesterday. Drove almost 200 miles today as a quick check out drive. With engine temp at 182 degrees and the new improved water pump, I was getting 100 deg air out my dash vent if on Max AC to close the damper. Barely warm enough. AC compessor is cycling on/off. If I go to the heat side thru dash vents, at max temp with the fresh air vent open, the duct temp drop to 80 deg. Looking at mechanically closing the fresh air vent until summer.

ok-rver · 01-09-2022, 02:17 PM

In above post, I talked about going to the heat side, I was talking about the selector switch on dash for AC and vent control. I did drill a small hole into the fresh air damper and with screw and washer, locked it in the closed position. Also found a couple of air ducts in dash that had slipped off. Hoping to keep my honey's feet a little warmer. getting to the Gulf Coast will help that a Bunch
My engine is an ISC. not sure if the SCA filter on these was deleted like the ISL